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Publication numberUS20060070872 A1
Publication typeApplication
Application numberUS 11/241,821
Publication dateApr 6, 2006
Filing dateSep 30, 2005
Priority dateOct 1, 2004
Also published asWO2006039436A2, WO2006039436A3
Publication number11241821, 241821, US 2006/0070872 A1, US 2006/070872 A1, US 20060070872 A1, US 20060070872A1, US 2006070872 A1, US 2006070872A1, US-A1-20060070872, US-A1-2006070872, US2006/0070872A1, US2006/070872A1, US20060070872 A1, US20060070872A1, US2006070872 A1, US2006070872A1
InventorsRashid Mavliev, Paul Butterfield, Raplh Wadensweiler
Original AssigneeApplied Materials, Inc.
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Pad design for electrochemical mechanical polishing
US 20060070872 A1
Abstract
A method and apparatus for processing a substrate by electrochemical mechanical planarization and electrochemical mechanical plating is disclosed. Included are various embodiments of a processing pad article comprising an open cell foam subpad that is adapted to retain an electrolyte while encountering centrifugal motion, and simultaneously provide electrical and/or abrasive contact to a feature side of a substrate. Also disclosed is a platen capable of holding an electrolyte during processing at a desired RPM, then releasing the electrolyte centrifugally at a higher RPM. The release is actuated by an operator or by centrifugal force.
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Claims(22)
1. A substrate processing article adapted to polish a substrate, comprising:
a conductive layer having a first contact surface and a fastener adapted to couple to a power supply; and
a second contact surface, wherein the first and second contact surfaces are adapted to polish the substrate.
2. The substrate processing article of claim 1, wherein the second contact surface is disposed in a plurality of perforations formed in the first contact surface.
3. The substrate processing article of claim 1, wherein the second contact surface comprises open-cell foam.
4. The substrate processing article of claim 1, wherein the second contact surface is adapted to couple to an electrode by a binder.
5. The substrate processing article of claim 4, wherein the binder is a pressure sensitive adhesive, a thermal sensitive adhesive, a stainless steel hook and loop connection, or combinations thereof.
6. The substrate processing article of claim 1, wherein the second contact surface is disposed under the first contact surface.
7. The substrate processing article of claim 1, wherein the first contact surface comprises a plurality of abrasive particles.
8. The substrate processing article of claim 1, wherein the second contact surface is adapted to receive and retain an electrolyte therein.
9. The substrate processing article of claim 1, further comprising:
an electrode adapted to couple to a power supply, wherein the second contact surface includes a plurality of electrochemical cells when in contact with an electrolyte and the substrate.
10. An apparatus for polishing a substrate, comprising:
a first contact surface adapted to couple to a power source; and
a second contact surface disposed below the first contact surface, the second contact surface adapted to receive and retain an electrolyte and couple to an electrode in communication with the power source, wherein at least one electrochemical cell is created when the power source is activated and the substrate is in contact with the first and second contact surfaces.
11. The apparatus of claim 10, wherein the power source supplies a separate signal to the first contact surface and the electrode.
12. The apparatus of claim 10, wherein the first contact surface includes a plurality abrasive particles.
13. The apparatus of claim 12, wherein the plurality of abrasive particles comprise ceramics, polymers, metals, or combinations thereof.
14. The apparatus of claim 12, wherein the plurality of abrasive particles have a hardness less than copper.
15. The apparatus of claim 12, wherein the plurality of abrasive particles have a hardness greater than copper.
16. The apparatus of claim 10, wherein the second contact surface comprises open cell foam.
17. An apparatus for performing an electrochemical process on a substrate, comprising:
a pad having a processing layer adapted to couple to an electrode, the processing layer comprising:
a plurality of elevated portions; and
a plurality of interstitial areas comprising open cell foam, supporting and surrounding the plurality of elevated portions, wherein a portion of the plurality of elevated portions and the open cell foam is adapted to contact the substrate.
18. The apparatus of claim 17, wherein each of the plurality of elevated portions include a plurality of abrasive particles.
19. The apparatus of claim 18, wherein the plurality of abrasive particles have a hardness less than copper.
20. The apparatus of claim 18, wherein the plurality of abrasive particles have a hardness greater than copper.
21. The apparatus of claim 17, wherein the processing layer further comprises:
a plurality of electrochemical cells when the processing layer and the electrode is coupled to a power source and the processing layer is in contact with the substrate.
22. The apparatus of claim 17, wherein the open cell foam is adapted to couple to the electrode by a stainless steel hook and loop connection.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. provisional patent application Ser. No. 60/615,198, filed Oct. 1, 2004, which is herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to a processing apparatus for planarizing or polishing a substrate. More particularly, the invention relates to polishing pad design for planarizing or polishing a semiconductor wafer by electrochemical mechanical planarization.

