JP2019059019A - Vitrified superabrasive grain wheel - Google Patents

Abstract

To provide a vitrified superabrasive grain wheel which has a durability, can improve the quality of a wafer and so on after processing, and has excellent grinding performance.SOLUTION: A vitrified superabrasive grain wheel having a superabrasive grain layer in which superabrasive grains are combined by a vitrified bond. The wheel includes spherical pores which are located on the superabrasive grain layer while being dispersed and have an average pore diameter of 250-600 μm, and an average value of a ratio (a/b) of a minor axis a to a major axis b of the spherical pore is 0.5-1.0. The vitrified superabrasive grain wheel having pores is used for grinding of various kinds of wafers of silicone, sapphire, a compound semiconductor or the like.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vitrified bonded superabrasive wheel having pores, in which superabrasive particles used for grinding processing of various wafers such as silicon, sapphire and compound semiconductor are bonded by a vitrified bond.

  If it classify | categorizes according to a bond as a main kind of grindstones for grinding and polishing, it will be divided into vitrified grindstone, resinoid grindstone, a metal grindstone, and an electrodeposition grindstone. Among them, the vitrified grindstone is widely used because of its good sharpness, high durability and good dressability.

  In order to maintain even better sharpness, a technology for putting a pore forming material in a vitrified bonded wheel is disclosed. Specifically, it is described that it is a superabrasive vitrified wheel and includes small pores having an average pore diameter of 0.1 to 15 μm and spherical large pores having an average pore diameter of 20 to 200 μm (patented) Literature 1).

  Similarly, a vitrified bonded grinding wheel is disclosed which uses an average grain size of 40 to 160 μm as a vitrified bonded grinding wheel and uses a pore-forming material of 130 to 1300 μm. (Patent Document 2)

JP, 2012-152881, A JP-A-8-57768

  However, along with the recent development of technology, quality requirements for various wafers have been raised, and reduction in processing costs is required, and vitrified bond superabrasives with better grinding performance can not be coped with by conventional techniques. Grain wheels are required. Therefore, an object of the present invention is to provide a vitrified superabrasive grain wheel which is durable, can improve the quality of a processed wafer, and has excellent grinding performance.

  In view of the above problems, the inventors of the present invention have made the vitrified bonded super-abrasive particle wheel have a larger diameter average pore diameter of 250 to 600 μm larger than the conventional upper limit average pore diameter of 200 μm regardless of the prior art. It has been found that the grinding performance of conventional vitrified bonded superabrasive wheels is surprisingly surpassed by dispersing spherical pores which are in the range of. Furthermore, a vitrified bond superabrasive wheel that exhibits grinding performance that exceeds expectations by performing development of a vitrified bond that is compatible with the superabrasive wheel, and combining the vitrified bond with a spherical pore-shaped material with a predetermined size diameter. The present invention is completed by finding

That is, the present invention is a vitrified bonded superabrasive particle wheel having a superabrasive particle layer in which superabrasive particles are bonded by a vitrified bond, and the average pore diameter dispersedly disposed in the superabrasive particle layer is 250 to 600 μm. And the average value of the ratio (a / b) of the minor axis a to the major axis b of the spherical pores is 0.5 or more and 1.0 or less, and various wafers such as silicon, sapphire and compound semiconductors The present invention relates to a vitrified bonded superabrasive wheel having pores, which is characterized in that it is used for the grinding process of the present invention.

Also, vitrified bond used in the present invention, _SiO 2 of 55~70wt%, 5~15wt% of _Al 2 _O 3, _15~25wt% of _B 2 _O 3, _1~6wt% of RO (RO is CaO, It has a composition comprising MgO and at least one of BaO, and 4 to 10 wt% of R ₂ O (where R ₂ O is selected from at least one of K ₂ O, Na ₂ O and Li ₂ O).

Furthermore, said R ₂ O contains K ₂ O, Na ₂ O and Li ₂ O, said Na ₂ O is 5 to 30 wt% with respect to the total amount of R ₂ O, and Li ₂ O is 20 with respect to the total amount of R ₂ O ~45wt%, _{K 2} O is 20 to 45 wt% with respect to _{R 2} O total amount, and each of _{K 2} O and Li ₂ O is characterized in that it is contained more than Na ₂ O.

