WO2008038583A1 - Cmp conditioner and process for producing the same - Google Patents

Abstract

[PROBLEMS] To provide a CMP conditioner having excellent corrosion resistance around abrasive grains. [MEANS FOR SOLVING PROBLEMS] A grindstone base having, formed on one side, an abrasive grain layer comprising a metallic bonding phase and abrasive grains fixed thereto is treated to form a first protective layer comprising an oxide on the surface of the metallic bonding phase of the abrasive grain layer by the sol-gel method. Subsequently, an aerosol obtained by dispersing fine particles of a brittle material in a gas is jetted and caused to strike on the surface of the first protective layer to form a second protective layer comprising a thick oxide film.

Description

 Specification

 Technical field

 TECHNICAL FIELD [0001] The present invention relates to a CMP conditioner used for conditioning a polishing pad of a CMP (Chemical Mechanical Polishing) apparatus for polishing a semiconductor wafer or the like, and a method for manufacturing the same.

Background art

 [0002] As this type of CMP conditioner, for example, Patent Document 1 discloses that a plurality of cylindrical protrusions are formed on the upper surface of a disk-shaped substrate (base metal) at intervals, and the surface of these protrusions is formed. Proposals have been made in which a plurality of abrasive grains such as diamond are fixed by a metal-bonded binder phase.

 [0003] In addition, Patent Document 2 proposes brazing diamond abrasive grains, and Patent Document 3 further discloses that SiC or the like is formed on the surface of the metal binder phase to which the abrasive grains are fixed. It has been proposed to apply ceramic coatings by vapor phase coating techniques such as CVD and ion plating.

 [0004] In a CMP apparatus in which a polishing pad is conditioned by such a CMP conditioner, a highly acidic or alkaline corrosive slurry is used when polishing a semiconductor wafer or the like, so that a metal bond that holds abrasive grains is used. There is a problem that the layer is corroded (eluted) by the slurry and the abrasive grains fall off, and the semiconductor grains are damaged by the dropped abrasive grains to cause scratches. In particular, when the abrasive grains are diamond and the binder phase is a metal-plated phase such as nickel, the wettability of the metal cling to the abrasive grains is poor, so the boundary between the two is minimal. As a result, a gap is generated, and this gap force also enters the slurry and corrodes the metal adhesion phase. As a result, the removal of the abrasive grains is further promoted.

[0005] In this regard, in a CMP conditioner in which a metal coating phase surface is coated with a ceramic coating as described in Patent Document 3, the ceramic coating protects the metal bonding layer, thereby preventing corrosion. Therefore, the falling off of the abrasive grains can be controlled. Where power On the other hand, when the ceramic film is coated by the vapor phase coating technique as described in Patent Document 3, the film is also coated on the surface of abrasive grains such as diamond protruding from the metal binder phase. The problem is that the sharpness of the abrasive grains is impaired and the polishing rate of the pad is significantly reduced.

[0006] Further, as a technique for forming a ceramic thick film on various substrates, an aerosol deposition method disclosed in Patent Documents 4 to 7 and the like is known.

[0007] Patent Document 1: Japanese Patent Laid-Open No. 2001-71269

 Patent Document 2: Japanese Patent Laid-Open No. 2002-273657

 Patent Document 3: Japanese Patent Laid-Open No. 2001-210613

 Patent Document 4: Japanese Patent No. 3348154

 Patent Document 5: Japanese Patent Application Laid-Open No. 2002-309383

 Patent Document 6: Japanese Unexamined Patent Publication No. 2003-034003

 Patent Document 7: Japanese Unexamined Patent Application Publication No. 2004-091614

 Patent Document 8: Japanese Unexamined Patent Publication No. 2003-183848

 Disclosure of the invention

 Problems to be solved by the invention

[0008] The present invention has been made under such a background, and it is possible to reliably prevent the abrasive grains from dropping even in a highly corrosive slurry used in a CMP apparatus and to suppress the generation of scratches. The purpose is to provide a possible CMP conditioner!

