TW201741077A - Ceramic bonded super-abrasive grinding wheel comprising spherical pores having an average pore diameter of 250 to 600 [mu]m that are dispersedly disposed in the super-abrasive layer - Google Patents

Abstract

The present invention provides a ceramic bonded super-abrasive grinding wheel which has high durability and excellent grinding performance that is capable of improving the quality of the fabricated wafer. The ceramic bonded super-abrasive grinding wheel with pores includes a super-abrasive layer which is formed by combining the super-abrasive grains via the ceramic bond, characterized by comprising spherical pores having an average pore diameter of 250 to 600 [mu]m that are dispersedly disposed in the super-abrasive layer. The average value of the ratio (a / b) of the short diameter a to the long diameter b of the spherical pores is not less than 0.5 and not more than 1.0. The ceramic bonded super-abrasive grinding wheel is used for abrasive cutting various wafers such as silicon, sapphire and compound semiconductor.

Description

Ceramic super abrasive grinding wheel

The present invention relates to a ceramic bond superabrasive wheel having a pore formed by combining superabrasive grains by a ceramic bond applied to grinding of various wafers such as ruthenium, sapphire, and compound semiconductor.

The main types of abrasives for grinding and grinding can be classified into ceramic abrasives, resin abrasives, metal abrasives, and electroplated abrasives according to the type of binder. Among them, ceramic abrasives are widely used because of good sharpness, high durability, and good dressing.

In order to maintain good sharpness, a technique of adding a pore-forming material to a ceramic bond grinding wheel has been disclosed. Specifically, Patent Document 1 discloses a superabrasive ceramic grinding wheel comprising small-diameter pores having an average pore diameter of 0.1 to 15 μm and spherical large-diameter pores having an average pore diameter of 20 to 200 μm.

Similarly, regarding the ceramic bond abrasive, Patent Document 2 discloses a ceramic bond abrasive using a pore-forming material having an average grain size of 40 to 160 μm and more than 130 to 1300 μm.

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2012-152881

[Patent Document 2] Japanese Patent Laid-Open No. Hei 8-57768

However, with the development of technology in recent years, the quality requirements of various wafers have been increased, and the processing cost has been lowered, and the conventional technology has been unable to cope with it, and the ceramic bond super abrasive grinding wheel with superior grinding performance is required. Therefore, the present invention is to provide a ceramic bond superabrasive wheel having high durability and excellent grinding performance after processing.

In view of the above problems, the inventors of the present invention are not bound by the prior art in the case of a ceramic bond superabrasive grinding wheel, and a larger diameter is obtained in such a manner that a spherical large-diameter air hole exceeds a conventional upper limit average pore diameter of 200 μm. The spherical pores in the range of the average pore diameter of 250 to 600 μm are unexpectedly found to surpass the grinding performance of the conventional ceramic bond superabrasive wheel. Further, development of a ceramic binder suitable for the superabrasive grinding wheel is carried out, and a spherical binder having a predetermined size diameter and a ceramic binder are combined to obtain a ceramic binder which can exhibit unexpected grinding performance. The superabrasive grinding wheel thus completed the present invention.

That is, the present invention is a porous ceramic bond superabrasive grinding wheel, which is a ceramic bond superabrasive grinding wheel having a superabrasive layer formed by combining superabrasive particles by a ceramic binder, wherein a spherical pore having an average pore diameter of 250 to 600 μm dispersed in the superabrasive layer, wherein an average value of a ratio (a/b) of a short diameter a to a long diameter b of the spherical pore is 0.5 Above and below 1.0, the ceramic bond superabrasive wheel is used for grinding various wafers such as tantalum, sapphire and compound semiconductors.

Further, the ceramic binder used in the present invention has a composition of 55 to 70% by weight of SiO ₂ , 5 to 15% by weight of Al ₂ O ₃ , 15 to 25% by weight of B ₂ O ₃ , and 1 to 6 % by weight of RO. (RO is at least one selected from the group consisting of CaO, MgO, and BaO), and 4 to 10% by weight of R ₂ O (R ₂ O is at least one selected from the group consisting of K ₂ O, Na ₂ O, and Li ₂ O).

