SURFACE MODIFIED POLISHING PAD

Abstract

In one embodiment, a polishing pad includes a hydrophilic polymer base having a polishing surface, and a metal oxide coating. The metal oxide coating has nanoparticles of metal oxide disposed on the polishing surface. In another embodiment, a processing station includes a rotatable platen, a polishing head, and a precursor delivery system. The polishing head is configured to retain a substrate against the polishing pad. The precursor delivery system is configured to form an oxide coating on a surface of a polishing pad disposed on the platen. In yet another embodiment, a method for modifying a surface of a polishing pad includes wetting the surface of the polishing pad and delivering a precursor to the wetted surface of the polishing pad surface. The method also includes forming a metal oxide coating having nanoparticles of metal oxide on the surface from the precursor.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to a polishing pad having a surface modification, and methods of fabricating and using the same. Additionally, embodiments of the present invention also relate to a chemical mechanical planarization system for use with a surface modified polishing pad.

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 and/or polishing. Planarization and polishing are procedures where previously deposited material is removed from the feature side of the substrate to form a generally even, planar or level surface. Chemical mechanical planarization (CMP) procedures are useful in removing undesired surface topography and surface defects, such as rough surfaces, agglomerated materials, crystal lattice damage, and scratches. The procedures are 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. A CMP process generally includes pressing a substrate against a polishing surface of a polishing pad in the presence of a polishing media, such as a polishing fluid or slurry. Relative motion is provided between the substrate and polishing surface to planarize the surface of the substrate in contact with the pad through one or combination of a chemical, mechanical or electrochemical process.

During polishing processes, the polishing surface of the pad that is in contact with a feature side of the substrate experiences a deformation and/or wear. The deformation may include smoothing of the polishing surface or creating an unevenness in the plane of the polishing surface, as well as clogging or blocking pores present on the polishing surface, whereby reducing the ability of the pad to properly and efficiently planarized the substrate. Periodic conditioning of the polishing surface is required to maintain a consistent roughness, porosity and/or generally flat profile across the polishing surface.

One method to condition the polishing surface utilizes an abrasive conditioning disk that is forced downward against the polishing surface while being rotated and/or swept across at least a portion of the polishing surface. An abrasive portion of the conditioning disk, which may be diamond particles or other hard materials, typically cut into the pad surface, which forms grooves in, and otherwise roughens, the polishing surface. However, while the rotation and/or downward force applied to the conditioning disk may be controlled, the conditioning disk may not cut into the polishing surface evenly, which creates a difference in roughness across the polishing surface.

Fluid jet systems have alternatively been utilized to condition the polishing pad in lieu of abrasive disks, but these systems use great amounts of fluid and are expensive to operate. Other systems utilizing optical devices (e.g., lasers) that cut into the polishing surface have also been utilized. However, the optical energy interacts with polishing fluids on the pad, causing boiling of the fluid which may rupture pores in the polishing surface, which is detrimental to uniform conditioning, and may also shorten pad service life.

Therefore, there is a need for an improved polishing pad.

SUMMARY OF THE INVENTION

Embodiments of the present invention generally relate to a polishing pad having a surface modification, and methods of fabricating and using the same. In one embodiment, a polishing pad is provided. The polishing pad includes a hydrophilic polymer base having a polishing surface, and a metal oxide coating. The metal oxide coating has nanoparticles of metal oxide disposed on the polishing surface.

In another embodiment, a processing station is provided. The processing station includes a rotatable platen, a polishing head, and a precursor delivery system. The polishing head is configured to retain a substrate against the polishing pad. The precursor delivery system is configured to form an oxide coating on a surface of a polishing pad disposed on the platen

In yet another embodiment, a method for modifying a surface of a polishing pad is provided. The method includes wetting the surface of the polishing pad and delivering a precursor to the wetted surface of the polishing pad surface. The method also includes forming a metal oxide coating having nanoparticles of metal oxide on the surface from the precursor.

In yet another embodiment, a method for polishing a substrate on a polishing pad is provided. The method includes providing a polishing fluid to a polishing surface of the polishing pad. The polishing surface has a metal oxide coating having nanoparticles of metal oxide disposed on the polishing surface. The method further includes pressing the substrate against the polishing surface in the presence of the polishing fluid. The method also includes polishing the substrate against the polishing surface in the presence of the polishing fluid.

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 cross-sectional view of one embodiment of a polishing pad;

FIG. 2 is a schematic view of a polishing pad disposed in packaging;

FIG. 3 is a top plan view of one embodiment of a processing station; and

FIG. 4 is a partial side view of a precursor delivery device having one embodiment of a polishing pad disposed below the precursor delivery device.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.

