Patent Application
20250235981
Disclosed implementations relate generally to the field of semiconductor fabrication. More particularly, but not exclusively, the disclosed implementations relate to a chemical mechanical polishing (CMP) tool and a polisher head having an over-rotation restrictor mechanism.
In the fabrication of integrated circuits and other electronic devices, multiple layers of conducting, semiconducting and dielectric materials are deposited onto and removed from a surface of a semiconductor wafer. Thin layers of conducting, semiconducting and dielectric materials may be deposited using a number of deposition techniques. Common deposition techniques in modern wafer processing include physical vapor deposition (PVD), also known as sputtering, chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD) and electrochemical plating, among others. Common removal techniques include wet and dry isotropic and anisotropic etching, among others.
As layers of materials are sequentially deposited and removed, the uppermost surface of the wafer becomes non-planar. Because subsequent semiconductor processing (e.g., metallization) requires the wafer to have a flat surface, the wafer needs to be planarized. Planarization is useful for removing undesired surface topography and surface defects, such as, e.g., rough surfaces, agglomerated materials, crystal lattice damage, scratches and contaminated layers or materials, and the like.
Chemical mechanical planarization, or chemical mechanical polishing (CMP), is a common technique used to planarize work pieces such as semiconductor process wafers. In conventional CMP, a wafer carrier, or polisher head, is mounted on a carrier assembly. The polisher head holds the wafer and positions the wafer in contact with a polishing layer of a polishing pad within a CMP apparatus. The carrier assembly provides a controllable pressure between the wafer and polishing pad. Because of the rotational and frictional forces generated during CMP processes, undesirable stress conditions may be developed that may negatively impact certain consumable parts of the polisher head in some arrangements.
The following presents a simplified summary in order to provide a basic understanding of one or more aspects of some examples of the present disclosure. This summary is not an extensive overview of the examples, and is neither intended to identify key or critical elements of the examples, nor to delineate the scope thereof. Rather, the primary purpose of the summary is to present some concepts of the present disclosure in a simplified form as a prelude to a more detailed description that is presented in subsequent sections further below.
In one example, a CMP tool includes a CMP polisher head configured to rotate around a first rotational axis and a platen having a polishing pad disposed thereon, the platen configured to rotate around a second rotational axis. A slurry dispenser is positioned proximate to the platen, the slurry dispenser operative to controllably deliver a slurry material on the polishing pad. The CMP polisher head includes a first rotational component having a flange for mounting to a spindle driven by a motor around the first rotational axis, the first rotational component having a rolling seal affixed proximate to a bottom terminus thereof. CMP polisher head also includes a second rotational component axially aligned with the first rotational component along the first rotational axis, the second rotational component attached to the first rotational component by engaging in a compressive arrangement with the rolling seal. An over-rotation limiting pin and a restrictor/lifter receptacle are provided with the first and second rotational components such that the over-rotation limiting pin and the restrictor/lifter receptacle operate, when respectively engaged, to provide a translation force to translate the second rotational component relative to the first rotational component along the first rotational axis.
In another example, a CMP polisher head is disclosed, which includes, inter alia, a polisher head having a floating head assembly configured to be driven around a rotational axis an upper head assembly disposed within the upper head assembly. An over-rotation limiting pin projects between the floating head assembly and the upper head assembly. A restrictor/lifter receptacle is located to receive the over-rotation limiting pin, the restrictor/lifter receptacle having a lateral width greater than a diameter of the over-rotation limiting pin.
In another example, a method of manufacturing a semiconductor wafer includes, inter alia, polishing a material layer over a semiconductor substrate, the polishing including applying a force between an upper head assembly of a CMP tool and a polishing pad. The semiconductor substrate is lifted off of the polishing pad, and simultaneous with the lifting, a translating force is applied between the upper head assembly and a floating head assembly via an over-rotation limiting pin projecting between the floating head assembly and the upper head assembly and a restrictor/lifter receptacle located to receive the over-rotation limiting pin.
