JP7633774B2 - Polishing cloth dresser - Google Patents

Description

The present invention relates to an abrasive cloth dresser that is used to maintain the flatness of the abrasive cloth and to remove clogging and foreign matter during the chemical mechanical planarization (CMP) process.

CMP polishing is used in equipment that polishes the surfaces of semiconductor wafers, equipment that flattens the surfaces of wiring and insulating layers during the manufacturing of integrated circuits, and equipment that flattens the surfaces of aluminum and glass plates used in magnetic hard disk substrates.

This CMP polishing is a method of planarizing the surface to be polished by supplying a slurry liquid containing fine abrasive grains to a rotating substrate to which a urethane polishing pad is attached, while pressing the surface to be polished against the substrate. Naturally, the polishing ability of this polishing pad decreases with use time, but to suppress this decrease, the surface of the polishing pad is ground at regular intervals to maintain the flatness of the polishing pad and to constantly dress it so that a new surface is presented. The part used for this dressing is called a dresser, and is obtained by joining abrasive grains to a metal substrate by electrochemical deposition or brazing.

Recently, there has been a demand for extremely narrow lines/spaces in integrated circuits with wiring rules of up to 3 nm. As wiring rules become narrower, there is a growing demand to eliminate microscratch damage on the polished surface in order to improve yields in the CMP process. In addition, the problem of preventing metal elution from dressers, which was not previously required, has emerged. This is because in advanced semiconductors with extremely narrow wiring rules, deterioration of electrical insulation due to metal elution can easily lead to reduced yields. In order to meet these demands, a dresser is needed that can prevent metal elution while also preventing the occurrence of microscratches.

Patent Document 1 discloses a dresser that can impart acid resistance to the abrasive layer and prevent erosion of the abrasive layer when using a strongly acidic abrasive. The dresser has a coating layer made of diamond-like carbon or molybdenum disulfide formed on the surface of the abrasive layer, which is made up of abrasive grains and a nickel-plated layer to which the abrasive grains are fixed.

Patent Document 2 discloses a dresser that not only does not have diamond abrasive grains falling off, but also does not become contaminated by elution of the binder and base metal, and that has a bonding layer formed by a single layer of diamond abrasive grains fixed to the surface of a metal base metal, and that is coated with a ceramic coating. The material of the ceramic coating is selected from CrN, TiN, SiC, TiAlN, Si ₃ N ₄ , Al ₂ O ₃ , and DLC (Diamond Like Carbon).

Patent Document 3 discloses a dresser that has enhanced corrosion resistance and abrasion resistance to reduce corrosion caused by slurry, and has an abrasive layer on one side of a base metal made of stainless steel, in which abrasive grains are fixed in a metal bonding phase, and a base plating layer made of Au is formed on the surface of the abrasive layer, and a hard corrosion-resistant plating layer made of Rh is formed on top of that.

Patent Document 4 discloses a dresser with excellent corrosion resistance against the acidic liquid in the slurry, which has abrasive grains fixed by a metal layer, and the fixing layer is coated with a synthetic resin layer containing a fluororesin having a cyclic perfluoroether structure.

Patent Document 5 discloses a dresser that can improve the adhesion of abrasive grains, prevent the aggregation of slurry, and prevent metal elution. The dresser has abrasive grains fixed by electrochemical deposition using a nickel plating layer, and a water-repellent coating is formed on the upper surface of the nickel plating layer. This water-repellent coating is a composite plating layer made of nickel and a water-repellent resin.

Patent Document 6 discloses a dresser with improved corrosion resistance, wear resistance, and abrasive grain retention, which has abrasive grains held by a nickel plating layer, and the nickel plating layer is covered with an amorphous chrome plating layer.

JP 2000-127046 A JP 2001-210613 A JP 2003-117822 A JP 2004-25377 A JP 2008-229775 A JP 2013-123771 A

As mentioned above, dressers that prevent metal elution from the dresser have been disclosed in the past. However, in Patent Documents 1, 2, 4, and 5, a ceramic film or a resin film is used as the coating film, and therefore the adhesion between the coating film and the metal adhesion layer is insufficient, and polishing slurry may penetrate into the gap between the coating film and the metal adhesion layer, causing metal elution. In addition, since the coating film is not dense enough, polishing slurry may penetrate through cracks in the coating film to the metal adhesion layer, causing metal elution. In Patent Document 3, the problem was that rhodium plating was expensive.