2. Description of the Related Art

In the fabrication of integrated circuits and other electronic devices on substrates, multiple layers of conductive, semiconductive, and dielectric materials are deposited on or removed from a feature side, i.e., a deposit receiving surface, of a substrate. As layers of materials are sequentially deposited and removed, the feature side of the substrate may become non-planar and require planarization. Planarization is a procedure where previously deposited material is removed from the feature side of a substrate to form a generally even, planar or level surface. The process is useful in removing undesired surface topography and surface defects, such as rough surfaces, agglomerated materials, crystal lattice damage and scratches. The planarization process is also useful in forming features on a substrate by removing excess deposited material used to fill the features and to provide an even or level surface for subsequent deposition and processing.

Electrochemical Mechanical Planarization (ECMP) is one exemplary process which is used to remove materials from the feature side of a substrate. ECMP typically uses a pad having conductive properties adapted to combine physical abrasion with electrochemical activity that enhances the removal of materials. The pad is attached to an apparatus having a rotating platen assembly that is adapted to couple the pad to a power source. The apparatus also has a substrate carrier, such as a polishing head, that is mounted on a carrier assembly above the pad that holds a substrate. The polishing head places the substrate in contact with the pad and is adapted to provide downward pressure, controllably urging the substrate against the pad. The pad is moved relative to the substrate by an external driving force and the polishing head typically moves relative to the moving pad. A chemical composition, such as an electrolyte, is typically provided to the surface of the pad which enhances electrochemical activity between the pad and the substrate. The ECMP apparatus effects abrasive or polishing activity from frictional movement while the electrolyte combined with the conductive properties of the pad selectively removes material from the feature side of the substrate.

Although ECMP has produced good results in recent years, there is an ongoing effort to develop pads with improved polishing qualities combined with optimal electrical properties that will not degrade over time and require less conditioning, thus providing extended periods of use with less downtime for replacement. Inherent in this challenge is the difficulty in producing a pad that will not react with process chemistry, which may cause degradation, or require excessive conditioning.

Platen rotation is another parameter that affects the planarizing process. Electrolyte retention in the current conductive pad design becomes difficult when the platen is rotated at higher revolutions per minute (RPM). When the pad is rotated to the desired RPM, the electrolyte tends to be removed axially from the substrate due to centrifugal force, and a break in the conductive current is sustained. This may result in uneven processing or possibly a total cessation of material removal.

Therefore, there exists a need in the art for a processing article or pad that is adapted for the removal of conductive materials and other materials on a feature side of a substrate designed to facilitate electrolyte retention during rotation.

SUMMARY OF THE INVENTION

The present invention generally provides an article of manufacture and an apparatus for planarizing a layer on a substrate using electrochemical dissolution processes, polishing processes, and/or combinations thereof.

In one embodiment, a substrate processing article is described having a conductive layer having a first contact surface and a fastener adapted to couple to a power supply, and a second contact surface, wherein the first and second contact surfaces are adapted to polish the substrate.

In another embodiment, an apparatus for polishing a substrate is described having a first contact surface adapted to couple to a power source and a second contact surface disposed below the first contact surface. The second contact surface is adapted to receive and retain an electrolyte and couple to an electrode in communication with the power source, wherein at least one electrochemical cell is created when the power source is activated and the substrate is in contact with the first and second contact surfaces.

In another embodiment, an apparatus for performing an electrochemical process on a substrate is described. The apparatus includes a pad having a processing layer adapted to couple to an electrode. The processing layer includes a plurality of elevated portions and a plurality of interstitial areas. The plurality of interstitial areas comprise open cell foam supporting and surrounding the plurality of elevated portions and a portion of the plurality of elevated portions and the open cell foam is adapted to contact the substrate.

A rotatable platen assembly is also described having a controlled valve assembly. In one embodiment, the valve assembly is RPM controlled. The valves are configured to open at a desired RPM whereby spent or used electrolyte is centrifugally forced out of the platen. In another embodiment, the valves are operator or mechanically actuated, at parameters defined by the user.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

FIG. 1 is a plan view of a processing apparatus.

FIG. 2 is a sectional view of one embodiment of an ECMP station.

FIG. 3 is a partial cross-sectional view of one embodiment of a process pad assembly.

FIG. 4 is a partial cross-sectional view of another embodiment of a process pad assembly.

FIG. 5 is a partial cross-sectional view of another embodiment of a process pad assembly.

FIG. 6 is a schematic isometric view of one embodiment of a pad body.

FIG. 7 is a schematic isometric view of another embodiment of a pad body.

FIG. 8 is a partial cross-sectional view of a compressed pad body.

FIG. 9 is an isometric view of another embodiment of a pad assembly.

FIG. 10 is a cross-sectional view of one embodiment of a platen.