DETAILED DESCRIPTION

FIG. 1 is a cross-sectional view of one embodiment of a polishing pad 100. The polishing pad 100 includes a body 102 having a polishing surface 104. The polishing surface 104 includes a coating 106 that extends the service life of the polishing pad 100.

The body 102 of the polishing pad 100 may be a polymer based material suitable for chemical mechanical polishing a substrate thereon. In one embodiment, the body 102 is fabricated from a hydrophilic polymer. The polymer material may be polyurethane, polycarbonate, a fluoropolymer, polytetrafluoroethylene, polyphenylene sulfide, combinations thereof, or any other suitable hydrophilic polymer. The body 102 may alternatively comprise open or closed cell foamed polymers, elastomers, felt, impregnated felt, plastics, and other suitable materials compatible with the processing chemistries.

The polishing surface 104 may include surface features, such as groves and/or microscopic pore structures (not shown), that assist in material removal from a feature side of a substrate that is in contact with the polishing surface 104 during processing. The surface features may be selected to influence processing attributes, such as polishing media retention, polishing or removal activity, and material and fluid transportation affect the removal rate. In order to facilitate uniform substrate to substrate processing results, the polishing surface 104 must be periodically conditioned to roughen the polishing surface 104.

The coating 106 provides a nano-abrasive rich layer on the polishing surface 104. The coating 106 improves the planarization and surface finish of the features side of the substrate. The coating 106 may be a metal oxide layer comprised of a plurality of nanoparticles 108. In one embodiment, the nanoparticles 108 have a diameter size between about 10 nm to about 30 nm, for example about 25 nm. In one embodiment, the thickness of the coating 106 may be between about 50 nm to about 500 nm, or 500 Angstroms to about 5,000 Angstroms.

In one embodiment, the coating 106 may be formed by wetting the polishing surface 104 with water and exposing the wetted surface 104 to a precursor which results in the formation of a layer of metal oxide layer comprised by nanoparticles 108. The amount of water provided to the polishing surface 104 may be controlled to ensure that the nanoparticles 108 form on and adhere to the body 102 without forming free particles of the precursor. In an embodiment wherein the body 102 is comprised of polyurethane, water is provided in the form of moisture inherently present in the body 102. The precursor may be selected from a moisture sensitive group of gasses that react with the water wetting on the hydrophilic polymer body 102. Examples of suitable precursors in gas form may include silane (SiH₄), trimethylaluminum (Al₂(CH₃)₆), germanium tetrafluoride (GeF₄) or any other suitable moisture sensitive gas which will form the coating 106 consisting of nanoparticles 108 made of metal oxide. Nanoparticles 108 formed from the above listed precursors when exposed to water may be comprised of silicon dioxide (SiO₂), aluminum oxide (Al₂O₃), and germanium dioxide (GeO₂) or other metal oxide. In one embodiment, the nanoparticles 108 form the coating 106 on the polishing surface 104 without the use of a binding agent.

In one embodiment, the composition of the nanoparticles 108 may be selected to be nonreactive with the polishing media used in during a CMP process. The nanoparticles 108 and polishing media may both comprise the same metal oxide. For example, a CMP process using an aluminum oxide slurry as the polishing media may utilize a polishing pad 100 having nanoparticles 108 comprised of aluminum oxide forming the coating 106. For coatings 106 comprised of metal oxide, use of the same metal oxide for both the polishing media and the nanoparticles 108 advantageously prevents the coating 106 from losing its adhesion to the polishing surface 104 during the CMP process. However, in another embodiment, polishing media which does not contain an abrasive or metal oxide may be used to process the substrate because the nanoparticles 108 will function as the abrasive which facilitates material removal from the substrate. This advantageously reduces the cost of the polishing media.

FIG. 2 is a schematic view of the polishing pad 100 with coating 106 disposed in packaging 200 suitable for transportation and/or storage of the polishing pad 100. In one embodiment, the packaging 200 may be a polymer bag or other suitable air-tight container. The packaging 200 may be vacuum sealed or back-filled with an inert gas 202, such as nitrogen or argon. As such, the coating 106 of the polishing pad 100 may be protected during shipment and/or storage while in the packaging 200. The polishing pad 100 may be removed from the packaging 200 when the polishing pad 100 is ready for installation and use.

The coating 106 may also be formed on the polishing pad 100 while the polishing pad 100 is disposed in a substrate processing station. Having a substrate processing station which is capable of applying the coating 106 to the polishing pad 100 allows conventional polishing pads to be converted into the polishing pad 100 at little expense. Having a substrate processing station which is capable of applying the coating 106 to the polishing pad 100 also allows the coating 106 to be reapplied to the polishing pad 100 in-situ the substrate processing station, thereby extending the service life of the polishing pad 100 and further reducing down time associated with changing pads, which advantageously reduces the cost of ownership while increasing substrate processing throughput.