In Patent Document 6, an amorphous chrome plating coating layer is used. Here, the amorphous chrome plating layer is very brittle, and the difference in thermal expansion coefficient between the underlying metal adhesion layer and the amorphous chrome plating layer and the stress applied during use as a dresser cause cracks in the amorphous chrome plating layer, which progresses to peeling of the film. Although the amorphous chrome plating layer itself has the effect of preventing metal elution, cracks or peeling cause the underlying metal adhesion layer to come into contact with the polishing slurry, so the metal elution prevention effect as a dresser cannot be expected.

In addition, none of the above-mentioned Patent Documents 1 to 6 disclose any technology to prevent the occurrence of micro-scratches, making them insufficient as dressers that can be used in the manufacturing process of advanced semiconductors.

As mentioned above, the conventional technology is insufficient in preventing metal elution and does not take measures against micro-scratches, resulting in a dresser that significantly reduces yield. Due to the demand for further improvement in yield in the CMP process, there is a demand for a dresser that can prevent metal elution while preventing micro-scratches.

The present invention aims to provide a dresser that prevents micro-scratches and also suppresses metal elution in order to solve the above-mentioned problems.

The gist of the present invention is as follows.
(1) A dresser for an abrasive cloth comprising a metal adhesion layer formed on the surface of a metal support material and having a plurality of abrasive grains adhered thereto, and a coating layer covering the metal adhesion layer, wherein the average particle size d of the plurality of abrasive grains is 3 μm≦d<200 μm, the metal adhesion layer is made of a Ni-based brazing material, and the coating layer is a crystalline chrome plating layer having a thickness of 1 μm or more.
(2) The dresser for an abrasive cloth according to (1), further comprising a cover layer that covers the chrome plating layer.

(3) A dresser for polishing cloth as described in the preceding paragraph (1) or (2), characterized in that the crystal grain size of the chrome plating layer is 20 μm or less.

(4) A dresser for polishing cloth described in any one of the preceding paragraphs (1) to (3), characterized in that the crystal grain size of the chrome plating layer is 2 μm or less.

(5) A dresser for polishing cloth described in any one of the preceding paragraphs (1) to (4), characterized in that the thickness of the chrome plating layer is 3 μm or more.

(6) A dresser for polishing cloth described in any one of the preceding paragraphs (1) to (5), characterized in that the thickness of the chrome plating layer is 5 μm or more.

(7) A dresser for an abrasive cloth according to any one of the preceding paragraphs (1) to (6), characterized in that the average particle size d of the abrasive grains is 3 μm≦d<100 μm.

(8) A dresser for an abrasive cloth according to any one of the preceding paragraphs (1) to (7), characterized in that the abrasive grains are at least one of diamond, cubic boron nitride, boron carbide, silicon carbide, and aluminum oxide.

(9) A dresser for polishing cloth according to any one of the preceding paragraphs (1) to (8), characterized in that the metal support is stainless steel.

By using the dresser of the present invention, uniform pad flatness of the polishing pad is ensured, so the pad surface roughness Ra can be kept small and low micro-scratches can be achieved. Metal elution can also be prevented, improving product yield. In particular, when the dresser of the present invention is applied as a pad conditioner for CMP polishing in semiconductor manufacturing, the flatness of the wafer substrate is improved, achieving excellent quality, while maintaining a high yield.

1 shows a schematic cross-sectional view of a dresser of the present invention. 1 shows a schematic plan perspective view of a dresser of the present invention.

As mentioned above, in the CMP polishing process of advanced semiconductors with wiring rules of less than 10 nm, suppression of micro-scratches and low metal elution are important due to the demand for improved yield. Therefore, in order to solve this problem, the present inventors conducted extensive research and came up with the invention of the dresser shown in Figures 1 and 2. Figure 1 shows a schematic cross-sectional view of the dresser of the present invention. Figure 2 shows a schematic plan view perspective view of the dresser of the present invention. Referring to Figures 1 and 2, the dresser 100 of the present invention comprises a metal adhesion layer 2 formed on a metal support 1 to which a plurality of abrasive grains 4 are adhered, and a coating layer 3 that covers the metal adhesion layer 2.