Preferably, the R ₂ O system contains K ₂ O, Na ₂ O and Li ₂ O, the Na ₂ O content of the R ₂ O total amount of 5 ~ 30wt%, Li ₂ O content of the ₂ O total amount of R is 20 to 45 wt%, the K ₂ O content is 20 to 45 wt% with respect to the total amount of R ₂ O, and the content of each of K ₂ O and Li ₂ O is more than that of Na ₂ O, respectively.

The ceramic bond superabrasive grinding wheel of the present invention can greatly improve durability, and can greatly improve work efficiency and quality in processing various wafers. Hereinafter, these effects will be referred to as "the effects of the present invention".

Fig. 1 is a cross-sectional enlarged photograph (SEM photograph × 50 times) of the grinding wheel obtained in Example 1.

Fig. 2 is a cross-sectional enlarged photograph (SEM photograph × 50 times) of the grinding wheel obtained in Comparative Example 1.

Fig. 3 is a cross-sectional enlarged photograph (SEM photograph × 2000 times) of abrasive grains and binder of the grinding wheel obtained in Example 1.

Fig. 4 is a cross-sectional enlarged photograph of an abrasive grain and a binder of the grinding wheel obtained in Comparative Example 1 (SEM photograph × 2000 times).

As described above, the porous ceramic bond superabrasive wheel of the present invention is a ceramic bond superabrasive wheel having a superabrasive layer obtained by combining superabrasive particles by a ceramic binder, wherein a spherical pore having an average pore diameter of 250 to 600 μm dispersed in the superabrasive layer, wherein an average value of a ratio (a/b) of a short diameter a to a long diameter b of the spherical pore is 0.5 or more and 1.0 or less The ceramic bond superabrasive wheel is used for grinding various wafers such as tantalum, sapphire and compound semiconductors.

When the average pore diameter of the spherical pores is less than 250 μm, the durability is lowered and the surface roughness becomes coarse. Further, when the average pore diameter of the spherical pores is higher than 600 μm, the grinding wheel may be cracked and a normal grinding wheel cannot be produced. The average pore diameter of the spherical pores is preferably from 250 to 600 μm, more preferably from 250 to 500 μm, most preferably from 300 μm to 400 μm. The pore-forming material for forming the pores can be used as long as it can form pores of a predetermined size, and it is preferable to use a resin material of an organic substance or the like.

The pore-forming material for forming the pores is preferably an organic substance, but an inorganic hollow body can also be used, and a spherical pore-forming material is preferable. In this case, the diameter of the pore forming material preferably has an average pore diameter of 250 to 600 μm, more preferably 250 to 500 μm, and most preferably 300 μm to 400. Mm. Specific examples of the pore-forming material are, for example, alumina hollow balls, mullite hollow spheres, carbon, and the like. In the present invention, the spherical shape means that the cross section has a substantially circular shape or a substantially elliptical shape, and an average value (hereinafter referred to as "true sphericity") of the ratio a/b of the short diameter a to the long diameter b is 0.5 or more. 1 or less. Therefore, there is no requirement that a strict true spherical shape, an elliptical spherical shape or the like be formed into a mathematically strict circular or elliptical three-dimensional shape. The pore-forming material used in the present invention has a true sphericity of 0.5 to 1.0, preferably 0.8 to 1.0, more preferably 0.9 to 1.0.

The ceramic bond superabrasive grinding wheel, in addition to the relatively large diameter pores formed by the pore forming material, also has a so-called natural pore which naturally produces a relatively small diameter. It has a correlation with the particle size of the abrasive grains used. When the particle size of the abrasive grains used is large, there is a tendency to generate large natural pores, and when the particle size of the abrasive grains used is small, A tendency to produce smaller natural pores. In general, the average pore diameter of the natural pores tends to be substantially the same diameter as the average particle diameter of the abrasive grains used. In the present specification, a relatively large-diameter pore formed by the pore-forming material of the present invention may be referred to as a large-diameter pore.

