JP4858507B2 - Carrier for holding an object to be polished - Google Patents

Description

〔Technical field〕
In the present invention, an object to be polished such as a silicon wafer serving as a substrate of a semiconductor element is sandwiched between a pair of upper and lower surface plates to which an abrasive cloth is attached, and either or both of the polishing cloth and the object to be polished are pressed. The present invention relates to a carrier for holding an object to be polished used for polishing the surface of the silicon wafer by rotating.

  In recent years, in the field of the semiconductor industry and the like, there are processing steps for precisely polishing the surface of these members in the manufacturing process of silicon wafers, compound semiconductor wafers, aluminum magnetic disk substrates, glass magnetic disks and the like. In this process, when polishing an object to be polished such as a silicon wafer, an outer peripheral tooth having a holding hole for holding the object to be polished and engaging with an internal gear or a sun gear of a double-side polishing machine at the outer peripheral edge. It is common to use a carrier with

  For example, FIG. 1 shows the appearance of a disk-shaped carrier (also called a holder) C used when polishing a silicon wafer. Here, 1 is a holding hole for a silicon wafer, and a plurality of holes are provided in accordance with the shape of the silicon wafer. Reference numeral 2 denotes an abrasive supply hole made of water slurry in which fine abrasive particles are suspended, and a plurality of abrasive supply holes are also provided. Reference numeral 3 denotes outer peripheral teeth provided on the outer peripheral portion of the carrier C. Reference numeral 4 denotes various shapes of holes for reducing the weight of the carrier C itself.

  In the first place, since the silicon wafer itself is very thin (less than 0.5 to 1 mm), the carrier body is also made of a thin material and polished together with the silicon wafer. Therefore, it is necessary to have excellent wear resistance. In addition, recent silicon wafers having a large diameter of 12 inches (about 30 cm) have appeared, and a plurality of silicon wafers are attached to one carrier C. The size of the carrier C is 1 m in diameter. Some are larger. Such a large carrier C has a problem that a large deformation stress is applied during the handling thereof, so that the silicon wafer is often damaged or dropped off. In addition, when the silicon wafer is polished, the carrier body is also polished, and the fine particles generated at this time cause a decrease in the purity of the silicon wafer. In particular, there is a need for high-quality silicon wafers today, and even the presence of trace amounts of metal ions eluted from the carrier body during polishing is avoided, so it is important to study the material of the carrier body and develop a surface treatment film. This is a serious study issue.

  In order to solve the problems of the carrier as described above, the following proposals have been conventionally made for carriers. For example, Patent Documents 1 and 2 disclose a polymer material reinforced with nonmetallic glass fibers, and Patent Document 3 discloses metals such as stainless steel, SKH steel, SKD steel, and SUJ steel. The use of materials is disclosed.

Patent Document 4 discloses a metal carrier having a carrier coated with a ceramic coating, and Patent Document 5 discloses a SK steel carrier having a surface coated with metal plating. Further, Patent Document 6 discloses a technique in which ceramic particles are deposited on the surface of a metal carrier, and then a DLC thin film (diamond-like carbon thin film) is coated thereon. A technique for forming the DLC thin film directly on the surface of a metal carrier is proposed.
JP 2001-038609 A JP-A-11-010530 Japanese Patent No. 3974632 JP-A-4-26177 JP 2002-018707 A JP-A-11-010530 JP 2005-254351 A

  Among the above-described prior arts, the so-called metal carrier main body surface disclosed in Patent Documents 3 and 7 is formed by coating the surface of the carrier main body with a DLC thin film. Finished product is used. This is because the DLC thin film formed on the surface of the carrier bodies disclosed in Patent Documents 3 and 7 has a very thin thickness of 0.1 μm to 20 μm. It means that there was. That is, in these techniques, a DLC thin film having a thickness of about 0.1 μm cannot be evenly formed unless mirror finishing called polishing is performed.

However, according to research by the inventors, in the case of a mirror-finished carrier body, it has been found that when a DLC thin film is formed on the mirror surface, there are the following problems.
(1) Mirror finish on the surface of the carrier body requires a lot of work time and increases costs. In particular, when forming a DLC thin film having a thickness of 0.1 μm, even if a slight polishing flaw is present, that portion often causes a defect in the DLC thin film.
(2) Since the DLC thin film is an amorphous solid mainly composed of carbon and hydrogen generated from a hydrocarbon-based gas, it has a problem that it has a large residual stress during film formation and is easily peeled off. is there. In particular, when the surface of the thin carrier body is a mirror surface, the carrier body is subjected to a large deformation stress, and in the case of a DLC thin film coated on the surface of the body, the carrier body is easily peeled off. In this regard, Patent Document 3 proposes that the residual stress of the DLC thin film be limited to 0.5 MPa or less. However, the formation of such a low residual stress DLC thin film and the application of the plasma CVD method are necessary. It becomes clear that it becomes.
(3) When regenerating only the DLC thin film, it is difficult to remove the remaining DLC thin film, and it takes a long time to finish the mirror finish, resulting in a reduction in work efficiency, resulting in the cost of the product. Invite up.
(4) Further, since the conventional DLC thin film exhibits hydrophobicity that is difficult to wet with water, a water slurry-like abrasive (for example, water in which colloidal silica is dispersed) is not evenly dispersed on the film surface. It has been pointed out that the finishing accuracy of the polished surface is lowered due to uneven contact with the surface. That is, since the polishing surface becomes local, a uniform mirror surface cannot be obtained, and the parallelism (flatness) of the polishing surface is lowered, so that there is a problem that it takes a long time to finish a predetermined polishing surface.
(6) As described above, the recent carriers are made larger, made of thin metal, and provided with a large number of holes of various sizes. There was a problem that the DLC thin film was likely to be cracked or locally peeled.