  The vitrified bonded superabrasive wheel of the present invention can provide a significant improvement in durability, and can also provide a significant improvement in working efficiency and quality in processing of various types of wafers. Hereinafter, these effects may be referred to as “effects of the present invention”.

FIG. 1 is a cross-sectional enlarged photograph of a wheel obtained in Example 1 (SEM photograph × 50 times). FIG. 2 is an enlarged sectional view of a cross section of the wheel obtained in Comparative Example 1 (SEM photograph × 50 times). FIG. 3 is an enlarged sectional view of the abrasive grains and the binder of the wheel obtained in Example 1 (SEM photograph × 2000 times). FIG. 4 is an enlarged sectional view of the abrasive grains and the binder of the wheel obtained in Comparative Example 1 (SEM photograph × 2000 times).

  As described above, the present invention is a vitrified bonded superabrasive particle wheel having a superabrasive particle layer in which superabrasive particles are bonded by vitrified bond, and the average pore diameter dispersedly disposed in the superabrasive particle layer is 250 And the average ratio of the minor diameter a to major diameter b (a / b) of the spherical pores is 0.5 or more and 1.0 or less, such as silicon, sapphire, compound semiconductor, etc. It is a porous, vitrified bonded superabrasive wheel characterized in that it is used for grinding of various wafers.

  When the spherical pore diameter is less than the average pore diameter of 250 μm, the durability decreases and the surface roughness becomes rough. In addition, when the spherical pore diameter exceeds the average pore diameter of 600 μm, the wheel is cracked and the normal wheel can not be manufactured. The average pore diameter of the spherical pore diameter is preferably 250 to 600 μm, more preferably 250 to 500 μm, and most preferably 300 μm to 400 μm. The pore-forming material used to form the pores may be any substance as long as it can form pores in a predetermined size, but an organic substance is preferably used such as a resin material.

The pore-forming material used to form the pores is preferably an organic substance, but an inorganic hollow body can also be used, and a spherical pore-forming material is preferred. In that case, the average pore diameter is preferably 250 to 600 μm, more preferably 250 to 500 μm, and most preferably 300 μm to 400 μm. Specific examples of the pore forming material include, for example, an alumina balloon, a mullite balloon, carbon and the like. In the present invention, the term "spherical" means that the cross section is substantially circular or elliptical, and the average value of the ratio a / b of the minor axis a to the major axis b (hereinafter referred to as "sphericity") is 0.5 or more. 1 or less. Therefore, it does not require a solid shape such as an exact spherical shape or an elliptical spherical shape such that the cross section is a mathematically exact circle or an ellipse. The sphericity of the pore-forming material used in the present invention is 0.5 to 1.0, preferably 0.8 to 1.0, and more preferably 0.9 to 1.0. .

  In the vitrified bonded superabrasive grain wheel, in addition to the relatively large diameter pores formed by the pore forming material described above, so-called natural pores of relatively small diameter naturally generated are generated. This has a correlation with the particle size of the abrasive used, and when the particle size of the abrasive used is large, large natural pores are generated, and when the particle size of the abrasive used is small, small natural pores are generated. is there. Usually, the average pore size of natural pores tends to be substantially the same as the average particle size of the abrasive used. In the present specification, the relatively large diameter pores formed by the pore-forming material of the present invention may be referred to as large diameter pores.

  Hereinafter, details of the vitrified bond preferably used in the present invention will be described.

Vitrified bond used in the present invention is the bond of the glass borosilicate, its chemical composition, _SiO 2 of 55~70wt%, 5~15wt% of _Al 2 _O 3, _15~25wt% of _B 2 O ₃ , 1 to 6 wt% of RO (RO is selected from at least one of CaO, MgO and BaO), and 4 to 10 wt% of R ₂ O (R ₂ O is K ₂ O, Na ₂ O and Li ₂ O) (Selected from at least one type) is used.

Regarding the ratio of each component in R ₂ O, Na ₂ O is 5 to 30 wt% with respect to the total amount of R ₂ O, Li ₂ O is 20 to 45 wt% with respect to the total amount of R ₂ O, and K ₂ O is R ₂ It is 20 to 45 wt% with respect to the total amount of O, and each of K ₂ O and Li ₂ O is contained more than Na ₂ O.

