DUAL CMP PAD CONDITIONER

Abstract: According to an example embodiment, the present invention is directed to a CMP polishing apparatus (100) having at least two conditioning arms (110+120) for use in conditioning a polishing pad (150). The CMP polishing apparatus includes a first pad conditioner (130) configured and arranged both to dispense slurry and to condition the pad. A second pad conditioner (140) is configured and arranged both to clean a portion of the polishing pad (150) and to dispense cleaning chemicals. Benefits of using this embodiment include enhanced pad cleaning, better slurry dispense, improved wafer quality, and faster production.

Description: DUAL CMP PAD CONDITIONER Field of the Invention The present device relates generally to semiconductor devices and their fabrication and, more particularly, to semiconductor devices and tools for their manufacture involving chemical-mechanical polishing (CMP). Background of the invention The electronics industry continues to rely upon advances in semiconductor manufacturing technology to realize higher- functioning devices while improving reliability and cost. For many applications, the manufacture of such devices is complex, and maintaining cost-effective manufacturing processes while concurrently maintaining or improving product quality is difficult to accomplish. As the requirements for device performance and cost become more demanding, realizing a successful manufacturing process becomes more difficult. A byproduct of the increased complexity of semiconductor devices includes uneven device surfaces, which become more prominent as additional levels are added to multilevel- interconnection schemes and circuit features are scaled to submicron dimensions. Typically, each level within the device is patterned, resulting in a surface with varied "step-heights" where metal forming the pattern remains on the surface. Planarization is a term describing the surface geometry of a semiconductor device. Complete planarization occurs when the surface of the dielectric is flat, as in a plane. No planarization occurs when the surface of the dielectric directly models the "step-height" surface of the metal pattern in the layer underneath. The degree of planarization refers to the degree to which the varied surface geometry can be "planarized," or smoothed out into a planar surface. Varied surface geometry is often undesirable. Therefore, as additional layers are formed within devices, the required degree of planarization increases. A commonly used new planarization process in semiconductor device manufacturing is chemical-mechanical polishing, or CMP. CMP is useful in the planarization of silicon wafers and of VLSI circuits between different manufacturing processes. CMP is a popular planarization method, due in part to its usefulness in the global planarization of semiconductor devices. Traditional planarization processes are restricted to effecting local planarity or topographical variation on a small scale, whereas CMP is often useful on a global scale greater than ten microns. In one application, a CMP process involves securing a semiconductor wafer to a wafer holder with the wafer located face-down on a polish pad. Both the polish pad and the wafer holder rotate. A slurry, typically a colloidal silica that is a suspension of SiO, particles, is applied to the process. The particle size typically varies from 100 angstroms to 3 microns. The slurry is generally applied using a wand feeding to the wafer holder and pad. The rate of removal of material from the wafer is a combination of chemical and mechanical rates. The mechanical removal rate is roughly proportional to the pressure and the relative velocity of the wafer. The chemical removal rate is a function of the size of the slurry particles and the solution pH, wherein the maximum removal rate is generally obtained using a slurry having a pH of about 11.5. In addition to the use of slurry in the CMP process, a conditioner is also typically used for conditioning the polish pad. The conditioner aids in the CMP polishing process and contributes to the longevity of the pad. Another need in the CMP process is for adequately and efficiently cleaning the pad and the wafer itself. In clean room environments, it is important to maintain a CMP process that produces as few contaminants as possible. Since the slurry particle size ranges in the sub-3 micron range, clean-up is difficult and thus of high importance. In addition, it is helpful to prevent the byproduct resulting from the polishing of each wafer from accumulating on the pad and reaching additional wafers. The traditional method for conditioning the pad and dispensing slurry is to use two separate mechanical components: a slurry dispense wand and a pad conditioner assembly. There are disadvantages in using two separate components. For instance, separate components take up more space in the apparatus. Also, the slurry cannot be spread uniformly across the pad and may accumulate in the pad conditioning head. The non-uniform distribution of slurry distribution hinders the polishing process. In addition, the reaction byproduct cannot be thoroughly removed from the pad. When more than one wafer is processed at once, inadequate cleaning of the pad results in the reaction byproduct and other materials from one wafer coming into contact with other wafers. These disadvantages may result in, for example, long arc style scratches, shallow micro-scratches, inter-die