As a result of diligent research to solve the above-described problems of the prior art, the inventors have obtained the following knowledge.
(1) The surface of the carrier body is not mirror-finished, and on the contrary, the surface of the carrier body is roughened by performing a process for performing some surface modification by spraying abrasive particles (hereinafter referred to as “process blast process”). At the same time, when the surface is subjected to stress application or work hardening, the surface is modified to a roughened / processed layer, and then the DLC thin film is coated, the adhesion of the film can be improved.
(2) The surface of the carrier body can be subjected to compressive residual stress applied to the carrier body or work-hardened by the above-described processing blast treatment, which can increase the rigidity of the carrier body and reduce the degree of deformation of the carrier body. can do.
(3) Since the DLC thin film formed on the carrier body having the roughened / processed layer is affected by the roughened / processed layer, microscopic unevenness is formed on the silicon wafer. At the time of polishing, the abrasive particles stay in the recess, and the polishing efficiency is improved.
(4) In the DLC thin film made of an amorphous solid film, the hydrogen content is controlled to 12 to 30 at% (atomic%), so that the DLC thin film itself is given flexibility and wear resistance. The film quality can follow the deformation.

That is, the present invention provides an aluminum alloy, a titanium alloy, or a surface of a metal carrier body made of one or more kinds of metals / alloys selected from special steels such as stainless steel, SK steel, and SKH steel,
The surface roughness formed by the following processing blast treatment is 0.05-0. 74 μm, Rz value of 0.09 to 1.99 μm, and Rsk value of less than ± 1 , provided with a roughening / working layer that expresses at least one of compressive residual stress or work hardening ,
On the roughened / processed layer, it has a film thickness exceeding the roughness Rz of the roughened / processed layer and in the range of 2.0 to 20 μm, and a hydrogen content of 13 to 30 atoms. workpiece holding carrier for the balance being DLC thin film is made form a carbon hydrogen solid film comprising carbon in%.
Record
Hard grinding particles of Hv: 300-2000 made of ceramic particles or cermet particles are sprayed on the surface of a thin carrier body at an angle of 60 ° -90 ° at a flight speed of V: 30-30 m / sec or more.

By adopting the technical means according to the present invention, the following effects can be obtained.
(1) Processing blasting for roughening the carrier main body surface and forming a processed layer is easier than conventional mirror finishing, reducing processing time and improving productivity.
(2) According to the present invention, the DLC thin film formed on the roughened / processed layer has a larger adhesion area than the DLC thin film formed on the mirror-finished surface because the adhesion area is increased.
(3) Since the roughened / processed layer formed according to the present invention is formed by processing blasting the surface of the carrier body, at least the surface thereof is processed and hardened, and compressive residual stress is also generated. The rigidity of the carrier body is increased. As a result, the carrier body is not deformed during handling, and handling and the like are facilitated.
(4) According to the carrier of the present invention, since deformation during handling is small, even if a large residual stress is generated in the DLC thin film formed on the surface, the carrier does not peel off. As a result, as a method for forming the DLC thin film, not only the plasma CVD method but also many methods such as an ionized vapor deposition method, an arc ion plating method, and a plasma booster method can be adopted.
(5) Since the carrier obtained by the present invention is hardly deformed during handling, the silicon wafer attached to the carrier is not easily subjected to stress accompanying deformation. Therefore, unlike the conventional case, the silicon wafer is not detached from the carrier during handling.
(6) By applying the present invention, the DLC thin film formed on the roughened / processed layer is affected by the surface of the carrier body, and maintains a microscopic unevenness while maintaining the flatness necessary for polishing a silicon wafer. Therefore, when polishing a silicon wafer, ultrafine particles (0.01 to 0.1 μm) such as colloidal silica contained in the water slurry abrasive are likely to remain in the recesses. Moreover, since such recesses are evenly present on the surface of the DLC thin film, not only the polishing efficiency of the silicon wafer is improved, but also the polishing itself is performed uniformly and the quality is improved.
(7) The processing blasting process is extremely effective not only when the DLC thin film is formed on the new carrier body but also as a method for removing the DLC thin film, so that it is used as it is as a pretreatment for regenerating the DLC thin film. This is advantageous in terms of cost.

Hereinafter, the configuration of the carrier for holding an object to be polished according to the present invention will be described together with the description of the manufacturing method.
(1) Process for forming a roughened / processed layer on the surface of a metal carrier body The following will describe an example in which stainless steel (SUS304) is used as a metal carrier. A metal carrier is generally finished to a thickness of about 0.5 to 1.0 mm, and its external appearance is provided with a number of large or small circular or irregular holes as shown in FIG. It is. Since such a metal carrier is thin, it has a characteristic of being greatly bent (deformed) when it is carried.

