METHOD OF MODIFYING THE SURFACE OF A SEMICONDUCTOR WAFER

Abstract: A method of modifying a surface of a semiconductor wafer is disclosed. The method includes: (a) contacting the wafer with a fixed abrasive article in the presence of a composition that includes water and a polar component having from 1 to 10 functional groups selected from the group consisting of -OH, -OOH, =O, and combinations thereof, and from 1 to 10 consecutive groups selected from the group consisting of -CH2-, -CH2O-, -C2H4O-, -C3H6O- and combinations thereof; and (b) relatively moving the wafer and the fixed abrasive article to modify the surface of the wafer.

Description: METHOD OF MODIFYING THE SURFACE OF A SEMICONDUCTOR WAFER Background of the Invention The invention relates to modifying a semiconductor wafer. Wafers used in the fabrication of semiconductors often require surface modification, e.g., polishing and planarization, at some point during the fabrication process. Traditional polishing methods include moving an abrasive substrate and the wafer in relation to each other, typically in the presence of a water-based solution. Polishing processes can be used to remove the highest points from the surface of a wafer. Polishing operations are performed on unprocessed and partially processed wafers. A typical unprocessed wafer is crystalline silicon or another semiconductor material, e.g., gallium arsenide. A typical wafer, when ready for polishing has a top layer of a dielectric material such as glass, silicon dioxide or a metal conformally overlying one or more patterned layers. The underlying patterned layers create local protrusions. Polishing smoothes the local features so that ideally the surface of the wafer is flat or planarized. In some cases, polishing is achieved through the solution working in combination with the fixed abrasive article in a chemical mechanical polishing process. As an example, the chemical polishing of a silicon dioxide substrate occurs when a basic compound in a solution reacts with the silicon dioxide to form a surface layer of silicon hydroxides. The mechanical process occurs when an abrasive article removes the metal hydroxides from the surface of the substrate. A number of chemical mechanical polishing techniques exist. Some chemical mechanical polishing techniques include orbiting or oscillating motions of either the article to be polished or of the polishing pad, or both. Other chemical mechanical polishing techniques include a belt-shaped polishing pad that is advanced translationally under the article to be polished, and the article to be polished is rotated, oscillated or both across the surface of the belt-shaped pad. In some chemical mechanical polishing techniques a slurry is distributed between a pad and the surface to be polished. These slurries often contain water and abrasive particles. In other chemical mechanical polishing techniques, the abrasive is fixed on a substrate and a polishing solution is distributed between the fixed abrasive and the surface to be polished. Often the polishing pad and the substrate to be polished are hydrophobic, which inhibits wetting. Wetting facilitates the transport of fresh chemistry into the region between the abrasive surface and the surface of the wafer to be planarized. The polishing liquid can also assist in the removal of debris and soluble material removed from the surface of the substrate being polished. Surfactants present in the composition can inhibit the removal rate. When a solution does not wet the abrasive surface, the polishing process can also be inhibited. SUMMARY In one aspect, the invention features a method of modifying a surface of a semiconductor wafer, the method including (a) contacting the wafer with a fixed abrasive article in the presence of a composition that includes water and a polar component having from 1 to 10 functional groups selected from the group consisting of -OH, -OOH, =O, and combinations thereof, and from 1 to 10 consecutive groups selected from the group consisting of -CH 2 -, -CH 2 O-, -C 2 I ιO-, -C 3 H6θ- and combinations thereof; and (b) relatively moving the wafer and the fixed abrasive article to modify the surface of the wafer. In some embodiments, the polar component includes no greater than 8 carbon atoms. In other embodiments, the polar component is selected from the group consisting of alcohols, glycols, ketones, ethers, acetates, and combinations thereof. In another embodiment, the polar component includes an alcohol selected from the group consisting of methanol, ethanol, propanol, isopropanol, butanol, isobutanol and mixtures thereof. In some embodiments, the polar component is selected from the group consisting of acetone, ethyl acetate, cellosolve acetate, and mixtures thereof. In one embodiment, the fixed abrasive article includes a three-dimensional textured abrasive surface having a plurality of abrasive particles and a binder arranged in a pattern. In some embodiments, the fixed abrasive comprises particles selected from the group consisting of ceria, silica, alumina, titania, zirconia, manganese oxide, and mixtures thereof. In other embodiments, the method includes chemically and mechanically modifying the surface of the