 Means for solving the problem

 [0009] In order to solve the above-mentioned problems, the CMP conditioner has the abrasive layer formed by adhering abrasive grains in the metal binder phase on one surface of the grindstone base, and at least the abrasive conditioner described above. An oxide film prepared by a sol-gel method is formed as a first protective layer on the surface of the metal binder phase of the grain layer, and the surface of the first protective layer is polycrystalline, A thick oxide film substantially free of a grain boundary layer composed of a glass layer was formed as a second protective layer at the interface.

 Here, the thick film is a film having a thickness of 1 β m or more.

The first protective layer is at least near the joint between the abrasive grains and the metal binder phase. The power is formed so as to cover the metal binder phase.

 Such a structure is made possible by forming an oxide film as a first protective layer by a sol-gel method. Since the sol-gel method is a method of forming an oxide film using a solution, the solution is attracted to the periphery of the abrasive grains by surface tension, and as a result, the film thickness at the periphery of the abrasive grains is thicker than other parts. Can be considered. The formed oxide film covers the metal binder phase, and has excellent corrosion resistance particularly in the periphery of the abrasive grains.

[0011] The first protective layer has a thin film thickness in other portions except the peripheral portion of the abrasive grains, and stable corrosion resistance cannot be obtained. Therefore, a thick oxide film is formed on the surface of the first protective layer, which is a second protective layer, which is polycrystalline, and a grain boundary layer composed of a glass layer does not substantially exist at the interface between the crystals. By doing so, stable corrosion resistance can be obtained.

 [0012] The second protective layer is preferably not formed on the surface of the abrasive grains, but only on the surface of the first protective layer. Since it is not formed on the surface of the abrasive grains, it does not cause problems such as changes in the polishing performance of the CMP conditioner.

 [0013] The second protective layer is desirably an oxide having excellent corrosion resistance, such as alumina.

 As a method for producing the second protective layer, a method in which an aerosol in which fine particles of a brittle material are dispersed in a gas is jetted onto the first protective layer to collide to form a thick oxide film.

 [0014] The above method is a method recognized as an aerosol deposition method, as described in Patent Documents 4 to 7.

The aerosol deposition method is a technique for forming a thick ceramic film on various substrates. The aerosol, in which ceramic fine particles are dispersed in a gas, is sprayed from a nozzle toward the substrate, and metal, glass, ceramics, Fine particles collide with a base material such as plastic, and the impact of the impact causes the fine particles to be deformed or crushed and joined together to directly form a membrane structure composed of the constituent materials of the fine particles on the base material. In particular, a structure can be formed at room temperature that does not require a heating means, and a structure having mechanical strength equivalent to that of a fired body can be obtained. The apparatus used in this method basically includes an aerosol generator for generating an aerosol and a nozzle for injecting the aerosol toward a substrate. When manufacturing a structure with a larger area than the nozzle opening, it has a position control means that moves and swings the base material and the nozzle relative to each other. It is common to have a chamber for forming the structure and a vacuum pump, and a gas generation source for generating aerosol.

[0015] The process temperature of the aerosol deposition method is room temperature, a temperature sufficiently lower than the melting point of the fine particle material, that is, several hundred. There is one characteristic power ^s where structures are formed below C.

 [0016] Further, the fine particles used are mainly brittle materials such as ceramics, fine particles of the same material can be used alone or in combination, and different types of fine particles can be mixed or combined. Is possible. It is also possible to use some metal materials or organic materials mixed with ceramic fine particles, or coated on the surface of ceramic fine particles. Even in these cases, the main component of the structure formation is ceramics.

 In the film structure formed by this method, when crystalline fine particles are used as a raw material, the film structure is a polycrystal having a crystallite size smaller than that of the raw material fine particles. It can be said that there is substantially no crystal orientation, and there is substantially no grain boundary layer composed of a glass layer at the interface between ceramic crystals, and part of the film structure is eaten on the substrate surface! /, Many anchor layers are formed!

 [0018] The membrane structure formed by this method clearly has a sufficient strength, unlike a so-called green compact in which fine particles are packed together by pressure and keeps its form by physical adhesion. ing.

 [0019] In the formation of the membrane structure, the fact that the fine particles are crushed and deformed is determined by measuring the fine particles used as a raw material and the crystallite size of the formed film structure by an X-ray diffraction method. it can.