Therefore, in the present invention, the surface of the carrier main body shown in FIG. 1 is subjected to a processing blast process for spraying abrasive particles, thereby generating a roughened / processed layer on the surface of the carrier main body. Examples of the abrasive particles used in this processing blast treatment include carbide particles such as SiC according to JIS R6111, oxides such as Al ₂ O ₃ , ceramic particles such as nitride such as TiN (average particle size of 10 to 80 μm), or these It is important to form a roughened / processed layer having the following roughness by spraying cermets such as Ni and Co with compressed air at a pressure of 0.2 to 0.5 MPa. is there.
Arithmetic average roughness Ra: 0.05 to 0.85 μm
Ten-point average roughness Rz: 0.09 to 1.99 μm
If the pressure of the compressed air is less than 0.2 MPa, it takes a long time for processing blasting and it is difficult to obtain a uniform rough surface. On the other hand, using compressed air with a pressure higher than 0.5 MPa is not preferable because the metal carrier body is deformed.

  Further, the preferred processing blast treatment applied in the present invention is the above-mentioned ceramic particles or cermet particles, preferably hard particles (Hv: 300 to 2000), and a flight speed V: (30 to 100) m / sec or more. The surface of the carrier body was sprayed at an angle of 60 ° to 90 ° at a speed to form a rough surface having fine irregularities on the surface of the carrier body, and either compression residual stress or work hardening occurred. A process for forming a layer. In this treatment, if the hardness of the sprayed particles is less than Hv: 300 or the flight speed thereof is 30 m / sec or less, it may be impossible to form the roughened / processed layer desirable in the present invention. The hardness of the hard particles also varies depending on the material of the carrier body, and thus cannot be generally defined, but desirably Hv ≧ 900 and the flying speed V is V: 80 m / sec or more, more preferably 100 m / sec. It is good to set it as sec or more.

  In the present invention, the reason for focusing on the roughness values (Ra, Rz, Rsk) will be described. When the surface to which the abrasive particles are sprayed, that is, the surface of the roughened / processed layer formed by processing blasting is measured with a stylus-type roughness inspection machine, Rz as well as Ra can be recorded in the same manner. According to the results of measurements conducted by the inventors, even if Ra is small, Rz is always large, and within the surface roughness range recommended by the present invention, Rz often reaches 10 times or more of Ra.

  When a DLC thin film is formed on the surface of such a roughened / processed layer having a high Rz, a state as shown in FIG. 2 is obtained. That is, the DLC thin film 24 formed on the surface of the stainless steel carrier body 21 after the processing blast treatment is a very thin film. Accordingly, the DLC thin film 24 formed on the rough surface portion having the convex portion 23 that determines Rz is not substantially effective even if the convex portion 25 is exposed or not exposed. It will be. For this reason, even if the DLC thin film 24 is slightly worn, only the convex portion 25 is exposed, and this portion is selectively eluted during the polishing operation of the silicon wafer (a water slurry solution containing an abrasive used when polishing the silicon wafer). ), And the eluted components adhere to the surface of the silicon wafer and cause contamination. In addition, 22 of illustration has shown the roughness substantially displayed by Ra.

  In the present invention, if necessary after the processing blast treatment, the above problem can be solved by removing only the convex portions mainly by lightly polishing using a buff or # 1000 or more polishing paper. Moreover, it may replace with a buff and polishing paper, and the method of spraying a small steel ball | bowl and a glass ball | bowl and selectively lose | disappearing only a convex part may be sufficient.

  The reason for restricting Ra to the range of 0.05 to 0.85 μm is that the effect of the processing blast treatment is less than 0.05 μm, and on the other hand, if it is more than 0.85 μm, the DLC thin film formed thereon is thin. This is because the uniformity is lacking or the convex portions 25 are easily exposed depending on the film forming conditions, and the effect of coating the DLC thin film becomes poor.

  Next, in the present invention, as the roughness characteristics of the roughened / processed layer, the Rsk value is also set within a predetermined control value range. That is, the roughness of the roughened / processed layer is managed by using the skewness value (Rsk) of the roughness curve indicating the distortion in the height direction.

This Rsk value is defined by the root mean square of the height (Z ^(x) ) at the reference length (I _r ) divided by the root mean square root (Rq ³ ) as shown in the following equation. Is.

  As shown in FIG. 4, in the roughness curve in which the concave portion is wider than the convex portion, the Rsk value has a distribution in which the probability density function is biased toward the concave portion. The reverse is defined as a negative value, but in the present invention, the “distortion” is regulated to ± 1 or less regardless of whether the Rsk value is positive or negative.

  In the present invention, of the roughness of the roughened / processed layer, the reason why the Rsk value is regarded as important is that the Rsk value determines the surface properties of the DLC thin film regardless of the surface roughness of the roughened / processed layer. This is because it is considered to be a numerical value shown.

  For example, when the surface roughness of a surface of a stainless steel substrate that has been mirror-finished by electrolytic polishing and that that has been subjected to processing blasting that sprays abrasive particles are measured, the results shown in Table 1 are obtained. was gotten.