FIG. 11 is a cross-sectional view of another embodiment of a platen.

DETAILED DESCRIPTION

The words and phrases used in the present invention should be given their ordinary and customary meaning in the art by one skilled in the art unless otherwise further defined. The embodiments described herein may relate to removing material from a substrate, but may be equally effective for electroplating a substrate by adjusting the polarity of an electrical source. Common reference numerals may be used in the Figures, where possible, to denote similar elements depicted in the Figures.

FIG. 1 is a plan view a processing system 100 having a planarizing module 105 that is suitable for electrochemical mechanical polishing and chemical mechanical polishing. The planarizing module 105 includes at least a first electrochemical mechanical planarization (ECMP) station 102, and optionally, at least one conventional chemical mechanical planarization (CMP) station 106 disposed in an environmentally controlled enclosure 188. An example of a processing system 100 that may be adapted to practice the invention is the REFLEXION LK Ecmp™ system available from Applied Materials, Inc. located in Santa Clara, Calif. Other planarizing modules commonly used in the art may also be adapted to practice the invention.

The planarizing module 105 shown in FIG. 1 includes a first ECMP station 102, a second ECMP station 103, and one CMP station 106. It is to be understood that the invention is not limited to this configuration and that all of the stations 102, 103, and 106 may be adapted to use an ECMP process to remove various layers deposited on the substrate. Alternatively, the planarizing module 105 may include two stations that are adapted to perform a CMP process while another station may perform an ECMP process. In one exemplary process, a substrate having feature definitions formed therein and filled with a barrier layer and then a conductive material disposed over the barrier layer may have the conductive material removed in two steps in the two ECMP stations 102, 103, with the barrier layer processed in the conventional CMP station 106 to form a planarized surface on the substrate. It is to be noted that the stations 102, 103, and 106 in any of the combinations mentioned above may also be adapted to deposit a material on a substrate by an electrochemical and/or an electrochemical mechanical plating process.

The exemplary system 100 generally includes a base 108 that supports one or more ECMP stations 102, 103, one or more polishing stations 106, a transfer station 110, conditioning devices 182, and a carousel 112. The transfer station 110 generally facilitates transfer of substrates 114 to and from the system 100 via a loading robot 116. The loading robot 116 typically transfers substrates 114 between the transfer station 110 and an interface 120 that may include a cleaning module 122, a metrology device 104 and one or more substrate storage cassettes 118.

The transfer station 110 comprises at least an input buffer station 124, an output buffer station 126, a transfer robot 132, and a load cup assembly 128. The loading robot 116 places the substrate 114 onto the input buffer station 124. The transfer robot 132 has two gripper assemblies, each having pneumatic gripper fingers that hold the substrate 114 by the substrate's edge. The transfer robot 132 lifts the substrate 114 from the input buffer station 124 and rotates the gripper and substrate 114 to position the substrate 114 over the load cup assembly 128, then places the substrate 114 down onto the load cup assembly 128. An example of a transfer station that may be used is described in U.S. Pat. No. 6,156,124, issued Dec. 5, 2000, entitled “Wafer Transfer Station for a Chemical Mechanical Polisher,” incorporated herein by reference to the extent it is not inconsistent with this application.

The carousel 112 generally supports a plurality of carrier heads 204, each of which retains one substrate 114 during processing. The carousel 112 articulates the carrier heads 204 between the transfer station 110 and stations 102, 103 and 106. One carousel that may used is generally described in U.S. Pat. No. 5,804,507, issued Sep. 8, 1998, entitled “Radially Oscillating Carousel Processing System for Chemical Mechanical Polishing,” which is hereby incorporated by reference to the extent it is not inconsistent with this application.

The carousel 112 is centrally disposed on the base 108. The carousel 112 typically includes a plurality of arms 138 and each arm 138 generally supports one of the carrier heads 204. Two of the arms 138 depicted in FIG. 1 are shown in phantom so that the transfer station 110 and a processing surface 125 of ECMP station 102 may be seen. The carousel 112 is indexable such that the carrier head 204 may be moved between stations 102, 103, 106 and the transfer station 110 in a sequence defined by the user.

Generally the carrier head 204 retains the substrate 114 while the substrate 114 is disposed in the ECMP stations 102, 103 or polishing station 106. The arrangement of the ECMP stations 102, 103 and polishing stations 106 on the system 100 allow for the substrate 114 to be sequentially processed by moving the substrate between stations while being retained in the same carrier head 204.

