Patent Application
20190300289
The present invention relates generally to micro-transfer printing micro-scale devices from source substrates to destination substrates and, in particular, to roll-to-roll manufacturing.
Monocrystalline semiconductor processing techniques are limited to relatively small size substrates. For example, semiconductor wafers photolithographically processed at very high resolutions have sizes of up to 300 mm in diameter and are limited by the photolithographic handling and processing equipment. Devices made from the wafers typically provide high performance and are relatively expensive.
Roll-to-roll manufacturing processes employ much larger substrates at a reduced cost compared to monocrystalline wafer processing. Roll-to-roll manufacturing is the process of applying coatings or performing other processes on a roll of flexible material. The flexible material is initially wound in a roll, the roll is turned about an axis to unwind or spool successive portions of the flexible material to a flat configuration for deposition or processing, and then rewound into a second roll of coated or processed flexible material. This process is also known as reel-to-reel processing or web processing, where the flexible material is referred to as a web. After processing, the web can be slit to a desired width and then cut to a desired sheet size.
Roll-to-roll processing has been used for many years to provide low-cost manufacturing for coated substrates such as photographic film and paper. In recent years, electronic devices have been printed on substrates in a roll-to-roll process by patterning a coating or applying patterned coatings to the web. For example, large, thin-film transistor circuits can be patterned onto the web. Such electronic devices typically have relatively low performance compared to monocrystalline semiconductor devices, for example the printed conductive or semiconductor materials such as doped polythiophenes typically have a lower electron mobility and current-carrying capacity as well as a coarser resolution. Inkjet and photolithographic processes are used in conjunction with roll-to-roll processing.
Roll-to-roll processes form electronically active components by pattern-wise printing materials onto a flexible substrate to form flexible circuits. For example, KR20101488419 B1 entitled “Method for mass-producing of double side flexible printed circuit board by using roll-to-roll printing process and system thereof” discloses a method for mass-manufacturing double-sided flexible printed circuit boards using a roll-to-roll continuous printing process and system. U.S. Pat. No. 8,689,687 B2 entitled “Method and apparatus for manufacturing electronic device using roll-to-roll rotary pressing process” illustrates an apparatus for manufacturing electronic devices using a roll-to-roll rotary pressing process. KR100763493 entitled “Microcontact printing device of roll-to-roll printing type” describes a micro-contact printing device of roll-to-roll print type provided to form a micro metal pattern on a paper or plastic substrate by using an elastomer stamp enclosing an outer periphery of a roller. A related application KR100787237 entitled “Microcontact printing device of roll-print type using PDMS stamp” describes a polydimethylsiloxane stamp and KR100873516B1 entitled “Micro-contact printing device using an elastomeric stamp” uses a piezo actuator for displacement control. KR101240319B1 entitled “Roll imprint method and apparatus with dual stamp” uses a double stamp arrangement for imprinting a surface with a 3D nano-structure.
The above techniques have some limitations. Despite processing methods used to improve the performance of thin-film transistors, such transistors can provide performance that is lower than the performance of other integrated circuits formed in mono-crystalline semiconductor material. Semiconductor material and active components can be provided only on portions of the substrate, leading to wasted material and processing costs. The choice of substrate materials (e.g., a web) can also be limited by the processing steps necessary to process the semiconductor material and the photo-lithographic steps used to pattern the active components. For example, plastic substrates have a limited chemical and heat tolerance and do not readily survive photo-lithographic processing. Furthermore, the manufacturing equipment used to process large substrates with thin-film circuitry is relatively expensive.
Some methods used for distributing electronically functional components over a relatively large substrate (such as circuit board assembly) include pick-and-place technologies for integrated circuits provided in a variety of packages, for example, pin-grid arrays, ball-grid arrays, and flip-chips. However, these techniques can be limited to relatively large integrated circuits or components that can be placed and do not take advantage of the efficiencies provided by roll-to-roll processing.
Another method for transferring active components from one substrate to another is described in “AMOLED Displays using Transfer-Printed Integrated Circuits” published in the Proceedings of the 2009 Society for Information Display International Symposium Jun. 2-5, 2009, in San Antonio Tex., US, vol. 40, Book 2, ISSN 0009-0966X, paper 63.2 p. 947. In this approach, small integrated circuits are formed over a buried oxide layer on the process side of a crystalline wafer. The small integrated circuits, or chiplets, are released from the wafer by etching the buried oxide layer formed beneath the circuits. A PDMS stamp is pressed against the wafer and the process side of the chiplets is adhered to the stamp. The chiplets are pressed against a destination substrate or backplane coated with an adhesive and thereby adhered to the destination substrate. The adhesive is subsequently cured. 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. These transfer methods employ linear motion which requires the stamp to stop and start each time the stamp comes into contact with the chiplets.