Hereinafter, the ceramic bond to be used in the present invention will be described in detail.

The ceramic binder used in the present invention is a binder of a borosilicate glass system, and its chemical composition contains: 55 to 70 wt% of SiO ₂ , 5 to 15 wt% of Al ₂ O ₃ , and 15 to 25 wt% of B _{2 .} O ₃ , 1 to 6 wt% of RO (RO is at least one selected from the group consisting of CaO, MgO, and BaO), and 4 to 10 wt% of R ₂ O (R ₂ O is selected from the group consisting of K ₂ O, Na ₂ O, and Li ₂ O) At least one).

Ratio of components having within of R ₂ O, Na ₂ O content of the R ₂ O total amount of 5 ~ 30wt%, Li ₂ O content of the R ₂ O total amount of 20 ~ 45wt%, K ₂ O content relative to R _The total amount of ₂ O is 20 to 45 wt%, and the content of each of K ₂ O and Li ₂ O is more than that of Na ₂ O, respectively.

When the SiO ₂ content is less than 55 wt%, the coefficient of thermal expansion rises and the softening point falls too low. When the content is more than 70% by weight, the softening point rises too high and the retention of the abrasive grains is insufficient, so that the borosilicate glass loses stability and phase separation occurs.

When the content of Al ₂ O _{3 is} less than 5% by weight, the softening point is lowered too low and the vitreous silicate glass loses stability and phase separation occurs, and when it is higher than 15% by weight, the softening point rises too high to cause abrasive grains. Insufficient retention.

When the B ₂ O ₃ content is less than 15% by weight, the softening point rises and the fluidity is insufficient, and the holding power of the abrasive grains is lowered. When the content is higher than 25% by weight, the softening point is lowered too low, gas is generated inside the grinding wheel, and a normal grinding wheel cannot be produced, and the borosilicate glass loses stability and phase separation occurs, and a normal grinding wheel cannot be manufactured and ground. The cutting performance is reduced.

When RO (RO is at least one selected from the group consisting of CaO, MgO, and BaO) is less than 1% by weight, the softening point rises too high to make the fluidity of the binder insufficient, and when it exceeds 6 wt%, the softening point falls too low.

When R ₂ O (R ₂ O is at least one selected from the group consisting of K ₂ O, Na ₂ O, and Li ₂ O) of less than 4%, the softening point rises too high to make the fluidity of the binder insufficient, and when it is more than 10% by weight The coefficient of thermal expansion rises too high.

The present inventors focused on the relative proportions of K ₂ O, Na ₂ O, and Li ₂ O in the R ₂ O component. In general, in R ₂ O, the use ratio of Na ₂ O is high. This is based on ease of operation and ease of acquisition (also related to cost). The present invention is preferably, less Na ₂ O, Li ₂ O is to replace ₂ O and the content of these substances K 2 Na ₂ O ratio of more. Specifically, Na ₂ O content of the R ₂ O total amount of 5 ~ 30wt%, Li ₂ O content of the R ₂ O total amount of 20 ~ 45wt%, K ₂ O content of the R ₂ O total amount of 20 ~ 45wt %, and each of K ₂ O and Li ₂ O has a higher content than Na ₂ O. By using such a relative ratio of the components, it is possible to obtain an advantage that the abrasive retaining force is further increased and the grinding performance is improved.

Unexpectedly obtained when a ceramic superabrasive wheel having a spherical pore diameter of an average pore diameter of 250 to 600 μm exceeding the average pore diameter upper limit of 200 μm of a known large diameter pore in Patent Document 1 is used More excellent grinding performance than the conventional ceramic super abrasive grinding wheel. Further, the development of a ceramic bond suitable for a ceramic superabrasive wheel is carried out, and the spherical large-sized pore-forming material and ceramic binder used in the present invention are combined to obtain a grinding which is far beyond the expectations of the inventors. Performance ceramic super abrasive grinding wheel.

Although not intending to be bound by theory, the ceramic superabrasive grinding wheel of the present invention can exhibit such excellent grinding performance, and should be based on the following reasons.