When SiO ₂ is lower than 55 wt%, the thermal expansion coefficient is increased and the softening point is lowered too much. If it is higher than 70% by weight, the softening point is excessively raised, the holding power of the abrasive grains is insufficient, and furthermore, the stability of the borosilicate glass is lost and a phase separation phenomenon occurs.

If the content of Al ₂ O ₃ is less than 5 wt%, the softening point is too low, the stability of the borosilicate glass is lost and phase separation occurs, and if it is more than 15 wt%, the softening point is too high and the retention of abrasive grains is insufficient .

When the content of B ₂ O ₃ is lower than 15 wt%, the softening point is increased, the fluidity is insufficient, and the retention of the abrasive grains is reduced. If it is higher than 25 wt%, the softening point is too low, gas etc. is generated inside the wheel and normal wheel can not be manufactured, and stability of borosilicate glass is lost and phase separation phenomenon occurs and normal wheel can be manufactured. And the grinding performance is reduced.

  When RO (RO is selected from at least one of CaO, MgO and BaO) is lower than 1 wt%, the softening point is too high, the fluidity of the bond is insufficient, and when it is higher than 6 wt%, the softening point is too low.

When R ₂ O (R ₂ O is selected from at least one of K ₂ O, Na ₂ O and Li ₂ O) is lower than 4%, the softening point is too high and the fluidity of the bond is insufficient, and when it is higher than 10 wt% Thermal expansion coefficient is too high.

Furthermore, the inventors focused on the relative proportions of K ₂ O, Na ₂ O and Li ₂ O in the R ₂ O component. Generally, the proportion of Na ₂ O used is large in R ₂ O. This is due to ease of handling and availability (also related to cost). In the present invention, preferably, Na ₂ O is low, and instead, two substances, Li ₂ O and K ₂ O, are more than Na ₂ O. 5-30 wt% in particular Na ₂ O is relative _{R 2} O total amount, 20~45wt% Li ₂ O is relative _{R 2} O total amount, 20 to 45 wt _{K 2} O is relative _{R 2} O total amount %, And each of K ₂ O and Li ₂ O is contained more than Na ₂ O. By adopting such relative proportions of the respective components, it is possible to obtain advantages such as a further increase in the abrasive holding power and an improvement in the grinding performance.

  If a vitrified superabrasive wheel having spherical pores with an average pore diameter in the range of 250 to 600 μm exceeding the upper limit average pore diameter of 200 μm (for example, Patent Document 1) conventionally known as large diameter pores is used surprisingly Also the grinding performance is better than the conventional vitrified superabrasive wheel. Furthermore, a vitrified bond suitable for a vitrified superabrasive wheel is developed, and when combined with the spherical large pore-forming material used in the present invention and the vitrified bond, a vitrified super that demonstrates grinding performance far exceeding the inventors' expectation. An abrasive wheel could be obtained.

  While not intending to be bound by theory, it is conceivable that the vitrified superabrasive wheel according to the present invention can exhibit such excellent grinding performance as follows.

In the case of an organic substance, the spherical pore-forming material decomposes, burns or burns off as it becomes organic as the temperature rises during firing, and the site becomes pores, which is a change from solid to gas. This combustion generally starts at about 200 ° C. and is completed at 400 to 500 ° C. However, when this is contained in the wheel, the combustion, decomposition or burnt-out gas can escape from the wheel at the highest retention It is considered to be a temperature close to the temperature. In other words, it is thought that the volume expands by changing from solid to gas, and this pressure acts on the layer containing the surrounding abrasive grains and bonds. In this case, when the softening of the bond starts, the abrasive grains and the bond layer are pressed to be intimately bonded, and as a result, it is considered that the retention of the abrasive grains is improved and the grinding performance of the wheel is improved. Furthermore, it was also found that the compounding amount of R ₂ O that controls the melting of the bond is optimal. It is believed that this will further enhance the effects of the present invention.

  When the large spherical pores become smaller than the average pore diameter of 250 μm, the amount of solid to gas changes, so the above-mentioned pressing force on the layer containing the abrasive grains and the bond is stronger than using large spherical large pores. It is considered small and intimate as described above can not be obtained.

  Furthermore, the interparticle distance of the large diameter pore forming material is reduced unless the content of the large diameter pore forming material is particularly reduced. Then, when it changes from a solid to a gas, it is considered that the large diameter pores and the adjacent ones will be connected to further weaken the pressing force on the layer containing abrasive grains and bonds.