  It can be seen from the results shown in Table 1 that the measured values of the surface roughness such as Ra and Rz indicate the roughness itself, but the Rsk value is not “roughness” but rather “distortion” of the measurement surface. ". Therefore, the inventors decided to regulate the Rsk value as necessary in addition to the roughness Ra and Rz.

  It has been experimentally found that the surface of the DLC thin film formed on the roughened / processed layer has a great influence on the performance of the silicon wafer polishing carrier. That is, a DLC thin film coated on a stainless steel carrier having a roughened / processed layer with an Rsk value of less than ± 1 has a microscopic “distortion” under the influence of the Rsk value. Become. It is considered that a fine silicon wafer abrasive such as colloidal silica stays in a portion corresponding to the “distortion” recess, and the abrasive particles improve the polishing efficiency of the silicon wafer. In particular, since the retained portions of the abrasive particles are evenly distributed over the entire DLC thin film, the polishing of the silicon wafer is not only improved in efficiency, but the entire polished surface is polished evenly.

(2) Effect of processing blasting The metal carrier body subjected to processing blasting has the following characteristics.
(A) By processing blasting (grinding particle spraying), the surface to be processed of the carrier body becomes a rough surface having fine irregularities, and compressive residual stress is generated and work hardening is performed. Increased rigidity. As a result, deformation such as “deflection” or “twist” that occurs when the carrier is transported or handled can be suppressed. Therefore, the damage rate due to cracking or peeling phenomenon occurring in the DLC thin film formed on the surface of the carrier main body can be reduced as compared with a mirror-finished surface of the carrier body.

  On the other hand, in the case of a mirror-finished DLC thin film on the surface of the carrier body, since the occurrence rate of damage increases due to the mirror surface, the residual stress during film formation is limited to 0.5 MPa or less (for example, Patent Document 3). ). In this respect, when the roughening / processed layer is formed according to the method of the present invention, such a restriction is eliminated. As a result, in forming the DLC thin film, not only the plasma CVD method but also many methods such as an ionization vapor deposition method, an arc ion plating method, and a plasma booster method can be adopted.

(B) FIG. 3 shows the surface of the carrier body made of SUS304 steel subjected to the processing blast treatment according to the present invention and the surface of the carrier body subjected to mirror polishing such as electrolytic polishing and polishing (buffing) with an electron microscope. The results are shown. On the processed blasted surface (a) suitable for the present invention, fine irregularities are uniformly generated over the entire field of view. On the other hand, the electrolytic polishing surface (b) is smooth, and the polishing surface (c) has a slight buffing mark on the smooth surface.
As is clear from these enlarged photographs, the processed blasted surface suitable for the present invention, that is, the roughened / processed layer has a bonding area with the DLC film formed on the surface due to the presence of fine irregularities. Since the number is greatly increased, the DLC film is hardly peeled even when a load such as some deformation, tension, and compression is added when the carrier body is handled.

(C) Since the time required for the processing blast treatment is shorter than that in the case where the surface of the carrier body is mirror-polished, in addition to the improvement of the working efficiency, the pretreatment when the carrier provided with the DLC thin film is reused (It can also be used for the process of removing the old DLC thin film).

(3) About carrier main body (base material) The following can be considered as a carrier main body for raising the effect of the processing blast processing mentioned above. For example, various stainless steels such as SUS304, titanium and titanium alloys, aluminum and alloys thereof, special steels such as SK steel, SKH steel, and SUJ steel are particularly suitable.

(4) DLC thin film coating formation method As a method of coating the DLC thin film on the surface of the roughened / processed layer of the carrier body formed by spraying abrasive particles, ionized vapor deposition, arc ion plating, plasma Methods such as the booster method and the high frequency / high voltage pulse superposition type plasma CVD method (hereinafter simply referred to as “plasma CVD method”) are advantageously suitable. Hereinafter, the plasma CVD method will be described.

  FIG. 5 is a schematic diagram of a plasma CVD apparatus used for coating a DLC thin film on the surface of a carrier on which a roughened / processed layer has been formed through the above-described treatment. The plasma CVD apparatus mainly includes a grounded reaction vessel 41, a high voltage pulse generating power source 44 for applying a high voltage pulse in the reaction vessel 41, and an object to be processed (hereinafter referred to as “carrier body”) 42. Is provided with a plasma generating power source 45 for generating unitary hydrogen-based gas plasma, and a superimposing device 46 for simultaneously applying a high voltage pulse and a high frequency voltage to the conductor 43 and the carrier body 42. The high voltage pulse generating power supply 44 and the plasma generating power supply 45 are interposed between the conductor 43 and the carrier main body 42 via the high voltage introducing portion 49.

  This plasma CVD apparatus includes a gas introducing device (not shown) for introducing an organic gas for film formation into the reaction vessel 41 and a vacuum device (not shown) for evacuating the reaction vessel 41, respectively. It is connected to the reaction vessel 41 via valves 47a and 47b.

  In order to form a DLC thin film on the surface of the object to be processed using this plasma CVD apparatus, first, the carrier body 42 is installed at a predetermined position in the reaction vessel 41, and the vacuum device is operated to operate the reaction vessel 41. After the inside air is discharged and deaerated, an organic gas is introduced into the reaction vessel 41 by a gas introduction device.