 [0020] Terms related to the aerosol deposition method will be described below.

 (Polycrystalline)

In this case, it refers to a structure in which crystallites are joined and accumulated. The crystallites substantially form a single crystal, and the diameter is usually 5 nm or more. However, the force S that rarely occurs when fine particles are incorporated into the structure without being crushed, is essentially polycrystalline. (Fine particles)

 When the primary particles are dense particles, the average particle size identified by particle size distribution measurement or scanning electron microscope is 10 m or less. When the primary particles are porous particles that are easily crushed by impact, the average particle size is 50 m or less.

 (Aerosol)

 The aforementioned fine particles are dispersed in a gas such as helium, nitrogen, argon, oxygen, dry air, or a mixed gas thereof, and it is desirable that the primary particles are dispersed. Containing aggregated grains. The gas pressure and temperature of the aerosol are arbitrary. The concentration of fine particles in the gas is 0.0003mL / L at the time of injection from the nozzle when the gas pressure is converted to 1 atm and the temperature is converted to 20 ° C. Desirable for structure formation to be in the range of 5 mL / L! /.

 (Interface)

 In this case, it refers to the region that forms the boundary between crystallites.

 (Grain boundary layer)

 At the interface or sintered body! /, A layer with a thickness (usually several nm to several μm) located at the grain boundary, which usually has an amorphous structure different from the crystal structure in the crystal grain, and in some cases impurities Accompanied by segregation.

 The invention's effect

 [0021] In the CMP conditioner according to the present invention, both the first protective layer having excellent corrosion resistance in the periphery of the abrasive grains and the second protective layer having a thick and stable corrosion resistance are formed. As a result, it is possible to prevent the abrasive grains from falling off due to the corrosion of the metal binder phase, and it is possible to polish high-quality semiconductor wafers and the like while suppressing the occurrence of scratches.

 Brief Description of Drawings

 FIG. 1 is an enlarged sectional view of a CMP conditioner showing an embodiment of a CMP conditioner of the present invention.

 FIG. 2 is a view showing an aerosol deposition apparatus according to an embodiment of a method for producing a CMP conditioner of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION FIG. 1 is a schematic sectional view of a CMP conditioner 10 according to the present invention. In the CMP conditioner, a base metal 101, a metal bonded phase 102 in contact with the base metal 101, and a large number of abrasive grains 105 such as diamond abrasive grains are fixed by the metal bonded phase 102 to form an abrasive grain layer 11. At least the surface of the metal binder phase 102 of the abrasive grain layer 11 is formed as a first protective layer 103 with an oxide film made of silica, titania or the like prepared by a sol-gel method, and the first protective layer 103. On the surface, an alumina film having a thickness of 1 μm or more produced by an aerosol deposition method is formed as the second protective layer 104.

 The sol-gel method, which is a method for forming the first protective layer, will be described below.

 SiO sol-gel solution prepared by mixing Si (OC H) and ethanol or Ti (OC H

 2 5 4 2 2 5

) And ethanol are mixed in a TiO sol-gel solution prepared for 1 minute.

4 2

 Then, it is dried at 200 ° C for 2 hours, and then treated at 500 ° C for 8 hours to form an oxide film. The sol-gel solution includes TiO, A10, SnO, ZnO, VO, V O, MO, WO,

 2 2 3 2 2 2 5 3 3

A sol-gel solution such as TaO or ZnO may be used. Also, instead of ethanol, 2-prop

5 2

 Nord may be used.

 [0025] Next, an aerosol deposition method, which is a method for forming the second protective layer 104, will be described below.