To facilitate control of the polishing system 100 and processes performed thereon, a controller 140 comprising a central processing unit (CPU) 142, memory 144 and support circuits 146 is connected to the polishing system 100. The CPU 142 may be one of any form of computer processor that can be used in an industrial setting for controlling various drives and pressures. The memory 144 is connected to the CPU 142. The memory 144, or computer-readable medium, may be one or more of readily available memory such as random access memory (RAM), read only memory (ROM), floppy disk, hard disk, or any other form of digital storage, local or remote. The support circuits 146 are connected to the CPU 142 for supporting the processor in a conventional manner. These circuits include cache, power supplies, clock circuits, input/output circuitry, subsystems, and the like.

Power to operate the polishing system 100 and/or the controller 140 is provided by a power supply 150. Illustratively, the power supply 150 is shown connected to multiple components of the polishing system 100, including the transfer station 110, the factory interface 120, the loading robot 116 and the controller 140.

FIG. 2 depicts a sectional view of an exemplary ECMP station 102 depicting a carrier head assembly 152 positioned over a platen assembly 230. The carrier head assembly 152 generally comprises a drive system 202 coupled to a carrier head 204. The drive system 202 may be coupled to the controller 140 (FIG. 1) that provides a signal to the drive system 202 for controlling the rotational speed and direction of the carrier head 204. The drive system 202 generally provides at least rotational motion to the carrier head 204 and additionally may be actuated toward the ECMP station 102 such that a feature side 115 of the substrate 114, retained in the carrier head 204, may be disposed against the pad assembly 222 of the ECMP station 102 during processing. Typically, the substrate 114 and processing pad assembly 222 are rotated relative to one another to remove material from the feature side 115 of the substrate 114. Depending on process parameters, the carrier head 204 is rotated at a rotational speed greater than, less than, or equal to, the rotational speed of the platen assembly 230. The carrier head assembly 152 is also capable of remaining fixed and may move in a path indicated by arrow 107 in FIG. 1 during processing. The carrier head assembly 152 may also provide an orbital or a sweeping motion across the processing surface 125 during processing.

The processing pad assembly 222 may be adapted to releasably couple to an upper surface of the platen assembly 230. The pad assembly 222 generally includes an electrode 292, an article support layer or sub-pad 350 and an elevated portion 330. A processing surface 125 is generally defined at least by the elevated portion 330 and, in another embodiment, may include the upper surfaces of a plurality of interstitial pads 320 disposed in a plurality of pad perforations 305. The elevated portion 330 may be a conventional polishing material, such as polymer based pad materials. Alternatively, the elevated portion 330 may be made of, or coated with, a conductive material, such as a conductive or dielectric filler material disposed in a conductive polymer matrix. In one embodiment, the elevated portions 330 are abrasive-free and may be include tin and/or nickel particles that may enhance conductivity in at least the elevated portions 330 of the processing pad assembly 222.

The electrode 292 is disposed on the top surface of the platen assembly 230 and is coupled to the power source 242 by connections that may be routed through a hollow drive shaft 260 coupled to the platen assembly 230. The electrode 292 is typically comprised of a conductive material, such as stainless steel, aluminum, gold, silver, among others. The electrode 292 may be solid, impermeable to electrolyte, permeable to electrolyte or perforated, or combinations thereof. In the embodiment depicted in FIG. 2, the electrode 292 is solid, but alternatively may be perforated to allow electrolyte to be in communication with a plenum 206.

The platen assembly 230 is rotationally disposed on a base 108 and is typically supported above the base 108 by a bearing 238 so that the platen assembly 230 may be rotated relative to the base 108. The platen assembly 230 may be fabricated from a rigid material, such as a metal or rigid plastic, and in one embodiment the platen assembly 230 has an upper surface that is fabricated from or coated with a dielectric material, such as CPVC. The platen assembly 230 may have a circular, rectangular or other plane form.

Electrolyte may be provided from the source 248, through appropriate plumbing and controls, such as conduit 241, to nozzle 255 above the processing pad assembly 222 of the ECMP station 102. Optionally, a plenum 206 may be defined in the platen assembly 230 for containing an electrolyte and facilitating ingress and egress of the electrolyte to the pad assembly 222. A detailed description of an exemplary planarizing assembly suitable for incorporation with the present invention can be found in the description of the Figures in United States Patent Publication No. 2004/0163946 (Attorney Docket No. 004100.P10), entitled “Pad Assembly for Electrochemical Mechanical Processing,” filed Dec. 23, 2003, which is incorporated herein by reference to the extent it is not inconsistent with this application.

In the embodiment shown in FIG. 2, an electrolyte 311 is provided from a nozzle 255. The electrolyte 311 may form a bath that is bounded by a platen lip 258 adapted to contain a suitable processing level of electrolyte 311 while rotating. After the electrolyte has reached its processing capacity and is ready for replacement, the platen assembly 230 is rotated at a higher RPM and the spent electrolyte 311 is released by the platen lip 258 in a process that will be discussed in reference to FIGS. 10 and 11.