In the case of a spherical pore-forming material, particularly an organic substance, as the temperature rises during firing, it is decomposed, burned, or burned out because it is organic matter, and this portion becomes a pore, which is caused by the conversion from a solid to a gas. . The combustion generally starts from about 200 ° C and ends at 400 to 500 ° C. When the spherical pore-forming material is contained in the grinding wheel, the combustion, decomposition or burn-out gas completely separates from the grinding wheel should be at the highest level. It is carried out at a temperature that maintains the temperature. That is, the conversion from a solid to a gas causes the volume to expand, and the pressure of the expansion exerts a pressing force on the surrounding layer containing the abrasive particles and the binder. When the softening of the bonding agent is started, the layer containing the abrasive grains and the bonding agent is pressed and tightly bonded, and as a result, the holding force of the abrasive grains is increased to cause an improvement in the grinding performance of the grinding wheel. It has further been found that the amount of the molten R ₂ O used to administer the binder is optimized. Therefore, the effect of the present invention can be further exerted.

When the average pore diameter of the spherical large-diameter pores is less than 250 μm, the amount of conversion from solid to gas becomes small, and when the pressing force of the layer containing the abrasive grains and the binder is smaller than when a large spherical large-diameter pore is used. The strength of the force, and can not get the close combination of the above.

Further, as long as the content of the large-diameter pore-forming material is not particularly reduced, the distance between particles of the large-diameter pore-forming material is shortened. Thus, when a solid is turned into a gas, adjacent large-diameter pores are connected, which is considered to cause a weakening of the pressing force for the layer containing the abrasive grains and the binder.

When the average pore diameter of the large diameter pores is larger than 600 μm, the pressing force of the layer containing the abrasive grains and the binder is too strong, although the distance of the adjacent large diameter pores becomes farther than when the smaller large diameter pores are used. Because the pressing force connecting the adjacent pores is too strong, the grinding wheel is cracked.

Regarding the abrasive grains to be used in the present invention, the particle diameter to more effectively exhibit the effect of the present invention is such that the average particle diameter of the abrasive grains to be used is small, specifically, when the average particle diameter is 45 μm or less. Therefore, the particle size range of the superabrasive grains (diamond, CBN, etc.) used in the present invention is a coarse particle size of an average particle size of 600 μm to fine particle size abrasive grains having an average particle diameter smaller than an average diameter of 1 μm (also referred to as submicron abrasive grains). a specific range of 80 nm, preferably 45 μm to 80 nm, more preferably 40 μm to 80 nm, and particularly preferably 35 μm to 80 nm. More than 45μm is not ideal. The reason for this is that, as described above, in the ceramic bond, in addition to the pores forced by the pore-forming material, there are naturally occurring natural pores. The natural pores become the same average pore diameter as the average particle diameter of the abrasive grains used. This is known to those skilled in the art, and when the particle size of the abrasive grains used is large, the same degree is exhibited. Natural pores, when the pore diameter of the natural pores is large, when a forced pore is formed, the spherical large-diameter pore forming material is converted from a solid to a gas during firing, and when it is detached from the grinding wheel, it passes through these pores. The large natural pores are discharged outside the grinding wheel, so that the effects of the present invention are not sufficiently exerted, which is not preferable.

Compared with the use of the amorphous pore-forming material, the spherical pore-forming material is less likely to cause aggregation between particles and can be uniformly dispersed in the grinding wheel, and thus the layer containing the abrasive grains and the binder in the above-mentioned grinding wheel is used. The pressure becomes uniform. Further, it is possible to avoid the agglomeration of the pores caused by the large pore-forming material and the occurrence of a particularly large pore-pore portion, so that the above effects can be further exerted, and the advantage of preventing the occurrence of cracking of the grinding wheel can be avoided. In addition, it has the advantage of reducing uneven grinding performance during grinding.