In the aerosol deposition method, aerosols in which fine particles such as brittle materials are dispersed in a gas are sprayed from a nozzle toward the base material, causing the fine particles to collide with a base material such as metal, glass, ceramics, or plastic. It is characterized by causing brittle material fine particles to be deformed or crushed by impact and joining them together to form a structure consisting of the constituent materials of the fine particles on the substrate, especially at room temperature that does not require heating means Thus, a structure can be formed, and a structure having mechanical strength equivalent to that of the fired body can be obtained. The apparatus used in this method is basically composed of an aerosol generator that generates aerosol and a nozzle that injects aerosol toward the substrate, and is used to produce a structure with a larger area than the nozzle opening. Has position control means that moves and swings the substrate and nozzle relative to each other, and has a chamber and vacuum pump for forming structures when producing under reduced pressure, and generates aerosol. It is common to have a gas generation source for generating the gas. The process temperature of the aerosol deposition method is room temperature, which is well below the melting point of the particulate material, that is, several hundred. One characteristic is that the structure is formed below C. Therefore, there are various kinds of base materials that can be selected, and there is no problem in application even if it is a low melting point metal or a resin material.

 [0026] Further, the fine particles used are mainly brittle materials such as ceramics and semiconductors, and fine particles of the same material can be used alone or in combination, and fine particles of different kinds of brittle materials can be mixed or combined. Can be used. It is also possible to use some metal materials or organic materials mixed with brittle material fine particles or coated on the surface of brittle material fine particles. Even in these cases, the main component of structure formation is brittle materials.

 [0027] In the structure formed by this method, when crystalline brittle material fine particles are used as a raw material, the brittle material portion of the structure has a smaller crystallite size than that of the raw material fine particles. It is a crystal body, and the crystal may have substantially no crystal orientation. It can be said that there is substantially no grain boundary layer composed of a glass layer at the interface between many brittle material crystals, and a part of the structure. Is characterized in that it often forms an anchor layer that bites into the substrate surface.

 [0028] The structure formed by this method is clearly different from a so-called green compact in which fine particles are packed together by pressure and maintained in a form by physical adhesion, and has sufficient strength. ing.

[0029] In this structure formation, the brittle material fine particles are crushed and deformed. The brittle material fine particles used as a raw material and the crystallite size of the formed brittle material structure are measured by an X-ray diffraction method. Can be judged. That is, the crystallite size of the structure formed by the aerosol deposition method is smaller than the crystallite size of the raw material fine particles. Newly formed surfaces in which atoms originally present inside and bonded to other atoms are exposed are formed on the slippage and fracture surfaces that are formed when the fine particles are crushed and deformed. It is considered that the active new surface having a high surface energy is bonded to the adjacent brittle material surface, the new surface of the adjacent brittle material, or the substrate surface to form a structure. In addition, when there are moderately hydroxyl groups on the surface of the fine particles, the fine particle impacts. It is also conceivable that a mechanochemical acid-base dehydration reaction occurs due to local shear stress generated between the microparticles or between the microparticles and the structure at the time of a collision, and these are joined together. The addition of continuous mechanical impact force from the outside causes these phenomena to occur continuously, and the progress and densification of joints are performed by repeated deformation and crushing of fine particles, and brittle material structures grow. it is conceivable that.

 FIG. 2 shows an aerosol deposition apparatus 20 for forming a second protective film in the CMP diamond conditioner of the present invention. A nitrogen gas cylinder 201 is passed through a gas transport pipe 202. The aerosol generator 203 is installed on the downstream side of the nozzle 206 having an inlet opening with a diameter of 2 mm and an outlet opening lOmm X O. It is connected. The aerosol generator 203 is filled with, for example, aluminum oxide fine particle powder. At the tip of the opening of the nozzle 206, for example, a film-formed object 208 held by a ΧΥΖΘ stage 207 is arranged! The ceramic film forming chamber 205 is connected to a vacuum pump 209! /.

 [0031] The operation of the aerosol deposition apparatus 20 for forming a ceramic film will be described below. The nitrogen gas cylinder 201 is opened, and the gas is fed into the aerosol generator 203 through the gas transfer pipe 202. At the same time, the aerosol generator 203 is operated to generate an aerosol in which aluminum oxide fine particles and nitrogen gas are mixed in an appropriate ratio. Let Further, the vacuum pump 209 is operated to generate a differential pressure between the aerosol generator 203 and the structure forming chamber 205. The aerosol rides on this differential pressure, is introduced into the aerosol transport pipe 204 on the downstream side, accelerates, and is sprayed from the nozzle 206 toward the base material 208. The substrate 208 is freely swung by the ΘΘstage 207, and while changing the aerosol collision position, a film-like alumina film is formed on the desired position of the workpiece 208 by collision of fine particles! /, The

 [0032] Here, the force of placing the ceramic film forming chamber 205 in a reduced pressure environment by the vacuum pump 209 is not necessarily required to be in a reduced pressure environment, and the film can be formed under atmospheric pressure. The gas is not limited to nitrogen, but helium, compressed air, etc. can be used.