In a typical ECMP process, a potential difference or bias is applied between the electrode 292, performing as a cathode, and the feature side 115 of the substrate 114, performing as the anode. The application of the bias allows removal of conductive material, such as copper-containing and tungsten-containing materials, on the feature side 115 of the substrate 114. Examples of suitable parameters for ECMP that may be used are disclosed in U.S. Patent Publication No. 2004/0020789 (Attorney Docket No. 004100.P5), entitled “Conductive Polishing Article for Electrochemical Mechanical Polishing,” filed Jun. 6, 2003, which is incorporated herein by reference to the extent the application is not inconsistent with this application.

It can be appreciated by those skilled in the art that polarity could be altered and material could be deposited on the feature side 115. For example, the feature side 115 could be biased by the processing surface 125 to perform as a cathode, and the electrode 292 could perform as an anode and a plating solution could be delivered to the processing surface 125.

As the feature side 115 of the substrate 114 may contain conductive material to be removed from the substrate 114, fewer biasing contacts for biasing the substrate 114 are required. As the conductive material to be removed from the substrate 114 comprises isolated islands of conductive material disposed on the substrate 114, more biasing contacts for biasing the substrate 114 are required. Embodiments of the processing pad assembly 222 suitable-for residual removal of material from the substrate 114 may generally include a processing surface 125 that is substantially conductive. In one embodiment, excess conductive material is removed from the feature side 115 of the substrate 114 wherein a conductive, abrasive-free processing surface 125 provides a suitable array and distribution of biasing contacts, and the residual material is removed by an electrochemical mechanical removal process provided by the conductive processing surface 125. In another embodiment, the processing surface 125 may further include abrasive particles as described herein to enhance mechanical removal.

The processing surface 125 may further include a patterned surface 251 formed on the upper surface of the elevated portions 330 to facilitate polishing of the substrate 114. Patterns of the pattered surface 251 may include a plurality of small protrusions adjacent shallow depressions in the processing surface 125. The protrusions may take any geometrical form, such as ovals, circles, rectangles, hexagons, octagons, triangles, or combinations thereof and may be formed by compression molding and/or embossment of the processing surface 125. Alternatively, the processing surface may be substantially flat or planar having negligible raised or lowered portions on the processing surface 125.

Processing Pad Articles

FIG. 3 is one embodiment of a process pad assembly 222 depicting a schematic partial side view of a pad body 302. The body 302 comprises a processing layer 290, which is in communication with an electrode 292 that is adapted to couple to the upper surface of the platen assembly (not shown). The electrode 292 has a first side 352 adapted to couple to the platen assembly by any methods known in the art, including, but not limited to, screws, bolts, vacuum, magnet, adhesives, or combinations thereof. In one embodiment, the electrode 292 is electrically insulated from the platen assembly. In another embodiment, the platen assembly is made from, or coated with, a dielectric material. A second side 314 of electrode 292 is connected to a first surface 321 of a perforated sub-pad 350 by a pressure and/or thermal sensitive adhesive or binder 340. The binder 340 can be any suitable adhesive known in the art that is conducive to the conditions occurring in the planarizing processes and may also be electrically conductive. In another embodiment, the electrode 292 may be coupled to the first surface 321 by stainless steel hook and loop binder or Velcro® connection 328. The hook and loop connection 328 maintains mechanical contact between the electrode 292, the perforated sub-pad 350, and an interstitial pad 320. The hook and loop binder 328 may be fastened by any method known in the art, such as binders 340 or screws (not shown). The pad assembly 222 is configured to create at least one electrochemical cell 310 in the pad body 302. The electrochemical cell 310 is active and complete when the feature side 115 of substrate 114 is in contact with the processing surface 125, and voltages are applied to the electrode 292 and the processing surface 125.

In this embodiment, the processing layer 290 has a plurality of elevated portions 330 having a first contact surface 332 and a support surface or second side 334 is coupled to the second surface 322 of perforated sub-pad 350. The second side 322 of perforated sub-pad 350 is disposed on the second side 334 of the elevated portion 330 by a layer of binder 340. The elevated portion 330 may be made of a material that is conductive and abrasive, or the elevated portion 330 may be a dielectric abrasive material that functions solely as an abrading element.

In one embodiment, the elevated portions 330 are abrasive-free and may include conductive fillers, such as tin or nickel. In another embodiment, the elevated portions 330 include a plurality of abrasive particles 335 that are adapted to provide increased mechanical abrasion to the feature side 115 of the substrate 114. The abrasive particles may be conductive, dielectric, or combinations thereof. Examples of abrasive particles 335 include ceramic particles, inorganic particles, organic particles, polymer particles, metals, or combinations thereof. Other abrasive particles 335 include particles comprising metals, such as aluminum, ceria, silica, combinations thereof or oxides thereof. In another embodiment, the elevated portions 330 are made a conductive composite material having any of the abrasive particles 335 mentioned above bound in a conductive polymer. In another embodiment, the abrasive particles 335 mentioned above are bound in a polymer that is substantially dielectric.