  When the large pores become larger than the average pore diameter of 600 μm, the pressing force on the layer containing the abrasive grains and the bond is too strong, and the next large pores, the distance becomes smaller despite the use of the smaller large pores. However, it is thought that it leads to cracks in the wheel because its strength is too strong, leading to pores in the vicinity.

With regard to the abrasive that can be used in the present invention, the effect of the present invention is more effectively exhibited when the average particle diameter of the abrasive used is small, specifically, when the average particle diameter is 45 μm or less. Accordingly, the particle size range of the superabrasive particles (diamond, CBN, etc.) used in the present invention is also referred to as a fine abrasive particle (submicron abrasive particle) having an average particle diameter of coarse particle diameter of 600 μm to an average particle diameter of 1 μm. Specifically, it can be used in the range of 80 nm, preferably 45 μm to 80 nm, more preferably 40 μm to 80 nm, and still more preferably 35 μm to 80 nm. It is unpreferable if it exceeds 45 micrometers. Because, as described above, vitrified bonds also exist naturally occurring as well as pores spontaneously developed in the pore forming material. It is known to those skilled in the art that the average pore diameter is as high as the average particle diameter of the abrasive used, but the same degree of natural porosity develops as the particle diameter of the abrasive used is larger, When the diameter of this natural pore is large, the forcibly formed spherical large diameter pore changes from solid to gas during firing, and when it leaves the wheel, it escapes from the wheel through these large natural pores. Therefore, the effects of the present invention can not be sufficiently obtained, which is not preferable.

  Since the use of spherical pore formers is less likely to cause cohesion between particles compared to the use of amorphous pore formers, they are uniformly dispersed in the wheel, and thus contain abrasive grains and bonds in the above wheel. The force pushing the stratum is even. Further, since it is possible to avoid that the pores obtained by the large pore-forming material are aggregated and the occurrence of a location of a particularly large pore diameter, the above effect is more exhibited, and a defect such as a crack generation of the wheel is avoided. is there. There is also the advantage that the variation in grinding performance is reduced during grinding.

Range effect of the average pore diameter 250~600μm spherical present invention, in a vitrified bond, _{R 2} O is 5-30 wt% Na ₂ O is relative _{R 2} O total amount, Li ₂ O within _{R 2} O total amount On the other hand, 25 to 45 wt%, K ₂ O is 25 to 45 wt% with respect to the total amount of R ₂ O, and each of K ₂ O and Li ₂ O is contained in a larger amount than Na ₂ O. There is an improvement in performance and it has been found that adopting these proportions of R ₂ O produces a greater effect.

  Although there is also an inorganic pore-forming material, it can be used as long as the purpose of the present invention is not deviated. Examples of the inorganic pore-forming material include an alumina balloon, a mullite balloon, carbon and the like.

  If the average pore diameter is in the range of 250 to 600 μm, even if it is a mixture of pore forming materials of different diameters, it can be suitably used without departing from the spirit of the present invention.

  The vitrified bonded superabrasive grain wheel of the present invention preferably has an abrasive grain volume ratio of 5 to 40%, preferably 10 to 35%. The pore volume ratio is 40 to 90% in total of spherical large diameter pores and natural pores. The breakdown is that the ratio of pores by the pore former is 15% to 65%. If it is less than 15%, the force for pressing the layer containing the abrasive grains and the bond during firing which is the effect of the present invention is insufficient, and the effect of the present invention is not exhibited. If it is more than 65%, the wheel is cracked. The proportion of pores by natural pores is 15% to 35%. If it is less than 15%, the design is inevitably high in molding pressure, cracks may occur in the wheel after molding, or cracks may occur in the pore-forming material, and the effects of the present invention may not be exhibited. If it is more than 35%, the handling of the wheel from molding to baking becomes difficult, which causes problems in production. Furthermore, the ratio of pores by the pore-forming material is more preferably 25% to 60%. 30% to 55% is more preferable. 40 to 80% of the natural pores and the spherical large pores are more preferable. The bond ratio is a value obtained by subtracting the abrasive particle volume ratio and the pore volume ratio from 100.

