Patent Application
20230360948
The present disclosure relates to printing components from a source wafer to a destination substrate with improved alignment accuracy using a transfer element, such as a stamp.
Substrates with electronically active components distributed over the extent of the substrate may be used in a variety of electronic systems, for example, in flat-panel display devices such as flat-panel liquid crystal or organic light emitting diode (OLED) displays, in imaging sensors, and in flat-panel solar cells. The electronically active components are typically either assembled on the substrate, for example using individually packaged surface-mount integrated-circuit devices and pick-and-place tools, or by depositing (e.g., sputtering or spin coating) a layer of semiconductor material on the substrate and then photolithographically processing the semiconductor material to form thin-film circuits on the substrate. Individually packaged integrated-circuit devices typically have smaller transistors with higher performance than thin-film circuits but the packages are larger than can be desired for highly integrated systems.
Other methods for transferring active components from one substrate to another are described in U.S. Pat. No. 7,943,491. In an example of these approaches, small integrated circuits are formed on a native semiconductor source wafer. The small unpackaged integrated circuits, or chiplets, are released from the native source wafer by etching a layer formed beneath the circuits. A viscoelastic stamp is pressed against the native source wafer and the process side of the chiplets is adhered to individual stamp posts. The chiplets on the stamp are then pressed against a destination substrate or backplane with the stamp and adhered to the destination substrate. In another example, U.S. Pat. No. 8,722,458 entitled Optical Systems Fabricated by Printing-Based Assembly teaches transferring light-emitting, light-sensing, or light-collecting semiconductor elements from a wafer substrate to a destination substrate or backplane. In certain applications, it can be important for transferred components to be located precisely and accurately on a destination substrate or backplane. When components are accurately located, they can be positioned closer together to form denser and smaller systems with improved performance. In particular, printed devices can be more accurately positioned with each other or with respect to photolithographically defined wires. For example, accurately positioned opto-electronic devices experience fewer conversion or connection losses. There is a need, therefore, for methods, devices, and structures to enable precise and accurate printing of components.
The present disclosure provides, inter alia, structures, materials, and methods that enable precise and accurate printing (e.g., micro-transfer printing) of components from a native source wafer to a non-native target substrate in alignment with structures disposed on the target substrate.
According to some embodiments of the present disclosure, a method of making a printed structure (e.g., a micro-transfer printed structure) comprises providing a target substrate and a structure protruding from a surface of the target substrate, providing a transfer element and a component adhered to the transfer element (e.g., wherein the component comprises a component substrate that is separate and independent from the target substrate), moving the transfer element with the adhered component vertically toward the surface of the target substrate and horizontally towards the structure at least until the component physically contacts the structure or is adhered to the surface of the target substrate, and separating the transfer element from the component. The transfer element can be a viscoelastic stamp. Thus, in embodiments the component is non-native to the target substrate. In some embodiments, the structure is formed on and native to the target substrate. In some embodiments, the structure is non-native to the target substrate, for example transferred to the target substrate from a structure source wafer.
Some methods of the present disclosure comprise moving the transfer element toward the target substrate after the component physically contacts the structure or is adhered to the surface of the target substrate and before the transfer element is separated from the component in order to press the component toward the target substrate. Some methods of the present disclosure comprise moving the transfer element toward the target substrate after the transfer element is separated from the component to press the component toward the target substrate.
According to some embodiments, the component physically contacts the structure while the component is above and not in contact with the surface of the target substrate. According to some embodiments, the component physically contacts the structure while the component is in contact with the surface of the target substrate. Some methods of the present disclosure comprise moving the transfer element vertically away from the target substrate and horizontally toward the structure after the component physically contacts the structure.
According to some embodiments of the present disclosure, a printed structure (e.g., a micro-transfer-printed structure) comprises a target substrate and one or more structures protruding from a surface of the target substrate and a component in alignment with at least one of the structures. The component can comprise a component substrate separate and independent from the target substrate. According to some embodiments, the component is disposed on the surface of the target substrate within one micron (e.g., within 1.0 micron, within 0.75 microns, within 0.5 microns, within 0.25 microns, or within 0.1 microns) of a structure. In some embodiments, the component is disposed on the surface of the target substrate within five microns (e.g., within two microns) of a structure. The component can comprise a broken or separated tether. The component can be in contact with a structure. A structure can comprise a broken or separated tether.
The component can be disposed on the surface of the target substrate laterally adjacent to the structure. The structure can have a structure edge and the component can be disposed adjacent to the structure edge and within a micron of all of the edge (e.g., within a micron of the bottom of the structure and structure edge adjacent to the target substrate or within a micron of the top of the structure and the structure edge on a side of the structure opposite the target substrate. In embodiments, the component is not disposed on the structure, for example not on a top side of the structure opposite the target substrate.
According to some embodiments of the present disclosure, the component and the structure are aligned optical elements. For example, the structure comprises a waveguide, such as a light pipe, light conductor, or fiber optic element. The component, the structure, or both the component and the structure can comprise one or more of a laser, an optical amplifier, an optical modulator, a light-emitting diode, a light sensor such as a photosensor (e.g., photodiode), and an optical fiber. According to embodiments of the present disclosure, the printed structure is a photonic system, a photonic integrated structure, or a silicon photonic structure. The target substrate can be a silicon substrate comprising integrated circuitry that is electrically connected to the component.
According to some embodiments of the present disclosure, the component has a length or a width or a length and a width less than or equal to 200 microns, less than or equal to 100 microns, less than or equal to 50 microns, less than or equal to 20 microns, less than or equal to 10 microns, less than or equal to 5 microns, less than or equal to 3 microns, less than or equal to 2 microns, or less than or equal to one micron.
In some configurations of the present disclosure, (i) the structure has a flat face adjacent to the component, (ii) the component has a substantially flat face adjacent to the structure, or (iii) both (i) and (ii). According to some embodiments, the structure has a non-planar face adjacent to the component and the component has a non-planar face complementary to the non-planar face of the structure. In some embodiments, at least a portion of the non-planar face of the structure is in contact with the non-planar face of the component.
According to some embodiments of the present disclosure, an adhesive is disposed on the surface of the target substrate. The adhesive can adhere the component to the target substrate. The adhesive can be disposed at least partially between the structure and the component.
According to some embodiments of the present disclosure, the structure, the component, or both the structure and the component are operable to receive or emit light. For example, both the structure and the component can comprise a light pipe and the light pipe in the structure can be in alignment with the light pipe in the component. In some embodiments, the structure comprises a light pipe and the component comprises a light emitter or light sensor in alignment with the light pipe in the structure. In some embodiments, the component comprises a light pipe and the structure comprises a light emitter or light sensor in alignment with the light pipe in the component.
According to some embodiments of the present disclosure, the component is disposed and operable to emit light to or receive light from the substrate, the structure is disposed and operable to emit light to or receive light from the substrate, or the component is disposed and operable to emit light to or receive light from the structure.
According to some embodiments of the present disclosure, the printed structure comprises a controller disposed on the surface of the substrate. The controller can be electrically connected to the component and operable to control operation of the component or the controller can be electrically connected to the structure and operable to control operation of the structure, or both.
According to some embodiments of the present disclosure, the printed structure comprises an encapsulation layer disposed at least partly over one or more of the component, the structure, and any gap between the component and the structure. The encapsulation layer can comprise or can be coated with a patterned or unpatterned light-reflective layer.
According to some embodiments, the component has a thickness equal to or greater than a thickness of the structure. The component can comprise a component material, the target substrate can comprise a substrate material, and the component material can be substantially different from the substrate material.
According to some embodiments of the present disclosure, the printed structure comprises a reflective material disposed (i) between the component and the target substrate, (ii) between the structure and the target substrate, or (iii) both (i) and (ii).
The component can be a first component and the printed structure can comprise a second component disposed on the surface of the target substrate within one micron (e.g., within 1.0 micron, within 0.75 microns, within 0.5 microns, within 0.25 microns, or within 0.1 microns) of the first component and the second component comprises a broken or separated tether.
The structure can comprise two or more structure faces, the component can comprise two or more component faces, and the component can be disposed on the surface of the target substrate so that at least one structure face is within one micron (e.g., within 1.0 micron, within 0.75 microns, within 0.5 microns, within 0.25 microns, or within 0.1 microns) of a component face.