There is a need, therefore, for structures and methods that provide high-performance micro-devices on large substrates at a reduced cost with greater efficiency, and at higher speeds to provide high-performance electronic systems.
According to certain embodiments of the present invention, a roll micro-transfer printer comprises a source substrate transport for transporting a source substrate. The source substrate comprises sacrificial portions spaced apart by anchors. A micro-device is disposed exclusively on, in, over, or under each of the sacrificial portions and physically connected to at least one of the anchors by one or more tethers. A roll stamp comprises a visco-elastic material disposed in alignment with the source substrate transport so that, when a source substrate is disposed on or in the source substrate transport, the roll stamp contacts one or more micro-devices to fracture or separate the one or more tethers physically connecting each of the one or more micro-devices to the source substrate and adhere the one or more micro-devices to the roll stamp. A destination substrate transport for transporting a destination substrate is disposed in alignment with the roll stamp so that, when one or more micro-devices are disposed on the roll stamp, the one or more micro-devices contact and adhere to the destination substrate. The roll stamp is disposed to rotate about a roll stamp axis, the source substrate transport is disposed to translate the source substrate in a source substrate direction orthogonal to the roll stamp axis, and the destination substrate transport is disposed to translate the destination substrate in a destination substrate direction opposite to the source substrate direction.
In some embodiments of the present invention, a source substrate is disposed on the source substrate transport and a destination substrate is disposed on the destination substrate transport and the roll micro-transfer printer is operated to translate the source substrate in a source substrate direction, to translate the destination in a destination substrate direction opposed to the source substrate direction, and to rotate the roll stamp so that micro-devices are micro-transfer printed from the source substrate to the destination substrate with the roll stamp.
In some embodiments of the present invention, a source substrate is one or more of a wafer, an intermediate substrate, a rigid sheet, and a flexible sheet. A destination substrate can be one or more of a wafer, an intermediate substrate, a rigid sheet, a flexible sheet, and a display substrate. The micro-device can be, without limitation, one or more of an integrated circuit, a sensor, and a light-emitting diode.
In certain embodiments, a cleaning roller rotates about a cleaning roller axis parallel to the roll stamp axis and is disposed to contact the roll stamp.
In some embodiments, micro-devices are arranged in one or more rows on a source substrate and a roll stamp contacts a row of micro-devices on the source substrate to transfer the row of micro-devices from the source substrate to the roll stamp and a destination substrate contacts a row of micro-devices on the roll stamp to transfer the row of micro-devices from the roll stamp to the destination substrate.
In some embodiments, a roll stamp has a roll stamp surface and comprises stamp posts that protrude from the roll stamp surface. Each stamp post is disposed to contact a micro-device on a source substrate.
In some embodiments, micro-devices are arranged in rows on a source substrate and one or more stamp posts contact a subset of the micro-devices in a row. In some embodiments, the stamp posts contact micro-devices in a subset of the rows. In some embodiments, the stamp posts contact a subset of micro-devices in a row and the stamp posts contact micro-devices in a subset of the rows.
In some embodiments of the present invention, a roll stamp is a first roll stamp, micro-devices are first micro-devices, and one or more tethers are one or more first tethers. A source substrate comprises second sacrificial portions and a second micro-device is disposed exclusively on, in, over, or under each of the second sacrificial portions and physically connected to at least one anchor by one or more second tethers. A roll micro-transfer printer can comprise a second roll stamp comprising a visco-elastic material disposed in alignment with the source substrate transport so that, when a source substrate is disposed on the source substrate transport, the second roll stamp contacts one or more second micro-devices to fracture or separate the one or more second tethers physically connecting each of the one or more second micro-devices to the source substrate and adheres the one or more second micro-devices to the second roll stamp. A destination substrate is disposed in alignment with the second roll stamp so that, when one or more second micro-devices are disposed on the second roll stamp, the one or more second micro-devices contact and adhere to the destination substrate.