The inventor discovered that micro-scratches can be suppressed when the surface roughness of the polishing pad is small. In order to reduce the surface roughness of the polishing pad, it is effective to make the grain size of the abrasive grains used in the dresser as small as possible. However, as the grain size is reduced, the bonding strength of the abrasive grains to the metal adhesion layer decreases, causing the abrasive grains to fall off during dressing, causing macrocracks to form on the polished surface, and significantly reducing the yield. Therefore, the inventor used a brazing method, which provides high bonding strength, as a method for bonding the abrasive grains 4. A means for suppressing micro-scratches had not been found in the past, and this invention was discovered by the inventor through many experiments.

In order to suppress metal elution, a crystalline chrome plating film with high stability in acidic solutions was used as the coating layer 3. It was also found that by coating the metal adhesion layer 2 using a Ni-based brazing material with a crystalline chrome plating layer, better adhesion was obtained and metal elution could be suppressed compared to the case of applying a similar coating to a metal adhesion layer using other brazing materials (e.g., Ag-based, Cu-based, Ti-based, etc.). Note that Ni-based brazing materials are alloys that contain nickel as the main component and have a liquidus temperature higher than 450°C, and examples of these include Ni-Cr-Fe-Si-B, Ni-Cr-Si, Ni-Cr-P, and Ni-Cr-Si-B systems, such as JIS standard materials such as BNi-1, BNi-1A, BNi-2, BNi-5, and BNi-7, but are not limited to these. From the viewpoint of composition, the Ni-based brazing material may be, for example, a Ni-based brazing material that satisfies the composition conditions of Ni+Fe 70% to 90% by mass (wherein Fe/(Ni+Fe) is 0 to 0.4), Cr 1% to 25% by mass, and Si+B 2% to 15% by mass (wherein B/(Si+B) is 0 to 0.8), but is not limited thereto. The present inventor has invented a dresser that can maintain a small pad surface roughness Ra, suppress microscratches, and prevent metal elution by coating a metal fixing layer 2 made of a Ni-based brazing material to which small-diameter abrasive grains 4 are fixed with a crystalline chrome plating layer 3. Aiming to improve the yield of the CMP process, the pad surface roughness Ra, the number of microscratches, and the amount of metal elution were evaluated using various dressers with different abrasive grain diameters and crystalline chrome plating layer thicknesses.

Specifically, CMP polishing was performed using various dressers with different abrasive grain sizes, and the appropriate abrasive grain size was determined by evaluating the pad surface roughness Ra and the number of microscratches. In addition, various dressers with different thicknesses of the crystalline chrome plating layer were dipped into the polishing slurry, and the amount of metal in the polishing slurry after dipping was analyzed to determine the appropriate thickness of the chrome plating layer. The results of this experiment and evaluation are shown in detail in the Examples.

The inventors have discovered that by controlling the grain size of the chromium crystals contained in the crystalline chromium plating layer to a small size, it is possible to further suppress the formation of penetrating cracks that reach the metal adhesion layer beneath the crystalline chromium plating layer, and thus to further suppress metal elution. This point will also be described in detail in the examples.

The dresser 100 may further include a cover layer that covers the coating layer 3 (crystalline chrome plating layer). Examples of the cover layer include, but are not limited to, a chrome plating layer having a composition similar to that of the coating layer 3 (crystalline chrome plating layer), a chrome plating layer having a composition different from that of the coating layer 3 (crystalline chrome plating layer), and a chrome carbide plating layer formed from chrome carbide. The cover layer may be a single layer or multiple layers.

<Reasons for Limiting the Invention>
When the average particle size of the abrasive grains 4 is d, the average particle size d is 3 μm≦d<200 μm. If the abrasive grains are less than 3 μm, the pad grinding rate decreases and the polishing pad's dressing performance is insufficient, making it impossible to use as a dresser. If the abrasive grains are more than 200 μm, the pad surface roughness Ra becomes large and it is not possible to prevent micro-scratches. If the average particle size d of the abrasive grains 4 is 3 μm≦d<100 μm, the pad surface roughness Ra becomes smaller and the suppression of micro-scratches works more effectively.