  Next, high frequency power from the plasma generating power supply 45 is applied to the carrier body 42. Since the reaction vessel 41 is in an electrically neutral state by the ground wire 48, the carrier main body 42 generates positive ions in a relatively negative plasma around the negatively charged carrier main body 42. It will be.

  When a high voltage pulse (negative high voltage pulse) from the high voltage pulse generator 44 is applied to the carrier body 42, the positive ions in the hydrocarbon-based introduced gas plasma are attracted and adsorbed on the surface of the carrier body 42. The By such treatment, a DLC thin film is generated and formed on the surface of the carrier body 42. That is, in the reaction vessel 41, a DLC thin film consisting of amorphous carbon hydrogen solids mainly composed of carbon and hydrogen is vapor-deposited around the carrier body 42 to cover the surface of the carrier body 42. Thus, it is thought that a film is formed.

  The inventors of the present invention use the plasma CVD apparatus to form a DLC thin film layer made of an amorphous carbon-hydrogen solid formed on the surface of the object through the following processes (a) to (d). I guess.

(A) ionization of the introduced hydrocarbon gas (neutral particles called radicals also exist),
(B) Ions and radicals changed from the hydrocarbon gas impact impact the surface of the carrier body 42 to which a negative voltage is applied,
(C) C—H having a low binding energy is cut by the energy at the time of collision, and then activated C and H are polymerized by repeating the polymerization reaction to form an amorphous state mainly composed of carbon and hydrogen. Vapor deposition of carbon hydrogen solids of
(D) When the reaction (c) occurs, a DLC thin film composed of a deposited layer of amorphous carbon hydrogen solids is formed on the surface of the carrier body 42.

In this apparatus, the carrier body 42 can be ion-implanted by changing the output power of the high voltage pulse generating power supply 44 as shown in the following (a) to (d). .
(A) When ion implantation is focused on: 10 to 40 kV
(B) When performing both ion implantation and film formation: 5 to 20 kV
(C) When only film formation is performed: several hundred V to several kV
(D) When focusing on sputtering, etc .: several hundred V to several kV

In the high voltage pulse generation source 44,
Pulse width: 1 μsec to 10 msec
Number of pulses: It is also possible to repeat one to a plurality of pulses.

  Further, the output frequency of the high frequency power of the plasma generating power supply 45 can be changed in the range of several tens of kHz to several GHz.

  As a film-forming organic gas introduced into the reaction vessel 41 of this plasma CVD processing apparatus, a hydrocarbon-based gas composed of carbon and hydrogen as shown in the following (A) to (C), and Si, A metal organic compound to which any one of Al, Y and Mg is added is used.

(I) Gas phase state at room temperature (18 ° C.) CH ₄ , CH ₂ CH ₂ , C ₂ H ₂ , CH ₃ CH ₂ CH ₃ , CH ₃ CH ₂ CH ₂ CH ₃
(B) Liquid phase at normal temperature C ₆ H ₅ CH ₃ , C ₆ H ₅ CH ₂ CH, C ₆ H ₄ (CH ₃ ) ₂ , CH ₃ (CH ₂ ) ₄ CH ₃ , C ₆ H ₁₂ , C ₆ H ₄ Cl
(C) Organic Si compound (liquid phase)
(C ₂ H ₅ O ₂ ) ₄ Si, (CH ₃ O) ₄ Si, [(CH ₃ ) ₄ Si] ₂ O

  The gas introduced into the reaction vessel 41 in the gas phase at normal temperature can be introduced into the reaction vessel 41 as it is, but the compound in the liquid phase is heated to gasify it. A DLC thin film can be formed by supplying gas (vapor) into the reaction vessel 41.

(5) DLC thin film according to the present invention The DLC thin film formed on the carrier surface provided with the roughened / processed layer as described above has the following characteristics.
(A) Ratio of carbon and hydrogen content constituting the DLC thin film The DLC thin film is hard and excellent in wear resistance, but lacks flexibility. For this reason, when the carrier body is made of a large and thin metal, etc., and a plurality of holes of various sizes are provided, if the DLC thin film is covered, the carrier is greatly bent or deformed when it is carried. When this occurs, cracks may occur in the DLC thin film with poor ductility, and sometimes it may peel off. As a countermeasure, in the present invention, attention is paid to the ratio of carbon and hydrogen constituting the DLC thin film, and in particular, the DLC thin film is resistant to wear by controlling the hydrogen content to 12 to 30 atomic% (at%) of the whole. It was decided to give flexibility as well as sex. Specifically, the hydrogen content contained in the DLC thin film was 12 to 30 atomic% (at%), and the balance was the carbon content. Formation of a DLC thin film having such a composition can be accomplished by mixing compounds having different hydrogen contents in the hydrocarbon-based gas for film formation.

Example 1
In this example, DLC thin films with different thicknesses are directly applied to the mirror finished surface of the SK steel substrate and the roughened / processed layer finished to various surface roughnesses by processing blasting. Formed. Subsequently, these test pieces were subjected to a salt spray test to investigate the surface roughness of the substrate and the corrosion resistance of the DLC thin film.