The structure can comprise or have a structure face and the component can comprise or have a component face opposed or adjacent to the structure face. The structure face can comprise an indentation and the component face comprises a protrusion complementary to the indentation, for example complementary in shape, in size, or in both shape and size. The structure face can comprise a protrusion and the component face can comprise an indentation complementary to the protrusion, for example complementary in shape, in size, or in both shape and size. A protrusion can fit into an indentation, for example when complementary in shape, in size, or in both shape and size.
According to some embodiments, the component comprises connection posts. The connection posts can be sharp, can comprise a sharp point or can have a distal end with a smaller area than a base area. The connection posts can be electrically conductive and can electrically connect to an electrically active circuit or structure in the component.
According to some embodiments of the present disclosure, a printed structure comprises a target substrate and structures extending from a surface of the target substrate. The structures can be spatially separated independent structures. A component can be disposed on the surface in alignment with the structures. The component can be non-native to the target substrate (e.g., the component comprises a component substrate separate and independent from the target substrate). The component can be micro-transfer printed from a component source wafer to the surface of the target substrate and can, in consequence, comprise a broken (e.g., fractured) or separated tether.
The component can be disposed on the surface of the target substrate within one micron (e.g., within 1.0 micron, within 0.75 microns, within 0.5 microns, within 0.25 microns, or within 0.1 microns) of at least one of the structures, of two or more of the structures, or of all of the structures.
A cavity can be disposed (e.g., formed by etching) within the target substrate, (e.g., etched into the surface of the target substrate). The cavity can comprise a cavity bottom (e.g., a floor) and cavity walls. The surface of the target substrate can be the cavity bottom, and at least one of the structures can comprise one of the cavity walls.
Multiple non-native components (e.g., each comprising component substrates separate and independent from the target substrate) can be disposed in the cavity in alignment with groups of structures on the surface.
In embodiments of the present disclosure, at least one of the structures is (e.g., some or all of the structures are) native to the target substrate (e.g., are grown on the target substrate or have been formed by etching into the target substrate). At least one of the structures or all of the structures can be defined by a patterned etching into the target substrate, for example in a common patterning and etching step. Each of one or more of the structures can be an island of the target substrate extending from the surface, for example where the surface is a cavity bottom. At least one, some, or all of the structures can be non-native to the target substrate, for example has been printed to the target substrate using micro-transfer printing and can comprise a broken (e.g., fractured) or separated tether). At least one, some, or all of the structures can be adhered to the target substrate by adhesive. At least one of the structures can be disposed in a cavity in which the component is also disposed. In some embodiment, the printed structure comprises a broken (e.g., fractured) or separated tether as a consequence of micro-transfer printing the printed structure from a source wafer to a target substrate.
According to embodiments of the present disclosure, each structure of two or more of the structures has a structure edge and the structure edges of the two or more of the structures are in a substantially straight line parallel to the surface of the target substrate. In some embodiments, the component has one or more component edges and at least one or more of the component edges is substantially parallel to at least one of the structure edges of the two or more of the structures. In some embodiments, each structure of two or more of the structures has a structure edge and the structure edges are disposed at an angle of substantially ninety degrees parallel to the surface of the target substrate. In some embodiments, each structure of two or more of the structures has a structure edge and the structure edges are disposed at an angle less than ninety degrees parallel to the surface of the target substrate or at an angle greater than ninety degrees parallel to the surface of the target substrate.
According to some embodiments, the component has two component edges and each structure of two or more of the structures has a structure edge and each component edge is disposed substantially parallel to the structure edge of one of the two or more of the structures. The two component edges can be component ends. In some embodiments, the two component edges are not parallel. In some embodiments, the two component edges are parallel.
In some embodiments, the structures comprise a first structure and a second structure, the component has a first component end and a second component end, and the first structure is disposed closer to the first component end than to the second component end and the second structure is disposed closer to the second component end than to the first component end. The structures can comprise a first structure having a first structure edge and a second structure having a second structure edge, the component has a first component end having a first component edge and an opposing second component end having a second component edge, the first structure edge is at a non-orthogonal angle with respect to the second structure edge in a direction parallel to the surface, and the first component edge is substantially parallel to the first structure edge and the second component edge is substantially parallel to the second structure edge.
According to embodiments of the present disclosure, a printed structure comprises a target substrate and one or more substrate structures extending from a surface of the target substrate. A component non-native to the target substrate can be disposed on the surface in alignment with the one or more substrate structures. The component can comprise a component substrate separate and independent from the target substrate and can comprise a broken (e.g., fractured) or separated tether. The component can comprise one or more component structures each extending from a (e.g., a portion of a common) side (e.g., edge or face) of the component. The one or more component structures can each be in contact with or within one micron of the one or more substrate structures. The one or more component structures can be two or more spatially separated component structures, for example extending from a common side (e.g., edge or face) or a portion of a common side of the component.
In some embodiments, the target substrate comprises a cavity having a cavity bottom and cavity walls disposed within the target substrate. The surface of the target substrate can be the cavity bottom and at least one of the substrate structures can comprise or be one of the cavity walls.
In some embodiments, the one or more component structures (e.g., two component structures) can protrude farther from a side of the component than the broken or separated tether. The broken or separated tether can be disposed between two component structures on a common side, face, or edge of the component.
In some embodiments, the printed structure comprises an adhesive disposed on the target substrate and wherein the component is disposed on the adhesive.
In some embodiment, the component has a longer side and a shorter side and the component can be adjacent to more structures on the longer side than on the shorter side. The longer side can extend in a length direction parallel to the surface and can extend a distance that is a length of the component. The shorter side can extend in a width direction parallel to the surface and can extend a distance that is a width of the component.
The component can be a photonic or electro-optic device such as a laser, an optical amplifier, an optical modulator, or a light sensor. At least one of the structures can comprise a waveguide. The waveguide can provide or receive light to or from the component and can be optically aligned with the component. In some embodiments, the printed structure is a photonic device
In some embodiments, the component protrudes above at least one of the structures. In some embodiments, a top surface of the component and a top surface of at least one of the structures reside in a common plane. In some embodiments, the component has a height, each of the structures extends above the target substrate by at least a minimum distance, and the height of the component is at least as large as the minimum distance. In some embodiments, one or more structures are disposed on a first side of a component and one or more structures are disposed on a second side of the component different from the first side (e.g., opposite or adjacent to the first side) [e.g., wherein each of the one or more structures disposed on the first side comprises an optical element (e.g., a waveguide, an optical amplifier, or an optical modulator) and the one or more structures disposed on the second side do not comprise an optical element].
In some embodiments, the component comprises a broken or separated tether that is disposed laterally between ones of the structures.
In some embodiments, each of the structures comprises an edge and the component is disposed adjacent to the structures such that a gap exists between each of the edges and the component. The gap can be no more than one micron between each of the edges and the component. In some embodiments, the component has a cut-off corner that defines the gap between the component and each of the edges.
In some embodiments, an adhesive is disposed on the target substrate and the component is disposed on the adhesive so that at least some of the adhesive is disposed between the component and the surface of the target substrate and adheres the component to the target substrate. At least some of the adhesive can be disposed laterally between the structures and at least some of the adhesive can be disposed laterally between a structure and the component. A thickness of the adhesive in the gap can be greater than a thickness of the adhesive between the component and the surface of the target substrate. A thickness of the adhesive in the gap can be greater than a thickness of the adhesive between the edges of two or more of the structures.
According to some embodiments, a printed structure comprises a gutter (a trench), or multiple separate gutters (multiple separate trenches), formed in the target substrate and disposed between the component and at least one of the structures, beneath the component, or both between the component and at least one of the structures and beneath the component. Where multiple gutters are present, in some embodiments some or all of the gutters can be connected. In some embodiments, some or all of the gutters are disconnected from any other of the gutters. The gutter can be at least partially filled with the adhesive. In some embodiments, the gutter has a depth no less than 500 nm (e.g., no less than one micron, no less than two microns, or no less than three microns). In some embodiments, the gutter has a depth no less than a thickness of the adhesive between the component and the surface (e.g., a depth no less than twice the thickness of the adhesive between the component and the surface, a depth no less than five times the thickness of the adhesive between the component and the surface, a depth no less than ten times the thickness of the adhesive between the component and the surface, a depth no less than twenty times the thickness of the adhesive between the component and the surface, a depth no less than fifty times the thickness of the adhesive between the component and the surface, or a depth no less than one hundred times the thickness of the adhesive between the component and the surface).