In some embodiments, the printer comprises a controller that controls (i) the roll stamp to rotate about the roll stamp axis, (ii) the source substrate transport to translate the source substrate in the source substrate direction, and (iii) the destination substrate transport to translate the destination substrate in the destination substrate direction.
In some embodiments, a first roll stamp comprises first stamp posts, a second roll stamp comprises second stamp posts and the first stamp posts are offset with respect to the second stamp posts in the roll stamp axis direction. The first roll stamp can be offset with respect to the second roll stamp in the roll stamp axis direction. In some embodiments, a controller controls a first roll stamp to contact first micro-devices of a source substrate at a first substrate offset at a first time and a second roll stamp to contact second micro-devices of the source substrate at a second substrate offset different from the first substrate offset and at a second time different from the first time.
In some embodiments, a source substrate is a first source substrate, a roll stamp is a first roll stamp, micro-devices are first micro-devices, and one or more tethers are one or more first tethers. A roll micro-transfer printer can comprise a second roll stamp comprising a visco-elastic material disposed in alignment with a source substrate transport and disposed in alignment with a destination substrate transport, so that, when a second source substrate is disposed in the source substrate transport in alignment with the second roll stamp, the second source substrate comprising second sacrificial portions spaced apart by second anchors and a second micro-device is disposed exclusively on, in, over, or under each of the second sacrificial portions and physically connected to at least one of the second anchors by one or more second tethers, the second roll stamp contacts one or more second micro-devices to fracture or separate the one or more second tethers physically connecting each of the one or more second micro-devices to the second source substrate and adheres the one or more second micro-devices to the second roll stamp, and the second roll stamp contacts the destination substrate with one or more second micro-devices and adheres the one or more second micro-devices to the destination substrate. The first source substrate can be offset with respect to the second source substrate in the roll stamp axis direction.
In some embodiments of the present invention, a method of micro-transfer printing from a source substrate to a destination substrate with a roll stamp comprises providing a roll micro-transfer printer comprising a source substrate transport for transporting a source substrate disposed on or in the source substrate transport, the source substrate comprising sacrificial portions spaced apart by anchors and wherein a micro-device is disposed exclusively on, in, over, or under each of the sacrificial portions and physically connected to at least one of the anchors by one or more tethers, a roll stamp comprising a visco-elastic material disposed in alignment with the source substrate transport and source substrate, and a destination substrate transport for transporting a destination substrate disposed in alignment with the roll stamp. The roll stamp is disposed to rotate about a roll stamp axis, the source substrate transport is controlled to translate a source substrate in a source substrate direction orthogonal to the roll stamp axis, and the destination substrate transport is disposed to translate a destination substrate in a destination substrate direction opposite to the source substrate direction. The roll stamp rotates to contact the micro-devices physically connected to the source substrate and fracture or separate the one or more tethers physically connecting each of the micro-devices to adhere the micro-devices to the roll stamp, and the micro-devices on the roll stamp are subsequently contacted with the destination substrate to adhere the micro-devices to the destination substrate.
In some embodiments, micro-devices each disposed exclusively on, in, over, or under each sacrificial portion are disposed in rows on a source substrate and the method comprises rotating the roll stamp (i) to contact fewer than all of the micro-devices in a row, (ii) to contact micro-devices in fewer than all of the rows, or (iii) both (i) and (ii).
In some embodiments, a method of the present invention comprises disposing a source substrate on or in a source substrate transport at a first offset with respect to a destination substrate during a first time, micro-transfer printing a first subset of micro-devices from the source substrate to the destination substrate at the first time, disposing the source substrate on the source substrate transport at a second offset with respect to the destination substrate during a second time different from the first time, and subsequently micro-transfer printing a second subset of micro-devices different from the first subset of micro-devices from the source substrate to the destination substrate during the second time.
In some embodiments, the roll stamp is a first roll stamp, micro-devices each disposed exclusively on, in, over, or under each sacrificial portion are first micro-devices, and one or more tethers physically connecting each of the micro-devices to a source substrate are one or more first tethers. A roll micro-transfer printer can comprise a second roll stamp comprising a visco-elastic material disposed in alignment with the source substrate transport and disposed in alignment with the destination substrate transport, so that, when a second source substrate is disposed in the source substrate transport in alignment with the second roll stamp, the second source substrate comprising second sacrificial portions spaced apart by second anchors and a second micro-device is disposed exclusively on, in, over, or under each of the second sacrificial portions and physically connected to an anchor by one or more second tethers, the method comprises rotating the second roll stamp to contact the one or more second micro-devices and fracture or separate the one or more second tethers physically connecting each of the one or more second micro-devices to the second source substrate to adhere the one or more second micro-devices to the second roll stamp, and subsequently contacting the one or more second micro-devices disposed on the second roll stamp with the destination substrate to adhere the second micro-devices to the destination substrate.