thickness variation, and residual slurry particles. These disadvantages ultimately result in a significant yield lost and in reliability problems due in part to possible metal stringers in the shallow scratch area and surrounding residual slurry particles. Summary of the Invention The present invention is directed to a method and apparatus for improving the CMP process, the improvements including but not limited to enhanced pad cleaning and conditioning, better slurry dispense, improved wafer quality, and faster production. The present invention is exemplified in a number of implementations and applications, some of which are summarized below. According to an example embodiment, the present invention includes a CMP polishing apparatus having at least two conditioning arms for uses including the conditioning of a polishing pad. The CMP polishing apparatus includes a first pad conditioner configured and arranged both to dispense slurry and to condition the pad. A second pad conditioner is configured and arranged both to clean a portion of the polishing pad and to dispense cleaning chemicals. According to another example embodiment, the present invention is directed to a method for conditioning a CMP polishing pad in a CMP polishing apparatus. The CMP apparatus includes at least two conditioning arms. Slurry is dispensed and the pad is conditioned using a first pad conditioner coupled to one of the conditioning arms. A portion of the polishing pad is cleaned using a second pad conditioner coupled to another of the conditioning arms. According to yet another example embodiment, the present invention is directed to a method for CMP, wherein the CMP apparatus includes a polishing pad and at least two conditioning arms for each semiconductor wafer to be processed. A first semiconductor wafer is coupled to the CMP apparatus. The pad is conditioned using a first pad conditioner coupled to a first conditioning arm. A slurry is supplied by way of the first pad conditioner. Using a second pad conditioner coupled to a second conditioning arm, a first cleaning material is supplied by way of the second pad conditioner, and a portion of the polishing pad is cleaned. According to still another example embodiment, the present invention is directed to a CMP polishing apparatus having a polishing pad. The apparatus includes means for both conditioning the polishing pad and supplying slurry, and means for both conditioning the pad and supplying cleaning material. The above summary of the present invention is not intended to describe each illustrated embodiment or every implementation of the present invention. The figures and detailed description which follow more particularly exemplify these embodiments. Brief Description of the Drawings The invention may be more completely understood in consideration of the following detailed description in connection with the accompanying drawings, in which: FIG. 1 shows an arrangement for a CMP process for polishing a semiconductor wafer, according to an example embodiment of the present invention; FIG. 2 shows an arrangement for a CMP process for polishing two semiconductor wafers, according to another example embodiment of the present invention; and FIG. 3 shows an arrangement for a CMP process for polishing a semiconductor wafer, according to another example embodiment of the present invention. While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. Detailed Description According to an example embodiment, the present invention makes possible the use of a single apparatus both for supplying slurry and for conditioning the pad in a CMP process. In addition, a single apparatus may be used both for supplying cleaning material and for conditioning the pad in the CMP process. The use of these apparatuses displaces the need for a dispensing wand for the dispense of materials including slurry and cleaning materials, such as de-ionized water and other materials used in conventional CMP processes. Referring now to FIG. 1, and according to another example embodiment, the present invention is directed to an apparatus 100 for CMP. The apparatus 100 has at least two conditioning arms 110 and 120 for uses including the conditioning of a polishing pad 150. The polishing pad 150 is configured and arranged to rotate. In addition, conditioning arms 110 and 120 are configured and arranged to move in a direction generally tangential to the rotation of the polishing pad 150. The CMP polishing apparatus 100 includes a first pad conditioner 130 configured and arranged both to dispense slurry and to condition the pad. A second pad conditioner 140 is configured and arranged to clean a portion of the polishing pad and to dispense cleaning materials. A wafer holder 160 is configured and arranged to hold a semiconductor wafer face-down on the polishing pad 150. The first pad conditioner 130 and the second pad conditioner 140 may be configured to condition and clean in a number of ways. For instance, the pad conditioners may include rotating means, such as bearings, wheels, and bushings. For effecting rotation, the rotating means may be coupled to devices such as gears, belts, pulleys, and direct drives. In addition, the pad conditioners may comprise a shower head type design, allowing material to be added uniformly over the CMP pad. The pad conditioners may also contain items such as brushes or grids for contacting the pad and aiding in conditioning, cleaning, and disbursement of materials such as cleaning materials