Effect of the present invention, the average pore diameter spherical 250 to the range of 600μm, and R vitrified bond of the ₂ O in, Na ₂ O content of the R ₂ O total amount of 5 ~ 30wt%, Li ₂ O content relative to R _The total amount of ₂ O is 25~45wt%, the content of K ₂ O is 25~45wt% relative to the total amount of R ₂ O, and the grinding performance can be improved when the content of each of K ₂ O and Li ₂ O is more than that of Na ₂ O, respectively. Significantly improved, by using these ratios of R ₂ O, a better effect can be exhibited.

It is an inorganic pore forming material, and can be used without departing from the scope of the present invention. The inorganic pore forming material is, for example, an alumina hollow sphere, a mullite hollow sphere, carbon or the like.

As long as the average pore diameter is in the range of 250 to 600 μm, even if the pore-forming materials having different diameters are mixed, it can be suitably used without departing from the scope of the present invention.

The ceramic bond superabrasive grinding wheel of the invention has a volume fraction of the abrasive grains of preferably 5 to 40%, and a volume fraction of the abrasive grains is preferably 10 to 35%. The porosity of the pores is such that the spherical large diameter pores and the natural pores are added to 40 to 90%. The proportion of the pores generated by the pore forming material is 15% to 65%. When the amount is less than 15%, the effect of the present invention, that is, the pressing force of the layer containing the abrasive grains and the binder in the firing is insufficient, and the effects of the present invention are not exhibited. When it is higher than 65%, the grinding wheel will crack. The proportion of pores produced by natural pores is 15% to 35%. When it is less than 15%, it will inevitably become a design with a high molding pressure, and cracks may occur in the grinding wheel after molding, or cracks may occur in the pore-forming material, and the effects of the present invention may not be exhibited. When it is more than 35%, the operation of the grinding wheel from the post-forming to the firing becomes difficult, and manufacturing is hindered. The proportion of the pores produced by the pore forming material is preferably from 25% to 60%. Very good is 30% to 55%. The total number of natural pores and spherical large diameter pores is preferably 40 to 80%. The volume ratio of the binder is a value obtained by subtracting the abrasive grain volume ratio and the pore volume ratio from 100.

The grinding wheel of the present invention is mainly used as a diamond abrasive grain as a superabrasive grain, and can be used in combination with other abrasive materials as long as the effects of the present invention can be exerted. Other abrasive particles that can be used with diamond abrasive grains include: other superabrasive grains The cubic boron nitride abrasive grains and the abrasives other than the superabrasive grains selected from the group consisting of alumina-based abrasive grains, cerium carbide-based abrasive grains, cerium oxide, cerium oxide, and mullite grain. The abrasive grains other than the above superabrasive grains are used together with the superabrasive grains. These are merely illustrative examples, and other abrasive grains not enumerated herein can be used without departing from the object of the present invention.

The ceramic bond superabrasive wheel of the present invention can be produced as follows.

That is, the ceramic superabrasive grinding wheel of the present invention can be manufactured in the order generally known to those skilled in the art. An example of this is shown below.

1. The abrasive grains, the binder, the primary binder (also referred to as a binder), etc., are measured by taking a predetermined weight.

2. Mix the metered substances until they are uniform (called mixed raw materials).

3. The mixed raw materials are metered by a predetermined weight and filled in a molding die.

4. Apply a predetermined pressure to a predetermined size.

5. Take out from the molding die and leave it in a heating atmosphere set to a temperature lower than the highest holding temperature of the firing temperature for a certain period of time.

6. Perform baking. For example, the firing temperature is in the range of the maximum holding temperature of 600 to 900 °C.

7. After firing, it is finished into a predetermined size and becomes a grinding wheel.

The order to be described herein is merely an example, and can be appropriately changed within the scope of the technical knowledge that is common to those skilled in the art in accordance with the manufacturing conditions and the like.

[Examples]

Hereinafter, the embodiments of the present invention and the comparative examples will be described together, and these are intended to illustrate the workability and usefulness of the present invention, and do not impose any limitation on the constitution of the present invention.

Manufacture of ceramic bond super abrasive grinding wheel

The ceramic bond superabrasive wheel of the present invention and the ceramic bond superabrasive wheel (test wheel) for comparison were produced as follows.