  The wheel of the present invention is mainly used as a diamond abrasive, which is a superabrasive, alone, but may be used in combination with other abrasives as long as the effects of the present invention are exhibited. Other abrasives that can be used with the diamond abrasive include cubic superabrasive cubic boron nitride abrasives, other than superabrasives, alumina based abrasives, silicon carbide based abrasives, silica, cerium oxide, mullite, etc. And one or more types of abrasive grains selected from the group consisting of Abrasive grains other than the above-mentioned superabrasive grains are used together with superabrasive grains. These are exemplary lists, and other abrasives not listed here may be used without departing from the object of the present invention.

  The vitrified bonded superabrasive wheel of the present invention can be manufactured as follows.

That is, the vitrified superabrasive wheel according to the present invention can be manufactured by procedures generally recognized by those skilled in the art. Here is an example:
1. Abrasive grains, bonds, primary binders (also referred to as binders), etc. are weighed by a predetermined weight.
2. Mix the weighed materials until uniform (called mixed ingredients).
3. The mixed material is weighed to a predetermined weight and filled into a molding die.
4. A predetermined pressure is applied to obtain a predetermined size.
5. Take out from the mold and place in a heating atmosphere set at a temperature lower than the maximum holding temperature of the firing temperature for a certain period of time.
6. Baking. For example, the firing temperature is in the range of 600 to 900 ° C. at the maximum holding temperature.
7. After firing, it is finished to a predetermined size and made into a wheel.

  The procedure mentioned here is an example, and it can be suitably changed within the limits of technical common knowledge which those skilled in the art usually have according to manufacturing conditions etc.

  Examples of the present invention will be described below together with comparative examples, but these illustrate the feasibility and utility of the present invention and are not intended to limit the configuration of the present invention.

Preparation of Vitrified Bonded Superabrasive Wheel A vitrified bonded superabrasive wheel of the present invention and a comparative vitrified bonded superabrasive wheel were manufactured as follows (test wheel).

That is, as the abrasive grains, diamond abrasive grains having an average particle diameter of 2 μm were used, and as the pore forming material, the material was spherical resin and the particle diameter was changed under each test condition. Adjust the vitrified bond to 13.7% by volume and the diamond abrasives to 13.7% by volume, adjust the total of the pores by the pore-forming material and the natural pores to 72.6% by volume, and add a known binder After mixing, they were formed into a chip-like molded body by a press and fired at a temperature of 800 ° C. After firing, the chip-like compact was finished to a predetermined size to obtain a wheel piece.
A piece of wheel was bonded to a base of φ 200 × 30 T × φ 40 (mm) to make a segmented wheel.

  The compositions of test vitrified bonds 1 to 7 used in the above manufacturing method are shown in Table 1 below.

  A comparative wheel is made using the test bond described above and a pore former of average particle size 15 μm, 75 μm and 700 μm, and a wheel of the present invention is manufactured using a pore former of 300 μm and 500 μm average diameter. did. Tables 2 to 4 show combinations of the test bond and the pore former.

This test combination is a bond chemical component in which the component ratio of SiO ₂ , Al ₂ O ₃ and B ₂ O ₃ is changed. In Comparative Example 1, SiO ₂ , Al ₂ O ₃ and B ₂ O ₃ are within the scope of claims, and in Comparative Examples 2 to 4, any of the above three components is outside the scope of claims.

  The indication of the average particle size of the pore-forming material used is the name of the purchasing manufacturer. The same applies to the following.

  This test is the same as Comparative Example 1 for bonding, but the average particle diameter of the spherical pore-forming material is changed.

Grinding Test The conditions of the grinding test were as follows.

Grinding wheel size: φ200 × 35T × φ40 (mm), cup-shaped grinding material: Silicon wafer (200 mm (diameter) × 0.7 mm (thickness) 20 sheets Grinding liquid: Distilled water, flow rate: 12 liters / min Grinding machine : Toshiba Machine Co., Ltd. vertical axis surface grinding machine, model UVG-380B
Dressing conditions:
Dresser: WA # 4000
Grinding wheel rotational speed: 3822 min ^-1
Dress incision: 20 μm / min
Grinding condition:
Grinding method: Wet in-feed grinding Wheel rotational speed: 3822 min ^-1
Table rotation speed: 121 min ^-1
Cutting allowance: 30 μm
Spark out: 10 seconds Evaluation item: Wheel consumption (μm), surface roughness Ra (μm)
However, the evaluation result is shown by a relative value with Comparative Example 1 being 100.