 [0033] (Example)

In order to investigate the performance of the CMP conditioner, which is effective in the present invention, it is immersed in a mixed solution of CMP slurry (W2000, manufactured by Cabot) and 3% hydrogen peroxide solution at 50 ° C for 48 hours. A corrosion resistance test was conducted by observing the front and back surface conditions.

 As an excellent CMP conditioner used in the corrosion resistance test, as a first protective film, an Si thin film is used as a CMP conditioner on a surface where diamond abrasive grains as abrasive grains are fixed in Ni as a metal binder phase. After immersing the conditioner in a sol-gel solution prepared by mixing the forming material (Mitsubishi Materials Co., Ltd.) and ethanol 1: 1, dried at 200 ° C for 2 hours, treated at 500 ° C for 8 hours to form a silica film. Next, as a second protective film, an aerosol is generated at a flow rate of 7 L / min of nitrogen gas using alumina fine particles with an average particle diameter of 0. A CMP conditioner with a 3 to 5 m thick alumina film was produced by spraying onto the surface of the film. As a result of the corrosion resistance test, it was found that there was no discoloration due to corrosion and sufficient corrosion resistance. The results are shown in Table 1. In Table 1, the results of Comparative Examples 1 and 2 shown below are also shown.

[0034] (Comparative Example 1)

 For comparison of corrosion resistance, a CMP conditioner in which only the second protective film in Example 1 was formed was fabricated, and the same corrosion resistance test as in Example 1 was performed. As a result of the corrosion resistance test, it was found that discoloration due to corrosion was observed in the vicinity of the diamond abrasive grains, and Ni was eluted.

[0035] (Comparative Example 2)

 For comparison of corrosion resistance, a CMP conditioner that did not form the first protective film and the second protective film in Example 1 was produced, and the same corrosion resistance test as in Example 1 was performed. As a result of the corrosion resistance test, it was found that the entire surface where the diamond abrasive grains exist discolored and Ni was eluted.

[Table 1] Example 1 Comparative Example 1 Comparative Example 2

 First protective film Yes No No

 Second protection rod Yes Yes No

 0 Δ X

 Corrosion due to corrosion

 Overview after corrosion resistance test No discoloration In the vicinity, discoloration due to corrosion

 Discoloration due to corrosion

Claims

The scope of the claims  [1] An abrasive layer in which abrasive grains are fixed in a metal binder phase is formed on one surface of a grindstone substrate, and at least the surface of the metal binder phase of the abrasive grain layer is oxidized by a sol-gel method. A thick oxide film in which a physical film is formed as a first protective layer, and the surface of the first protective layer is polycrystalline, and a grain boundary layer composed of a glass layer does not substantially exist at the interface between the crystals. A CMP conditioner characterized in that is formed as a second protective layer. [2] In the CMP conditioner according to claim 1, the first protective layer covers the metal binder phase at least in the vicinity of a joint portion between the abrasive grains and the metal binder phase. The CMP conditioner is characterized by being formed as follows. [3] The CMP conditioner according to claim 1 or 2, wherein the second protective layer is alumina. [4] A method for producing a CMP conditioner, wherein at least the abrasive layer of the abrasive layer is formed with respect to a grindstone substrate in which an abrasive grain layer formed by adhering abrasive grains to a metal binder phase is formed on one disk-like surface. A first protective layer made of an oxide is formed on the surface of the metal binder phase by a sol-gel method, and then an aerosol in which fine particles of brittle material are dispersed in a gas is sprayed on the surface of the first protective layer. To form a CMP conditioner comprising the grinding wheel substrate, the abrasive grain layer, the first protective layer, and the second protective layer. A manufacturing method for CMP conditioners.