The abrasive grain size can be measured by any method. For example, the abrasive grain size can be measured after removing and collecting the abrasive grains 4 before they are fixed, or after the fixed abrasive grains 4 are peeled off. In this case, the abrasive grain size can be the number average grain size obtained by sieve classification, laser diffraction, centrifugal sedimentation, direct observation with an optical microscope or scanning electron microscope (SEM), or the like. In the case of the present invention, it is preferable to use the number average grain size obtained by the laser diffraction method or the direct observation with an optical microscope or scanning electron microscope. When measuring the grain size of the fixed abrasive grains 4 as is, the number average grain size can be the number average grain size obtained from the circle equivalent diameter obtained by direct observation with an optical microscope or SEM.

The thickness of the crystalline chrome plating layer 3 is 1 μm or more. If it is less than 1 μm, the metal elution prevention effect is insufficient, but if it is 1 μm or more, the metal elution prevention effect is effective. If the thickness of the crystalline chrome plating layer 3 is 3 μm or more, the metal elution prevention effect is further improved and it is preferable. In particular, if the thickness of the crystalline chrome plating layer is 5 μm or more, the metal elution prevention effect is further improved and it is even more preferable.

The crystalline chrome plating layer 3 is generally a polycrystal (a chrome plating layer with a crystalline structure) consisting of fine crystals with grain sizes ranging from several tens of μm to submicrons. Known methods can be used to measure the grain size of the crystalline chrome plating layer 3. The grain size can be the number average grain size obtained by a known method. The smaller the grain size of the crystalline chrome plating layer, the better the sealing performance against the polishing slurry and the better the metal elution prevention effect. The grain size is preferably 20 μm or less, and more preferably 2 μm or less, as this can better demonstrate the metal elution prevention effect.

The abrasive grains 4 constituting the polishing cloth dresser of the present invention are preferably those having high hardness and not easily reacting with acidic or alkaline slurries, and for example, abrasive grains 4 made of diamond, cubic boron nitride, boron carbide, silicon carbide, aluminum oxide, silicon oxide, or cerium oxide are used. Particularly preferred are abrasive grains 4 made of diamond, cubic boron nitride, boron carbide, silicon carbide, or aluminum oxide. One type of abrasive grains 4 may be used alone, or multiple types of abrasive grains 4 may be used in combination. It is also possible to use abrasive grains whose surfaces are coated with at least one selected from titanium, zirconium, and chromium, or at least one selected from titanium carbide, zirconium carbide, and chromium carbide.

In this way, the dresser of the present invention is a dresser that can prevent micro-scratches by controlling the particle size of the dresser's abrasive grains 4, and can also suppress the amount of metal elution by coating the metal adhesion layer 2 using a Ni-based brazing material with a crystalline chrome plating layer 3. The present invention was made possible by achieving both micro-scratches and metal elution suppression.

<Method of manufacturing the dresser according to the present invention>
The dresser according to the present invention is manufactured as follows. The metal support 1 is preferably made of stainless steel, which is unlikely to react with acidic or alkaline slurries, like the abrasive grains 4. Typical stainless steels such as SUS304, SUS316, and SUS430 are suitable. General structural steels such as carbon steels with a surface plated with Ni or the like can also be used.

The shape of the metal support material 1 is not particularly limited and may be a polygonal shape such as an octagon or icosagon, but since the metal support material 1 itself rotates while grinding the pad, it is preferable that it be disk-shaped to ensure uniform grinding.

Next, a Ni-based brazing material is applied to the surface of the metal support 1, and the abrasive grains 4 are arranged in a single layer at a specified interval on the applied Ni-based brazing material. Here, a single layer means that the abrasive grains 4 are arranged in a plane that includes the surface of the metal support 1. In this case, the abrasive grains 4 are temporarily fixed with glue or the like to prevent them from shifting.

Next, after drawing a vacuum to about 10 ⁻³ Pa, a brazing heat treatment is performed by raising the temperature to the temperature at which the brazing material melts, and a metal fixing layer 2 is formed on the metal support material 1. Note that the temperature at which a conventional brazing material is melted is preferably equal to or higher than the melting point of the brazing material, and is preferably as low as possible, and is preferably within a range of about the liquidus temperature + 20°C at most.

The crystalline chrome plating layer is formed as follows. It is formed by plating using a plating bath containing chromic anhydride (chromium trioxide) as the main component, and sulfuric acid added as a catalyst root at a weight ratio of about 1/100 to the chromic anhydride, under conditions of a bath temperature of 48 to 58°C and a current density of 15 to 35 amperes/ ^dm2 . However, the formation method is not limited to the above.