The elevated portions 330 and the sub-pad 350 are made of materials that exhibit a differing modulus of elasticity or hardness. The sub-pad 350 is softer and capable of deformation under compressive forces while the elevated portion 330 is harder as it must resist the compressive forces to function as an abrading mechanism.

In this embodiment, the interstitial pad 320 is disposed in the pad perforations 305 by the binder 340 or the stainless steel Velcro® connection 328. Electrolyte 311 is provided to the process pad assembly 222 via the nozzle 255. The interstitial pad 320 is open cell foam that is capable of retaining water at about 10 to about 20 times its own weight, for example, from about 14 to about 18 times its own weight. The interstitial pad 320 is configured to retain the electrolyte when the platen assembly 230 is rotated and is configured to provide enhanced electrolyte retention at higher RPM's. The interstitial pad 320 may be made of a polymer material such as a microcellular polyurethane material having a modulus range from about 2 psi to about 90 psi at 25% deflection. In one embodiment, the interstitial pad 320 is a high performance foam available from Rogers Corporation, such as a urethane foam sold under the trade name PORON®. The open cell foam also facilitates conductivity in a plurality of electrochemical cells 310 formed when the feature side 115 of the substrate 114 is in communication with the processing pad assembly 222 and a potential bias is applied between the electrode 292 and the elevated portions 330.

In an operation in reference to FIGS. 2 and 3, the substrate 114, held by the carrier head 204, is urged against the rotating platen assembly 230 containing electrolyte 311 in the process pad assembly 222. In one embodiment, the platen assembly 230 is rotated between about 10 RPM to less than about 70 RPM, preferably less than 60 RPM, for example, about 50 RPM. In one embodiment, the feature side 115 of the substrate 114 contacts the first contact surface 332 of the elevated portions 330 and the electrolyte 311. After a potential difference is applied to the elevated portions 330 and the electrode 292, at least one electrochemical cell 310 is created. In another embodiment, the feature side 115 of the substrate 114 contacts the first contact surface 332 of the elevated portion 330 then the urging or compressive force exerted by the carrier head 204 deforms the perforated sub-pad 350, allowing the second contact surface 317 of the interstitial pad 320 to contact the feature side 115 of the substrate 114, as seen in FIG. 8. After a potential difference is applied to the elevated portions 330 and the electrode 292, at least one electrochemical cell 310 is created. The compression of the interstitial pad 320 may release the retained electrolyte 311 and may also provide additional abrasion to the feature side of the substrate 114. It is to be noted that the electrolyte 311 may be added, as needed, to the process pad assembly 222 or the electrolyte 311 level may remain static, using the previously retained electrolyte 311 from the interstitial pad 320.

FIG. 4 depicts another embodiment of a process pad assembly 222 depicting a partial schematic side view of a pad body 302. The embodiment shown is similar to the pad assembly 222 shown in FIG. 3 except the perforated sub-pad 350 is replaced by an interstitial pad 320 that serves as a support layer for the elevated portions 330. The interstitial pad 320 comprises open-cell foam that enhances electrolyte 311 retention and may provide enhanced polishing when the substrate 114 is urged against the second contact surface 317. The elevated portions 330 and the interstitial pad 320 are made of materials that exhibit a differing modulus of elasticity or hardness. The interstitial pad 320 is softer and capable of deformation under compressive forces, while the elevated portions 330 are harder. The interstitial pad 320 is disposed in the pad body 302 and coupled to the electrode 292 by a process resistant binder 340 or stainless steel coupling 328, such as a Velcro® connection. The stainless steel coupling 328 is bound to the electrode 292 and the first surface 312 of the interstitial pad 320 by a process resistant binder. A plurality of open areas 460 are also shown between portions of the interstitial pad 320 and the electrode 292. The open areas 460 are configured to allow increased electrolyte retention in the pad body 302 and may enhance compressibility of the interstitial pad 320. The hook and loop connection 328 may increase the electrochemical active area of the electrode 292 by exposing a larger surface area of the electrode 292 to the electrolyte 311, while maintaining mechanical contact between the electrode 292 and the interstitial pad 320. At least one electrochemical cell 310 is active and complete when the feature side 115 of substrate 114 is in contact with the processing surface 125, and voltages are applied to the electrode 292 and the processing surface 125.