In embodiments according to the present disclosure, a printed structure can comprise a target substrate. A component can be disposed on the surface of the target substrate. The component can be non-native to the target substrate, for example the component can comprise a component substrate separate and independent from the target substrate. The component can comprise a broken (e.g., fractured) or separated tether as a consequence of micro-transfer printing the component from a component source wafer to the surface of the target substrate. In some embodiments, a structure extends from a surface of the target substrate and the component is disposed in alignment with the structure. The structure can be native or non-native to the target substrate.
A gutter can be formed in the target substrate and disposed laterally adjacent to the component or beneath the component, or both. The gutter can be disposed laterally between the component and the structure. The gutter can be disposed within five microns (e.g., within three microns, within two microns, within one micron, within 1.0 micron, within 0.75 microns, within 0.5 microns, within 0.25 microns, or within 0.1 microns) of the component. In some embodiments, the gutter has a depth no less than 500 nm (e.g., no less than one micron, no less than two microns, or no less than three microns) In some embodiments, the gutter has a depth no less than a thickness of the adhesive between the component and the surface (e.g., a depth no less than twice the thickness of the adhesive between the component and the surface, a depth no less than five times the thickness of the adhesive between the component and the surface, a depth no less than ten times the thickness of the adhesive between the component and the surface, a depth no less than twenty times the thickness of the adhesive between the component and the surface, a depth no less than fifty times the thickness of the adhesive between the component and the surface, or a depth no less than one hundred times the thickness of the adhesive between the component and the surface).
Some embodiments of the present disclosure comprise an adhesive that adheres the component to the target substrate and the gutter is at least partially filled with the adhesive. The adhesive can be disposed between the component and the surface of the target substrate.
In some embodiments, a printed structure comprises a target substrate having a substrate surface, a gutter disposed in the target substrate, an adhesive disposed on the target substrate and at least partially in the gutter, and a component printed onto the substrate surface adjacent to or at least partially over the gutter. The component can comprise a broken (e.g., fractured) or separated tether as a consequence of transfer printing from a component source wafer to the target substrate. In some embodiments, the printed structure comprises a substrate structure extending from the substrate surface adjacent to the gutter. In some embodiments, the gutter is at least partially laterally between the printed component and the substrate structure. In some embodiments, the printed component is in contact with the substrate structure and the gutter is beneath the component (e.g., in a direction toward the target substrate from the component).
The component can be disposed on the surface of the target substrate within one micron (e.g., within 1.0 micron, within 0.75 microns, within 0.5 microns, within 0.25 microns, or within 0.1 microns) of the structure. The component can be a photonic device such as a laser, an optical amplifier, an optical modulator, or a light sensor. At least one of the structures comprises a waveguide (e.g., that is optically aligned with the laser, the optical amplifier, the optical modulator, or the light sensor). The printed structure is a photonic device, a photonic structure, or a photonic system.
According to embodiments of the present disclosure, a method of making a printed structure comprises providing a target substrate and two or more structures extending from a surface of the target substrate (e.g., wherein the structures are spatially separated independent structures), providing an adhesive on the surface of the target substrate, providing a transfer element and a component adhered to the transfer element (e.g., wherein the component comprises a component substrate that is separate and independent from the target substrate), moving the transfer element with the adhered component vertically toward the surface of the target substrate and horizontally towards at least one of the structures at least until the component physically contacts a structure of the at least one of the structures or is adhered to the surface of the target substrate, thereby pushing at least a portion of the adhesive with the component, and separating the transfer element from the component, thereby printing the component to the target substrate. The step of moving the transfer element can comprise pushing the adhesive with the component, for example pushing the adhesive laterally along the surface of the target substrate, for example toward a structure, and piling up the adhesive on the surface between the component and the structure.
Thus, in some embodiments, the structures comprise two or more spatially separated independent structures protruding from the surface of the target substrate and the method comprises pushing the portion of the adhesive laterally into a gap between the two structures or toward the two structures. In some embodiments, the two or more structures comprise structure edges forming an angle defined by lines extending along the structure edges parallel to a surface of the target substrate and the method comprises pushing the portion of the adhesive between the structures toward an intersection of the lines (e.g., into or toward a corner). The two or more spatially separated structures can be separated by a separation distance and the transfer element can move the adhered component horizontally towards one of the structures a shear distance, and the shear distance can be less than the separation distance in a direction separating the structures. The structure can comprise edges forming an angle defined by lines extending along the edges parallel to a surface of the target substrate, the component has a cut-off corner forming the gap between the component and an intersection of the lines and comprising pushing the portion of the adhesive toward the intersection. The target substrate can comprise a gutter disposed between the structure and the component and methods of the present disclosure can comprise pushing the portion of the adhesive into the gutter. Methods of the present disclosure can comprise moving the component horizontally towards one of the structures after the component is in contact with the adhesive or the target substrate. The component can be disposed on the surface of the target substrate within one micron (e.g., within 1.0 micron, within 0.75 microns, within 0.5 microns, within 0.25 microns, or within 0.1 microns) of or in contact with at least one of the structures, of two or more of the structures, or of all of the structures after the transfer element is separated from the component.
In some embodiments, the component has two component edges at component ends, each of two of the structures has a structure edge, the two component edges are not parallel, and the method comprises moving the component with the transfer element until each of the two component edges is disposed substantially parallel to the structure edge of one of the two of the structures. In some embodiments, each of the two component edges are disposed on the surface of the target substrate a distance of no greater than one micron from the structure edge of the one of the two of the structures.
According to embodiments of the present disclosure, a method of making a printed structure comprises providing a target substrate and one or more structures extending from a surface of the target substrate and a gutter in the target substrate that is adjacent to at least one structure of the one or more structures, providing an adhesive on the surface of the target substrate, providing a transfer element and a component adhered to the transfer element (e.g., wherein the component comprises a component substrate that is separate and independent from the target substrate), moving the transfer element with the adhered component vertically toward the surface of the target substrate and horizontally towards a structure of the one or more structures at least until the component physically contacts the structure or is adhered to the surface of the target substrate, thereby pushing at least a portion of the adhesive with the component into the gutter such that the gutter becomes at least partially filled with the adhesive, and separating the transfer element from the component.
According to embodiments of the present disclosure, a method of making a printed structure comprises providing a target substrate and two structures extending from a surface of the target substrate, wherein each of the two structures has a structure edge and the two structure edges define two lines parallel to the surface that are not parallel, providing a transfer element and a component adhered to the transfer element, wherein the component comprises two component edges at component ends that are not parallel (e.g., and comprises a component substrate that is separate and independent from the target substrate), moving the transfer element with the adhered component vertically toward the surface of the target substrate and horizontally towards both of the two structures at least until (i) each of the two component edges is disposed substantially parallel to the of one a structure edge of one of the two structures and (ii) each of the component edges physically contacts one of the structures or is adhered to the surface of the target substrate, and separating the transfer element from the component.
According to embodiments of the present disclosure, a method of making a printed structure comprises providing a target substrate comprising a gutter formed in the target substrate and adhesive disposed on the target substrate adjacent to the gutter and printing a component to a target substrate by moving the component vertically towards the target substrate and horizontally over the target substrate such that the component becomes adhered to the target substrate with the adhesive, wherein the gutter becomes at least partially filled with the adhesive during the printing (e.g., due to the component pushing the adhesive as the component is printed). Methods can comprise providing a structure disposed on the target substrate (e.g., native or non-native to the target substrate), wherein printing the component comprises printing the component in alignment with the structure. The component can be an opto-electronic component and the structure can comprise a waveguide and printing the component can comprise aligning the component with the waveguide. In some embodiments, no adhesive is disposed in an optical path between the optoelectronic component and the waveguide after the printing. In some embodiments, the printing of the component comprises moving a transfer element on which the component is adhered and separating the transfer element from the component after the component is adhered to the target substrate with the adhesive. In some embodiments, the printed structure comprises the component, the adhesive, and the target substrate.