wafer. In another embodiment, the fixed abrasive article includes a backing and an abrasive coating on a surface of the backing, and the abrasive coating includes abrasive particles and a binder. In another aspect, the invention features a method of modifying a surface of a first article, the method includes (a) contacting the first article with a fixed abrasive article in the presence of a composition that includes water and a polar component having from 1 to 10 functional groups selected from the group consisting of -OH, -OOH, =O, and combinations thereof, and from 1 to 10 consecutive groups selected from the group consisting of -CH -, -CH O-, -C 2 H O- ,-C 3 H6O- and combinations thereof; and (b) relatively moving the first article and the fixed abrasive article to modify the surface of the first article. In one embodiment, the polar component includes no greater than 8 carbon atoms. In other embodiments, the polar component is selected from the group consisting of alcohols, glycols, ketones, ethers, acetates, and combinations thereof. In some embodiments, the polar component includes an alcohol selected from the group consisting of methanol, ethanol, propanol, isopropanol, butanol, isobutanol and mixtures thereof. In another embodiment, the polar component is selected from the group consisting of acetone, ethyl acetate, cellosolve acetate, and mixtures thereof. In another embodiment, the fixed abrasive article includes a three- dimensional textured abrasive surface comprising a plurality of abrasive particles and a binder arranged in a pattern. The composition used in the method preferably exhibits reduced surface tension relative to water and is able to wet hydrophobic substrates. The method is particularly well suited to wetting abrasives that include hydrophobic oxide abrasives, e.g., cerium oxide particles. The method also facilitates web polishing by maintaining the solution within the confines of the web such that it does not seep underneath the web where it might cause mechanical difficulties. The improved wetting also provides good rates of removal of surface material. The composition also provides good low vibration and friction during chemical mechanical planarization operations. Other features and advantages of the invention will be apparent from the following description -of the preferred embodiments thereof, and from the claims. Detailed Description The inventors have discovered that aqueous polishing solutions tend to form large beads of liquid when in contact with a hydrophobic web. The large beads tend to be mobile on the abrasive surface during polishing. As a result, under the action of the polishing head the solution travels beyond the edge of the abrasive surface and seeps between the abrasive surface polishing pad and the sub pad on which the fixed abrasive polishing pad sits. This can cause the polishing pad to stick to the sub pad, which in turn causes mechanical problems. The method of modifying a surface of a semiconductor wafer includes contacting the wafer with a fixed abrasive article in the presence of a composition that includes water and a polar component, and moving at least one of the wafer and the fixed abrasive article relative to each other so as to modify the surface of the wafer. The method preferably modifies the surface of the wafer to achieve a surface that is more planar or uniform, or less rough, or a combination thereof, relative to the wafer surface prior to treatment. The polar component preferably provides a composition that is capable of sufficiently wetting the hydrophobic substrate to be modified as well as the fixed abrasive pad. The polar component includes from 1 to 10 functional groups selected from the group consisting of -OH, -OOH, =O, and combinations thereof, and from 1 to 10 consecutive groups selected from the group consisting of -CH 2 -, - CH 2 O-, -C H θ-, -C 3 H6O- and combinations thereof. Preferably the polar component includes no greater than 8 carbon atoms. Examples of useful polar components include alcohols, e.g., methanol, ethanol, propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, isobutanol, and octanol; acetates including methyl acetate, ethyl acetate, and cello solve acetate; ketones, e.g., acetone; ketone alcohols, e.g. diacetone alcohol; ethers including, e.g., methyl ether; alkylene glycols or thioglycols containing a C 2 - C 6 alkylene group, e.g. ethylene glycol, propylene glycol, tripropylene glycol, butylene glycol, pentylene glycol and hexylene glycol; poly(alkylene-glycol)s and thioglycols, e.g. diethylene glycol, thiodiglycol, polyethylene glycol and polypropylene glycol; polyols, e.g. glycerol and 1,2,6-hexanetriol; and lower alkyl glycol and polyglycol ethers, e.g.2-methoxyethanol, 2-(2-methoxyethoxy)ethanol, 2-(2-ethoxyethoxy)ethanol, 2-(2-butoxyethoxy)ethanol,3-butoxypropan-l-ol, 2-[2- (2-methoxyethoxy)-ethoxy]ethanol, 2-[2-(2-ethoxyethoxy)ethoxy]-ethanol; cyclic esters and cyclic amides, e.g. substituted pyrollidones; sulpholane; multiple functionality polar components; and mixtures thereof. The pH of the composition is selected to be suitable for the substrate being modified. Useful compositions have a pH of greater than 1.5, more preferably