In this embodiment, the operational process is substantially similar to the previous embodiment and certain parameters are omitted for the sake of brevity. Electrolyte 311 is provided to the process pad assembly 222 by the nozzle 255. The platen assembly 230 is rotated and the electrolyte 311 is retained in the open cell foam that comprises the interstitial pad 320. In one embodiment, the feature side 115 of the substrate 114 is urged against the process pad assembly 222 and the feature side 115 contacts the first contact surface 332 of the elevated portion 330. In another embodiment, continued urging or compression causes the interstitial pad 320 to compress under the elevated portions 330 as shown in FIG. 8. As seen in FIG. 8, the second contact surface of the interstitial pad 320 and the elevated portions 330 may provide abrading to the feature side 115 of substrate 114. The compression may also release the retained electrolyte 311 from the interstitial pad 320 that may provide expanded electrochemical activity.

FIG. 5 is another embodiment of a process pad assembly 222 depicting a partial schematic side view of a pad body 302. The embodiment shown is similar to the pad assembly 222 shown in FIG. 4 with the exception of complete contact of the interstitial pad 320 with the electrode 292. In this embodiment, the elevated portion 330 is coupled to the second contact surface 317 of interstitial pad 320 by a layer of binder 340 and the interstitial pad 320 is coupled to the electrode 292 by a layer of binder 340 or a stainless steel hook and loop connection 328. The elevated portion 330 and the interstitial pad 320 are made of materials that exhibit a differing modulus of elasticity or hardness to allow the elevated portions 330 to compress under pressure. The interstitial pad 320 is softer and capable of deformation under compressive forces while the elevated portion 330 is harder as it must resist the compressive forces to function as an abrading mechanism. The first contact surface 332 of elevated portion 330 may comprise abrasive particles 335 that may enhance abrading and planarization. The operation is similar to other embodiments and the parameters are omitted for the sake of brevity.

FIG. 6 depicts a partial isometric view of the pad body 302 shown in FIG. 3. Shown is a pad body 302 with the perforated sub-pad 350 and the interstitial pad 320 disposed in a plurality of perforations 305 above the electrode 292 with a layer of binder 340 therebetween. Although the plurality of perforations 305 are shown having a round shape in an x-y pattern, other shapes of perforations 305 are contemplated, such as rectangles, hexagons, octagons, or combinations thereof, and the perforations may be formed in any pattern. Also shown is at least one connector 338 coupled to the pad body 302. The at least one connector 338 may be coupled to the electrode 292 to provide mechanical and/or electrical coupling for the electrode 292. Other connectors 338 may be coupled to the electrode 292 to create independently bias able zones in the electrode 292. Another connector, shown in FIG. 6 as a conductive fastener 605 may also be coupled to the processing layer 302 to provide electrical communication to the processing layer 290. The at least one connector 338 and the conductive fastener 605 may be a metal tab made of process resistant materials, such as nickel, stainless steel, aluminum, gold, silver, and may have a thickness that allows the tab to be flexible to facilitate connection to a power connection (not shown) on the upper surface of the platen that is in communication with a power supply 242. The conductive fastener 605 may be coupled to the power supply 242 through the hollow drive shaft 260 (FIG. 2) for providing an electrical signal to the processing layer 290. The at least one connector 338 may also be coupled to the power supply 242 and the power supply 242 communicates a separate voltage to the connector 338 and the conductive fastener 605. If more than one connector 338 is coupled to the electrode 292, the power supply 242 may communicate separate voltages to each connector 338. Although not shown, multiple power supplies may be used to supply distinct signals to various parts of the pad body 302 via the various connectors and conductive fasteners. At least one window 313 is also shown in the pad body 302 to provide communication for an endpoint detection mechanism, such as an interferometric device adapted to detect a processing endpoint.

FIG. 7 depicts an isometric view of pad body as shown in FIG. 5. Shown is a pad body 302 with the interstitial pad 320 disposed in a plurality of perforations 305 above the electrode 292 with a layer of binder 340 therebetween. Although the plurality of perforations 305 are shown having a round shape in an x-y pattern, other shapes of perforations 305 are contemplated, such as rectangles, hexagons, octagons, or combinations thereof, and the perforations may be formed in any pattern. Also shown is at least one connector 338 coupled to the pad body 302. The at least one connector 338 may be coupled to the electrode 292 to provide mechanical and/or electrical coupling for the electrode 292. A conductive fastener 705 is also shown coupled to a power supply 242. The conductive fastener 705 and the connector 338 may be made of the materials described above in reference to the conductive fastener 605 and connector 338, and function similarly as described in FIG. 6. More than one connector 338 may also be coupled to the electrode 292 for providing independent zones in the electrode 292. At least one window 313 is also shown in the pad body 302 to provide communication for an endpoint detection mechanism.