The present invention will be described in detail below with reference to examples.
Example 1
Diamond abrasive grains having an average particle size d of 2 μm, 4 μm, 10 μm, 20 μm, 35 μm, 50 μm, 65 μm, 75 μm, 95 μm, 110 μm, 150 μm, 190 μm, 250 μm, and 300 μm were fixed to a metal adhesion layer formed on a metal support material made of SUS304 stainless steel, and the metal adhesion layer was coated with a crystalline chrome plating having a thickness shown in Table 1 to produce the dressers shown in Figures 1 and 2. Using these dressers, the pad surface roughness Ra, the number of micro scratches, and the amount of metal elution were evaluated. The crystal grain size of the crystalline chrome plating layer in each example and comparative example was 6 μm. There are various methods for measuring the crystal grain size, but in this example, the grain size was measured by observation on a two-dimensional plane using a microscope. The metal support material 1 was formed in a disk shape with a diameter of 108 mm and a thickness of 6 mm. The surface shape of the metal adhesion layer was formed in a flat shape. The metal adhesive layer was made of a Ni-Cr-Si-B brazing material, BNi-2 manufactured by Tokyo Blaze Co., Ltd.

<Evaluation of pad surface roughness Ra and number of micro-scratches>
The fabricated dresser was applied to the CMP process of a patterned wafer, and the pad surface roughness Ra after the CMP process and the microscratch level of the patterned wafer were evaluated. The pad surface roughness Ra was measured using a laser surface roughness measuring instrument, and the microscratch level was measured using a defect inspection device manufactured by KLA-Tencor Corporation.

Regarding the pad surface roughness Ra (μm/min), if the pad surface roughness Ra was 4.9 (μm/min) or less, it was evaluated as "surface roughness is sufficiently small" and as "○", and if it was more than 4.9 (μm/min), it was evaluated as "surface roughness is large" and as "×". In addition, if the pad surface roughness Ra was 2.9 (μm/min) or less, it was evaluated as "surface roughness is even more sufficiently small" and as "◎◎", and if it was 2.4 (μm/min) or less, it was evaluated as "surface roughness is even more sufficiently small".

The microscratch level was set to 10 for No. 14, which had the largest average grain size. The microscratch levels for No. 1 to No. 13 were calculated by dividing the number of microscratches for each by the number of microscratches for No. 14, multiplying the result by 10, and rounding off to the nearest tenth. As a result, when the microscratch level was 8 or less, it was evaluated as ○, meaning that the number of microscratches was sufficiently small, and when the microscratch level was 9 or more, it was evaluated as ×, meaning that the number of microscratches was large. When the microscratch level was 3 or less, it was evaluated as ◎, meaning that the number of microscratches was even smaller, and when the microscratch level was 2 or less, it was evaluated as ◎◎, meaning that the number of microscratches was even smaller.

<Evaluation of Metal Leaching Amount>
The amount of metal elution from the dresser was evaluated by dipping the manufactured dresser in the polishing slurry for 72 hours, and the slurry after dipping was subjected to ICP analysis to evaluate the amount of metal elution (ppm). At this time, in order to grasp the amount of metal contained in the slurry from the beginning, the slurry before the dip test was also subjected to ICP analysis. The amount of metal eluted from the dresser was determined by subtracting the amount of metal in the slurry before dipping from the amount of metal in the slurry after dipping. The elements analyzed by ICP were nickel, chromium, iron, copper, manganese, sodium, aluminum, cobalt, potassium, and magnesium, and the sum of the amounts of these metals was determined as the amount of metal eluted from the dresser. As a result, when the amount of metal elution was 100 ppm or less, it was evaluated as ○, which means that "metal elution is sufficiently suppressed," and when the amount of metal elution was more than 100 ppm, it was evaluated as ×, which means that "metal elution is not sufficiently suppressed." In addition, when the amount of metal elution was 40 ppm or less, it was evaluated as ◎, which means that "metal elution was more sufficiently suppressed", when the amount of metal elution was 15 ppm or less, it was evaluated as ◎◎, which means that "metal elution was even more sufficiently suppressed", and when the amount of metal elution was 3 ppm or less, it was evaluated as ◎◎◎, which means that "almost no metal elution occurred".