(1) Test base material The test base material was SK steel (SK60 annealing material), and a test piece having a width of 50 mm, a length of 70 mm, and a thickness of 2 mm was prepared from this base material. Then, the surface roughness about what performed the following process blast process as pre-processing with respect to the whole surface of the test piece is shown.
(A) Processing blast treatment Ra: 0.05 to 0.74 μm, Rz: 0.09 to 5.55 μm
(B) For reference, the following experiment for mirror finishing was also performed.
a. Electropolishing Ra: 0.013-0.014 μm Rz: 0.14-0.16 μm
b. Buffing Ra: 0.015 μm Rz: 0.20 μm
In the processing blast treatment, SiC having a particle size range of 10 to 80 μm is used as grinding particles, and this is sprayed using compressed air of 0.3 MPa.

(2) DLC thin film forming method and film thickness Plasma CVD is used to form the DLC thin film, and 0.5 to 20 μm thick DLC thin film containing SiO ₂ : 0.8 atomic% is used for all test pieces. Formed.

(3) Test Method and Conditions The test piece on which the DLC thin film was formed was subjected to the salt spray test specified in JIS Z2371 for 96 hours, and the presence or absence of red rust generated on the DLC thin film surface after the test was investigated.

(4) Test results The test results are summarized in Table 2. As is clear from this result, the DLC thin film test piece formed on the surfaces of the electrolytic polishing surfaces (No. 10, 11) and the buff polishing surface (No. 12) of the reference example, which is mirror-finished, is a 0.5 μm film. The occurrence of red rust was not observed.
On the other hand, in the test piece in which the DLC thin film is formed on the base material roughened by the processing blast treatment which is a conformity example of the present invention, it is influenced by the surface roughness and is thinner than the Ra value or Rz value (No. In 6, 7, 8, and 9), the corrosion resistance was not sufficient and red rust was observed. However, when the DLC thin film on the processed blasted surface was also formed thicker than the Rz value of the surface roughness (No. 1 to 8), it was confirmed that red rust was not generated and sufficient corrosion resistance was exhibited.
On the other hand, the DLC thin film test piece formed on the surface of the electrolytic polishing surface (No. 10, 11) or the buff polishing surface (No. 12) equal to the mirror surface shown as a reference example generates red rust even with a 0.5 μm film. There was no.

  From these test results, when the surface of the base material by the processing blast treatment is in the range of roughness Ra: 0.05 to 0.74 μm and Rz: 0.09 to 0.95 μm, the thickness of the DLC thin film is set to 0. When the roughness is Ra: 0.74 μm and Rz: 1.99 μm, when the thickness of the DLC thin film is 2.0-20 μm and is larger than the Rz value, It can be seen that film formation without elution is possible.

  From the above results, as in the case of the electrolytic polishing and buff polishing in the mirror state shown as the reference example, even when the processing blast treatment is performed to form the roughened / processed layer, at least larger than the Rz roughness value. It was found that when a DLC thin film having a thickness of 20 μm or less was formed, the surface of the film was completely inferior to that of a conventional mirror surface with respect to the corrosion resistance of the film.

(Example 2)
In this example, a DLC thin film with varying hydrogen content was formed on the surface of a stainless steel (SUS304) substrate, and the hydrogen content, resistance to bending deformation of the substrate and subsequent changes in corrosion resistance were investigated. .

(1) Properties of the test substrate and DLC thin film The test sample was stainless steel (SUS304), and a test piece having a size of width 15 mm × length 70 mm × thickness 1.8 mm was prepared from this substrate. Thereafter, the entire surface of the test substrate was subjected to a processing blast treatment to perform a roughening treatment of Ra: 0.05 to 0.21 μm, Rz: 0.1 to 0.99 μm. A test piece having a hydrogen content in the processed layer of 5 to 50 atomic% and the balance being a carbon component was formed to a thickness of 1.5 μm.
(2) Test method and conditions The test piece on which the DLC thin film was formed was bent at 180 ° from the inside (U-bend shape), and the appearance of the DLC in the bent portion was observed with a 20-fold magnifier. Further, the bending test piece after the observation was immersed in a 10% HCl aqueous solution and allowed to stand at a room temperature of 21 ° C. for 48 hours, and a change in color tone due to ions eluted in the HCl aqueous solution was examined.
(3) Test results Table 3 summarizes the test results. As is clear from this test result, the DLC film with a small hydrogen content (test specimens No. 1, 2, 3) generates cracks when it is deformed by 180 ° or has a small area, but is locally In particular, shedding of the membrane was observed. It was confirmed that these DLC thin films lack flexibility. On the other hand, when the test piece after the bending test is immersed in 10% HCl, the cracked DLC thin film (No. 3) is changed from a base material stainless steel to metal ions (iron as a main component, a small amount of Cr and Ni was eluted), and the aqueous HCl solution changed from colorless and transparent to yellowish green. In contrast, the HCl aqueous solution in which a DLC thin film (No. 4 to 8) containing 1.5 to 59 atomic% of hydrogen content is immersed is colorless and transparent, and is flexible even if it is deformed by 90 °. It has been found that the film having the film maintains the initial state of formation.
However, since the DLC thin film becomes soft as the hydrogen content in the DLC thin film increases, quality control becomes difficult. Therefore, in the present invention, the hydrogen content in the range of 13 to 30 atomic% is adopted.

