Patent Grant
9446497
The present invention relates generally to the field of polishing pads for chemical mechanical polishing. In particular, the present invention is directed to multilayer chemical mechanical polishing pads having a plug in place, broad spectrum, endpoint detection window block; wherein the broad spectrum, endpoint detection window block exhibits a spectrum loss ≦60%. The present invention is also directed to a method of chemical mechanical polishing of a substrate using a multilayer chemical mechanical polishing pad with a plug in place, broad spectrum, endpoint detection window block; wherein the broad spectrum, endpoint detection window block exhibits a spectrum loss ≦60%.
Chemical mechanical planarization, or chemical mechanical polishing (CMP), is a common technique used to planarize or polish workpieces such as semiconductor wafers. In conventional CMP, a wafer carrier, or polishing head, is mounted on a carrier assembly. The polishing head holds the wafer and positions the wafer in contact with a polishing layer of a polishing pad that is mounted on a table or platen within a CMP apparatus. The carrier assembly provides a controllable pressure between the wafer and polishing pad. A polishing medium is optionally dispensed onto the polishing pad and flows into the gap between the wafer and polishing layer. To effect polishing, the polishing pad and wafer typically rotate relative to one another. The wafer surface is polished and made planar by chemical and mechanical action of the polishing layer and polishing medium on the surface.
An important step in planarizing a wafer is determining an endpoint to the process. One popular in situ method for endpoint detection involves providing a polishing pad with a window, which is transparent to select wavelengths of light to facilitate optical endpointing techniques. The in situ optical endpointing techniques can be divided into two basic categories: (1) monitoring the reflected optical signal at a single wavelength or (2) monitoring the reflected optical signal from multiple wavelengths. Typical wavelengths used for optical endpointing include those in the visible spectrum (e.g., 400 to 700 nm), the ultraviolet spectrum (315 to 400 nm), and the infrared spectrum (e.g., 700 to 1000 nm). In U.S. Pat. No. 5,433,651, Lustig et al disclosed a polymeric endpoint detection method using a single wavelength in which light from a laser source is transmitted on a wafer surface and the reflected signal is monitored. As the composition at the wafer surface changes from one metal to another, the reflectivity changes. This change in reflectivity is then used to detect the polishing endpoint. In U.S. Pat. No. 6,106,662, Bibby et al disclosed using a spectrometer to acquire an intensity spectrum of reflected light in the visible range of the optical spectrum. In metal CMP applications, Bibby et al. teach using the whole spectrum to detect the polishing endpoint.
To accommodate these optical endpointing techniques, chemical mechanical polishing pads have been developed having windows. For example, in U.S. Pat. No. 5,605,760, Roberts discloses a polishing pad wherein at least a portion of the pad is transparent to laser light over a range of wavelengths. In some of the disclosed embodiments, Roberts teaches a polishing pad that includes a transparent window piece in an otherwise opaque pad. The window piece may be a rod or plug of transparent polymer in a molded polishing pad. The rod or plug may be insert molded within the polishing pad (i.e., an “integral window”), or may be installed into a cut out in the polishing pad after the molding operation (i.e., a “plug in place window”).
Aliphatic isocyanate based polyurethane materials, such as those described in U.S. Pat. No. 6,984,163 provided improved light transmission over a broad light spectrum. Unfortunately, these aliphatic polyurethane windows tend to lack the requisite durability required for demanding polishing applications.
Conventional polymer based endpoint detection windows often exhibit undesirable degradation upon exposure to light having a wavelength of 330 to 425 nm. This is particularly true for polymeric endpoint detection windows derived from aromatic polyamines, which tend to decompose or yellow upon exposure to light in the ultraviolet spectrum. Historically, filters have sometimes been used in the path of the light used for endpoint detection purposes to attenuate light having such wavelengths before exposure to the endpoint detection window. Increasingly, however, there is pressure to utilize light with shorter wavelengths for endpoint detection purposes in semiconductor polishing applications to facilitate thinner material layers and smaller device sizes.
A problem associated with the use of plug in place windows in polishing pads involves the leakage of polishing fluid around the window and into a porous subpad layer, which can result in undesirable variability in the polishing properties across the pad surface and during the life of the pad.
One approach to alleviating window leakage in polishing pads is disclosed in U.S. Pat. No. 6,524,164 to Tolles. Tolles discloses a polishing pad for a chemical mechanical polishing apparatus and a method of making the same, wherein the polishing pad has a bottom layer, a polishing surface on a top layer and a transparent sheet of material interposed between the two layers. The transparent sheet is disclosed by Tolles to prevent slurry from the chemical mechanical polishing process from penetrating into the bottom layer of the polishing pad.
To alleviate delamination problems associated with some multilayer polishing pads (i.e., wherein the polishing layer separates from a subpad layer during polishing), some multilayer chemical mechanical polishing pads are constructed by directly bonding a polishing layer to a porous subpad layer, wherein the porous subpad layer is permeable to various polishing media (e.g., slurry) used during polishing. The approach to alleviating window leakage disclosed by Tolles does not lend itself for use with such polishing pads in which the construction does not facilitate the inclusion of an impermeable layer material between the polishing layer and a porous subpad layer.
Another approach to alleviating window leakage in polishing pads is disclosed in U.S. Pat. No. 7,163,437 (Swedek et al.). Swedek et al. disclose a polishing pad that includes a polishing layer having a polishing surface, a backing layer with an aperture and a first portion that is permeable to liquid, and a sealant that penetrates a second portion of the backing layer adjacent to and surrounding the aperture such that the second portion is substantially impermeable to liquid. The second portion into which the sealant material penetrates exhibits a decreased compressibility relative to the rest of the backing layer. Given that the window sealing region is within the polishing track, the same thickness, decreased compressibility second portion acts like a speed bump during polishing operations resulting in an increased potential for the creation of polishing defects.