Some embodiments of the present disclosure provide methods, devices, and structures that enable precise and accurate micro-transfer printing components from a native source wafer to a non-native destination substrate. The components can be aligned with the structures and can be optical components.
The foregoing and other objects, aspects, features, and advantages of the present disclosure will become more apparent and better understood by referring to the following description taken in conjunction with the accompanying drawings, in which:
Features and advantages of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The figures are not necessarily drawn to scale.
Certain embodiments of the present disclosure are directed toward methods of printing (e.g., micro-transfer printing) components from a component source wafer onto a target substrate using a transfer element (e.g., stamp or other transfer device), and to structures extending or protruding from a surface of the target substrate. The structures can be used to align components to a location on the target substrate, to the structure, or to another component. Transfer-printed components are moved both vertically and horizontally over the target substrate to contact the structure and position the component on the target substrate with respect to the structure. The structure and the component can be aligned optical components.
Referring to the flow diagram of
In step 160, transfer element 40 and adhered component 30 are moved vertically toward surface 11 of target substrate 10 and horizontally towards structure 20 in movement direction M (shown in
In some embodiments, and as shown in the
At the conclusion of separation step 170, component 30 is disposed on target substrate 10 within a separation distance D of structure 20 (e.g., as shown in
As used herein, vertical movement is defined as movement in a direction M substantially or effectively orthogonal to surface 11 of target substrate 10 and horizontal movement in a direction M is defined as movement substantially or effectively parallel to surface 11 of target substrate 10. A movement of transfer element 40 toward structure 20 means that at least a portion of transfer element 40 is moving toward structure 20, for example horizontally or vertically or both horizontally and vertically. A component 30 can be separated from transfer element 40 by moving transfer element 40 toward structure 20 at least horizontally and optionally vertically toward structure 20. Movement in a direction M can be temporally continuous or discontinuous, can move simultaneously in horizontal and vertical directions, or can alternate in horizontal and vertical directions. Movement can be in a straight line or in a curved line. A transfer element 40 can accelerate or decelerate during movement.
Depending on the amount and force of vertical motion in step 160, it can be helpful to additionally or repeatedly press component 30 toward (e.g., onto) surface 11 of target substrate 10, for example such that component 30 moves onto or into a layer such as adhesive layer 12 disposed on surface 11 of target substrate 10 after the conclusion of step 160 (as shown in
Referring to the flow diagram of
In some embodiments of the present disclosure component 30 is above and not in contact with surface 11 of target substrate 10 when component 30 physically contacts structure 20 due to movement of transfer element 40 (e.g., as shown in
Some methods of the present disclosure can be iteratively repeated so that components 30 disposed on target substrate 10 can subsequently serve as a structure 20 when another component 30 is disposed on target substrate 10 (or on adhesive layer 12 disposed on surface 11 of target substrate 10) using the methods described above. Referring to
Some methods of the present disclosure accomplish component 30 transfers using micro-transfer printing (e.g., dry contact printing). Such printing methods can transfer components 30 formed on a native component source substrate. The component source substrate is processed to release components 30 (with component substrate 38) from the component source substrate so that components 30 are physically attached to the component source substrate only with one or more tethers 32 physically connecting components 30 to one or more anchors of the component source substrate. A stamp 40 contacts one or more components 30, adhering component 30 to stamp 40 (for example, to a stamp post 42). Stamp 40 separates and removes components 30 from the component source wafer, breaking (e.g., fracturing) or separating each tether 32 physically connecting each component 30 to the native component source wafer. For clarity, broken or separated tethers 32 are omitted from
Referring to
If a second component 30 (e.g., second component 30B, as shown in
Micro-transfer printing is especially useful when transferring or otherwise disposing components 30 (e.g., first or second components 30A, 30B, or both) that are relatively small. In some embodiments, for example, component 30 has a length, a width, or both a length and a width less than or equal to 200 microns, e.g., less than or equal to 100 microns, less than or equal to 50 microns, less than or equal to 20 microns, less than or equal to 10 microns, less than or equal to 5 microns, less than or equal to 2 microns, or less than or equal to 1 micron in length or width and, optionally also has a thickness less than or equal to 50 microns, e.g., less than or equal to 25 microns, less than or equal to 10 microns, less than or equal to 5 microns, less than or equal to 2 microns, less than or equal to one micron, less than or equal to 0.5 microns, less than or equal to 0.2 microns, or less than or equal to 0.1 microns.
According to some embodiments of the present disclosure and as shown in
In some embodiments, adhesive layer 12 is substantially transparent to light 60 that is received or emitted by components 30 or structures 20. A substantially transparent adhesive layer 12 is one that does not compromise the effective transmission of light 60 received or emitted by components 30 or structures 20, for example an adhesive layer 12 comprising an adhesive that is at least 50%, e.g., at least 75%, at least 80%, at least 85%, at least 90%, or at least 95% transparent to light 60 received or emitted by components 30 or structures 20. In some embodiments, adhesive layer 12 can conduct light 60, for example serve as, or as a portion of, a light pipe 24 (e.g., a light guide or fiberoptic channel) or can transmit light 60 between component 30 and structure 20. In some embodiments, an encapsulation layer 74 (for example, a dielectric layer 74) is disposed at least partly over any combination of component 30, structure 20, and any gap between component 30 and structure 20. Such a gap, for example can define or be a separation distance D as described above. Encapsulation layer 74 can comprise a light-reflective layer or encapsulation layer 74 can be coated with a light-reflective layer (for example upper light-reflective layer 52). Such a light-reflective layer, together with lower light-reflective layer 50, can control and direct light 60 as desired with respect to components 30 and structures 20.
In some embodiments, emitted or received light 60 is controlled or conducted by material optical index differences, for example as in a fiber-optic device. According to some embodiments, component 30 comprises a component material, target substrate 10 comprises a substrate material, and the component material is substantially different from the substrate material, for example comprising different material, having different material transparency, reflection, or absorption, or having different optical indices (e.g., having at least a 10% difference in refractive index). In some embodiments, target substrate 10 comprises a reflective material disposed between component 30 and target substrate 10 or between structure 20 and target substrate 10, e.g., lower light-reflective layer 50.
Referring to
As shown, for example, in
Referring to
Referring to
According to some embodiments of the present disclosure, and as shown in
As shown in
For example, referring to
Thus, according to some embodiments of the present disclosure, a structure 20 of printed structure 99 has a structure face and component 30 has a component face opposed to the structure face. In some embodiments, either (i) the structure face has an indentation 26 and the component face has a protrusion 36 complementary to indentation 26 (e.g., in size and/or shape), or (ii) the structure face has a protrusion 36 and the component face has an indentation 26 complementary to protrusion 36 (e.g., in size and/or shape) so that protrusion 36 can be inserted into indentation 26.
Referring to
As discussed with respect to the embodiments illustrated in
As used herein, a length of component 30 is a dimension of component 30 that is longer than a width of component 30 in a direction parallel to surface 11. A component 30 can be longer in a length direction and shorter in a width direction and a component end is a side or face of component 30 having a component edge that is not parallel to the length direction. A component edge can be orthogonal to the length direction (and parallel to the width direction) or not orthogonal to the length direction (and not parallel to the width direction. A horizontal direction is parallel to surface 11 and a vertical direction is a direction orthogonal to surface 11. Laterally means in a horizontal direction parallel to surface 11 of target substrate 10. In some embodiments, component 30 and one or more structures 20 are disposed in alignment with each other such that component 30 is laterally adjacent to one or more structures 20 and no other structure 20 is closer to component 30 than one or more structures 20, for example each of one or more structures 20 can be disposed in contact with or within a distance of five micron or less (e.g., two microns or less or one micron or less). Alignment between component 30 and structure 20 can also mean that component 30 has a component edge (or side), structure 20 has a structure edge (or side), and the component edge and structure edge are substantially parallel within manufacturing and design limitations. Components 30 are non-native to target substrate 10 (e.g., constructed on a separate native component source wafer and transferred to target substrate 10). Structures 20 and components 30 can have a substantially flat face substantially orthogonal to surface 11, e.g., within manufacturing tolerances and limitations. Where structures 20 have a substantially flat face (e.g., wall) that is not orthogonal to surface 11, components 30 can have an edge (or side) that is no greater than one micron from the bottom of structure 20 adjacent to surface 11 or no greater than one micron from the top of structure 20 on a side of structure 20 opposite surface 11 (e.g., top surface 13). An edge of structure 20 or component 30 can also be a face, wall, or side of structure 20 or component 30.