(Example 3)
In this example, a DLC thin film is formed by various methods on the entire surface of a test piece having a mirror-finished surface of a SK steel substrate and a roughened / processed layer subjected to a processing blast treatment according to the present invention. Formed. Subsequently, the 180 ° bending test and the salt spray test were performed on the test piece, and the resistance to the bending deformation and the corrosion resistance of the DLC thin film were investigated.

(1) Test base material and its surface treatment The test base material was SK steel (SK60 annealed material), and a test piece having a width of 15 mm, a length of 70 mm and a thickness of 1.8 mm was prepared from this base material. Thereafter, the entire surface of the test piece was subjected to buffing and processing blasting. The roughness after each treatment was as follows.
(A) Surface roughness of buffed surface Ra: 0.02 to 0.08 Rz: 0.66 to 0.81
(B) Surface roughness of the processed blasted surface Ra: 0.05 to 0.81 Rz: 0.72 to 0.88
(2) Method for forming DLC thin film A test piece for forming a DLC thin film was bent at 180 ° from the center (U-bend shape), and the appearance of the DLC thin film at the bent portion was observed with a 20 × magnifier. Moreover, the test piece after observation was exposed to the salt spray test of JIS Z2371 for 96 hours as it was, and the change of the DLC thin film was investigated.
(4) Test results Table 4 summarizes the test results. As is apparent from the test results, the surface of the test piece was buffed and a DLC thin film was formed thereon (No. 1, 3, 5, 7). Thin film peeling was also observed. Just No. Only the DLC thin film formed by the plasma CVD method of No. 7 had very few cracks and had good adhesion to the substrate.

  On the other hand, according to the results of the salt spray test carried out after the bending test, it was observed that all the test pieces in which cracks and delamination were observed in the DLC thin film generated red rust, the cracks reached the base material, and the anticorrosive action disappeared. It was done. On the other hand, the test piece that maintained a healthy state even in the bending test exhibited excellent corrosion resistance without generating red rust in the salt spray test. From this result, it was confirmed that the DLC thin film according to the present invention is not limited to the plasma CVD method and can be applied to other existing DLC thin film forming methods.

Example 4
In this example, stainless steel (SUS304) was used as a base material, a DLC thin film was formed on each of the processed blasted surface and the mirror polished surface, and then the adhesion strength of the DLC thin film was evaluated.

(1) Test base material and pretreatment A test piece having a width of 25 mm, a length of 30 mm, and a thickness of 3 mm was cut out from stainless steel as a test base material, and then subjected to the following pretreatment.
(A) Electropolishing: Ra: 0.01 to 0.014 μm, Rz: 0.11 to 0.15 μm
(B) Processing blast treatment: Ra: 0.05 to 0.75 μm, Rz: 0.11 to 0.96 μm
(2) Formation method and film thickness of DLC thin film A DLC thin film having a film thickness of 2 μm was formed on all test pieces by using a plasma CVD method.
(3) Test method For the adhesion of the DLC thin film to the substrate, a drawing test which is widely used as an adhesion strength test of the coating film was applied. That is, a straight cut was made on the DLC thin film with a diamond needle loaded with a constant load, and the adhesion force was determined based on whether or not the DLC thin film was peeled off at that time.
(4) Test results The test results are summarized in Table 5. As is apparent from the results, the DLC thin film (Nos. 1 and 2) formed with the roughening / processed layer by the processing blast treatment according to the present invention generates scratches due to the diamond needle, but the DLC thin film Peeling hardly occurs. On the other hand, in the DLC thin film (Nos. 3 and 4) formed on the mirror-finished surface, the DLC thin film located around the scratch was largely peeled off. From these results, it was confirmed that the roughening treatment of the substrate surface by the processing blast treatment is effective in improving the adhesion of the DLC thin film. FIG. 5 shows the appearance of the DLC thin film after the adhesion test.

(Example 5)
In this example, the effect of the present invention was demonstrated by polishing a Si wafer having a diameter of 200 mm and a thickness of 0.8 mm using the carrier body of SUS304 steel shown in FIG. The following pretreatment and DLC film were formed on the entire surface of the carrier body.

(1) Pretreatment and DLC film according to the present invention After roughening the surface of the carrier body to Ra: 0.08 to 0.11 μm, Rz: 0.82 to 0.94 μm by processing blast treatment, A DLC film having a thickness of 3 μm was formed thereon. The hydrogen content in the DLC film is 14 atomic% and the balance is carbon.
(2) Pre-processing of comparative example and DLC film After finishing the surface of the carrier body to a mirror surface of Ra: 0.02-0.11 μm, Rz: 0.12-0.17 μm by puff polishing, A DLC film of the same quality as the invention was coated to a thickness of 3 μm.
(3) Test results When the carrier body formed with the DLC film of the present invention was used as a polishing agent using a water slurry with colloidal silica as an abrasive, and the DLC film of the present invention was used, It took about 25 minutes to finish the surface to Ra 0.01 μm, while it took 65 minutes for the carrier body coated with the DLC film of the comparative example. Moreover, generation | occurrence | production of a scratch-like wrinkle was not recognized on the grinding | polishing surface of the Si wafer ground with the carrier main body in which the DLC film of the comparative example was formed.

(Example 6)
In this example, the influence of the Rsk value of the carrier body on the carrier and Si wafer polishing conditions shown in FIG. 1 was investigated.
The following pretreatment and DLC film were formed on the entire surface of the carrier body.