Accordingly, what is needed is a broad spectrum, endpoint detection window block that enables the use of light having a wavelength <400 nm for substrate polishing endpoint detection purposes, wherein the broad spectrum, endpoint detection window block is resistant to degradation upon exposure to that light and exhibits the required durability for demanding polishing applications. There is also a continuing need for new low defectivity multilayer window polishing pad configurations, wherein window leakage into the subpad layer is alleviated.
The present invention provides a multilayer chemical mechanical polishing pad for polishing a substrate selected from at least one of a magnetic substrate, an optical substrate and a semiconductor substrate; comprising: a polishing layer having a polishing surface, a counterbore opening, an outer perimeter, a polishing layer interfacial region parallel to the polishing surface and an average non-interfacial region thickness, TP-avg, measured in a direction perpendicular to the polishing surface from the polishing surface to the polishing layer interfacial region; a porous subpad layer having a bottom surface, an outer perimeter and a porous subpad layer interfacial region parallel to the bottom surface; a pressure sensitive adhesive layer; and, a broad spectrum, endpoint detection window block having a thickness, TW, along an axis perpendicular to a plane of the polishing surface; wherein the broad spectrum, endpoint detection window block, comprises an olefin copolymer; wherein the olefin copolymer is a reaction product of initial components comprising: ethylene; a branched or straight chain C3-30 α-olefin; a silane; and, optionally, a polyolefin; wherein the broad spectrum, endpoint detection window block exhibits a uniform chemical composition across its thickness, TW; wherein the broad spectrum, endpoint detection window block exhibits a spectrum loss ≦60%; wherein the polishing layer interfacial region and the porous subpad layer interfacial region form a coextensive region; wherein the coextensive region secures the polishing layer to the porous subpad layer without the use of a laminating adhesive; wherein the pressure sensitive adhesive layer is applied to the bottom surface of the porous subpad layer; wherein the multilayer chemical mechanical polishing pad has a through opening that extends from the polishing surface to the bottom surface of the porous subpad layer; wherein the counterbore opening opens on the polishing surface, enlarges the through opening and forms a ledge; wherein the counterbore opening has an average depth, DO-avg, from a plane of the polishing surface to the ledge measured in a direction perpendicular to the polishing surface; wherein the average depth, DO-avg, is less than the average non-interfacial region thickness, TP-avg; wherein the broad spectrum, endpoint detection window block is disposed within the counterbore opening; wherein the broad spectrum, endpoint detection window block is bonded to the polishing layer; and, wherein the polishing surface is adapted for polishing the substrate.
The present invention provides a multilayer chemical mechanical polishing pad for polishing a substrate selected from at least one of a magnetic substrate, an optical substrate and a semiconductor substrate; comprising: a polishing layer having a polishing surface, a counterbore opening, an outer perimeter, a polishing layer interfacial region parallel to the polishing surface and an average non-interfacial region thickness, TP-avg, measured in a direction perpendicular to the polishing surface from the polishing surface to the polishing layer interfacial region; a porous subpad layer having a bottom surface, an outer perimeter and a porous subpad layer interfacial region parallel to the bottom surface; a pressure sensitive adhesive layer; and, a broad spectrum, endpoint detection window block having a thickness, TW, along an axis perpendicular to a plane of the polishing surface; wherein the broad spectrum, endpoint detection window block, comprises an olefin copolymer; wherein the olefin copolymer is a reaction product of initial components comprising: ethylene; a branched or straight chain C3-30 α-olefin; a silane; and, optionally, a polyolefin; wherein the broad spectrum, endpoint detection window block exhibits a uniform chemical composition across its thickness, TW; wherein the broad spectrum, endpoint detection window block exhibits a spectrum loss ≦60%; wherein the broad spectrum, endpoint detection window block is ≧90 wt % of the olefin copolymer; wherein the broad spectrum, endpoint detection window block comprises <1 ppm halogen; wherein the broad spectrum, endpoint detection window block comprises <1 liquid filled polymeric capsule; and, wherein the broad spectrum, endpoint detection window block has an average thickness, TW-avg, along an axis perpendicular to the plane of the polishing layer of 5 to 75 mils; wherein the polishing layer interfacial region and the porous subpad layer interfacial region form a coextensive region; wherein the coextensive region secures the polishing layer to the porous subpad layer without the use of a laminating adhesive; wherein the pressure sensitive adhesive layer is applied to the bottom surface of the porous subpad layer; wherein the multilayer chemical mechanical polishing pad has a through opening that extends from the polishing surface to the bottom surface of the porous subpad layer; wherein the counterbore opening opens on the polishing surface, enlarges the through opening and forms a ledge; wherein the counterbore opening has an average depth, DO-avg, from a plane of the polishing surface to the ledge measured in a direction perpendicular to the polishing surface; wherein the average depth, DO-avg, is less than the average non-interfacial region thickness, TP-avg; wherein the broad spectrum, endpoint detection window block is disposed within the counterbore opening; wherein the broad spectrum, endpoint detection window block is bonded to the polishing layer; and, wherein the polishing surface is adapted for polishing the substrate.