In some embodiments, the roll micro-transfer printer comprises a controller that controls (i) the roll stamp to rotate about the roll stamp axis, (ii) the source substrate transport to translate the source substrate in the source substrate direction, and (iii) the destination substrate transport to translate the destination substrate in the destination substrate direction.
In some embodiments, the micro-devices comprise light-emitting elements. In some embodiments, the light-emitting elements are inorganic light-emitting diodes. In some embodiments, the inorganic light-emitting diodes are micro-transfer printed light-emitting diodes each comprising a broken (e.g., fractured) or separated tether. In some embodiments, each micro-device has at least one or more of a width from 2 to 5 μm, 5 to 10 μm, 10 to 20 μm, or 20 to 50 μm, a length from 2 to 5 μm, 5 to 10 μm, 10 to 20 μm, or 20 to 50 μm, and a thickness from 2 to 5 μm, 4 to 10 μm, 10 to 20 μm, or 20 to 50 μm. In other embodiments, each micro-device has at least one or more of a width from 50 to 100 μm, 100 to 250 μm, 250 to 500 μm, or 500 to 999 μm, a length from 50 to 100 μm, 100 to 250 μm, 250 to 500 μm, or 500 to 999 μm, and a thickness from 5 to 50 μm or 50 to 100 μm.
Certain embodiments of the present invention provide, inter alia, methods, devices, and systems that enable the transfer of high-performance micro-devices from a source to a destination substrate with lower cost, with greater efficiency, and at higher speeds.
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:
The 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 drawn to scale since the variation in size of various elements in the Figures is too great to permit depiction to scale.
The present invention provides, inter alia, systems and methods for micro-transfer printing micro-devices from a source substrate to a destination substrate with a roll micro-transfer printer. A source substrate can be a native source substrate on which the micro-devices are formed, and a destination substrate can be any suitable surface, including glass and plastic surfaces. A source substrate can be a flexible substrate provided in roll form or a series of relatively planar rigid substrates provided in a serial stream. Likewise, a destination substrate can be a flexible substrate provided in roll form or a series of relatively planar rigid substrates provided in a serial stream. A roll micro-transfer printer can comprise a visco-elastic roll stamp, for example a cylinder or roller rotating about an axis of the cylinder or roller. The roll stamp contacts the source substrate and destination substrate to transfer micro-devices from the source substrate to the destination substrate. The source and destination substrates move in opposite directions corresponding to the direction of their contact with the rotating cylinder. The contact between the roll stamp and the substrates can be in a planar configuration or in a curve.
Referring to
A roll stamp 30 comprising a visco-elastic material, such as PDMS (polydimethylsiloxane), is disposed in alignment with a source substrate transport 10 and source substrate 11 to contact one or more micro-device 20A attached to the source substrate 11 and fracture or separate the one or more tethers 24 to adhere the one or more micro-device 20A to the roll stamp 30. The roll stamp can be primarily cylindrical. In certain embodiments of the present invention, a roll stamp 30 comprises a cylinder with a visco-elastic material formed in a layer or wrapped around the cylinder.
A destination substrate transport 50 for transporting a destination substrate 51 is disposed in alignment with the roll stamp 30. A destination substrate transport 50 can be, for example, a substrate holder (e.g., a holder comprising one or more clamps), an element with a surface on which a destination substrate 51 can be disposed (e.g., attached or suctioned to) (e.g., as shown in
The roll stamp 30 is disposed (e.g., controlled) to rotate about a roll stamp axis 34 that extends in a roll-stamp axis direction 36. A source substrate transport 10 is disposed (e.g., controlled) to translate a source substrate 11 in a source substrate direction 18 orthogonal to the roll-stamp axis direction 36, and a destination substrate transport 50 is disposed (e.g., controlled) to translate a destination substrate 51 in a destination substrate direction 52 opposite to the source substrate direction 18. Translation and rotation can occur through mechanical means or by a controller (e.g., electromechanically), for example. An opposite direction can be, but is not necessarily a parallel direction, but is at least partially in an opposed direction. That is, vectors describing the directions in a common dimension are opposed so that, for example the x dimension of the source substrate direction 18 is opposed to the x dimension of the destination substrate direction 52. The roll stamp 30, source substrate transport 10, and destination substrate transport 50 can be controlled by a controller, for example a control computer incorporating integrated circuits in conjunction with a mechanical assembly responsive to control signals provided by the control computer.