FIG. 3 is a top plan view of the processing station 300 that is configured to perform a polishing process, such as a CMP or electrochemical mechanical planarization (ECMP) process, while also being configured to apply the coating 106 to the processing pad 100. The processing station 300 may be a stand-alone unit or part of a larger processing system. Examples of a larger processing system that the processing station 300 may be utilized with include REFLEXION®, REFLEXION GT™, REFLEXION LK™, REFLEXION LK ECMP™, and MIRRA MESA® polishing systems, all available from Applied Materials, Inc., located in Santa Clara, Calif. It is contemplated that other processing stations may be adapted to benefit from the invention, including those from other equipment manufacturers.

The processing station 300 includes a substrate carrier head 320 (shown in phantom), a platen 330, a slurry delivery arm 306, a conditioning module 302, and a precursor delivery device 304. The platen 330, the slurry delivery arm 306, the conditioning module 302, and the precursor delivery device 304 may be mounted to a base 312 of the processing station 300.

The platen 330 supports the polishing pad 100. The platen 330 is rotated by a motor (not show) so that the polishing pad 100 is rotated relative to a substrate 308 retained in the substrate carrier head 320 during processing.

Additionally, water may be provided to the processing station 300 by any number of sources. For example, the conditioning module 302, the precursor delivery device 304 and the slurry deliver arm 306 may all include water sources suitable for providing water to the surface of the polishing pad 100. Alternatively, a stand-alone water source may be utilized to provide water to the processing station 300. In the embodiment depicted in FIG. 3, the conditioning module 302 includes one or more nozzles 350, coupled to a water source 340, for providing water to the surface of the polishing pad 100 upstream of the precursor delivery device 304.

The substrate carrier head 320 is configured to retain the substrate 308 and controllably urge the substrate 308 against the polishing surface 104 of the polishing pad 100 during processing. The substrate carrier head 320 may also rotate the substrate 308 during processing.

The slurry delivery arm 306 is configured to deliver a polishing media, such as a fluid or slurry, to the polishing pad 100 while the substrate 308 is polished on the polishing surface 104. The slurry delivery arm 306 may be located in front of or behind the polishing head 320.

The conditioning module 302 is configured to condition the polishing pad 100 by removing polishing debris and opening the pores of the polishing pad 100. The conditioning module 302 includes a conditioning disk 310. The conditioning disk 310 may be a brush having bristles made of a polymer material or include an abrasive surface comprising abrasive particles. In one embodiment, the conditioning disk 310 may contain abrasive particles such as diamonds.

The precursor delivery device 304 is configured to deliver precursor fluid, such as a gas or liquid, to the polishing surface 104 of the polishing pad 100 where the precursor fluid reacts with the water to form the coating 106. The precursor delivery device 304 includes a delivery head 314 and a delivery arm 316, coupled to a precursor fluid source 350 by a delivery line 352. In one embodiment, the precursor delivery device 304 may include a heater 402 (shown in FIG. 4) to heat the precursor fluid as it is deposited on the polishing surface 104. The heater 402 may be a cartridge heater, a band heater or other suitable heater for heating a fluid.

FIG. 4 is a partial sectional view of the precursor delivery device 304. The delivery head 314 of the precursor delivery device 304 includes one or more nozzles 400 configured to deliver precursor fluid to the polishing surface 104 in a closed environment. However, it is also contemplated that the nozzle 400 may be configured to spray precursor having solid particles to the polishing surface 104. In embodiments where the precursor is a gas that may be flammable at room temperature, for example silane, the close proximity of the nozzle 400 to the polishing surface 104 is beneficial. In one embodiment, the precursor delivery device 304 is in direct contact with the polishing surface 104.

In one embodiment, the one or more nozzles 400 includes a plurality of nozzles, illustratively shown as nozzles 400a, 400b and 400c. Nozzle 404b is a precursor delivery nozzle coupled to the precursor fluid source 350 by the delivery line 352 and is configured to deliver a precursor fluid, such as silane. Nozzles 400a and 400c are inert gas nozzles. Nozzles 400a and 400c are configured to deliver a curtain of inert fluid, as nitrogen (N₂) or argon, on either side of the precursor delivery nozzle 404b to provide an isolated environment for isolating potentially flammable gasses from the surrounding environment.

Referring additionally back to FIG. 3, the delivery arm 316 is coupled to the delivery head 314 and attached to the base 312. The delivery arm 316 is adapted to provide the nozzle 400 to at least a portion of the radius of the polishing pad 100 in a linear, arcing or sweeping motion.