The present invention provides a method for manufacturing a multilayer chemical mechanical polishing pad for polishing a substrate selected from at least one of a magnetic substrate, an optical substrate and a semiconductor substrate; comprising: providing a polishing layer having a polishing surface adapted for polishing the substrate, an outer perimeter, a polishing layer interfacial region parallel to the polishing surface and an average non-interfacial region thickness, TP-avg, measured in a direction perpendicular to the polishing surface from the polishing surface to the polishing layer interfacial region; providing a porous subpad layer having a bottom surface, an outer perimeter and a porous subpad layer interfacial region parallel to the bottom surface; providing a pressure sensitive adhesive layer; providing a broad spectrum, endpoint detection window block comprising an olefin copolymer; wherein the olefin copolymer is a reaction product of initial components comprising: ethylene; a branched or straight chain C3-30 α-olefin; a silane; and, optionally, a polyolefin; interfacing the polishing layer and the porous subpad layer forming a stack, wherein the outer perimeter of the polishing layer coincides with the outer perimeter of the porous subpad layer and wherein the polishing layer interfacial region and the porous subpad layer interfacial region form a coextensive region; providing a through opening the extends through the stack from the polishing surface to the bottom surface; providing a counterbore opening that opens on the polishing surface, enlarges the through opening and forms a ledge; wherein the counterbore opening has an average depth, DO-avg, from a plane of the polishing surface to the ledge measured in a direction perpendicular to the polishing surface; wherein the average depth, DO-avg, is less than the average non-interfacial region thickness, TP-avg; disposing the broad spectrum, endpoint detection window block within the counterbore opening and bonding the broad spectrum, endpoint detection window block to the polishing layer; and, applying the pressure sensitive adhesive layer to the bottom surface of the porous subpad layer.
The present invention provides a method of polishing a substrate, comprising: providing a substrate selected from at least one of a magnetic substrate, an optical substrate and a semiconductor substrate; providing a multilayer chemical mechanical polishing pad according to claim 1; providing a polishing medium at an interface between the polishing surface and the substrate; and, creating dynamic contact at the interface between the polishing surface and the substrate; wherein permeation of the polishing medium into the porous subpad layer is impeded by the polishing layer and the irreversibly collapsed, densified region.
The term “average total thickness, TT-avg” as used herein and in the appended claims in reference to a multilayer chemical mechanical polishing pad having a polishing surface means the average thickness of the multilayer chemical mechanical polishing pad measured in a direction normal to the polishing surface.
The term “polishing medium” as used herein and in the appended claims encompasses particle-containing polishing solutions and non-particle-containing solutions, such as abrasive-free and reactive-liquid polishing solutions.
The term “substantially circular cross section” as used herein and in the appended claims in reference to a multilayer chemical mechanical polishing pad (10) means that the longest radius, r, of the cross section from the central axis (12) to the outer perimeter (15) of the polishing surface (14) of the polishing layer (20) is ≦20% longer than the shortest radius, r, of the cross section from the central axis (12) to the outer perimeter (15) of the polishing surface (14). (See
The term “poly(urethane)” as used herein and in the appended claims encompasses (a) polyurethanes formed from the reaction of (i) isocyanates and (ii) polyols (including diols); and, (b) poly(urethane) formed from the reaction of (i) isocyanates with (ii) polyols (including diols) and (iii) water, amines or a combination of water and amines.
The term “crushable porous material” as used herein and in the appended claims refers to a porous material that when subjected to a critical compressive force collapses leaving a densified (i.e., less porous) material.
The term “critical compressive force” as used herein and in the appended claims refers to a compressive force sufficient to collapse a given crushable porous material. One of ordinary skill in the art will understand that the magnitude of the critical compressive force will depend on a variety of factors including the temperature of the crushable porous material. Also, one of ordinary skill in the art will understand that the magnitude of the critical compressive force will depend on the type of force imposed on the crushable porous material (i.e., a static force or a dynamic force).
The term “substantially impermeable to water” as used herein and in the appended claims in reference to the polishing layer means that water dispensed on the polishing surface at atmospheric conditions will not permeate through the polishing layer to the porous subpad layer for at least 24 hours.
The term “halogen free” as used herein and in the appended claims in reference to a broad spectrum, endpoint detection window block means that the broad spectrum, endpoint detection window block contains <100 ppm halogen concentration.
The term “liquid free” as used herein and in the appended claims in reference to a broad, spectrum, endpoint detection window block means that the broad spectrum, endpoint detection window block contains <0.001 wt % material in a liquid state under atmospheric conditions.
The term “liquid filled polymeric capsule” as used herein and in the appended claims refers to a material comprising a polymeric shell surrounding a liquid core.
The term “liquid filled polymeric capsule free” as used herein and in the appended claims in reference to a broad, spectrum, endpoint detection window block means that the broad spectrum, endpoint detection window block contains <1 liquid filled polymeric capsule.
The term “spectrum loss” as used herein and in the appended claims in reference to a given material is determined using the following equation
SL=|(TL300+TL800)/2|
wherein SL is the absolute value of the spectrum loss (in %); TL300 is the transmission loss at 300 nm; and TL800 is the transmission loss at 800 nm.
The term “transmission loss at λ,” or “TLλ” as used herein and in the appended claims in reference to a given material is determined using the following equation
TLλ=100*((PATLλ−ITLλ/ITLλ)
wherein λ is the wavelength of light; TLλ is the transmission loss at λ (in %); PATLλ is the transmission of light with a wavelength λ through a sample of the given material measured using a spectrometer following the abrasion of the sample under the conditions described herein in the Examples according to ASTM D1044-08; and, ITLλ is the transmission of light at a wavelength λ through the sample measured using a spectrometer before abrasion of the sample according to ASTM D1044-08.
The term “transmission loss at 300 nm” or “TL300” as used herein and in the appended claims in reference to a given material is determined using the following equation
TL300=100*((PATL300−ITL300)/ITL300)
wherein TL300 is the transmission loss at 300 nm (in %); PATL300 is the transmission of light at a wavelength of 300 nm through a sample of the given material measured using a spectrometer following the abrasion of the sample under the conditions described herein in the Examples according to ASTM D1044-08; and, ITL300 is the transmission of light at a wavelength of 300 nm through the sample measured using a spectrometer before abrasion of the sample according to ASTM D1044-08.