In some embodiments, a source substrate 11 is a source wafer, for example a native substrate on which one or more micro-devices 20A are formed or disposed, such as a native semiconductor wafer, or an intermediate substrate on which one or more micro-devices 20 are assembled using micro-transfer printing, for example in a circuit employing compound micro-assembly and processed using photolithography. A source substrate 11 can be rigid and planar and can be a sheet. In some embodiments, a source substrate 11 is a flexible substrate, such as a web, and can be wound in a roll on a feed roller 60, unwound for micro-transfer printing, and then wound up again in a roll on a take-up roller 62 (e.g., as shown in
Similarly, in some embodiments, a destination substrate 51 is a substrate, such as a glass or plastic substrate to which one or more micro-devices 20C are adhered after printing. A destination substrate 51 can be a display substrate, an intermediate substrate, or a wafer. A destination substrate 51 can be rigid and planar and can be a sheet. In some embodiments, a destination substrate 51 is a flexible substrate, such as a web, and can be wound in a roll on a feed roller 60, unwound for micro-transfer printing, and then wound up again in a roll on a take-up roller 62 (e.g., as shown in
A roll stamp 30 can comprise a cylinder with a roll stamp surface and can comprise one or more protruding stamp posts 32 that contact micro-devices 20A on a source substrate 11, adhere micro-devices 20B to stamp posts 32, and then contact the micro-devices 20B to a destination substrate 51 to adhere the micro-devices 20C to the destination substrate 51. In some embodiments, a roll stamp 30 does not have protruding stamp posts 32.
In some embodiments, micro-devices 20 are one or more of an integrated circuit, a sensor, and a light-emitting diode. In certain embodiments of the present invention, other micro-devices 20 are included, such as small circuits electrically connected on an intermediate substrate, for example in a structure using compound micro-assembly (e.g., thereby forming a compound micro-system). Certain embodiments of the present invention have the advantage that very small micro-devices 20 can be transferred from source to destination substrates, for example micro-devices with at least one of a thickness less than or equal to 20 μm and a length less than or equal to 100 μm, 50 μm, 20 μm, 10 μm, or 5 μm and a width less than or equal to 100 μm, 50 μm, 20 μm, 10 μm, or 5 μm. Such small devices cannot be readily picked up from a source supply and accurately disposed on a destination surface using conventional methods. In particular, the use of one or more tethers 24 to precisely locate each transferable micro-device 20 on a source substrate 11 and stamp posts 32 on a roll stamp 30 to pick up the micro-devices 20 enables very accurate, efficient, and rapid micro-device 20 from a source substrate 11 to a destination substrate 51.
A roll micro-transfer printer 99 can comprise a control computer and mechanical assembly that controls a source substrate transport 10, a destination substrate transport 50, and a roll stamp 30. In operation, a source substrate transport 10 is disposed (e.g., controlled) to translate a source substrate 11 in a source substrate direction 18 and a destination substrate transport 50 is disposed (e.g., controlled) to translate a destination substrate 51 in a destination substrate direction 52 opposite to the source substrate direction 18. A roll stamp 30 is rotated about its roll stamp axis 34 so that the surface or the stamp posts 32 of the roll stamp 30 contact micro-devices 20A on a source substrate 11 at a speed and in a direction matching the speed and direction of the source substrate 11. Likewise, a surface or stamp posts 32 of the roll stamp 30 contact a destination substrate 51 with micro-devices 20B on the surface or stamp posts 32 of the roll stamp 30 (for example at a location on the roll stamp 30 diametrically opposite the contact with the source substrate 11) at a speed and in a direction matching the speed and direction of the destination substrate 51. Thus, a source substrate 11 and a destination substrate 51 can move at the same speed in opposite directions.
As shown in the detail of
Referring to the detail of
A source substrate 11 translates in a source substrate direction 18 and a surface or stamp post 32 of a roll stamp 30 rotates into contact with and adheres a micro-device 20A to the stamp post 32 or stamp surface. As a stamp post 32 or surface contact rotates away from the source substrate 11 with an adhered micro-device 20, the tether 24 fractures or separate, leaving the micro-device 20B adhered to a stamp post 32 or surface of the roll stamp 30.