    The amount of wheel wear was calculated as the amount of dimensional change of the wheel before grinding and after grinding of 20 silicon wafers using the amount of change in machine coordinates of the grinder.

    The finished surface roughness Ra was measured on a ground surface of the 20th silicon wafer after grinding 20 silicon wafers with SP-81DS2 (contact type) manufactured by Kosaka Corporation.

Arithmetic mean roughness Ra extracts only a reference length from the roughness curve in the direction of the mean line, takes the X axis in the direction of the mean line of this sampling portion, and takes the Y axis in the direction of longitudinal magnification. When a curve is represented by y = f (x), it means what represented the value calculated by the following formula in micrometers (μm).

          Assuming that the wheel durability of Comparative Example 1 is 100, the values of the other examples are shown by their relative values.

The larger the value of the finished surface roughness Ra based on 100, the lower the value of the surface roughness, and the higher the improvement effect.

Test Results Tables 5 to 7 below show the results of grinding tests on the test wheel.

  The spherical pore diameter and aspect ratio are values after the wheel is made.

  This calculation is measured by polishing the surface of the wheel after firing and observing its cross section. The minor diameter a and the major diameter b are measured for 100 pore portions exposed on the surface of the wheel after completion of polishing, and the average value of the ratio a / b is taken as sphericity. The same applies to the following.

In the case of Comparative Example 1 and Comparative Example 2 (using Test Bond-1 and Test Bond-2 respectively), the content of R ₂ O is the same, but Comparative Example 2 has less SiO ₂ than Comparative Example 1. Although the amount of Al ₂ O ₃ and B ₂ O ₃ was increased by that amount, the softening of the bond was at the same level by the increase and decrease of these chemical components, but the wheel durability and surface roughness were inferior to Comparative Example 1 It was a thing.

Comparative Example 3 (test bond-3) increases B ₂ O ₃ more than Comparative Example 1 and decreases the amount of SiO ₂ correspondingly, but the softening became larger than Comparative Example 1. The wheel durability and the surface roughness were inferior to those of Comparative Example 1.

Comparative Example 4 (Test Bond-4) reduces Al ₂ O ₃ and SiO ₂ from Comparative Example 1 and increases the amount of B ₂ O ₃ by that amount. Was improved but the wheel durability was inferior.

From the above results, SiO ₂ , Al ₂ O ₃ and B ₂ O ₃ are either 55-70 wt% SiO ₂ , 5-15 wt% Al ₂ O ₃ , or 15-25 wt% B ₂ O ₃ . When it comes off, it is understood that the grinding performance is inferior.

The grinding performance is improved as the size of the spherical pores is increased to 14.0 μm, 71.3 μm and 314.2 μm, and it is understood that the grinding performance is remarkably improved particularly in the case of 314.2 μm.

  Astonishingly, it can be seen that in the case where the spherical pores exceed 200 μm and the pores are 314.2 μm, the durability of the wheel is significantly increased and the surface roughness is improved, that is, the quality of the wafer is significantly improved. .

In Example 2, the ratio of Na ₂ O was the largest in the amount of R ₂ O, and the wheel durability was 20% (improved), with Li ₂ O being increased more than Example 1 (Test Bond-5).

In Example 3, the ratio of Na ₂ O was the largest and the ratio of K ₂ O was increased more than in Example 1 (Test Bond-6), and the wheel durability was 18% (improved). The same effect as in Example 1 was observed.

In Example 4, the proportion of Na ₂ O is small and the proportion of K ₂ O and Li ₂ O is increased compared to Example 1 (Test Bond-7), but the wheel durability is improved by 49%, and the surface is rough. With a 7% improvement, we achieved a significant improvement in grinding performance far beyond the expectation of those skilled in the art, and the reduction in wafer surface roughness has a significant effect on wafer quality improvement. The

Example 5 uses a spherical pore-forming material larger than Example 4 (Example 5 uses a mixed pore-forming material of 300 μm / 500 μm = 1: 1; Example 6) (Using a pore-forming material of 500 μm), which also achieved a significant improvement in grinding performance far beyond the expectation of those skilled in the art as in Example 4 and also reduced wafer surface roughness, There was also a remarkable effect on the quality improvement of the wafer.