The term “transmission loss at 800 nm” or “TL800” as used herein and in the appended claims in reference to a given material is determined using the following equation
TL800=100*((PATL800−ITL800)/ITL800)
wherein TL800 is the transmission loss at 800 nm (in %); PATL800 is the transmission of light at a wavelength of 800 nm through a sample of the given material measured using a spectrometer following the abrasion of the sample under the conditions described herein in the Examples according to ASTM D1044-08; and, ITL800 is the transmission of light at a wavelength of 800 nm through the sample measured using a spectrometer before abrasion of the sample according to ASTM D1044-08.
The multilayer chemical mechanical polishing pad (10) of the present invention is preferably adapted for rotation about a central axis (12). (See
The multilayer chemical mechanical polishing pad of the present invention is specifically designed to facilitate the polishing of a substrate selected from at least one of a magnetic substrate, an optical substrate and a semiconductor substrate.
Preferably, the multilayer chemical mechanical polishing pad (10) of the present invention, comprises: a polishing layer (20) having a polishing surface (14), a counterbore opening (40), an outer perimeter (21), a polishing layer interfacial region (24) parallel to the polishing surface (14) and an average non-interfacial region thickness, TP-avg, measured in a direction perpendicular to the polishing surface (14) from the polishing surface (14) to the polishing layer interfacial region (24); a porous subpad layer (50) having a bottom surface (55), an outer perimeter (52) and a porous subpad layer interfacial region (27) parallel to the bottom surface (55); a pressure sensitive adhesive layer (70); and, a broad spectrum, endpoint detection window block (30); wherein the polishing layer interfacial region and the porous subpad layer interfacial region form a coextensive region (25) (preferably, the coextensive region is a commingled region); wherein the coextensive region (25) secures the polishing layer (20) to the porous subpad layer (50) without the use of a laminating adhesive; wherein the pressure sensitive adhesive layer (70) is applied to the bottom surface (55) of the porous subpad layer (50); wherein the multilayer chemical mechanical polishing pad (10) has a through opening (35) that extends from the polishing surface (14) to the bottom surface (55) of the porous subpad layer (50); wherein the counterbore opening (40) opens on the polishing surface (14), enlarges the through opening (35) and forms a ledge (45) (preferably, wherein the ledge (45) is parallel to the polishing surface (14)); wherein the counterbore opening (45) has an average depth, DO-avg, from a plane (28) of the polishing surface (14) to the ledge (45) measured in a direction perpendicular to the polishing surface (14); wherein the average depth, DO-avg, is less than the average non-interfacial region thickness, TP-avg; wherein the broad spectrum, endpoint detection window block (30) is disposed within the counterbore opening (40); wherein the broad spectrum, endpoint detection window block (30) is bonded to the polishing layer (20); and, wherein the polishing surface (14) is adapted for polishing the substrate. (See
Preferably, in the multilayer chemical mechanical polishing pad of the present invention, the outer perimeter (21) of the polishing layer (20) extends beyond the outer perimeter (52) of the porous subpad layer (50) in a direction along the plane (28) of the polishing surface (14) perpendicular to the central axis (12).
Preferably, the outer perimeter (21) of the polishing layer (20) and the outer perimeter (52) of the porous subpad layer (50) coincide, wherein the outer perimeter (21) of the polishing layer (20) and the outer perimeter (52) of the porous subpad layer (50) extend an equal distance from the central axis (12) measured perpendicularly from the central axis (12).
Preferably, the coextensive region (25) comprises a direct bond between the polishing layer (20) and the porous subpad layer (50), wherein there is substantially no commingling between the layers (i.e., coextensive region <0.001% of the average total thickness, TT-avg, of the multilayer chemical mechanical polishing pad). Preferably, there is interpenetration between the polishing layer (20) and the porous sub pad layer (50), wherein the polishing layer interfacial region (24) and the porous subpad layer interfacial region (27) commingle to form the coextensive region (25). Preferably, the coextensive region (25) comprises 0.001 to 5% (more preferably, 0.05 to 5%; most preferably 0.1 to 5%) of the average total thickness, TT-avg.
Preferably, the multilayer chemical mechanical polishing pad of the present invention, further comprises: an irreversibly collapsed, densified region (60) of the porous subpad layer (50) along the outer perimeter (52) of the porous subpad layer (50). Preferably, the multilayer chemical mechanical polishing pad is subjected to a critical compressive force along the outer perimeter (52) of the porous subpad layer (50) to form the irreversibly collapsed, densified region (60). (See
The counterbore opening (40) in the multilayer chemical mechanical polishing pad of the present invention preferably defines a cylindrical volume with an axis, B, that is parallel to the central axis (12). (See
The counterbore opening (40) in the multilayer chemical mechanical polishing pad of the present invention preferably defines a non-cylindrical volume.
The broad spectrum, endpoint detection window block (30) in the multilayer chemical mechanical polishing pad of the present invention is disposed within the counterbore opening (40). Preferably, the broad spectrum, endpoint detection window block (30) is disposed within the counterbore opening (40) and is bonded to the polishing layer (20). Preferably, the broad spectrum, endpoint detection window block (30) is bonded to the polishing layer (20) using at least one of thermal bonding, melt bonding, ultrasonic welding and an adhesive (preferably, the broad spectrum, endpoint detection window block is bonded to the polishing layer using combination of heat and pressure to provide a thermal bond). Preferably, the average depth of the counterbore opening, DO-avg, along an axis, B, parallel with an axis, A, and perpendicular to the plane (28) of the polishing surface (14) is 5 to 75 mils (preferably 10 to 60 mils; more preferably 15 to 50 mils; most preferably, 20 to 40 mils). Preferably, the average depth of the counterbore opening, DO-avg, is ≦ the average thickness, TW-avg, of the broad spectrum, endpoint detection window block (30). (See
0.90*TW-avg≦DO-avg≦TW-avg.