Implementations of the present disclosure are illustrated by way of example, and not by way of limitation, in the Figures of the accompanying drawings. It should be noted that different references to “an” or “one” implementation in this disclosure are not necessarily to the same implementation, and such references may mean at least one. Further, when a particular feature, structure, or characteristic is described in connection with an implementation, it is submitted that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other implementations whether or not explicitly described.
The accompanying drawings are incorporated into and form a part of the specification to illustrate one or more example implementations of the present disclosure. Various advantages and features of the disclosure will be understood from the following Detailed Description taken in connection with the appended claims and with reference to the attached drawing Figures in which:
Examples of the disclosure are described with reference to the attached Figures wherein like reference numerals are generally utilized to refer to like elements. The Figures are not drawn to scale and they are provided merely to illustrate example examples. Numerous specific details, relationships, and methods are set forth below to provide an understanding of one or more examples. However, it should be understood that some examples may be practiced without such specific details. In other instances, well-known subsystems, components, structures and techniques have not been shown in detail in order not to obscure the understanding of the examples. Accordingly, it will be appreciated by one skilled in the art that the examples of the present disclosure may be practiced without such specific components.
In the following description, reference may be made to the accompanying drawings wherein certain directional terminology, such as, e.g., “upper”, “lower”, “top”, “bottom”, “left-hand”, “right-hand”, “front side”, “backside”, “vertical”, “horizontal”, etc., may be used with reference to the orientation of the Figures or illustrative elements thereof being described. Because components of some examples can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. Likewise, references to features referred to as “first”, “second”, etc., are not indicative of any specific order, importance, and the like, and such references may be interchanged mutatis mutandis, depending on the context, implementation, etc. Further, the features of examples described herein may be combined with each other unless specifically noted otherwise.
As used herein, the term “couple” or “couples” is intended to mean either an indirect or direct mechanical connection or attachment between two components or structures unless otherwise qualified.
Referring now to the drawings,
Polisher head 102, also referred to as a wafer carrier in some arrangements, is rotatable about an axis 110 by a motor (not shown) via a suitable drive mechanism, e.g., a shaft or spindle, to which polisher head 102 may be coupled as is known in the art. Polisher head 102 may be supported above polishing layer 130, wherein a carrier support assembly (not shown in this FIG.) may be adapted to transfer the rotational drive provided by the motor to polisher head 102 along with a downward force (F) to press a top surface of the work piece against polishing layer 130 such that a desired pressure exists between the work piece that is mounted in polisher head 102 in a face-down configuration and polishing layer 130 during a polishing operation.
As noted above, dispenser 140 of CMP system 100 may be operative to supply polishing medium 132, also sometimes referred to as a “slurry”, from a reservoir (not shown) to a location adjacent polishing pad 124 where the polishing medium is dispensed onto polishing layer 130. A flow control valve (not shown) may be used to control the dispensing of polishing medium 132 onto pad 124. In general, polishing medium 132 may comprise a slurry material having a suitable composition (e.g., a colloidal composition) depending on types of material to be polished or removed. In some arrangements, slurry material may comprise a reactant, an abrasive, a surfactant, and/or a solvent, or a combination or sub-combination thereof, as well as oxidizers, organic compounds such as dispersants, passivation agents and deionized (DI) water, and the like. In some arrangements, the slurry materials may comprise a nano-sized abrasive power dispersed in a chemically reactive solution, wherein a chemical etching process is operative to soften the work piece material while a mechanical abrasion action removes the material, thus flattening the topographic features (e.g., asperities) and making the surface planar.