In other words, as the abrasive grains, diamond abrasive grains having an average particle diameter of 2 μm were used, and as the pore-forming material, those having a spherical shape of a resin material were used, and the particle diameter thereof was changed depending on various test conditions. The ceramic binder was adjusted to be 13.7 vol%, the diamond abrasive grains were 13.7 vol%, and the pores and natural pores generated by the pore-forming material were 72.6 vol% in total. After mixing with a known binder, the shape of the press was The chip-shaped molded body was fired at a temperature of 800 °C. After the firing, the sheet-shaped formed body is finished into a predetermined size to become a grinding wheel.

A grinding wheel is attached to a susceptor of Φ200×30T×Φ40 (mm) to form a segment type grinding wheel.

The composition of the test ceramic bond 1 to 7 used in the above production method is shown in Table 1 below.

[Table 1] In the table, the numerical unit is wt% (in the case of R ₂ O, the upper column). The % value described in the lower column of the wt% of R ₂ O represents the weight % of each of Li ₂ O, Na ₂ O, and K ₂ O when the total amount of R ₂ O is set to 100%.

The above-mentioned test bonding agent, a pore-forming material having an average particle diameter of 15 μm, 75 μm, and 700 μm were used to form a comparative grinding wheel, and the grinding wheel of the present invention was produced using a pore-forming material having an average particle diameter of 300 μm and 500 μm. Tables 2 to 4 show combinations of test bonding agents and pore forming materials.

In this test combination, the ratio of the SiO ₂ , Al ₂ O ₃ and B ₂ O ₃ components was changed in the chemical composition of the binder. In Comparative Example 1, SiO ₂ , Al ₂ O ₃ and B ₂ O ₃ were within the scope of the patent application, and in Comparative Example 2 to Comparative Example 4, any of the above three components was outside the scope of the patent application.

The representation of the average particle size of the pore-forming material used is a nominal for the vendor. The same is true below.

In this test, the binder was the same as in Comparative Example 1, and the average particle diameter of the spherical pore-forming material was changed.

Grinding test

The conditions of the grinding test are as follows.

Abrasive size: Φ200×35T×Φ40(mm), cup type abrasive

Material to be cut: 矽 wafer (200mm (diameter) × 0.7mm (thickness) 20 pieces of grinding

Grinding fluid: distilled water, flow rate: 12 l / min

Grinding disc: vertical axis surface grinder made by Toshiba Machine Co., Ltd., type UVG-380B

Finishing conditions:

Dresser: WA#4000

Abrasive rotation number: 3822min ^-1

Dressing thickness: 20μm/min

Grinding conditions:

Grinding method: wet infeed grinding

Abrasive rotation number: 3822min ^-1

Number of pedestals: 121min ^-1

Grinding amount: 30μm

Spark out: 10 seconds

Evaluation items: The evaluation results of the grinding wheel consumption (μm) and the finished surface roughness Ra (μm) were relative values when Comparative Example 1 was set to 100.

The amount of grinding wheel consumption is calculated by using the amount of change in the mechanical coordinates of the grinding disc to calculate the dimensional change of the grinding wheel after grinding of 20 pieces of the wafer before grinding.

The surface roughness Ra of the finished surface was measured by using SP-81DS2 (contact type) manufactured by Otaru Seiki Co., Ltd. to measure the grinding surface of the 20th wafer after grinding of 20 wafers.

The arithmetic mean roughness Ra is from the roughness curve along its average line The direction is taken as the reference length, the direction of the average line of the intercepted portion is the X-axis, the direction of the vertical magnification is the Y-axis, and when the roughness curve is represented by y=f(x), the value obtained according to the formula I is obtained. Expressed in microns (μm).

The durability of the grinding wheel of Comparative Example 1 was set to 100, and the values of the other examples were expressed by their relative values.

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

test results

The grinding test results of the test grinding wheel are shown in Tables 5 to 7 below.

The spherical pore diameter and the short diameter to diameter ratio are values after the grinding wheel is formed.