In operation, a method for polishing of the substrate 308 may begin by providing the precursor fluid by the precursor delivery device 304 to the polishing surface 104. Water used in the CMP process, water from the moisture in the polishing pad body 102, or water from a separate source is also provided to wet the polishing surface 104. The precursor fluid and the water form and adhere the coating 106 on the polishing surface 104. In one embodiment, the polishing pad 100 may be rinsed with water or deionized water, or any other suitable rinsing fluid to remove excess reactant material and by-products from the coating 106 after forming. The slurry delivery arm 306 then provides polishing media to the coated polishing pad 100. The substrate carrier head 320 urges the substrate 308 towards the polishing surface 104 to be polished and forms a planarized surface on the features side of the substrate 308. The conditioning module 302 then conditions the polishing surface 104 of the polishing surface 104 as discussed above, or by other suitable conditioning techniques.

The coating 106 may be renewed in-situ, prior to or after polishing the substrate 308. Renewing of the coating 106 may occur between processing different substrates on the polishing pad 100. The coating 106 may be renewed on the polishing surface 104 between every substrate polishing, after polishing of a predetermined number of substrates, or as needed. In some embodiments, the polishing surface 104 may be cleaned of residual polishing media or other debris using high-pressure water or deionized water prior to the delivery of the precursor fluid to the polishing surface 104 and forming the coating 106. As a result, being able to renew the coating 106 advantageously lengthens the lifetime of the polishing pad 100 and reduces costs associated with replacing the polishing pad 100. Additionally, the in-situ delivery of the coating 106 to the polishing surface 104 eliminates the downtime associated with having to replace the polishing pad 100.

While the foregoing is directed to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof.

Claims

1. A polishing pad comprising:

a hydrophilic polymer base having a polishing surface; and

a metal oxide coating having nanoparticles of metal oxide disposed on the polishing surface.

2. The polishing pad of claim 1, wherein the base comprises polyurethane, polycarbonate, a fluoropolymer, polytetrafluoroethylene, or polyphenylene sulfide.

3. The polishing pad of claim 1, wherein the nanoparticles of metal oxide comprise silicon dioxide (SiO2), aluminum oxide (Al2O3), or germanium dioxide (GeO2).

4. The polishing pad of claim 1, wherein the metal oxide coating has a thickness between about 50 nm to about 500 nm.

5. The polishing pad of claim 1, wherein the nanoparticles have a diameter size between about 10 nm to about 30 nm.

6. The polishing pad of claim 1, wherein the pad is disposed in packaging configured for storage of the polishing pad.

7. A processing station comprising:

a rotatable platen;

a polishing head configured to retain a substrate against the polishing pad; and

a precursor delivery system configured to form an oxide coating on a surface of a polishing pad disposed on the platen.

8. The processing station of claim 7, wherein the precursor delivery system comprises a precursor delivery nozzle configured to deliver a precursor fluid to the surface of the polishing pad.

9. The processing station of claim 8, wherein the precursor delivery system further comprises a plurality of inert gas nozzles adjacent the precursor delivery nozzle, and configured to deliver a curtain of inert gas.

10. The processing station of claim 7, wherein the precursor delivery system comprises a heater configured to heat a precursor fluid.

11. A method for modifying a surface of a polishing pad, comprising:

wetting the surface of the polishing pad;

delivering a precursor to the wetted surface of the polishing pad surface; and

forming a metal oxide coating comprising nanoparticles of metal oxide on the surface from the precursor.

12. The method of claim 11, wherein the precursor is a moisture-sensitive gas.

13. The method of claim 12, wherein the precursor gas is silane (SiH4), trimethylaluminum (Al2(CH3)6), or germanium tetrafluoride (GeF4).

14. The method of claim 10, wherein the surface of the polishing pad is hydrophilic.

15. A method for polishing a substrate on a polishing pad comprising:

providing a polishing fluid to a polishing surface of the polishing pad, the polishing surface having a metal oxide coating having nanoparticles of metal oxide disposed on the polishing surface;

pressing the substrate against the polishing surface in the presence of the polishing fluid; and

polishing the substrate against the polishing surface in the presence of the polishing fluid.

16. The method of claim 15, comprising:

forming the metal oxide coating polishing surface in-situ polishing the substrate.

17. The method of claim 15, comprising:

forming the metal oxide coating polishing surface prior to polishing the substrate.

18. The method of claim 15, comprising:

forming the metal oxide coating polishing surface after polishing the substrate.

19. The method of claim 15, comprising wetting the polishing surface of the polishing pad to form the metal oxide coating.

20. The method of claim 15, wherein the polishing fluid comprises the metal oxide.