During the polishing operation, platen driver rotates platen 120 and polishing pad 124 and the slurry dispenser system is activated to dispense polishing medium 132 onto the rotating polishing pad. Polishing medium 132 spreads out over polishing layer 130 due to centrifugal force caused by the rotation of polishing pad 124. Polisher head 102 may be rotated at a selected speed, e.g., 0 rpm to about 200 rpm, so that work piece surface confronting polishing layer 130 moves relative thereto. In general, polisher head 102 may be controlled to provide a downward force so as to induce a desired pressure, e.g., 0 psi to 15 psi, between the work piece and polishing pad 124. In some arrangements, polishing platen 120 may also be rotated at speeds of up to 200 rpm or thereabouts. As polishing pad 124 is rotated beneath polisher head 102 containing the work piece, polisher head 102 may be configured to sweep out in a radial arc or some other polishing track, e.g., track 152, on polishing layer 130. Depending on implementation, polisher head 102 and platen 120 may be rotated in the same direction, e.g., clockwise or counterclockwise, or in opposite directions.
Although not shown in
In one implementation, polisher head 102 may comprise a two-component arrangement wherein a first component and a second component may be disposed in a rotational union such that they rotate around a common rotational axis, e.g., axis 110. In such an arrangement, an upper head assembly 104 may be provided as one of the components (e.g., a first or second component) whereas a floating head assembly 106 may be provided as the other component (e.g., a second or first component, depending on how upper head assembly 104 is designated), wherein a rolling seal (not shown in this FIG.) affixed to or otherwise provided with upper head assembly 104 may be configured to operate as an attachment mechanism between upper head assembly 104 and floating head assembly 106 suitable for transferring rotational force(s) therebetween. In some arrangements, floating head assembly 106 may include or otherwise be provided with a membrane 108 that may be configured to provide a pneumatic-based attachment (e.g., a vacuum or pressure attachment) to a backside of the work piece, e.g., a backside surface of the substrate of a semiconductor process wafer. In some arrangements, a retainer ring (not shown in this FIG.) may be provided as part of or otherwise coupled to floating head assembly 106 to provide a housing for holding membrane 108 as is known in the art. In still further arrangements, upper head assembly 104 may be provided with a plurality of apertures 105 configured to support tubing for facilitating multi-zonal control of membrane 108 (e.g., pneumatic control) such that the work piece may be oriented in multiple ways (e.g., zonal pressure control) in order to achieve differential planarization or material removal across the surface area(s) of the work piece.
Depending on implementation, an example of CMP tool system 100 may be adapted to process dielectric layers including inter-layer and inter-metal dielectrics (ILDs/IMDs) (e.g., silicon dioxide, silicon nitride, etc.), metal and metal interconnect layers such as tungsten, aluminum, copper, etc., as well as for forming shallow trench isolation (STI) structures, polysilicon via plugs, and carbon nanotubes, etc.
As illustrated in
CMP tool 200 includes a platen 260 having a polishing pad 262 disposed thereon may be coupled to a chuck 264 that is driven by a motor (e.g., an induction motor, not shown in this FIG.) around a second rotational axis, e.g., axis 266, in clockwise and/or counterclockwise directions as illustrated by a second rotational direction 268. Although not explicitly shown in
In some examples, CMP tool 200 may include a vacuum system (not shown) coupled to polisher head 201 for effectuating zonal control of membrane 242, and height of the floating head assembly 204 over the polishing pad 262, by way of tubing facilitated by one or more apertures 209 formed in upper head assembly 202. For example, membrane 242 may be configured to pick up and hold wafer 250 using vacuum suction applied onto a backside surface of wafer 250. Additionally dechucking the wafer 250 may be effectuated by employing a vacuum to raise the floating head assembly 204 from the polishing pad 262.
In some examples, semiconductor process wafer 250 may be a semiconductor wafer comprising, for example, a semiconductor substrate (e.g., comprising silicon, a III-V semiconductor material, or the like), active devices (e.g., transistors, or the like) on the semiconductor substrate, and/or various interconnect structures. Representative interconnect structures may include conductive features, which electrically connect active devices in order to form functional circuits. In examples, CMP processing may be applied to semiconductor process wafer 250 during any stage of fabrication in order to planarize or otherwise remove features (e.g., dielectric material, semiconductor material, conductive material, or the like) from a top surface 254 of semiconductor process wafer 250, which is disposed in a face-down orientation for polishing.