  In Comparative Example 9, a spherical pore-forming material of 700 μm was used, but a crack occurred in the wheel, resulting in an unacceptable product that can not be used as a vitrified bonded superabrasive wheel.

Relationship between Spherical Pore Forming Material and Actual Wheel Pore Diameter Measured Wheel: Comparative Example 1 Example 1
Diameter of pore forming material: 75 μm 300 μm
Calculation of spherical pore diameter and aspect ratio is measured by polishing the surface of the wheel after firing and observing the cross section. The minor diameter a and the major diameter b are measured for 100 pore portions exposed on the surface of the wheel after completion of polishing, and the average value of the ratio a / b is taken as sphericity.

  Although the above results were obtained, it was found that Example 1 was larger than the diameter before wheel manufacture, unlike Comparative Example 1.

  When the organic spherical pore-forming material changes from solid to gas, the volume expands, and a pressure is exerted on the layer containing the surrounding abrasive grains and bonds at this pressure, and when the softening of the bonds starts, the abrasive grains It is believed that the layer of the binder and the layer of the binder are pressed to form a tight bond, and as a result, the retention of the abrasive grains is improved, resulting in the invention of a good wheel. On the other hand, Comparative Example 1 was smaller than the diameter of the original pore-forming material, and it was confirmed that the effect of the present invention was not exhibited.

  Hereinafter, the attached drawings will be described in detail.

  The enlarged photograph which shows the state of the pore of a wheel is attached to FIGS.

While the pores are dispersed uniformly in Example 1 of FIG. 1, in Comparative Example 1 of FIG. 2, many locations where the pores are attached are also found and are not at least uniform. FIG. 3 shows the state of the abrasive and the binder between the pores of Example 1. FIG. 4 shows the state of the abrasive and the binder between the pores of Comparative Example 1. In Comparative Example 1, almost all the places where the structure state can clearly observe the shape of the abrasive grains were found. The large unevenness is considered to be due to the irregular dropping of the abrasive grains and the binder at the time of finish planarization of the sample. Since this is considered to occur also at the time of grinding, it is considered that the abrasive holding power at the wheel is weak. In Example 1, in the vicinity of natural pores, there was a place where the shape of the abrasive grain similar to Comparative Example 1 could be clearly observed, but in the other places, there were places where the shape of the abrasive grain could not be observed. This is a state in which the abrasive grains and the binder are intimately bonded. There is no large unevenness in the portion, and it is considered that the abrasive grains and the binder did not irregularly fall off when the sample is finished and flattened, and there is no large fall off of the abrasive grains during grinding. This is supported by the fact that the holding power of the abrasive grains is improved by pressing and intimately bonding the abrasive grains and the layer of the binder. Therefore, it is supported that Comparative Example 1 did not express the effect of Example 1.
The present invention includes the following embodiments.
(1) A vitrified bonded super-abrasive wheel having a super-abrasive layer in which super-abrasives are bonded by vitrified bonding,
The super-abrasive grain layer includes spherical pores having an average pore diameter of 250 to 600 μm, and the average particle diameter of the spherical pores is a ratio of minor axis a to major axis b (a / b) of 0. 5 or more and 1.0 or less,
A porous, vitrified bonded superabrasive wheel, which is used for grinding processing of various wafers such as silicon, sapphire and compound semiconductors.
(2) the vitrified bond, _SiO 2 of 55~70wt%, 5~15wt% of _Al 2 _O 3, _15~25wt% of _B 2 _O 3, _1~6wt% of RO (RO is CaO, MgO and BaO And 4 to 10 wt% of R ₂ O (where R ₂ O is selected from at least one of K ₂ O, Na ₂ O and Li ₂ O) The porous vitrified bonded superabrasive wheel according to 1).
(3) The R ₂ O contains K ₂ O, Na ₂ O and Li ₂ O,
5-30 wt% the Na ₂ O is relative _{R 2} O total amount, 20~45wt% Li ₂ O is relative _{R 2} O total amount, _{K 2} O is 20 to 45 wt% with respect to _{R 2} O total amount And each of K ₂ O and Li ₂ O is contained in a larger amount than Na ₂ O. The voided vitrified bonded superabrasive wheel according to (2), characterized in that
The present invention includes the following other embodiments.
(1) A vitrified bonded super-abrasive wheel having a super-abrasive layer in which super-abrasives are bonded by vitrified bonding,
The pores are dispersed and disposed in the superabrasive grain layer, and include spherical pores having an average pore diameter of 250 to 600 μm based on the pore forming material, and the ratio of the minor diameter a to the major diameter b of the spherical pores ( The average value of a / b) is 0.5 or more and 1.0 or less,
A porous, vitrified bonded superabrasive wheel, which is used for grinding processing of various wafers such as silicon, sapphire and compound semiconductors.
(2) the vitrified bond, _SiO 2 of 55~70wt%, 5~15wt% of _Al 2 _O 3, _15~25wt% of _B 2 _O 3, _1~6wt% of RO (RO is CaO, MgO and BaO And 4 to 10 wt% of R ₂ O (where R ₂ O is selected from at least one of K ₂ O, Na ₂ O and Li ₂ O) The porous vitrified bonded superabrasive wheel according to 1).
(3) The R ₂ O contains K ₂ O, Na ₂ O and Li ₂ O,
5-30 wt% the Na ₂ O is relative _{R 2} O total amount, 20~45wt% Li ₂ O is relative _{R 2} O total amount, _{K 2} O is 20 to 45 wt% with respect to _{R 2} O total amount And each of K ₂ O and Li ₂ O is contained in a larger amount than Na ₂ O. The voided vitrified bonded superabrasive wheel according to (2), characterized in that