from about 3 to about 12.5, most preferably from about 5 to about 12. Additives can be included in the composition to achieve a desired pH. Examples of such additives include bases, e.g., potassium hydroxide and ammonium hydroxide, and acids, e.g., KIO 3 , potassium phthalate, phthalic acid, phosphoric acid, nitric acid, and sulfuric acid. Buffers can also be included in the composition to maintain the desired pH. The composition may also include other components including, e.g., liquid etchants, e.g., strong acids (e.g., sulfuric acid and hydrofluoric acid) and oxidizing gents (e.g., peroxides), lubricants and combinations thereof Examples of suitable lubricants include metal salts of fatty acids including, e.g., zinc stearate, calcium stearate and lithium stearate, graphite, mica, molybdenum disulfide, talc, polyamides, boron nitride, sulfides, waxes, silicone compounds, polyvinyl acetate, polyvinyl alcohols, polymers, and combinations thereof. The method is suitable for use with a variety of fixed abrasive articles. Examples of useful fixed abrasive articles include those fixed abrasive articles that are in the form of a pad or a web, e.g., a continuous belt. The fixed-abrasive article preferably includes a number of abrasive particles in a binder attached to a substrate, e.g., a backing. The abrasive particles in the binder may be in the form of an abrasive coating (e.g., a continuous or discontinuous coating), abrasive composites (e.g., shaped bodies) or a combination thereof. The abrasive components (e.g., the particles and the composites) may be arranged in a pattern or random configuration. The fixed abrasive article can be textured such that it includes raised portions and recessed portions. The fixed abrasive article can also be three-dimensional such that it includes numerous abrasive particles extending throughout at least a portion of its thickness such that removing some of the abrasive particles during the surface modifying process exposes additional abrasive particles capable of performing the surface modifying function. Examples of useful fixed abrasive articles are described in U.S. Patent Nos. 5,958,794, 5,692,950 and 5,990,012. The abrasive article may include any number of different abrasive particles. Suitable abrasive particles include, e.g., ceria, silica, alumina, iron oxide, chromia, titania, tin oxide, zirconia, manganese oxide and combinations thereof. Other useful abrasive particles include fused aluminum oxide, heat treated aluminum oxide, white fused aluminum oxide, black silicon carbide, green silicon carbide, titanium diboride, boron carbide, silicon nitride, tungsten carbide, titanium carbide, diamond, cubic boron nitride, hexagonal boron nitride, garnet, fused alumina zirconia, alumina-base sol gel derived abrasive particles and combinations thereof. The movement of at least one of the abrasive article and the wafer relative to each other to modify a surface of the wafer can be rotational, e.g., in a circular, spiral, elliptical, or non uniform fashion, in a figure eight or a corkscrew, translational, vibrational, oscillatory, or a combination thereof. Preferably the movement includes rotation of one or both of the fixed abrasive article and the wafer. For example, the wafer and the abrasive article can be rotated in a circular fashion and in the same direction. Alternatively, the wafer and the fixed abrasive article can be rotated in opposite directions. Examples of suitable methods for relatively moving at least one of a fixed abrasive article and a wafer relative to each other so as to modify a surface of the substrate are described in U.S. Patent Nos. 5,871,390, 5,961,372, 6,000,997, 5,851,136, 5,335,453, WO 99/06182, 5,759,918 and 5,938,884. The method may be used to modify the surface of a variety of articles including, e.g., semiconductor wafers and components of semiconductor wafers. The semiconductor wafer may be in a variety of forms including, e.g., a blank wafer (i.e., a wafer prior to processing, e.g., prior to adding topographical features such as metallized and insulating areas) or a processed wafer (i.e., a wafer that has been subjected to one or more processing steps to add topographical features to the wafer surface). The wafer can include a number of materials including, e.g., silicon, silicon dioxide, silicon nitride, gallium arsenide, copper, aluminum, tungsten, titanium, titanium nitride, polymer, and combinations thereof. The invention will now be described by way of the following examples. All ratios and percentages are by weight unless otherwise indicated. EXAMPLES EXAMPLE 1 The chemicals set forth in Table 1 were added at 10 % by volume to distilled water and then placed on SWR 159 cerium oxide fixed abrasive (3M, St. Paul, Minnesota). The wetting nature was observed and is reported in Table 1. TABLE 1 Other embodiments are within the following claims. For example although the method has been described with respect to a semiconductor wafer, the article to be modified can be a variety of articles and can include materials such as silicon, silicon dioxide, silicon nitride, gallium arsenide, copper, aluminum, tungsten, titanium, titanium nitride, polymers, and combinations thereof.