Most preferably, the average depth of the counterbore opening, DO-avg, satisfies the following expression:
0.95*TW-avg≦DO-avg<TW-avg.
The broad spectrum, endpoint detection window block used in the multilayer chemical mechanical polishing pad of the present invention, comprises an olefin copolymer. Preferably, the broad spectrum, endpoint detection window block is ≧90 wt % of the olefin copolymer (more preferably, ≧95 wt % of the olefin copolymer; most preferably ≧98 wt % of the olefin copolymer). Preferably, the broad spectrum, endpoint detection window block is halogen free. More preferably, the broad spectrum, endpoint detection window block comprises <1 ppm halogen. Most preferably, the broad spectrum, endpoint detection window block comprises <0.5 ppm halogen. Preferably, the broad spectrum, endpoint detection window block is liquid free. Preferably, the broad spectrum, endpoint detection window block is liquid filled polymeric capsule free.
The olefin copolymer is preferably a reaction product of initial components comprising: ethylene; a branched or straight chain C3-30 α-olefin (preferably, a branched or straight chain C3-20 α-olefin; more preferably, an α-olefin selected from the group consisting of propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methy 1-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, and, mixtures thereof; most preferably, 1-octene); a condensation crosslinker (preferably, a silane; more preferably, an unsaturated alkoxy silane; still more preferably a vinylsilane selected from the group consisting of vinyltrimethoxysilane, vinyltriethoxysilane, γ-(meth)acryloxy propyl trimethoxy silane and mixtures thereof; most preferably, vinyltrimethoxysilane); and, optionally, a polyolefin (preferably, a polyolefin selected from the group consisting of butadiene; isoprene; 4-methyl-1,3-pentadiene; 1,3-pentadiene; 1,4-pentadiene; 1,5-hexadiene; 1,4-hexadiene; 1,3-hexadiene; 1,3-octadiene; 1,4-octadiene; 1,5-octadiene; 1,6-octadiene; 1,7-octadiene; 7-methyl-1,6-octadiene; 4-ethylidene-8-methyl-1,7-nonadiene; 5,9-dimethyl-1,4,8-decatriene; and, mixtures thereof).
Preferably, the olefin copolymer is a reaction product of initial components comprising: 20 to 90 wt % (preferably, 60 to 90 wt %; more preferably, 65 to 75 wt %) ethylene; 10 to 80 wt % (preferably, 10 to 40 wt %; more preferably, 20 to 35 wt %) of a C3-30 α-olefin (preferably, a branched or straight chain C3-20 α-olefin; more preferably, an α-olefin selected from the group consisting of propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, and, mixtures thereof; most preferably, 1-octene); 0.1 to 5 wt % (preferably, 0.1 to 3 wt %; more preferably, 1 to 3 wt %) of a condensation crosslinker (preferably, a silane; more preferably, an unsaturated alkoxy silane; still more preferably a vinylsilane selected from the group consisting of vinyltrimethoxysilane, vinyltriethoxysilane, γ-(meth)acryloxy propyl trimethoxy silane and mixtures thereof; most preferably, vinyltrimethoxysilane); and, optionally, 0 to 10 wt % (preferably, 0 to 6 wt %) of a polyolefin (preferably, a polyolefin selected from the group consisting of butadiene; isoprene; 4-methyl-1,3-pentadiene; 1,3-pentadiene; 1,4-pentadiene; 1,5-hexadiene; 1,4-hexadiene; 1,3-hexadiene; 1,3-octadiene; 1,4-octadiene; 1,5-octadiene; 1,6-octadiene; 1,7-octadiene; 7-methyl-1,6-octadiene; 4-ethylidene-8-methyl-1,7-nonadiene; 5,9-dimethyl-1,4,8-decatriene; and, mixtures thereof).
The olefin copolymer preferably exhibits a glass transition temperature of 100 to 200° C. (more preferably, 130 to 150° C.) as determined using conventional differential scanning calorimetry.
The olefin copolymer preferably exhibits a weight average molecular weight, MW, of 10,000 to 2,500,000 g/mol (more preferably, 20,000 to 500,000 g/mol; most preferably, 20,000 to 350,000 g/mol). Preferably, the olefin copolymer exhibits a polydispersity of ≦3.5 (more preferably, ≦3.0). Preferably, the olefin copolymer exhibits a density of ≦0.90 g/cm3 (more preferably, ≦0.88 g/cm3; most preferably, ≦0.875 g/cm3). Preferably, the olefin copolymer exhibits a density of ≧0.85 g/cm3 (more preferably, ≧0.86 g/cm3).
The multilayer chemical mechanical polishing pad of the present invention is preferably adapted to be interfaced with a platen of a polishing machine. Preferably, the multilayer chemical mechanical polishing pad is adapted to be affixed to the platen of a polishing machine. The multilayer chemical mechanical polishing pad can be affixed to the platen using at least one of a pressure sensitive adhesive and vacuum.
The multilayer chemical mechanical polishing pad optionally further comprises at least one additional layer. Preferably, the at least one additional layer can be selected from a foam, a film, a woven material, and a nonwoven material. The at least one additional layer can preferably be interfaced with the bottom surface of the porous subpad layer by direct bonding or by using an adhesive. The adhesive can be selected from a pressure sensitive adhesive, a hot melt adhesive, a contact adhesive and combinations thereof. Preferably, the adhesive is selected from a pressure sensitive adhesive and a hot melt adhesive. For some polishing operations, the adhesive is preferably a pressure sensitive adhesive. For some polishing operations, the adhesive is preferably a hot melt adhesive.