As is clear from the comparison between the comparative examples and the examples in Table 1, in the examples of the present invention (samples No. 2 to 12), the pad surface roughness Ra, microscratch level, and metal elution amount were all rated as "○" or higher. On the other hand, in sample No. 1 (comparative example), the average abrasive grain size is small at 2 μm, so although the pad surface roughness Ra is small, the pad's sharpening performance is insufficient, and the microscratch level was rated as "×". In addition, in samples No. 13 and No. 14 (comparative examples), the abrasive grain size is too large, so the pad surface roughness Ra becomes rough, microscratches increase, and the microscratch level is rated as "×". In addition, when the average abrasive grain size d is 3 μm≦d<100 μm (samples No. 2 to 9), the pad surface roughness Ra becomes smaller (rated as "◎" or higher). There has never been a dresser with low microscratches and low metal elution amount like the examples.

Example 2
Diamond abrasive grains 4 with an average grain size d of 50 μm were fixed to a metal adhesion layer formed on a metal support material made of SUS304 stainless steel, and the metal adhesion layer was coated with a crystalline chrome plating having a thickness shown in Table 2. The dressers shown in FIG. 1 and FIG. 2 were manufactured, and the amount of metal eluted from the dressers was evaluated. The crystal grain size of the crystalline chrome plating layer in each example and comparative example was 6 μm. The method of measuring the crystal grain size was the same as in Example 1. The metal support material 1 used was formed into a disk shape with a diameter of 108 mm and a thickness of 6 mm. The surface shape of the metal adhesion layer was formed into a flat shape. Ni-Cr-Fe-Si-B brazing material was used for the metal adhesion layer. BNi-1 manufactured by Tokyo Blaze Co., Ltd. was used as the Ni-Cr-Fe-Si-B brazing material.

<Evaluation of Metal Leaching Amount>
The amount of metal eluted from the dresser was evaluated in the same manner as in Example 1. The results are shown in Table 2.

As can be seen from the examples in Table 2, by making the crystalline chrome plating 1 μm or more thick (samples No. 23 to No. 29), it is possible to suppress metal elution. Furthermore, the effect of suppressing metal elution is remarkable when the chrome plating is 3 μm or thicker (sample No. 25), and in particular, chrome plating with a thickness of 5 μm or thicker (samples No. 26 to No. 29) has a more desirable effect of suppressing metal elution. On the other hand, by making the crystalline chrome plating less than 1 μm thick, metal elution is not sufficiently suppressed, and the evaluation was "X".

Example 3
Diamond abrasive grains 4 with an average grain size d of 50 μm were fixed to a metal adhesion layer formed on a metal support made of SUS304 stainless steel, and a crystalline chrome plating layer with a thickness of 9 μm was coated on the metal adhesion layer, with the grain size varied as shown in Table 3. The dresser shown in FIG. 1 and FIG. 2 was manufactured, and the amount of metal elution from the dresser was evaluated. In addition, the adhesion of the crystalline chrome plating film to the metal adhesion layer was also evaluated. The grain size of the crystalline chrome plating layer was measured with a microscope in the same manner as in Example 1. The metal support 1 used was formed in a disk shape with a diameter of 108 mm and a thickness of 6 mm. The surface shape of the metal adhesion layer was formed in a flat shape. Ni-Cr-Si-B brazing material was used for the metal adhesion layer. BNi-2 manufactured by Tokyo Blaze Co., Ltd. was used as the Ni-Cr-Si-B brazing material. In this example, as comparative examples, a case where an amorphous chromium plating film was coated and a case where a Cu-Ag-P based brazing material was used as the brazing material were also evaluated. BCuP-3 manufactured by Tokyo Blaze Co., Ltd. was used as the Cu-Ag-P based brazing material.

<Evaluation of Metal Dissolution Amount and Adhesion of Chromium Plating Film to Metal Adhesive Layer>
The amount of metal eluted from the dresser was evaluated in the same manner as in Example 1. The adhesion of the chrome plating layer was evaluated by dressing the polishing pad continuously for 20 hours and the state of the chrome plating layer on the dresser surface after dressing was evaluated under a microscope. If no cracks or peeling were observed and the condition was the same as before dressing, it was evaluated as ○, and if cracks or peeling were observed, it was evaluated as ×. The results are shown in Table 3.