(1) Pretreatment and properties of DLC film according to the present invention The surface of the carrier body is roughened to Ra: 0.08 to 0.11 μm, Rz: 0.83 to 0.95 μm by processing blasting, and simultaneously measured. It was confirmed that the Rsk value was in the range of ± 0.4 to 0.8. Thereafter, a DLC film according to the present invention was formed on this surface to a thickness of 3 μm.
(2) Pretreatment of Comparative Example and Properties of DLC Film The surface roughness of the carrier body polished by buffing is Ra: 0.013 to 0.015 μm, Rz: 0.20 to 0.29 μm, and the Rsk value is +1 or more Was in the range. On this surface, the same DLC film as that of the present invention was formed to a thickness of 3 μm.
(3) Test results As a result of polishing a Si wafer using a water slurry abrasive using colloidal silica as an abrasive, the surface of the Si wafer was changed to Ra0 when the carrier body formed with the DLC film of the present invention was used. The finishing to about 0.01 μm was completed in about 23 minutes, and the parallelism of the polished surface was within the control value range and was polished with very high accuracy. On the other hand, when the carrier body having the DLC film of the comparative example is used, it takes 30 minutes to obtain a predetermined polished surface, and the parallelism of the polished surface is also reduced and variations are recognized. It was.

(Example 7)
In this example, an experiment was conducted to investigate qualitatively the rigidity improvement of the carrier body roughened by the processing blasted surface.

(1) Test base material and test piece Stainless steel (SUS304) was used as the test base material, and a test piece having a width of 30 mm, a length of 200 mm, and a thickness of 1 mm was cut out.
(2) Processing blast treatment for test piece The following processing blast treatment was performed on one side of the test piece, and electrolytically polished stainless steel (SUS304) was used as a test piece for comparison.
(B) Surface roughness Ra of the substrate surface by processing blast treatment: 0.05 to 0.74 μm, Rz: 0.55 to 0.95 μm (b) Ra: 0 by electropolishing .013 μm, Rz: 016 μm mirror-finished (3) Test method As shown in FIG. 7, one end of each test piece was fixed, and 1000 g of weight was placed on one tip, The change width of the tip of the test piece depending on the weight was measured.
(4) Test results The test results are summarized in Table 6. As is clear from this result, the test piece (Nos. 1 to 4) roughened by the processing blast treatment has a smaller displacement width than the test piece of the comparative example having a mirror finish, and it is difficult to deform. Admitted.

  The DLC thin film forming technology and the roughening of the metal carrier body according to the present invention, that is, the processing blast processing technology and the properties of the DLC thin film are not limited to the polishing of semiconductor wafers such as Si and GAP. It can be applied as a polishing technique for display glass and hard disks.

It is a top view of the metal carrier main body for silicon wafer polishing. It is a cross-sectional schematic diagram of the surface of the metal carrier body processed and blasted, and a DLC thin film formed thereon. (A) is a case where a DLC thin film thinner than Rz is formed, (b) is Rz This is a case where a thicker DLC thin film is formed. It is a SEM photograph of the processed surface which gave various pretreatments to the carrier body surface. It is a schematic diagram which shows the skewness value (Rsk) in the surface roughness display of a process blast processing surface. It is the schematic of the plasma CVD apparatus for forming a DLC thin film in the carrier main body for grinding | polishing of a silicon wafer. It is an enlarged photograph which shows the DLC thin film surface state after a scratch test part. It is the schematic of the condition which tested the rigidity of the SUS304 steel which carried out the processing blast process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Silicon wafer holding hole 2 Abrasive supply hole 3 Peripheral tooth 4 Hole 5 Carrier surface 21 forming DLC thin film Carrier main body 22 Roughness indicated by Ra 23 Roughness indicated by Rz 24 DLC thin film 25 Roughness convexity 41 indicated by Rz that could not be covered with DLC thin film Reaction vessel 42 Object to be treated (carrier body)
43 conductor 44 high voltage pulse generation source 45 plasma generation source 46 superposition device 47a, 48b valve 48 ground wire 49 high voltage introduction terminal 61 base material 62 DLC thin film 63 DLC thin film 64 containing SiO ₂ particles water slurry abrasive containing colloidal silica 65 Residual colloidal silica powder

Claims (1)

On the surface of the metal carrier body made of one or more metals / alloys selected from aluminum alloys, titanium alloys, or special steels such as stainless steel, SK steel and SKH steel,
The surface roughness formed by the following processing blast treatment is 0.05-0. 74 μm, Rz value of 0.09 to 1.99 μm, and Rsk value of less than ± 1 , provided with a roughening / working layer that expresses at least one of compressive residual stress or work hardening ,
On the roughened / processed layer, it has a film thickness exceeding the roughness Rz of the roughened / processed layer and in the range of 2.0 to 20 μm, and a hydrogen content of 13 to 30 atoms. workpiece holding carrier for the balance being DLC thin film is made form a carbon hydrogen solid film comprising carbon in%.
Record
Hard grinding particles of Hv: 300-2000 made of ceramic particles or cermet particles are sprayed on the surface of a thin carrier body at an angle of 60 ° -90 ° at a flight speed of V: 30-30 m / sec or more.

Images