In the multilayer chemical mechanical polishing pad of the present invention, a polishing layer is directly bound to a porous subpad layer. That is, the polishing layer is bound to the porous subpad layer without the use of a laminating adhesive. The polishing layer precursor material is deposited directly onto a surface of the porous subpad layer in liquid form. The polishing layer precursor material bonds to the porous subpad layer. The bonding between the polishing layer and the porous subpad layer can be physical, chemical or a combination of both. The polishing layer precursor material can flow into the porous subpad layer before solidifying. The degree of penetration of the precursor material into the porous subpad layer depends on a variety of factors including the system temperature, the viscosity of the precursor material at the system temperature, the open porosity of the porous subpad layer in the porous subpad layer interfacial region, the pressure forcing the precursor material into the porous subpad layer, the kinetics of the reaction of the precursor material (i.e., rate of solidification). The polishing layer precursor material can chemically bond to the porous subpad layer. The degree of chemical bonding formed between the polishing layer precursor material and the porous subpad layer depends on a variety of factors including the composition of each layer and the reactivity between the layers. The precursor material can be applied to the porous subpad layer in one coat. The precursor material can be applied to the porous subpad layer in a plurality of coats.
The polishing layer can comprise a solidified/polymerized material selected from poly(urethane), polysulfone, polyether sulfone, nylon, polyether, polyester, polystyrene, acrylic polymer, polyurea, polyamide, polyvinyl chloride, polyvinyl fluoride, polyethylene, polypropylene, polybutadiene, polyethylene imine, polyacrylonitrile, polyethylene oxide, polyolefin, poly(alkyl)acrylate, poly(alkyl)methacrylate, polyamide, polyether imide, polyketone, epoxy, silicone, EPDM, protein, polysaccharide, polyacetate and combinations of at least two of the foregoing materials. Preferably, the polishing layer comprises a poly(urethane). More preferably, the polishing layer comprises a polyurethane. Preferably, the polishing layer is substantially impermeable to water.
The polishing layer is preferably produced from an aqueous based fluid precursor material. Aqueous based fluid precursor materials suitable for use with the present invention include, for example, water based urethane dispersions, acrylic dispersions and combinations thereof. The aqueous based fluid precursor material preferably comprises a water based urethane dispersion (e.g. Witcobond-290H, Witcobond-293, Witcobond-320 and Witcobond-612 available from Chemtura Corporation).
The polishing layer preferably contains a plurality of microelements. Preferably, the plurality of microelements are uniformly dispersed within at least a portion of polishing layer adjacent to and coincident with the polishing surface. The plurality of microelements can be selected from entrapped gas bubbles, hollow core polymeric materials, liquid filled hollow core polymeric materials, water soluble materials and an insoluble phase material (e.g., mineral oil). The plurality of microelements can comprise hollow core polymeric materials. The plurality of microelements can comprise a hollow core copolymer of polyacrylonitrile and polyvinylidene chloride (e.g., Expancel™ from Akso Nobel of Sundsvall, Sweden).
The polishing surface preferably exhibits a macrotexture. Preferably, the macrotexture is designed to alleviate at least one of hydroplaning; to influence polishing medium flow; to modify the stiffness of the polishing layer; to reduce edge effects; and, to facilitate the transfer of polishing debris away from the area between the polishing surface and the substrate. Preferably, the polishing surface exhibits a macrotexture selected from at least one of perforations and grooves. Perforations can extend from the polishing surface part way or all of the way through the total thickness, TT, of the multilayer chemical mechanical polishing pad. Grooves can be arranged on the polishing surface such that upon rotation of the pad during polishing, at least one groove sweeps over the substrate. The grooves are preferably be selected from curved grooves, linear grooves and combinations thereof.
The polishing surface preferably comprises a groove pattern. Groove patterns can comprise at least one groove. The at least one groove can be selected from curved grooves, straight grooves and combinations thereof. The groove pattern can be selected from a groove design including, for example, concentric grooves (which may be circular or spiral), curved grooves, cross-hatch grooves (e.g., arranged as an X-Y grid across the pad surface), other regular designs (e.g., hexagons, triangles), tire-tread type patterns, irregular designs (e.g., fractal patterns), and combinations of at least two of the foregoing. The groove pattern can be selected from random, concentric, spiral, cross-hatched, X-Y grid, hexagonal, triangular, fractal and combinations of at least two of the foregoing. The at least one groove can exhibit a groove profile selected from rectangular with straight side-walls or the groove cross-section may be “V”-shaped, “U”-shaped, triangular, saw-tooth, and combinations of at least two of the foregoing. The groove pattern can change across the polishing surface. The groove pattern can be engineered for a specific application. The groove dimensions in a specific groove pattern can be varied across the polishing surface to produce regions of different groove densities.
The at least one groove preferably exhibits a depth of ≧20 mils.
The groove pattern preferably comprises at least two grooves exhibiting a depth of ≧15 mils; a width of ≧10 mils and a pitch of ≧50 mils.
The porous subpad layer comprises a crushable porous material. The porous subpad layer can comprise a material selected from an open cell foam, a woven material, and a nonwoven material (e.g., felted, spun bonded, and needle punched materials). Nonwoven materials suitable for use in the porous subpad layer of the present invention include, for example, polymer impregnated felts (e.g., polyurethane impregnated polyester felts). Woven materials suitable for use in the porous subpad layer of the present invention include, for example, thick flannel materials.