As can be seen from the examples in Table 3, by forming a crystalline chrome plating layer on a metal adhesion layer using Ni-Cr-Si-B brazing material (samples No. 32 to No. 39), metal elution was suppressed (rated "◎" or better). In addition, by making the crystal grain size of the chrome plating layer 20 μm or less (samples No. 33 to No. 37), the effect of suppressing metal elution was remarkable (rated "◎◎"). Furthermore, by making the crystal grain size of the chrome plating layer 2 μm or less (samples No. 38 to No. 39), the effect of suppressing metal elution was even more remarkable (rated "◎◎◎"). When the crystalline chrome plating layer was applied, no cracking or peeling was observed, and it was at a level that could be used as a dresser.

On the other hand, when the amorphous chrome plating layer of sample No. 31, which is a comparative example, was coated, the amorphous chrome plating layer was extremely brittle, and the difference in the thermal expansion coefficient between the base metal adhesion layer and the amorphous chrome plating layer, as well as the stress applied during use as a dresser, caused the amorphous chrome plating layer to crack and peel off, resulting in an adhesion rating of x. In addition, the amount of metal elution was 187 ppm (evaluated as "x"), and metal elution could not be suppressed.

In addition, when the comparative sample No. 40 Cu-Ag-P brazing filler metal was used, the adhesion between the crystalline chrome plating layer and the metal fixing layer made of the Cu-Ag-P brazing filler metal was insufficient, and in the adhesion evaluation, cracks and peeling occurred in the crystalline chrome plating layer, resulting in an adhesion rating of x. In addition, the amount of metal elution was 109 ppm (rating "x"), and metal elution could not be suppressed.

Example 4
Diamond abrasive grains 4 with an average grain size d of 50 μm were fixed to a metal adhesion layer formed on a metal support material made of SUS304 stainless steel, and a crystalline chrome plating layer with a thickness of 9 μm was coated on the metal adhesion layer, with the grain size varied as shown in Table 4. The dresser shown in FIG. 1 and FIG. 2 was manufactured, and the amount of metal elution from the dresser was evaluated. In addition, the adhesion of the crystalline chrome plating film to the metal adhesion layer was also evaluated. The grain size of the crystalline chrome plating layer was measured with a microscope in the same manner as in Example 1. The metal support material 1 used was formed in a disk shape with a diameter of 108 mm and a thickness of 6 mm. The surface shape of the metal adhesion layer was formed in a flat shape. Ni-Cr-Fe-Si-B brazing material was used for the metal adhesion layer. BNi-1 manufactured by Tokyo Blaze Co., Ltd. was used as the Ni-Cr-Fe-Si-B brazing material. In this example, the case where an amorphous chrome plating film was coated was also evaluated as a comparative example.

<Evaluation of Metal Dissolution Amount and Adhesion of Chromium Plating Film to Metal Adhesive Layer>
The amount of metal eluted from the dresser and the adhesion of the chromium plating layer were evaluated in the same manner as in Example 3. The results are shown in Table 4.

As can be seen from the examples in Table 4, by forming a crystalline chrome plating layer on a metal adhesion layer using Ni-Cr-Fe-Si-B brazing material (samples No. 42 to No. 49), metal elution was suppressed (rated "◎" or better). In addition, by making the crystal grain size of the chrome plating layer 20 μm or less (samples No. 43 to No. 47), the effect of suppressing metal elution was remarkable (rated "◎◎"). Furthermore, by making the crystal grain size of the chrome plating layer 2 μm or less (samples No. 48 to No. 49), the effect of suppressing metal elution was even more remarkable (rated "◎◎◎"). When the crystalline chrome plating layer was applied, no cracking or peeling was observed, and it was at a level that could be used as a dresser.

On the other hand, when the amorphous chrome plating layer of sample No. 41, which is a comparative example, was coated, the difference in the thermal expansion coefficient between the base metal adhesion layer and the amorphous chrome plating layer and the stress applied during use as a dresser caused the amorphous chrome plating layer to crack and peel off, similar to the amorphous chrome plating layer of Example 3, and the adhesion was rated x. In addition, the amount of metal elution was 181 ppm (rated "x"), and metal elution could not be suppressed.