Referring to
As shown in
As shown in
Referring to
Referring to
As shown in
In some embodiments of the present invention, micro-devices 20A are arranged in rows on a source substrate 11 and stamp posts 32 contact a subset of the micro-devices 20A in a row and the stamp posts 32 contact the micro-devices 20A in a subset of the rows. For example, if a source substrate 11 has a four-by-four array of micro-devices 20A and stamp posts 32 contact every other micro-device 20A in every other row, a destination substrate 51 will adhere a two-by-two array of micro-devices 20C spaced apart twice as far as on the source substrate 11.
Referring again to
Thus, in some embodiments, a roll micro-transfer printer 99 comprises a roll stamp 30 that is a first roll stamp 30A, micro-devices 20 are first micro-devices 20, and one or more tethers 24 are one or more first tethers 24. A source substrate 11 comprises second sacrificial portions 12 and a second micro-device 20A is disposed exclusively on, in, over, or under each of the second sacrificial portions 12 and is physically connected to at least one anchor 22 by one or more second tethers 24. The roll micro-transfer printer 99 comprises a second roll stamp 30B. When a source substrate 11A is disposed on a source substrate transport 10, a second roll stamp 30B contacts one or more second micro-devices 20A to fracture or separate one or more second tethers 24 physically connecting each of one or more second micro-devices 20 to the source substrate 11A and adheres one or more second micro-devices 20B to the second roll stamp 30B. The destination substrate 51 is disposed in alignment with the second roll stamp 30B so that, when one or more second micro-devices 20B are disposed on the second roll stamp 30B, the one or more second micro-devices 20C contact and adhere to the destination substrate 51.
A first roll stamp 30A can comprise first stamp posts 32, a second roll stamp 30B can comprise second stamp posts 32, wherein the first stamp posts 32 are offset with respect to the second stamp posts 32 in a roll-stamp axis direction 36. In some embodiments, a first roll stamp 30A is offset with respect to a second roll stamp 30B in a roll-stamp axis direction 36 to distribute micro-devices 20C over the surface of a destination substrate 51.
A roll micro-transfer printer 99 can comprise a controller such as a control computer or state machine that controls a first roll stamp 30A to contact first micro-devices 20A of a source substrate 11 at a first substrate offset at a first time and controls a second roll stamp 30B to contact second micro-devices 20A of the source substrate 11 at a second substrate offset different from the first substrate offset and at a second time different from the first time. The substrate offsets are with respect to the destination substrate 51 and destination substrate transport 50.
In the exemplary embodiment shown in
Thus, in some embodiments, a source substrate 11 is a first source substrate 11, a roll stamp 30 is a first roll stamp 30A, micro-devices 20 are first micro-devices 20, and one or more tethers 24 are one or more first tethers 24. A roll micro-transfer printer 99 comprises a second roll stamp 30B comprising a visco-elastic material disposed in alignment with a source substrate transport 10 and the first source substrate 11 and disposed in alignment with a destination substrate transport 50 and destination substrate 51 so that when a second source substrate 11 is disposed in the source substrate transport 10 in alignment with the second roll stamp 30, the second source substrate 11 comprising second sacrificial portions 12 spaced apart by second anchors 22 and a second micro-device 20A is disposed exclusively on, in, over, or under each of the second sacrificial portions 12 and physically connected to at least one of the second anchors 22 by one or more second tethers 24, the second roll stamp 30B contacts one or more second micro-devices 20A to fracture or separate the one or more second tethers 24 physically connecting each of one or more second micro-devices 20 to the second source substrate 11 and adheres one or more second micro-devices 20B to the second roll stamp 30B, and the second roll stamp 30B contacts a destination substrate 51 with one or more second micro-devices 20B and adheres one or more second micro-devices 20C to the destination substrate 51. In some embodiments, a first source substrate 11 is offset with respect to a second source substrate 11 in a roll-stamp axis direction 36 to distribute the micro-devices 20C over the surface of the destination substrate 51.
Referring to
According to some embodiments, during operation of a roll micro-transfer printer 99, a source substrate 11 is located above a roll stamp 30 and the roll stamp 30 is located above a destination substrate 51 with respect to the direction of gravity. Thus, the force of gravity assists in removing micro-devices 20A from a source substrate 11 and in adhering micro-devices 20C to a destination substrate 51.