The multilayer chemical mechanical polishing pads of the present invention are designed for use with a polishing medium that is provided at an interface between the polishing surface and a substrate during polishing of the substrate. Permeation of polishing medium into the porous subpad layer during polishing can result in undesirable variability in the polishing properties across the polishing surface and during the life of the polishing pad. To alleviate the potential for polishing medium permeating into the porous subpad layer during polishing, the outer perimeter of the porous subpad layer is preferably sealed by a process that irreversibly collapses a portion of the porous subpad layer. The irreversibly collapsed, densified region in the porous subpad layer exhibits a decreased thickness relative to the rest of the porous subpad layer. That is, the porous subpad layer in the irreversibly collapsed, densified region has a thickness that is less than the average thickness of the rest of the porous subpad layer (i.e., a reduced thickness, decreased compressibility region). The incorporation of decreased thickness, reduced compressibility region of the porous subpad layer of the multilayer chemical mechanical polishing pad of the present invention provides sealing without the introduction of the speed bump effect associated with same thickness, decreased compressibility regions created by certain prior art sealing methods. The porous subpad material exhibits an average void volume of 20 to 80%; preferably 50 to 60%. The irreversibly collapsed, densified region of the porous subpad layer is collapsed to reduce the void volume to ≦20%, preferably ≦10%. The relative difference in the average void volume of the edge sealed region from the average void volume of the rest of the porous subpad layer can be determined using comparative thickness measurements. Preferably, the porous subpad material exhibits an average void volume of 50 to 60% and the first and second irreversibly collapsed, densified regions of the porous subpad layer exhibit a thickness that is ≦75%, more preferably ≦70% of the average thickness of the porous subpad layer.
Preferably, the method for manufacturing a multilayer chemical mechanical polishing pad of the present invention, comprises: providing a polishing layer having a polishing surface adapted for polishing the substrate, an outer perimeter, a polishing layer interfacial region parallel to the polishing surface and an average non-interfacial region thickness, TP-avg, measured in a direction perpendicular to the polishing surface from the polishing surface to the polishing layer interfacial region; providing a porous subpad layer having a bottom surface, an outer perimeter and a porous subpad layer interfacial region parallel to the bottom surface; providing a pressure sensitive adhesive layer; providing a broad spectrum, endpoint detection window block; interfacing the polishing layer and the porous subpad layer forming a stack, wherein the outer perimeter of the polishing layer coincides with the outer perimeter of the porous subpad layer and wherein the polishing layer interfacial region and the porous subpad layer interfacial region form a coextensive region; providing a through opening the extends through the stack from the polishing surface to the bottom surface; providing a counterbore opening that opens on the polishing surface, enlarges the through opening and forms a ledge (preferably, wherein the ledge is parallel to the polishing surface); wherein the counterbore opening has an average depth, DO-avg, from a plane of the polishing surface to the ledge measured in a direction perpendicular to the polishing surface; wherein the average depth, DO-avg, is less than the average non-interfacial region thickness, TP-avg; disposing the broad spectrum, endpoint detection window block within the counterbore opening and bonding the broad spectrum, endpoint detection window block to the polishing layer; and, applying the pressure sensitive adhesive layer to the bottom surface of the porous subpad layer.
Preferably, the through opening in the multilayer chemical mechanical polishing pad of the present invention is formed using at least one of a laser, a mechanical cutting tool (e.g., a drill, a milling bit, a cutting die) and a plasma. More preferably, the through opening in the multilayer chemical mechanical polishing pad of the present invention is formed using a cutting die. Most preferably, the through opening in the multilayer chemical mechanical polishing pad of the present invention is formed by placing a mask, defining the cross section of the through opening parallel to the polishing surface, over the polishing pad and using a plasma to form the through opening.
Preferably, the counterbore opening in the multilayer chemical mechanical polishing pad of the present invention is formed using at least one of a laser, a mechanical cutting tool (e.g., a drill, a milling bit). More preferably, the through opening in the multilayer chemical mechanical polishing pad of the present invention is formed using a laser. Most preferably, the counterbore opening in the multilayer chemical mechanical polishing pad of the present invention is formed by placing a mask, defining the cross section of the counterbore opening parallel to the polishing surface, over the polishing pad and using a plasma to form the through opening.
The counterbore opening is preferably formed before, after or simultaneously with the formation of the through opening. Preferably, the counterbore opening and the through opening are formed simultaneously. More preferably, the counterbore opening is formed first followed by the formation of the through opening.
The method for manufacturing a multilayer chemical mechanical polishing pad of the present invention, optionally, further comprises: raising a temperature of and applying a critical compressive force to a region of the stack corresponding to the outer perimeter of the porous subpad layer using the sealing die, wherein the raised temperature and the magnitude of the critical compressive force are collectively sufficient to form an irreversibly collapsed, densified region in the porous subpad layer along the outer perimeter of the porous subpad layer. The pressure sensitive adhesive layer can be applied to the bottom surface of the porous subpad layer before or after the formation of the irreversibly collapsed, densified region.
The method for manufacturing a multilayer chemical mechanical polishing pad of the present invention, optionally, further comprises: providing a mating surface; providing a stamper with a raised feature corresponding to the irreversibly collapsed, densified region; wherein the stack is placed between the mating surface and the stamper; wherein the mating surface and the stamper are pressed together creating the critical compressive force forming the irreversibly collapsed, densified region in the porous subpad layer.
The mating surface can be flat. Alternatively, the mating surface can be designed to include a feature, such as, one or more raised portions or contouring. The feature included on the mating surface can be designed to facilitate the formation of the irreversibly collapsed densified region in the porous subpad layer. The feature included on the mating surface can be designed to facilitate manipulation of polishing layer so that the multilayer chemical mechanical polishing pad is biased to lie flatly on the platen of a polishing machine during polishing.