or slurry. In another example embodiment, cleaning or polishing materials are supplied to the pad conditioners using supply lines coupled to the pad conditioners. Such supply lines may include, for example, flexible tubing of plastic, metal, or other suitable material. The supply lines may be coupled to the pad conditioners in an appropriate manner, such as using fixed or flexible couplings. In addition, multiple fluids may be supplied to an individual pad conditioner. For example, such multiple fluids may be supplied individually, pre-mixed, mixed in the pad conditioner itself, or mixed in the supply lines using devices such as mixing tubes. FIG. 2 shows an apparatus 200 for CMP, according to another example embodiment of the present invention. FIG. 2 includes all of the embodiments illustrated by FIG. 1, and adds the ability to perform the CMP process on an additional semiconductor wafer. The apparatus 200 has at least two additional conditioning arms 210 and 220 for use including conditioning of the polishing pad 150. The additional conditioning arms 210 and 220 are configured and arranged to move in a direction generally tangential to the rotation of the polishing pad 150. The CMP polishing apparatus 200 includes a third pad conditioner 230 configured and arranged both to dispense slurry and to condition the pad. A fourth pad conditioner 240 is configured and arranged to clean a portion of the polishing pad and to dispense cleaning chemicals. A second wafer holder 260 is configured and arranged to hold a second semiconductor wafer face-down on the polishing pad 150. In addition, at least one of the pad conditioners and the wafer holder may further be configured and arranged to rotate. FIG. 3 shows an apparatus 300 for CMP, according to another example embodiment of the present invention. The apparatus 300 has at least two conditioning arms 310 and 320 for use including the conditioning of a polishing belt 350. The polishing belt 350 is configured and arranged to move relative to the conditioning arms. In addition, the conditioning arms are configured and arranged to move in a direction generally perpendicular to the movement of the belt. The CMP polishing apparatus 300 includes a first belt conditioner 330 configured and arranged both to dispense slurry and to condition the belt. A second belt conditioner 340 is configured and arranged to clean a portion of the polishing belt and to dispense cleaning materials. A wafer holder 360 is configured and arranged to hold a semiconductor wafer face-down on the polishing belt 350. In addition, at least one of the belt conditioners and the wafer holder may further be configured and arranged to rotate. According to another example embodiment, the present invention is directed to a method for conditioning a CMP polishing pad in a CMP polishing apparatus. The CMP apparatus has at least two conditioning arms. Slurry is dispensed and the pad is conditioned using a first pad conditioner coupled to one of the conditioning arms. A portion of the polishing pad is cleaned using a second pad conditioner coupled to another of the conditioning arms. For instance, referring to FIG. 1, a semiconductor wafer is attached to a wafer holder 160, and is held face-down against a polishing pad 150. The polishing pad is caused to rotate, as shown by arrow 170. Conditioning arm 110 is moved in a direction about generally tangential to the rotation of the polishing pad 150, which is depicted with arrow 180 in FIG. 1. Pad conditioner 130 is used to dispense slurry for the CMP process to be performed on the wafer, and to condition the pad 150. Conditioning arm 120 is also moved in a direction about generally tangential to the rotation of the polishing pad 150, as depicted with arrow 190 in FIG. 1. Pad conditioner 140 is used to dispense cleaning materials, remove any excess slurry, used slurry, and reaction byproduct, and to condition the pad. In addition, at least one of the pad conditioners and the wafer holder may further be configured and arranged to rotate. In another example embodiment, and referring to FIG. 2, two semiconductor wafers are processed in a CMP apparatus. A second semiconductor wafer is attached to a wafer holder 260, and is held face-down against a polishing pad 150. The polishing pad is caused to rotate as shown by arrow 170. As in the preceding example embodiment, conditioning arm 110 is moved in a direction about generally tangential to the rotation of the polishing pad 150, which is depicted with arrow 180 in FIG. 1. Pad conditioner 130 is used to dispense slurry for the CMP process to be performed on the wafer, and to condition the pad 150. Conditioning arm 120 is also moved in a direction about generally tangential to the rotation of the polishing pad 150, as depicted with arrow 190 in FIG. 1. Pad conditioner 140 is used to dispense cleaning materials, remove excess slurry, used slurry, and reaction byproduct, and to condition the pad. Pad conditioner 140 may, for example, remove these materials and thereby prevent about all them from reaching the second wafer attached to wafer holder 260. The second semiconductor wafer is processed similarly to the first. Conditioning arm 210 is moved in a direction about generally tangential to the rotation of the polishing pad 150, which is depicted with arrow 280 in FIG. 2. Pad conditioner 230 is used to dispense slurry for the CMP process to be performed on the second wafer, and to condition the pad 150. Conditioning