FIG. 8 is a partial schematic view of a substrate 114 against a pad body 302 which is similar to the embodiment of the pad body depicted in FIG. 4. The feature side 115 of the substrate 114 is in contact with the first contact surface 332 of the elevated portions 330 and the second contact surface 317 of the interstitial pad 320. As the substrate 114 is urged against the processing surface 125, the elevated portions 330 are compressed downward to allow the feature side 115 to contact the interstitial pad 320. Material is removed from the feature side 115 of the substrate 114 by the elevated portions 330 and the second contact surface 317 of the interstitial pad 320. Additional abrasion may be provided by a plurality of abrasive particles 335 in the elevated portions 330. Electrolyte 311 retained in the open-cell foam of the interstitial pad 320 may form at least one electrochemical cell 310 in the pad body 302 to assist in removal of conductive material from the feature side 115 of the substrate 114. Residual material remaining on the feature side 115 of the substrate 114 may also be removed by an electrochemical mechanical process provided by the one or both of the elevated portions 330 and the second contact surface 317 of the interstitial pad 320.

FIG. 9 is a partial isometric view of an alternative pad assembly 900 that may be used with any of the embodiments of the pad assembly 222. Shown is a conductive contact assembly 930 surrounded by the elevated portions 330 and the interstitial pad 320. The conductive contact assembly 930 is shown in communication with a power source 242, while the electrode 292 is connected to a ground. The contact assembly 930 contains a plurality of moveable contact elements or balls 910 that are adapted to depress upon the application of pressure to the substrate 114, while exerting a counter-pressure to maintain contact to the feature side 115. One skilled in the art will note that the conductive contact assembly 930 is not limited to the center of process pad assembly 302 and may be placed off-center or comprise another shape, such as a zigzag or cross shape. The contact assembly may also be at least one annular ring. The conductive contact assembly may also be adapted to provide an electrolyte to the process pad assembly 900 by way of channels formed around the balls 910 or perforations (not shown) within the conductive contact assembly 930. Examples of conductive contact assemblies that may be incorporated into the present invention are the descriptions of FIGS. 3-13 in U.S. Patent Publication No. 2005/000001 (Attorney Docket No. 004100.P11), entitled “Method and Apparatus for Electrochemical Mechanical Processing,” filed Jun. 30, 2004, which is incorporated herein by reference to the extent it is not inconsistent with this application.

Platen Assembly

FIGS. 10 and 11 depict schematic side views of a platen valve assembly 600. The assembly 600 includes a platen lip assembly 258 disposed above the upper plate 236 of the platen assembly 230. FIG. 10 depicts the platen assembly in motion and electrolyte 311 is shown in a fluid-tight connection between the platen lip assembly 258 and the upper plate 236. Electrolyte 311 is held by viscous force in the interstitial pad 320 and by the lip assembly 258, thereby resisting centrifugal forces and providing sufficient electrolyte to the electrochemical cell 310. Also shown are RPM or spring controlled valves 620 on pivot points 610 in a closed position to facilitate electrolyte retention in the pad body 302. The rotational speed of the platen is between about 10 RPM to less than about 70 RPM, preferably less than 60 RPM, for example, about 50 RPM.

FIG. 11 shows a schematic side view of the platen valve assembly 600 in an open or cleaning position. The RPM is increased from about greater than 70 RPM, for example, greater than about 90 RPM, and electrolyte 311 is released from the pad body 302. The increase in RPM allows an opening 630 to form in the RPM controlled valves 620 and continued rotation promotes removal of electrolyte 311. De-ionized water or another cleaning agent may be introduced in the pad body 302 during this process. After spent electrolyte 311 is removed from the pad body 302 by the process steps above, the platen assembly 230 is rotated below the RPM range mentioned above, which causes the RPM controlled valves 620 to close. The pad-body 302 may again be filled to a suitable level of electrolyte 311 and substrate processing or planarization will continue. It is also contemplated that the valves 620 may be operator actuated by a suitable software program, or manually.

While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US7427340 *Apr 8, 2005Sep 23, 2008Applied Materials, Inc.Conductive pad
US7520968 *Oct 4, 2005Apr 21, 2009Applied Materials, Inc.Conductive pad design modification for better wafer-pad contact
US8012000Apr 2, 2007Sep 6, 2011Applied Materials, Inc.Extended pad life for ECMP and barrier removal
Classifications
U.S. Classification204/224.00M, 204/224.00R
International ClassificationB24B37/22, C25D17/00
Cooperative ClassificationH01L21/32125, C25F7/00, B24B37/22, B23H5/08
European ClassificationH01L21/321P2B, B24B37/22, C25F7/00, B23H5/08
Legal Events
DateCodeEventDescription
Nov 11, 2005ASAssignment
Owner name: APPLIED MATERIALS, INC., CALIFORNIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:MAVLIEV, RASHID A.;BUTTERFIELD, PAUL D.;WADENSWEILER, RALPH M.;REEL/FRAME:016768/0735
Effective date: 20051107