Claims (4)

A vitrified bonded superabrasive wheel having a super abrasive layer in which super abrasives are bonded by a vitrified bond,
The pores are dispersed and disposed in the superabrasive layer, and the spherical pores having an average pore diameter of 300 μm or more and 600 μm or less formed using an organic pore-forming material The average value of the ratio (a / b) of the minor diameter a to the major diameter b is 0.5 or more and 1.0 or less,
A porous, vitrified bonded superabrasive wheel, which is used for grinding processing of various wafers such as silicon, sapphire and compound semiconductors. The vitrified bond, _SiO 2 of 55~70wt%, 5~15wt% of _Al 2 _O 3, _15~25wt% of _B 2 _O 3, _1~6wt% of RO (RO is CaO, at least one of MgO and BaO And 4 to 10 wt% of R ₂ O (where R ₂ O is selected from at least one of K ₂ O, Na ₂ O and Li ₂ O). A porous, vitrified bonded superabrasive wheel as described. R ₂ O includes K ₂ O, Na ₂ O and Li ₂ O,
5-30 wt% the Na ₂ O is relative _{R 2} O total amount, 20~45wt% Li ₂ O is relative _{R 2} O total amount, _{K 2} O is 20 to 45 wt% with respect to _{R 2} O total amount , And each of K ₂ O and Li ₂ O is contained in a larger amount than Na ₂ O. The voided vitrified bonded superabrasive grain wheel according to claim 2, characterized in that A vitrified bonded superabrasive wheel having a super abrasive layer in which super abrasives are bonded by a vitrified bond,
The pores are dispersed and disposed in the superabrasive grain layer, and include spherical pores having an average pore diameter of 250 to 600 μm based on the pore forming material, and the ratio of the minor diameter a to the major diameter b of the spherical pores ( The average value of a / b) is 0.5 or more and 1.0 or less,
The vitrified bonded superabrasive wheel is used to grind various wafers such as silicon, sapphire and compound semiconductors.
The vitrified bond, _SiO 2 of 55~70wt%, 5~15wt% of _Al 2 _O 3, _15~25wt% of _B 2 _O 3, _1~6wt% of RO (RO is CaO, at least one of MgO and BaO And 4 to 10 wt% of R ₂ O (R ₂ O is selected from at least one of K ₂ O, Na ₂ O and Li ₂ O),
R ₂ O includes K ₂ O, Na ₂ O and Li ₂ O,
5-30 wt% the Na ₂ O is relative _{R 2} O total amount, 20~45wt% Li ₂ O is relative _{R 2} O total amount, _{K 2} O is 20 to 45 wt% with respect to _{R 2} O total amount And a porous vitrified bonded superabrasive wheel characterized in that each of K ₂ O and Li ₂ O is contained more than Na ₂ O.