arm 220 is also moved in a direction about generally tangential to the rotation of the polishing pad 150, as depicted with arrow 290 in FIG. 2. Pad conditioner 240 is used to dispense cleaning materials, remove excess slurry, used slurry, and reaction byproduct, and to condition the pad. Pad conditioner 240 may remove this material such that about all of the material is prevented from reaching the first wafer held by the first wafer holder 160. In addition, at least one of the pad conditioners and the wafer holder may further be configured and arranged to rotate. In another example embodiment, and according to FIG. 3, the present invention is directed to a method for conditioning a CMP polishing belt in a CMP. A semiconductor wafer is attached to a wafer holder 360, and is held face-down against a polishing belt 350. The polishing belt is caused to move as shown by arrow 370 in FIG. 3. Conditioning arm 310 is moved in a direction about generally perpendicular to the polishing belt 350, which is depicted with arrow 380 in FIG. 3. Pad conditioner 330 is used to dispense slurry for the CMP process to be performed on the wafer, and to condition the belt 350. Conditioning arm 320 is also moved in a direction about generally perpendicular to the movement of the polishing belt 350, as depicted with arrow 390 in FIG. 3. Pad conditioner 340 is used to dispense cleaning materials, remove any excess slurry, used slurry, and reaction byproduct, and to condition the belt. Again, at least one of the pad conditioners and the wafer holder may further be configured and arranged to rotate. The disclosed methods of CMP have many advantages. For instance, the distribution of the slurry may be made more uniform. In addition, excessive slurry, used slurry, and the reaction byproduct can be completely removed from the pad. The removal of these materials is particularly advantageous because, when this process is used with multiple semiconductor wafers, the materials can be removed prior to their reaching another wafer. Many other beneficial results occur using various embodiments of the invention described herein. For instance, results may include more thorough conditioning of the pad and better cleaning of the pad after polishing processes. The life for the pad and the conditioner grid are extended, which results in lowering the die cost and increasing the profitability. The polish rate becomes more uniform. The occurrence of scratches, such as long-arc type scratches and shallow micro-scratches, is reduced. In addition, residue slurry is reduced, decreasing particle defects as a result of such residue, which results in lowering the defect density, increasing the die sort yield and improving the die reliability. Additional capabilities are also provided, including the use of multiple chemicals with each individual conditioning pad. Skilled artisans will recognize that the above-discussed example embodiments may be implemented by modifying commercially-available equipment. Examples of such equipment include MIRRA and 6DS SP, respectively manufactured by Applied Material and Strausbaugh. While the present invention has been described with reference to several particular example embodiments, those skilled in the art will recognize that many changes may be made thereto. Fox example, many features of the above embodiments are combinable in a single conditioner arrangement and/or conditioning process. Such changes do not depart from the spirit and scope of the present invention, which is set forth in the following claims.

Claims: What is claimed is: 1. A CMP polishing apparatus having at least two conditioning arms and a polishing pad, the CMP polishing apparatus comprising: a first pad conditioner configured and arranged to dispense slurry and to condition the pad; and, a second pad conditioner configured and arranged to clean and condition a portion of the pad and to dispense cleaning materials. 2. A CMP polishing apparatus, according to claim 1 , wherein the first pad conditioner is implemented in place of a wand for dispensing of materials including slurry and cleaning materials. 3. A CMP polishing apparatus, according to claim 1, wherein the pad conditioners include a head adapted to shower materials through holes in the head. 4. A CMP polishing apparatus, according to claim 1, wherein at least one of the pad conditioners includes means for rotation. 5. A CMP polishing apparatus, according to claim 1, wherein at least one of the pad conditioners include means for cleansing. 6. A CMP polishing apparatus, according to claim 5, wherein the means for cleansing includes at least one brush. 7. A CMP polishing apparatus, according to claim 5, wherein the means for cleansing includes at least one grid conditioner. 8. A CMP polishing apparatus, according to claim 1, wherein at least one of the conditioning arms include means for supplying fluid or gas agent. 9. A CMP polishing apparatus, according to claim 1, wherein at least one of the conditioning arms include means for supplying at least two different fluids or gases. 10. A CMP polishing apparatus, according to claim 1, wherein the polishing pad includes a belt. 11. A CMP polishing apparatus, according to claim 1 , wherein the polishing pad includes a disk.

Inventors: LIU ALBERT H, VINES LANDON, LIU, ALBERT, H., VINES, LANDON
Applicants: PHILIPS SEMICONDUCTOR INC, PHILIPS SEMICONDUCTOR, INC.
Application year: 2000
Main classification: H01L
IPC codes: B24B37, B24B53, B24B57, H01L21