In some embodiments and as shown in
In some embodiments and as shown in
Multiple structures 20 can form mechanical stops for component 30 when micro-transfer printing component 30 onto surface 11 of target substrate 10 or onto bottom surface 11 of cavity 15 in target substrate 10 by physically moving component 30 toward or against structures 20. By using multiple structures 20 with spatial gaps or spatial separations between structures 20 (rather than a single structure 20 with a single edge), broken (e.g., fractured) or separated tethers 32 of component 30 can be disposed laterally between the separated structures 20 so that tethers 32 do not form a mechanical standoff to structures 20 and do not prevent component 30 from aligning with (e.g., contacting) structures 20 when micro-transfer printing components 30 in alignment with structures 20.
Furthermore, structure edges (or sides) of structures 20 can be arranged in a line so that a component edge (e.g., a straight edge or side) of component 30 is substantially aligned with structures 20. For example, and as shown in
In some embodiments, structures 20 can have structure edges that are disposed at an angle of substantially ninety degrees parallel to surface 11 of target substrate 10 (e.g., orthogonal or perpendicular) as shown in
As shown in
In some embodiments, and as shown in
In some embodiments, and as illustrated in
Two or more component structures 28 can be spatially separated and broken (e.g., fractured) or separated tethers 32 (e.g., broken (e.g., fractured) or separated component tethers 32) can be disposed spatially and laterally between component structures 28 on a common side of component 30. In some embodiments, component structures 28 extend a greater distance from a side of component 30 than a broken (e.g., fractured) or separated tether 32 so that broken (e.g., fractured) or separated tethers 32 do not interfere with aligning component 30 (and component structures 28) to one or more substrate structures 20, for example by preventing component structures 28 from contacting one or more substrate structures 20.
In some embodiments, and as shown in
Aligning components 30 with structures 20 is very useful for photonic systems, for example comprising laser, light emitters such as diodes, waveguides (light pipes 24), optical amplifiers, and optical modulators. Optical components 30 are often constructed in or on relatively expensive compound semiconductor material wafers rather than relatively inexpensive glass, polymer, or silicon substrates. Moreover, silicon substrates can comprise light pipes 24 (e.g., made with patterned silicon nitride on the silicon substrate) and control circuits for controlling compound semiconductor components 30 in a photonic integrated circuit (e.g., a photonic system). Printed structures 99 of the present disclosure can be photonic structures, devices, or systems. Components 30 that are optically aligned with [e.g., due to close spatial proximity (e.g., within five microns, within two microns, within one micron)] light pipes 24 in structures 20 have improved light coupling from component 30 to light pipe 24 (or vice versa) and better optical system performance. Alignment between components 30 and one or more structures 20 can include both a close distance in any of three spatial dimensions (or a combination thereof) and a horizontal rotation to improve light coupling between optical components 30 and one or more light pipe(s) 24 in one or more structures 20.
According to some embodiments of the present disclosure, an adhesive 12 (adhesive layer 12) such as an epoxy or resin is disposed on surface 11 of target substrate 10, for example by spray or spin coating. Adhesive 12 can be disposed between component 30 and surface 11 to adhere component 30 to surface 11 and thereby facilitate micro-transfer printing component 30 onto surface 11 and prevent component 30 from moving with respect to surface 11 and structures 20 when subject to mechanical or thermal stress. In some embodiments, component 30 is contacted to adhesive 12 and then moved at least partially horizontally (e.g., in the x direction) as illustrated in
To mitigate or prevent adhesive 12 from pushing, bulging, or piling up between component 30 and structure 20 during micro-transfer printing, structures 20 can be arranged or constructed as shown in
In some embodiments and as illustrated in
It can be difficult to provide a layer of adhesive 12 that has a constant thickness and, because of capillary effects or because of spin coating non-uniformity due to topographic structures (e.g., structures 20), adhesive 12 can be thicker adjacent to structures 20, thereby making close and accurate alignment between component 30 and structure 20 difficult. The presence of gutter 16 adjacent to (e.g., close to or at an edge of) structure 20, beneath structure 20, or both adjacent to and beneath structure 20 can mitigate the thicker adhesive 12 so that component 30 and structure 20 can be aligned. Moreover, if horizontal movement of component 30 toward structure 20 in contact with adhesive 12 pushes adhesive 12 toward structure 20 and inhibits alignment between component 30 and structure 20, rather than piling up adhesive 12 between component 30 and structure 20, excess adhesive 12 can move into gutter 16, enabling alignment between component 30 and structure 20.
Thus, according to embodiments of the present disclosure, a printed structure 99 can comprise a target substrate 10, a structure 20 extending from a surface 11 of target substrate 10, a component 30 disposed in alignment with structure 20 (e.g., and comprising a component substrate separate and independent from target substrate 10 and/or a broken or separated tether 32 as a consequence of micro-transfer printing component 30 onto or over surface 11), and a gutter 16 formed in target substrate 10 between component 30 and structure 20 or beneath component 30, or both between component 30 and structure 20 and beneath component 30 (e.g., where component 30 overlaps a portion of, but not all of, gutter 16). Adhesive 12 can be disposed in gutter 16 and between component 30 and surface 11. Adhesive 12 in gutter 16 can be thicker than adhesive 12 between component 30 and surface 11 or between component 30 and structure 20, for example because adhesive 12 can be pushed into gutter 16 by component 30. Gutter 16 can surround structures 20, for example where structures 20 form islands on surface 11 or can be disposed along exposed edges of structures 20, for example where structures 20 comprise edges, faces, or walls of cavity 15.
In some embodiments, a printed structure 99 comprises a target substrate 10 having a substrate surface 11, a gutter 16 disposed in target substrate 10, an adhesive 12 disposed on target substrate 10 and at least partially in gutter 16, and a component 30 printed onto substrate surface 11 adjacent to or at least partially over gutter 16. Adjacent can mean within ten, five, two, one, or one half microns on surface 11. Component 30 can comprise a broken (e.g., fractured) or separated tether 32. In some embodiments, printed structure 99 comprises substrate structure 20 extending from substrate surface 11 adjacent to gutter 16. Extending from can mean upward in a direction away from target substrate 10. In some embodiments, gutter 16 is at least partially laterally between printed component 16 and substrate structure 20. In some embodiments, printed component 30 is in contact with substrate structure 20 and gutter 16 is beneath component 30 (e.g., in a direction toward target substrate 10 from component 30.
To facilitate micro-transfer printing, component 30 can have a thickness greater than a thickness of structures 20 (e.g., component 30 extends a greater vertical distance from surface 11 than structures 20) so that a micro-transfer printing device (e.g., a stamp or stamp post) does not contact structures 20 during transfer.
According to embodiments of the present disclosure and as illustrated in
In some embodiments, the two or more structures 20 comprise structure edges forming an angle defined by lines extending along the structure edges parallel to surface 11 of target substrate 10 and methods of the present disclosure comprise pushing the portion of adhesive 12 between structures 20 toward an intersection of the lines as shown in
In some embodiments, the two or more spatially separated structures 20 are separated by a separation distance S (shown in
According to methods of the present disclosure as shown in
By using devices, system, and methods of the present disclosure, some embodiments have been constructed and demonstrated comprising component 30 disposed on surface 11 of target substrate 10 within one micron (e.g., within 1.0 micron, within 0.75 microns, within 0.5 microns, within 0.25 microns, or within 0.1 microns) of or in contact with at least one of structures 20, of two or more of structures 20, or of all of structures 20. Some constructions have disposed a micro-laser component 30 in alignment with four structures 20 along the length of the micro-laser in cavity 15 of a silicon target substrate 10. The micro-laser (component 30) has an angled component end (e.g., as shown in
In some demonstrations, gutter 16 was 3 microns deep, adhesive 12 was spin coated on surface 11 at 70-100 nm depth but, because of surface 11 topography (e.g., gutter 16, structures 20, and cavity 15 was 30-70 nm deep within gutter 16. Alignment distance in both x and y directions was less than 500 nm (in some cases less than 100 nm) and component 30 was in contact with structures 20 along the length of component 30. In some embodiments, the cavity wall (which can be a substrate structure 20) has a height of approximately 4 microns, 3-5 microns, 5-10 microns, or 10-20 microns, from surface 11. Component 30 was a micro-laser with a width in the shorter, width direction of 60 microns and a length in the longer, length direction of 550 microns, with an angled component end. A light pipe 24 was formed in a structure 20 in alignment with (e.g., close and oriented to receive light from) the micro-laser (component 30).