Claims: What is claimed is: 1. A method of modifying a surface of a semiconductor wafer, said method comprising: (a) contacting the wafer with a fixed abrasive article in the presence of a composition comprising water and a polar component comprising from 1 to 10 functional groups selected from the group consisting of -OH, -OOH, =O, and combinations thereof, and from 1 to 10 consecutive groups selected from the group consisting of -CH 2 -, -CH O-, and combinations thereof; and (b) relatively moving the wafer and the fixed abrasive article to modify the surface of the wafer. 2. The method of claim 1, wherein the polar component comprises no greater than 8 carbon atoms. 3. The method of claim 1, wherein the polar component is selected from the group consisting of alcohols, glycols, ketones, ethers, acetates, and combinations thereof. 4. The method of claim 1, wherein said polar component comprises an alcohol selected from the group consisting of methanol, ethanol, propanol, isopropanol, butanol, isobutanol and mixtures thereof. 5. The method of claim 1, wherein said polar component is selected from the group consisting of acetone, ethyl acetate, cellosolve acetate, and mixtures thereof. 6. The method of claim 1, wherein said fixed abrasive article comprises a three-dimensional textured abrasive surface comprising a plurality of abrasive particles and a binder arranged in a pattern. 7. The method of claim 1, wherein said fixed abrasive comprises particles selected from the group consisting of ceria, silica, alumina, titania, zirconia, manganese oxide and mixtures thereof. 8. The method of claim 6, wherein said abrasive particles are selected from the group consisting of ceria, silica, alumina, titania, zirconia, manganese oxide and mixtures thereof. 9. The method of claim 1, wherein said method comprises chemically and mechanically modifying the surface of the wafer. 10. The method of claim 1, wherein said fixed abrasive article comprises a backing and an abrasive coating on a surface of said backing, said abrasive coating comprising abrasive particles and a binder. 11. A method of modifying a surface of a first article, said method comprising: (a) contacting the first article with a fixed abrasive article in the presence of a composition comprising water and a polar component comprising from 1 to 10 functional groups selected from the group consisting of -OH, -OOH, =O, and combinations thereof, and from 1 to 10 consecutive groups selected from the group consisting of -CH 2 -, -CH O-, -C 2 H4θ-,-C 3 H6θ- and combinations thereof; and (b) relatively moving the first article and the fixed abrasive article to modify the surface of the first article. 12. The method of claim 11, wherein the polar component comprises no greater than 8 carbon atoms. 13. The method of claim 11 , wherein the polar component is selected from the group consisting of alcohols, glycols, ketones, ethers, acetates, and combinations thereof. 14. The method of claim 11, wherein said polar component comprises an alcohol selected from the group consisting of methanol, ethanol, propanol, isopropanol, butanol, isobutanol and mixtures thereof. 15. The method of claim 11, wherein said polar component is selected from the group consisting of acetone, ethyl acetate, cellosolve acetate, and mixtures thereof. 16. The method of claim 11, wherein said fixed abrasive article comprises a three-dimensional textured abrasive surface comprising a plurality of abrasive particles and a binder arranged in a pattern.

Inventors: GAGLIARDI JOHN J, GAGLIARDI, JOHN, J.
Applicants: 3M INNOVATIVE PROPERTIES CO, 3M INNOVATIVE PROPERTIES COMPANY
Application year: 2000
Main classification: H01L21
IPC codes: B24B1, B24B37, C09K3, H01L21