(Example 5)
Diamond abrasive grains 4 with an average grain size d of 50 μm were fixed to a metal adhesion layer formed on a metal support material made of SUS304 stainless steel, and a crystalline chrome plating layer with a thickness of 9 μm was coated on the metal adhesion layer, with the grain size varied as shown in Table 5. The dresser shown in FIG. 1 and FIG. 2 was manufactured, and the amount of metal elution from the dresser was evaluated. In addition, the adhesion of the crystalline chrome plating film to the metal adhesion layer was also evaluated. The grain size of the crystalline chrome plating layer was measured with a microscope in the same manner as in Example 1. The metal support material 1 used was formed into a disk shape with a diameter of 108 mm and a thickness of 6 mm. The surface shape of the metal adhesion layer was formed into a flat shape. Ni-Cr-Si brazing material was used for the metal adhesion layer. BNi-5 manufactured by Tokyo Blaze Co., Ltd. was used as the Ni-Cr-Si brazing material. In this example, the case where an amorphous chrome plating film was coated was also evaluated as a comparative example.

<Evaluation of Metal Dissolution Amount and Adhesion of Chromium Plating Film to Metal Adhesive Layer>
The amount of metal eluted from the dresser and the adhesion of the chromium plating layer were evaluated in the same manner as in Example 3. The results are shown in Table 5.

As can be seen from the examples in Table 5, by forming a crystalline chrome plating layer on a metal adhesion layer using Ni-Cr-Si brazing material (samples No. 52 to No. 59), metal elution was suppressed (rated "◎" or better). In addition, by making the crystal grain size of the chrome plating layer 20 μm or less (samples No. 53 to No. 57), the effect of suppressing metal elution was remarkable (rated "◎◎"). Furthermore, by making the crystal grain size of the chrome plating layer 2 μm or less (samples No. 58 to No. 59), the effect of suppressing metal elution was even more remarkable (rated "◎◎◎"). When the crystalline chrome plating layer was applied, no cracking or peeling was observed, and it was at a level that could be used as a dresser.

On the other hand, when the amorphous chrome plating layer of sample No. 51, which is a comparative example, was coated, the difference in the thermal expansion coefficient between the base metal adhesion layer and the amorphous chrome plating layer and the stress applied during use as a dresser caused the amorphous chrome plating layer to crack and peel off, similar to the amorphous chrome plating layer of Example 3, and the adhesion was rated x. In addition, the amount of metal elution was 186 ppm (rated "x"), and metal elution could not be suppressed.

From the above, it was found that metal elution can be suppressed by covering the crystalline chrome plating layer with a metal adhesion layer made of Ni-based brazing material. Furthermore, the effect of suppressing metal elution is remarkable when the crystal grain size of the chrome plating layer is 20 μm or less, and a grain size of 2 μm or less in particular has a more desirable effect of suppressing metal elution.

1 Metal support 2 Metal adhesion layer 3 Crystalline chrome plating layer 4 Abrasive grain 100 Dresser

Claims (9)

A dresser for an abrasive cloth comprising: a metal adhesion layer formed on a surface of a metal support, the metal adhesion layer having a plurality of abrasive grains adhered thereto; and a coating layer that covers the metal adhesion layer,
The average particle diameter d of the plurality of abrasive grains is 3 μm≦d<200 μm,
The metal adhesion layer is made of a Ni-based brazing material,
13. A dresser for an abrasive cloth, comprising: a polishing cloth dresser, the polishing cloth dresser comprising: a polishing cloth dresser for dressing a polishing cloth; The polishing cloth dresser also has
2. The dresser for a polishing cloth according to claim 1, further comprising a cover layer that covers the chrome plating layer. The dresser for polishing cloth according to claim 1 or 2, characterized in that the grain size of the chrome plating layer is 20 μm or less. A dresser for polishing cloth according to any one of claims 1 to 3, characterized in that the grain size of the chrome plating layer is 2 μm or less. A dresser for polishing cloth according to any one of claims 1 to 4, characterized in that the thickness of the chrome plating layer is 3 μm or more. A dresser for polishing cloth according to any one of claims 1 to 5, characterized in that the thickness of the chrome plating layer is 5 μm or more. A dresser for polishing cloth according to any one of claims 1 to 6, characterized in that the average particle size d of the abrasive grains is 3 μm≦d<100 μm. A dresser for an abrasive cloth according to any one of claims 1 to 7, characterized in that the abrasive grains are at least one of diamond, cubic boron nitride, boron carbide, silicon carbide, and aluminum oxide. A dresser for polishing cloth according to any one of claims 1 to 8, characterized in that the metal support is stainless steel.