In some embodiments of the present disclosure, to allow adhesive 12 to effectively flow into gutter 16, gutter 16 can have a depth no less than a thickness of adhesive 12 on surface 11 or between component 30 and surface 11, no less than two times the thickness of adhesive 12 on surface 11 or between component 30 and surface 11, no less than five times the thickness of adhesive 12 on surface 11 or between component 30 and surface 11, no less than ten times the thickness of adhesive 12 on surface 11 or between component 30 and surface 11, no less than twenty times the thickness of adhesive 12 on surface 11 or between component 30 and surface 11, no less than fifty times the thickness of adhesive 12 on surface 11, or no less than 100 times the thickness of adhesive 12 on surface 11 or between component 30 and surface 11. In some embodiments, gutter 16 has a depth no less than 500 nm, no less than one micron, no less than two microns, or no less than three microns.
As noted, component ends with angled edges can be aligned with structures 20 having non-orthogonal edges (e.g., as shown in
Embodiments of the present disclosure have been constructed and successfully operated, for example in a target substrate 10 with a gutter 16 adjacent to a substrate structure 20. A laser component 30 has been successfully micro-transfer printed onto a target substrate 10 adjacent to substrate structures 20 surrounded by one or more gutters 16 in alignment with one or more light pipes 24.
Adhesive 12 is described in various embodiments as being, inter alia, adjacent to gutter 16, adjacent to structure 20, on target substrate 10, beneath component 30, between component 30 and target substrate 10, and between structure 20 and target substrate 10. It should be understood that unless accompanied by the word “solely” or “exclusively” or a similar word, at least a portion of adhesive 12 can be disposed as described while a portion, or in some embodiments none, of adhesive 12 is disposed elsewhere. For example, when adhesive 12 is described as being disposed between component 30 and target substrate 10, it should be understood that some of adhesive 12 can be, but is not necessarily, disposed on target substrate 10 and not between component 30 and target substrate 10 (e.g., adhesive 12 extends along target substrate 10 beyond a perimeter of component 30 in at least one direction). Similarly, in some embodiments, adhesive 12 disposed adjacent to gutter 16 means that adhesive 12 is disposed along (e.g., within 5 microns) at least one edge of gutter 16 though adhesive 12 can extend along target substrate 10 elsewhere (e.g., between component 30 and target substrate 10, beneath). For embodiments described that include adhesive 12 and where the word “solely” or “exclusively” or a similar word was not used in such description, additional analogous embodiments where adhesive 12 is disposed solely/exclusively as described (e.g., between component 30 and target substrate 10) are also contemplated. (Solely and exclusively are used interchangeably in this context with respect to adhesive 12.) In some embodiments, vertical alignment between component 30 and one or more structures 20 can be improved by providing one or more gutters 16, for example by allowing a thinner and/or more consistent thickness layer of adhesive 12 to be used, where excess adhesive 12 is displaced (e.g., pushed) into the one or more gutters 16.
Structure 20 can be native or non-native to target substrate 10. Structures 20 can include a combination of both one or more native structure 20 and one or more non-native structures 20. In some embodiments, each of one or more structures 20 defines an island on target substrate 10. An island structure 20 can be formed by patterned etching of target substrate 10 or growth (e.g., epitaxial growth) of material on target substrate 10. Structures 20 can be formed simultaneously with formation of cavity 15 in target substrate 10, for example in the same patterned etching of target substrate 10. One or more structures 20 can extend from a wall of cavity 15 in target substrate 10, regardless of whether such structure(s) 20 are native or non-native to target substrate 10. One or more structures 20 can form a continuous structure a portion of target substrate 10, for example be lateral protrusion(s) from a wall of cavity 15. Such lateral protrusion(s) can, but need not necessarily, terminate in a same plane. A combination of one or more island structures 20 and one or more protrusion structures 20 can be used in some embodiments. Multiple structures 20 can exist as part of a larger common structure, for example where the larger common structure has a complex geometry including multiple lateral protrusions. Such larger common structures can be part of a cavity 15 or can be separate structures (e.g., regardless of whether any cavity 15 is present or not).
In some embodiments, component 30 or structure 20 is adjacent to gutter 16. In some embodiments, component 30 or structure 20 that is adjacent to gutter 16 is disposed within five microns, within two microns, within one micron, within 1.0 micron, or within 0.5 microns of gutter 16, for example component 30 or structure 20 can partially overlap gutter 16. In some embodiments, when component 30 is aligned with gutter 16, component 30 disposed within 5 microns, within 2 microns, within 1 micron, within 1.0 microns, or within 0.5 microns of gutter 16.
Component 30 that is disposed in alignment with (e.g., are aligned to or aligned with) one or more structures 20 can be disposed within five microns, within two microns, within one micron, within 1.0 microns, or within 0.5 microns of each of one or more structures 20. In some embodiments, a face of component 30 can be within ±10 degrees (e.g., within ±8 degrees, within ±6 degrees, within ±4 degrees, or within ±2 degrees) of parallel to a face of structure 20 when component 30 is aligned with structure 20. In some embodiments, component 30 is aligned with one or more structures 20 in that component 30 is disposed in optical alignment with one or more structures 20, for example when component 30 is an optical component and structure 20 includes one or more optical elements, such as a waveguide, optical amplifier, optical modulator, or combination thereof (such that structure 20 is itself an optical component). When component 30 and one or more structures 20 are optically aligned, light from component 30 can be received by (e.g., and processed by) one or more optical elements in structure(s) 20. Printing component 30 to target substrate 10 by contacting component 30 to one or more structures 20 during printing aligns component 30 with one or more structures 20. Component 30 will not necessarily physically contact each of one or more structures 20 after printing, for example each of one or more structures 20 can be separated from component 30 by a small distance of no more than one micron. In some embodiments, printed structure 99 is designed to have component 30 be disposed in a certain location relative to one or more structures 20 such that component 30 is then considered aligned with one or more structures 20 when disposed within a certain tolerance (e.g., no more than five microns, no more than two microns, no more than one micron, no more than 1.0 micron, or no more than 0.5 microns) of the certain location; such one or more structures 20 can facilitate such disposition, for example during printing. In some embodiments, component 30 is disposed at the certain location to within manufacturing (e.g., printing) tolerances.
Reference is made throughout the present description to examples of printing that are micro-transfer printing with stamp 40 comprising stamp post 42 when describing certain examples of printing components 30 (e.g., in describing
According to some embodiments, micro-transfer printing can include any method of transferring components 30 from a component source wafer (e.g., a native source wafer) to a target substrate 10 by contacting components 30 on the component source wafer with a patterned or unpatterned stamp surface of a stamp 40 (e.g., a distal end of stamp post 42), removing (e.g., separating) components 30 from the component source wafer, transferring stamp 40 and contacted components 30 to target substrate 10, and contacting components 30 to a surface 11 of target substrate 10, for example adhesive layer 12 by moving stamp 40 or target substrate 10. Components 30 can be adhered to stamp 40 or target substrate 10 by, for example, van der Waals forces, electrostatic forces, magnetic forces, chemical forces, adhesives, or any combination of the above. In some embodiments, components 30 are adhered to stamp 40 with separation-rate-dependent adhesion, for example kinetic control of viscoelastic stamp materials such as can be found in elastomeric transfer elements or transfer devices such as a PDMS stamp 40. Stamps 40 can be patterned or unpatterned and can comprise stamp posts 42 having a stamp post area on the distal end of stamp posts 42. Stamp posts 42 can have a length, a width, or both a length and a width, similar or substantially equal to a length, a width, or both a length and a width of component 30.