Referring to
In some embodiments, micro-devices 20A, each disposed exclusively on, in, over, or under each sacrificial portion 12, are disposed in rows on a source substrate 11. An exemplary method according to certain embodiments of the present invention comprises rotating a roll stamp 30 (i) to contact fewer than all of the micro-devices 20A in a row, (ii) to contact micro-devices 20A in fewer than all of the rows, or (iii) both (i) and (ii).
In some embodiments of the present invention, and referring to
Referring to
According to certain embodiments of the present invention, micro-devices 20 can be any one or more of integrated circuits, sensors, and organic or inorganic light-emitting diodes. In some embodiments, each micro-device 20 has at least one or more of a width of no more than 100 μm or no more than 50 μm (e.g., from 2 μm to 5 μm, 5 μm to 10 μm, 10 μm to 20 μm, or 20 μm to 50 μm), a length of no more than 100 μm or no more than 50 μm (e.g., from 2 μm to 5 μm, 5 μm to 10 μm, 10 μm to 20 μm, or 20 μm to 50 μm), and a thickness of no more than 100 μm or no more than 50 μm (e.g., from 2 μm to 5 μm, 5 μm to 10 μm, 10 μm to 20 μm, or 20 μm to 50 μm). In some embodiments, each micro-device 20 has at least one of a width of no more than 1 mm (e.g., from 50 μm to 100 μm, 100 μm to 250 μm, 250 μm to 500 μm, or 500 μm to 999 μm), a length of no more than 1 mm (e.g., from 50 μm to 100 μm, 100 μm to 250 μm, 250 μm to 500 μm, or 500 μm to 999 μm), and a thickness from 5 μm to 50 μm or 50 μm to 100 μm. U.S. Pat. No. 6,825,559 describes methods of making micro-transfer-printable inorganic micro-devices 20; the disclosure of the methods of making micro-transfer-printable inorganic micro-devices of which is hereby incorporated by reference.
Structures and elements in accordance with certain embodiments of the present invention can be made and assembled using micro-transfer printing methods and materials. In some embodiments, micro-devices 20A are prepared on a native source substrate 11, for example a sapphire wafer with compound semiconductors such as GaN or silicon wafers with CMOS circuits thereon, with each type of micro-device 20A prepared on a different source substrate 11 and released for micro-transfer printing with one or more micro-device tethers 24 physically connecting the micro-devices 20A to an anchor 22 portion of the respective source substrate 11. In certain embodiments, micro-devices 20A are then contacted with a micro-transfer printing roll stamp 30 to fracture or otherwise break (or separate) the micro-device tethers 24 and adhere the micro-devices 20B to the transfer roll stamp 30, the transfer roll stamp 30 rotates, and the micro-devices 20C are contacted and adhered to the destination substrate 51.
For a discussion of micro-transfer printing techniques see U.S. Pat. Nos. 8,722,458, 7,622,367 and 8,506,867; the disclosure of micro-transfer printing techniques of each of which is hereby incorporated by reference. Methods of forming micro-transfer printable structures are described, for example, in the paper “AMOLED Displays using Transfer-Printed Integrated Circuits” (Journal of the Society for Information Display, 2011, DOI # 10.1889/JSID19.4.335, 1071-0922/11/1904-0335, pages 335-341) and U.S. Pat. No. 8,889,485. Micro-transfer printing using compound micro-assembly structures and methods can also be used with certain embodiments of the present invention, 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; the disclosure of micro-transfer printing using compound micro-assembly structures of which is hereby incorporated by reference in their entirety. Additional details useful in understanding and performing aspects of the present invention are described in U.S. patent application Ser. No. 14/743,981, filed Jun. 18, 2015, entitled Micro Assembled LED Displays and Lighting Elements, the disclosure of which is hereby incorporated by reference in their entirety.
As is understood by those skilled in the art, the terms “over”, “under”, “above”, “below”, “beneath”, and “on” are relative terms and can be interchanged in reference to different orientations of the layers, elements, and substrates included in the present invention. For example, a first layer on a second layer, in some embodiments means a first layer directly on and in contact with a second layer. In other embodiments, a first layer on a second layer can include another layer there between.
Having described certain embodiments, it will now become apparent to one of skill in the art that other embodiments incorporating the concepts of the disclosure may be used. Therefore, the invention should not be limited to the described embodiments, 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 components, 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 components, 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 invention 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 invention.