In some arrangements, inner wall 223 of floating head assembly 204 may structural features such as, e.g., grooves, lips, steps, recesses, etc., exemplified by structural features 224 that may be dimensioned to facilitate a compressive fit arrangement with rolling seal 210 of upper head assembly 202. For example, an interference fit, also known as press fit or friction fit, may be facilitated between structural features 224 and rolling seal 210 as a form of fastening the two components (e.g., head assemblies 202, 204) in a mechanical joint that may be held together by friction, pressure, compression, and/or other tribological conditions that may be generated after the components are pushed or otherwise brought together. As previously noted, such an attachment may be implemented in polisher head 201 to effectuate a rotational union of head assemblies 202, 204, thereby facilitating the transfer of rotational forces therebetween.
In the example arrangement of
Accordingly, after assembly of polisher head 201, the one or more over-rotation limiting pins 229 are in a mechanical engagement with respective restrictor/lifter receptacles 212, regardless of how they are provided with respect to floating head assembly 204, such that the arresting portions of over-rotation limiting pins 229 operate to limit, arrest or otherwise restrict excessive rotational difference encountered between the two rotational components, e.g., upper head assembly 202 and floating head assembly 204, thereby counteracting and/or preventing over-rotation that may damage the rolling seal 210 during a polishing operation of wafer 250 including, e.g., wafer dechuck operations.
In one example implementation, polisher head 201 may be driven by a servo motor configured to provide a continuous torque of about 30-65 Newton-meters (Nm), with rotational speeds of up to 200 rpm and a peak torque rating of about 130 Nm. Whereas a baseline CMP operation may have an operating range of 35 Nm to 55 Nm, over-rotation-caused spikes in the range of peak torque ratings can occur during some wafer dechuck sequences depending on the process flows and consumable conditions as discussed.
Skilled artisans will recognize that the number of over-rotation limiting pins and corresponding receptacles, respective form factors, as well as their placement/positioning on inner and/or outer bodies of a polisher head may vary depending on the implementation and application of a CMP tool according to the teachings herein. In an example arrangement, over-rotation limiting pins 229 may be symmetrically positioned along a circular perimeter of outer wall 203 of the upper head assembly 202 or a portion thereof, with corresponding restrictor/lifter receptacles 212 likewise symmetrically positioned along a circular perimeter disposed or defined at a corresponding location on the inner wall 223 of the floating head assembly 204 or a portion thereof.
The use of a single over-rotation limiting pin 505 and restrictor/lifter receptacle 512 as illustrated in the example of
The preceding examples are provided without implied limitation. Those skilled in the pertinent art will appreciate that over-rotation limiting pins and the restrictor/lifter receptacles 610 may be placed in any of one or more locations on the upper head assembly and the floating head assembly to effectuate a useful translation force on the floating head assembly, e.g. during a dechuck operation.
Although various implementations have been shown and described in detail, the claims are not limited to any particular implementation or example. None of the above Detailed Description should be read as implying that any particular component, element, step, act, or function is essential such that it must be included in the scope of the claims. Where the phrases such as “at least one of A and B” or phrases of similar import are recited or described, such a phrase should be understood to mean “only A, only B, or both A and B.” Reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” All structural and functional equivalents to the elements of the above-described implementations that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims.
It should further be understood that the order or sequence of the acts, steps, functions, components or blocks illustrated in any of the flowcharts and/or block diagrams depicted in the drawing Figures of the present disclosure may be modified, altered, replaced, customized or otherwise rearranged within a particular flowchart/block diagram, including deletion or omission of a particular act, step, function, component or block. Moreover, the acts, steps, functions, components or blocks illustrated in a particular flowchart may be inter-mixed or otherwise inter-arranged or rearranged with the acts, steps, functions, components or blocks illustrated in another flowchart in order to effectuate additional variations, modifications and configurations with respect to one or more processes for purposes of the present disclosure. Accordingly, those skilled in the art will recognize that the example implementations described herein can be practiced with various modifications and alterations within the spirit and scope of the claims appended below.