In exemplary methods, a viscoelastic elastomer (e.g., PDMS) stamp 40 (e.g., comprising a plurality of stamp posts 42) is constructed and arranged to retrieve and transfer arrays of components 30 from their native component source wafer onto non-native patterned target substrates 10. In some embodiments, stamp 40 mounts onto motion-plus-optics machinery (e.g., an opto-mechatronic motion platform) that can precisely control stamp 40 alignment and kinetics with respect to both component source wafers and target substrates 10. During micro-transfer printing, the motion platform brings stamp 40 into contact with components 30 on the component source wafer, with optical alignment performed before contact. Rapid upward movement of the print-head (or, in some embodiments, downward movement of the component source wafer) breaks (e.g., fractures) or separates tether(s) 32 forming broken (e.g., fractured) or separated tethers 32, transferring component(s) 30 from native component source wafer to stamp 40 or stamp posts 42. Stamp 40 populated with components 30 then travels to patterned target substrate 10 (or vice versa) and one or more components 30 are then aligned to target substrate 10 and printed (for example as described in relation to
A component source wafer can be any source wafer or substrate with (e.g., native) transfer-printable components 30 that can be transferred with a transfer element 40 (e.g., a stamp 40). For example, a component source wafer can be or comprise a semiconductor (e.g., silicon) in a crystalline or non-crystalline form, a compound semiconductor (e.g., comprising GaN or GaAs), a glass, a polymer, a sapphire, or a quartz wafer. Sacrificial portions of native component source wafer enabling the release of components 30, for example by etching, can be formed of a patterned oxide (e.g., silicon dioxide) or nitride (e.g., silicon nitride) layer or can be an anisotropically etchable portion of a sacrificial layer of a component source wafer over which components 30 are disposed while also physically connected by tether 32 to an anchor of the component source wafer. Typically, component source wafers are smaller than patterned target substrates 10 and can have a higher density of components 30 disposed thereon than components 30 disposed on target substrate 10.
Components 30 can be any transfer-printable element, for example including any one or more of a wide variety of active or passive (or active and passive) components 30 (e.g., devices or subcomponents). Components 30 can be any one or more of integrated devices, integrated circuits (such as CMOS circuits), light-emitting diodes, photodiodes, sensors, electrical or electronic devices, optical devices, opto-electronic devices, magnetic devices, magneto-optic devices, magneto-electronic devices, and piezo-electric device, materials or structures. Components 30 can comprise electronic component circuits electrically connected to electrodes 72 that operate component 30. Component 30 can be responsive to electrical energy, to optical energy, to electromagnetic energy, or to mechanical energy, or a combination thereof, for example. In some embodiments, an electro-optic device comprises component 30 (e.g., and, optionally, structure 20). In some embodiments, components 30 are light emitters, for example are one or more of light-emitting diodes, lasers, diode lasers, vertical-cavity surface-emitting lasers, micro-lasers, micro-light-emitting diodes, organic light-emitting diodes, inorganic light-emitting diodes, quantum-dot based light emitters, and super-luminescent diodes.
Components 30 formed or disposed in or on component source wafers can be constructed using integrated circuit, micro-electro-mechanical, or photolithographic methods for example. Components 30 can comprise one or more different component materials, for example non-crystalline (e.g., amorphous), polycrystalline, or crystalline semiconductor materials such as silicon or compound semiconductor materials or non-crystalline or crystalline piezo-electric materials. In some embodiments, component 30 comprises a layer of dielectric material, for example an oxide or nitride such as silicon dioxide or silicon nitride.
In certain embodiments, components 30 can be native to and formed on sacrificial portions of component source wafers and can include seed layers for constructing crystalline layers on or in component source wafers. Components 30, sacrificial portions, anchors, and tethers 32 can be constructed, for example using photolithographic processes. Components 30 can be micro-devices having at least one of a length and a width less than or equal to 200 microns, e.g., less than or equal to 100 microns, less than or equal to 50 microns, less than or equal to 25 microns, less than or equal to 15 microns, less than or equal to 10 microns, or less than or equal to five microns, and alternatively or additionally a thickness of less than or equal to 50 microns, e.g., less than or equal to 25 microns, less than or equal to 15 microns, less than or equal to 10 microns, less than or equal to five microns, less than or equal to two microns, or less than or equal to one micron. Components 30 can be unpackaged dice (each an unpackaged die) that, in some embodiments, are transferred directly from one or more (e.g., native) component source wafers on or in which components 30 are constructed to target substrate 10. Anchors and tethers 32 can each be or can comprise portions of a native component source wafer that are not sacrificial portions and can include layers formed on component source wafers, for example dielectric or metal layers and for example layers formed as a part of photolithographic processes used to construct or encapsulate components 30.
Target substrate 10 can be any destination substrate or target substrate to which components 30 are transferred (e.g., micro-transfer printed), for example flat-panel display substrates, printed circuit boards, or similar substrates can be used in various embodiments. Target substrates 10 can be, for example substrates comprising one or more of glass, polymer, quartz, ceramics, metal, and sapphire. Target substrates 10 can be semiconductor substrates (for example silicon) or compound semiconductor substrates. In some embodiments, target substrate 10 is a semiconductor substrate and comprises an electronic substrate circuit. Electronic substrate circuits can be electrically connected through electrodes 72 to control, provide signals to, or respond to component 30.
In some embodiments, a layer 12 of adhesive, such as a layer of resin, polymer, or epoxy, either curable or non-curable, adheres components 30 onto target substrate 10 and can be disposed, for example by coating or lamination. In some embodiments, an adhesive layer 12 is disposed in a pattern, for example disposed in locations on target substrate 10 where components 30 are to be printed (e.g., micro-transfer printed). A layer of adhesive can be disposed using inkjet, screening, or photolithographic techniques, for example. In some embodiments, adhesive layer 12 is coated, for example with a spray or slot coater, and then patterned, for example using photolithographic techniques. If an adhesive 12 is disposed over at least a portion of surface 11 of target substrate 10, a component 30 disposed on adhesive 12 is also said to be disposed on surface 11 of target substrate 10. In some embodiments, structures 20 are disposed on an adhesive 12. In some embodiments, components 30 are disposed on an adhesive 12. In some embodiments, both components 30 and structures 20 are disposed on an adhesive 12 (e.g., a common adhesive layer 12).
Patterned electrical conductors (e.g., wires, traces, or electrodes such as electrical substrate contact pads 14 found on printed circuit boards, flat-panel display substrates, and in thin-film circuits) can be formed on any combination of components 30, structures 20, and target substrate 10, and any one can comprise electrical conductors such as wires or electrical contact pads that electrically connect to components 30 or structures 20. Such patterned electrical conductors and electrodes (e.g., contact pads) can comprise, for example, metal, transparent conductive oxides, or cured conductive inks and can be constructed using photolithographic methods and materials, for example metals such as aluminum, gold, or silver deposited by evaporation and patterned using pattern-wise exposed, cured, and etched photoresists, or constructed using imprinting methods and materials or inkjet printers and materials, for example comprising cured conductive inks deposited on a surface 11 or provided in micro-channels in or on target substrate 10.
Gutter 16, where present, can be formed in target substrate 10 in any suitable fashion. In some embodiments, gutter 16 is formed by photolithographic patterning (e.g., of an original flat substrate). In some embodiments, gutter 16 is formed by patternwise etching of target substrate 10. In some embodiments, gutter 16 is formed by focused ablation (e.g., laser ablation). In some embodiments, gutter 16 is formed in target substrate 10 by patternwise depositing a layer of material on target substrate 10 that defines gutter 16 by where material is not deposited, where the layer of material defines substrate surface 11. Such deposition can happen by photolithographic processing or other means, such as slot-die coating, inkjet printing, or other related techniques.
Examples of micro-transfer printing processes suitable for disposing components 30 onto target substrates 10 are described in Inorganic light-emitting diode displays using micro-transfer printing (Journal of the Society for Information Display, 2017, DOI #10.1002/jsid.610, 1071-0922/17/2510-0610, pages 589-609), U.S. Pat. No. 8,722,458 entitled Optical Systems Fabricated by Printing-Based Assembly, U.S. Pat. No. 10,103,069 entitled Pressure Activated Electrical Interconnection by Micro-Transfer Printing, U.S. Pat. No. 8,889,485 entitled Methods for Surface Attachment of Flipped Active Components, U.S. patent application Ser. No. 14/822,864 entitled Chiplets with Connection Posts, U.S. Pat. No. 10,224,460 entitled Micro Assembled LED Displays and Lighting Elements, and U.S. Pat. No. 10,153,256, entitled Micro-Transfer Printable LED Component, the disclosure of each of which is incorporated herein by reference in its entirety.