The calculation was carried out by grinding the surface of the grinding wheel after the firing, and performing cross-sectional observation and measurement. After the completion of the polishing, the short diameter a and the long diameter b were measured at the pore portion 100 exposed on the surface of the grinding wheel, and the average value of the ratio a/b was used as the true sphericity. The same is true below.

In the case of Comparative Example 1 and Comparative Example 2 (Test Binding Agent-1 and Test Binding Agent-2, respectively), the content of R ₂ O was the same, but Comparative Example 2 was compared with Comparative Example 1 to reduce the SiO ₂ content. In this case, the amount of reduction was increased by Al ₂ O ₃ and B ₂ O ₃ , and by increasing or decreasing these chemical components, although the degree of softening of the binder was the same, the durability and surface roughness of the grinding wheel were inferior to those of Comparative Example 1.

In Comparative Example 3 (Test Binding Agent-3), B ₂ O _{3 was} increased as compared with Comparative Example 1, and the amount of SiO ₂ was decreased in accordance with this increase, and the degree of softening was larger than that of Comparative Example 1. The durability and surface roughness of the grinding wheel were inferior to those of Comparative Example 1.

In Comparative Example 4 (Test Binding Agent-4), Al ₂ O ₃ and SiO _{2 were} decremented compared to Comparative Example 1, and the amount of B ₂ O ₃ was increased in accordance with this reduction amount, as compared with Comparative Example 1. Although the surface roughness is improved, the durability of the grinding wheel is poor.

According to the above results, it is understood that SiO ₂ , Al ₂ O ₃ and B ₂ O ₃ are either 55 to 70 wt% of SiO ₂ , 5 to 15 wt% of Al ₂ O ₃ , and 15 to 25 wt% of B ₂ O _{3 .} Within the range, the grinding performance will deteriorate.

In the spherical pores, as the pore diameter becomes larger (14.0 μm, 71.3 μm, 314.2 μm), the grinding performance is improved, and particularly in the case of 314.2 μm, the grinding performance is remarkably improved.

Unexpectedly, when the spherical pores exceed 200 μm and become pores of 314.2 μm, the durability of the grinding wheel is remarkably increased, and the surface roughness is also Improvements, that is, results in a significant increase in wafer quality.

In Example 2, in terms of the amount of R ₂ O, in the case of Example 1 having the largest ratio of Na ₂ O, Li ₂ O was increased (Test Bonding Agent-5), and the durability of the grinding wheel was 20% (improved).

In Example 3, in comparison with Example 1 in which the ratio of Na ₂ O was the highest, the ratio of K ₂ O was increased (Test Bonder-6), and the durability of the grinding wheel was 18% (improved). These have the same effect as in the first embodiment.

In Example 4, the proportion of Na ₂ O was small, and the ratio of K ₂ O and Li ₂ O was increased (test binder-7) as compared with Example 1, and the durability of the grinding wheel was improved by 49%. The degree is also improved by 7%, which is far beyond the expectations of those skilled in the art, and the grinding performance can be greatly improved, and the surface roughness of the wafer is reduced, and the wafer quality is also improved.

In Example 5 and Example 6, a spherical pore-forming material larger than that of Example 4 was used (Example 5 is a pore-forming material using 300 μm/500 μm = 1:1 mixing; Example 6 is using a pore of 500 μm). The forming material is also the same as that of the fourth embodiment, and is far beyond the ordinary art. The improvement of the grinding performance can be achieved with the expectation of the reader, and the surface roughness of the wafer is reduced, which also has a remarkable effect in improving the quality of the wafer.

In Comparative Example 9, although a spherical pore-forming material of 700 μm was used, the grinding wheel was cracked, and it was not suitable for use as a ceramic bond superabrasive wheel.

Relationship between spherical stomata forming material and actual grinding wheel pore size

Grinding wheel measured: Comparative Example 1 Example 1

Particle size of the pore forming material: 75 μm 300 μm

The calculation of the spherical pore diameter and the short diameter to diameter ratio is performed by grinding the surface of the grinding wheel after the firing, and performing cross-sectional observation and measurement. After the completion of the polishing, the short diameter a and the long diameter b were measured at the pore portion 100 exposed on the surface of the grinding wheel, and the average value of the ratio a/b was used as the true sphericity.