The method for manufacturing a multilayer chemical mechanical polishing pad of the present invention can, optionally, further comprise: heating at least a portion of the porous subpad layer to facilitate the formation of the irreversibly collapsed, densified region in the porous subpad layer (i.e., using both heat and pressure to form the irreversibly collapsed, densified regions).
Preferably, radio frequency welding techniques and equipment are used to facilitate the formation of the irreversibly collapsed, densified region in the porous subpad layer.
Preferably, ultrasonic welding techniques and equipment are used to facilitate the formation of the irreversibly collapsed, densified region in the porous subpad layer.
The method of the present invention for polishing a substrate, comprises: providing a substrate selected from at least one of a magnetic substrate, an optical substrate and a semiconductor substrate; providing a multilayer chemical mechanical polishing pad of the present invention; providing a polishing medium at an interface between the polishing surface and the substrate; and, creating dynamic contact at the interface between the polishing surface and the substrate; wherein permeation of the polishing medium into the porous subpad layer is impeded by the polishing layer and the irreversibly collapsed, densified region. Preferably, the coextensive region is a commingled region. Any permeation of the polishing medium into the porous subpad layer is impeded to the point that it does not negatively affect the polishing performance of the multilayer chemical mechanical polishing pad. Preferably, permeation of the polishing medium into the porous subpad layer is precluded by the polishing layer and the irreversibly collapsed, densified region under the polishing conditions used to polish the substrate.
Preferably, the method of the present invention for polishing a substrate further comprises: providing a light source; providing a light detector; providing a control system; wherein the light source directs light through the broad spectrum, endpoint detection window block in the multilayer chemical mechanical polishing pad incident on the substrate; wherein the light detector detects light reflected from the substrate; wherein the control system receives an input from the light detector and determines when a polishing endpoint is reached.
Some embodiments of the present invention will now be described in detail in the following Examples.
A polyurethane, condensation polymer endpoint detection window block was prepared as follows. A diethyl toluene diamine “DETDA” (Ethacure® 100 LC available from Albemarle) was combined with an isocyanate terminated prepolymer polyol (LW570 prepolymer polyol available from Chemtura) at stoichiometric ratio of —NH2 to —NCO of 105%. The resulting material was then introduced into a mold. The contents of the mold were then cured in an oven for eighteen (18) hours. The set point temperature for the oven was set at 93° C. for the first twenty (20) minutes; 104° C. for the following fifteen (15) hours and forty (40) minutes; and then dropped to 21° C. for the final two (2) hours. Window blocks having a diameter of 10.795 cm and an average thickness of 30 mils were then cut from the cured mold contents.
Circular test windows having a 10.795 cm diameter were cut from a 20 mil thick sheet of a modified olefin block copolymer (available from The Dow Chemical Company as additive free Enlight™ 4015 film).
The window block materials prepared according to Comparative Example WBC and Example WB1 were then tested according to ASTM D1044-08 using a Verity SD1024D Spectrograph outfitted with a Verity FL2004 flash lamp and Spectraview 1 software version VI 4.40 and a Taber 5150 Abraser model abrasion tool set up with a Type H22 abrasive wheel, a 500 g weight, 60 rpm and 10 cycles. The transmission loss at various wavelengths measured for the window block materials are reported in TABLE 1. Also reported in Table 1 is the spectrum loss for each of the window block materials.
| Number | Name | Date | Kind |
|---|---|---|---|
| 5266627 | Meverden et al. | Nov 1993 | A |
| 6458014 | Ihsikawa | Oct 2002 | B1 |
| 6524164 | Tolles | Feb 2003 | B1 |
| 6984163 | Roberts | Jan 2006 | B2 |
| 7150815 | Ashmead et al. | Dec 2006 | B2 |
| 7255629 | Birang et al. | Aug 2007 | B2 |
| 7273407 | Saikin | Sep 2007 | B2 |
| 7306507 | Benvegnu et al. | Dec 2007 | B2 |
| 7731568 | Shimomura et al. | Jun 2010 | B2 |
| 7874894 | Fukuda et al. | Jan 2011 | B2 |
| 7927183 | Fukuda et al. | Apr 2011 | B2 |
| 20030129931 | Konno | Jul 2003 | A1 |
| 20040053562 | Petroski et al. | Mar 2004 | A1 |
| 20050014376 | Shiho et al. | Jan 2005 | A1 |
| 20050148183 | Shiro et al. | Jul 2005 | A1 |
| 20050266771 | Wiswesser | Dec 2005 | A1 |
| 20060084365 | Sakurai | Apr 2006 | A1 |
| 20080078445 | Patel et al. | Apr 2008 | A1 |
| 20080115825 | Patel et al. | May 2008 | A1 |
| 20090253353 | Ogawa | Oct 2009 | A1 |
| 20100009933 | Marat | Jan 2010 | A1 |
| 20100099344 | String et al. | Apr 2010 | A1 |
| 20100330879 | Paik et al. | Dec 2010 | A1 |
| Entry |
|---|
| Natta, et al., Some Remarks on Amorphous and Atactic α-Olefin Polymers and Random Ethylene-Propylene Copolymers, Journal of Polymer Science: Part A, vol. 3, pp. 1-10 (1965). |
| McCormic, et al., Tailored Rheology of a Metallocene Polyolefin through Silane Grafting and Subsequent Silane Crosslinking, Journal of Pjolymer Science: Part B: Polymer Physics, vol. 38, pp. 2468-2479 (2000). |
| Spencer, et al., Composition distribution in poly(ethylene-graft-vinyltrimethoxysilane), Polymer, 44, pp. 2015-2023 (2003). |
| Copending U.S. Appl. No. 13/788,594. |
| Copending U.S. Appl. No. 13/788,539. |
| Number | Date | Country | |
|---|---|---|---|
| 20140256232 A1 | Sep 2014 | US |