For a discussion of various micro-transfer printing techniques, see also U.S. Pat. Nos. 7,622,367 and 8,506,867, each of which is hereby incorporated by reference in its entirety. Micro-transfer printing using compound micro-assembly structures and methods can also be used in certain embodiments, for example, as described in U.S. patent application Ser. No. 14/822,868, filed Aug. 10, 2015, entitled Compound Micro-Assembly Strategies and Devices, which is hereby also incorporated by reference in its entirety. In some embodiments, any one or more of component 30, structure 20, and printed structure 99 is a compound micro-assembled structure (e.g., a compound micro-assembled macro-system).
According to various embodiments, a component source wafer (e.g., a native component source wafer) can be provided with components 30, patterned sacrificial portions, tethers 32, and anchors already formed, or they can be constructed as part of a method in accordance with certain embodiments. Component source wafers and components 30, transfer element 40 (e.g., a stamp 40), and target substrate 10 can be made separately and at different times or in different temporal orders or locations and provided in various process states.
The spatial distribution of any one or more of components 30 and structures 20 is a matter of design choice for the end product desired. In some embodiments, all components 30 in an array on a component source wafer are transferred to a transfer element 40. In some embodiments, a subset of components 30 in an array on a native component source wafer is transferred. By varying the number and arrangement of stamp posts 42 on transfer stamps 40, the distribution of components 30 on stamp posts 42 of transfer stamp 40 can be likewise varied, as can the distribution of components 30 and structures 20 on target substrate 10.
Structures 20 can be disposed in an array on target substrate 10. For example, structures 20 can be disposed by printing (e.g., micro-transfer printing) them onto target substrate 10. Structures 20 can be disposed in a regular array. Structures 20 can be disposed in an array having a linear density in one or two dimensions. The linear density can be, for example, no more than 200 structures 20 per mm and/or no less than 0.1 structure 20 per mm. Components 30 can be disposed in an array (e.g., a regular array) that corresponds to the array (e.g., regular array) in which structures 20 are disposed. Because components 30, in certain embodiments, can be made using integrated circuit photolithographic techniques having a relatively high resolution and cost and target substrate 10, for example a printed circuit board, can be made using printed circuit board techniques having a relatively low resolution and cost, electrical conductors (e.g., electrodes 72) can be much larger than electrical contacts or component electrodes on component 30, thereby reducing manufacturing costs. For example, in certain embodiments, printable component 30 has at least one of a width, length, and height from 0.5 μm to 200 μm (e.g., 0.5 to 2 μm, 2 to 5 μm, 5 to 10 μm, 10 to 20 μm, 20 to 50 μm, or 50 to 100 μm, or 100 to 200 μm).
In certain embodiments, target substrate 10 is or comprises a member selected from the group consisting of polymer (e.g., plastic, polyimide, PEN, or PET), resin, metal (e.g., metal foil) glass, a semiconductor, and sapphire. In certain embodiments, a target substrate 10 has a thickness from 5 microns to 20 mm (e.g., 5 to 10 microns, 10 to 50 microns, 50 to 100 microns, 100 to 200 microns, 200 to 500 microns, 500 microns to 0.5 mm, 0.5 to 1 mm, 1 mm to 5 mm, 5 mm to 10 mm, or 10 mm to 20 mm).
Components 30, in certain embodiments, can be constructed using foundry fabrication processes used in the art. Layers of materials can be used, including materials such as metals, oxides, nitrides and other materials used in the integrated-circuit art. Each component 30 can be or include a complete semiconductor integrated circuit and can include, for example, any combination of one or more of a transistor, a diode, a light-emitting diode, and a sensor. Components 30 can have different sizes, for example, at least 100 square microns (e.g., at least 1,000 square microns, at least 10,000 square microns, at least 100,000 square microns, or at least 1 square mm). Alternatively or additionally, components 30 can be no more than 100 square microns (e.g., no more than 1,000 square microns, no more than 10,000 square microns, no more than 100,000 square microns, or no more than 1 square mm). Components 30 can have variable aspect ratios, for example from 1:1 to 10:1 (e.g., 1:1, 2:1, 5:1, or 10:1). Components 30 can be rectangular or can have other shapes, such as polygonal or circular shapes for example.
Various embodiments of structures and methods were described herein. Structures and methods were variously described as transferring components 30, printing components 30, or micro-transferring components 30. In some embodiments, micro-transfer-printing involves using a transfer element 40 (e.g., an elastomeric stamp 40, such as a PDMS stamp 40) to transfer a component 30 using controlled adhesion. For example, an exemplary transfer device can use kinetic or shear-assisted control of adhesion between a transfer element and a component 30. It is contemplated that, in certain embodiments, where a method is described as including printing (e.g., micro-transfer-printing) a component 30, other similar embodiments exist using a different transfer method. In some embodiments, transferring or printing a component 30 (e.g., from a native component source substrate or wafer to a destination patterned target substrate 10) can be accomplished using any one or more of a variety of known techniques. For example, in certain embodiments, a pick-and-place method can be used to print components 30 or structures 20. As another example, in certain embodiments, a flip-chip method can be used (e.g., involving an intermediate, handle or carrier substrate). In methods according to certain embodiments, a vacuum tool, an electro-static tool, a magnetic tool, or other transfer device is used to transfer a component 30.
The figures that show transfer element 40 are simplified to show transfer element 40 printing a single component 30. In some embodiments, a single component 30 is printed using transfer element 40 in a single print step. Accordingly, 10 components 30 can be printed using transfer element 40 in 10 print steps. In some embodiments, a plurality of components are printed using transfer element 40 in a single print step. For example, in some embodiments, at least 10 components 30, e.g., at least 50 components 30, at least 100 components 30, at least 1,000 components 30, at least 10,000 components 30, or at least 50,000 components 30 can be or are printed in a single print step.
Those of ordinary skill in the art will appreciate that high-precision structures, components therefor, and methods of making that can be adapted into, applied to, and/or used with embodiments disclosed in the present application are disclosed in U.S. Pat. No. 10,714,374, the disclosure of which is hereby incorporated by reference in its entirety.
As is understood by those skilled in the art, the terms “over” and “under” are relative terms and can be interchanged in reference to different orientations of the layers, elements, and substrates included in various embodiments of the present disclosure. Furthermore, a first layer or first element “on” a second layer or second element, respectively, is a relative orientation of the first layer or first element to the second layer or second element, respectively, that does not preclude additional layers being disposed therebetween. For example, a first layer on a second layer, in some implementations, means a first layer directly on and in contact with a second layer. In other implementations, a first layer on a second layer includes a first layer and a second layer with another layer therebetween (e.g., and in mutual contact).
Having described certain implementations of embodiments, it will now become apparent to one of skill in the art that other implementations incorporating the concepts of the disclosure may be used. Therefore, the disclosure should not be limited to certain implementations, but rather should be limited only by the spirit and scope of the following claims.
Throughout the description, where apparatus and systems are described as having, including, or comprising specific elements, or where processes and methods are described as having, including, or comprising specific steps, it is contemplated that, additionally, there are apparatus and systems of the disclosed technology that consist essentially of, or consist of, the recited elements, and that there are processes and methods according to the disclosed technology that consist essentially of, or consist of, the recited processing steps.
It should be understood that the order of steps or order for performing certain action is immaterial so long as the disclosed technology remains operable. Moreover, two or more steps or actions in some circumstances can be conducted simultaneously. The disclosure has been described in detail with particular reference to certain embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the following claims.
This application claims the benefit of U.S. Patent Application No. 63/339,934 filed May 9, 2022 entitled High-Precision Structures and Methods of Making, the content of which is hereby incorporated by reference in its entirety. Reference is made to U.S. patent application Ser. No. 16/186,173 filed Nov. 9, 2018 entitled “Interconnection by Lateral Printing” by Meitl et al., the disclosure of which is incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63339934 | May 2022 | US |