From the above results, it was found that, unlike Comparative Example 1, the gas wheel diameter of the grinding wheel of Example 1 was larger than the particle diameter of the pore forming material before the grinding wheel was produced.

The spheroidal pore-forming material of organic matter, which is converted into a gas to expand the volume, and the pressure of expansion exerts a pressing force on the surrounding layer containing the abrasive grains and the binder. When the softening of the binder starts, the mill is contained. The layers of the granules and the binder are pressed and tightly bonded, and as a result, the retention of the abrasive grains is increased to achieve the invention of a good grinding wheel.

On the other hand, in Comparative Example 1, the diameter of the original pore-forming material was smaller than that of the original pore-forming material, and it was confirmed that the effects of the present invention could not be exhibited.

Hereinafter, the attached drawings will be described in detail.

1 to 4 are enlarged photographs showing the state of the pores of the grinding wheel.

In Example 1 of Fig. 1, the pores were uniformly dispersed. On the other hand, in Comparative Example 1 of Fig. 2, it was found that a plurality of pores adhered to each other, at least not uniform. Fig. 3 shows the state of the abrasive grains and the binder between the pores of Example 1. 4 shows the state of the abrasive grains and the binder between the pores of Comparative Example 1. The state of the structure of Comparative Example 1 was almost always a portion where the shape of the abrasive grains was clearly observed. There is a large unevenness, which is caused by the irregular peeling of the abrasive grains and the bonding agent during the planarization of the finishing of the sample. The same problem occurs during grinding, so the abrasive retention of the grinding wheel is weak. In the first embodiment, the portion in the vicinity of the natural pores was observed in the same manner as in Comparative Example 1, and the shape of the abrasive grains was clearly observed. However, the portions other than the above were not observed in the shape of the abrasive grains. This means that the abrasive particles and the binder become in a tightly bonded state. There is no large unevenness in this portion, and the abrasive grains and the binder do not fall off irregularly when the sample is finished and planarized, and the abrasive grains do not largely fall off during grinding. This confirms that the layers of the abrasive particles and the binder are pressed tightly to bond, thereby increasing the retention of the abrasive grains. Therefore, Comparative Example 1 was confirmed to fail to exhibit the effect of Example 1.

Claims (3)

A ceramic bond superabrasive grinding wheel with pores, which is a ceramic bond superabrasive grinding wheel with a superabrasive layer formed by combining superabrasive particles and a ceramic binder, characterized in that it contains a dispersion arrangement in the foregoing a spherical pore having an average pore diameter of 250 to 600 μm in the superabrasive layer, and an average value of a ratio (a/b) of a short diameter a to a long diameter b of the spherical pores is 0.5 or more and 1.0 or less, and the ceramic binder is super Abrasive grinding wheels are used for grinding various wafers such as tantalum, sapphire and compound semiconductors. The porous ceramic bond superabrasive grinding wheel according to claim 1, wherein the ceramic binder comprises 55 to 70 wt% of SiO ₂ , 5 to 15 wt% of Al ₂ O ₃ , and 15 to 25 wt%. B ₂ O ₃ , 1 to 6 wt% of RO (RO is at least one selected from the group consisting of CaO, MgO, and BaO), and 4 to 10 wt% of R ₂ O (R ₂ O is selected from K ₂ O, Na ₂ O, and Li _{2 )} At least one of O). The porous ceramic bond superabrasive grinding wheel according to claim 2, wherein the R ₂ O system comprises K ₂ O, Na ₂ O and Li ₂ O, and the Na ₂ O content is 5 relative to the total amount of R ₂ O. ~ 30wt%, Li ₂ O content of the R ₂ O total amount of 20 ~ 45wt%, K ₂ O content of the R ₂ O total amount of 20 ~ 45wt%, and K ₂ O and Li ₂ O content of each respective ratio of Na ₂ O more.