JPH09183061A - Manufacture of surface processed board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent microcracking from occurring by polishing the surface of a board before baking and grinding its surface by a ductile mode finish. SOLUTION: The surface of a cured board is polished so as to level the flatness Ra of it and improve the irregularities of board thickness of each cured board and dispersion of average board thickness between cured boards. Also the polished cured board is baked so as to obtain a baked board. The surface of the baked board thus obtained is ground by a ductile mode finish so as to obtain a surface finished board. Because the amount of biting of each abrasive to each board can be set below the ductility brittleness transition point or below of the board after the surface of a brittle material board is ground by the ductile mode finish, the finish configuration of boards can be controlled from a brittle fracture to a ductile deformation center so as to suppress microcracking from occurring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a surface processed substrate used for a magnetic recording medium or the like.

[0002]

2. Description of the Related Art In recent years, there has been a demand for a precision processing technique for a substrate made of a brittle material typified by ceramics or carbon, especially a super smoothing technique. For example, substrates such as glass substrates, carbon substrates, and ceramic substrates have applications as substrates for magnetic recording media. Further, a silicon wafer or the like is used as a semiconductor material. Since ultra-smoothness is required for the above-mentioned substrate for a magnetic recording medium and a silicon wafer, these substrates are generally smoothed using free abrasive grains. As the recording density and the storage capacity increase, the requirement for the smoothness becomes stricter year by year, and the average roughness Ra is required to be 10 Å or less or 5 Å or less.

When a brittle material such as a glass substrate, a carbon substrate, a ceramics substrate, or a silicon wafer is polished using free abrasive grains in particular, microcracks may occur during polishing due to the brittleness of the substrate. Such cracks may cause a recording / reproducing error when the substrate is made into a magnetic recording medium, or induce corrosion of the substrate due to contaminants entering during polishing or the like or water condensing in a capillary during standing. Danger exists. For this reason, conventionally,
Generally, the polishing process is divided into multiple stages at the expense of productivity to reduce the occurrence of microcracks. In addition, polishing with loose abrasive grains has many artistic technical elements, and requires high skill to stabilize quality.

[0004] As another problem, there is a problem that a part of the abrasive grains remains in the polished substrate. This residue is difficult to completely remove even by washing. If a sputtered film is formed on the substrate with the abrasive particles remaining, a film defect due to the remaining abrasive particles will occur, and as a result, the magnetic head will be damaged. In addition, when the above substrate is polished by using free abrasive grains, polishing unevenness due to inhomogeneity of the material, that is, recesses (shallow pits) due to deep polishing of portions that are easily polished occurs. There is.

By the way, since the cured resin used in the production of the carbon substrate is obtained by a dehydration reaction, not only the obtained resin surface has irregularities, but in some cases, individual disc-shaped cured resins ( (Cured resin substrate)
May have different thicknesses. Therefore, if it is baked as it is, there is a problem that the yield at the time of baking is lowered because the shrinkage rate of each substrate is different, the warp is more than allowable, or the substrates are welded to each other. The above idea is the same also in the case of an inorganic substrate such as ceramics. That is, these are generally inorganic powders mixed with an organic binder such as PVA (polyvinyl alcohol) or methyl cellulose and a dispersant and temporarily cured, and this is degreased at about 200 to 500 ° C. to decompose the organic binder and the dispersant.・ Splash and then 12
Generally, the final substrate is obtained by baking at a temperature of about 00 to 1800 ° C. Since volume contraction of about 10 to 20% occurs during this firing process, warpage occurs and surface irregularities occur. Further, conventionally, polishing is performed after firing, but the hardness of the fired product is Hv≈500 in the case of a carbon substrate and extremely higher than this in the case of a ceramic substrate, and there is a problem that polishing takes time.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a more efficient method of manufacturing a surface-treated substrate in which microcracks do not occur in order to solve the above problems.

[0007]

Means for Solving the Problems As a result of intensive studies for achieving the above object, the present inventors have found that when cutting a substrate surface, the cutting depth of each abrasive grain in a grindstone is adjusted to the substrate depth. By performing grinding while maintaining the ductility-brittleness transition point or less, generation of microcracks is suppressed, and since the cured resin before carbonization by firing is relatively soft, wrapping is easily performed for a short time. Moreover, since it can be performed at low cost, it has been found that if the surface of the substrate that has been lapped before grinding is ground, the processing margin can be reduced and the grinding time can be shortened. The above idea is the same also in the case of an inorganic substrate such as ceramics. Further, volumetric shrinkage of about 10 to 20% occurs during this firing process, so warpage occurs and surface irregularities occur. Since removing the warp and unevenness after the secondary firing is a heavy burden, if the lapping is performed before the firing (after the temporary curing and degreasing), the same effect as the lapping after the secondary firing can be obtained. As mentioned above, the finishing grinding time is shortened by introducing the lapping process before firing,
The present inventors have completed the present invention by finding that the total polishing cost is reduced and the productivity is improved.

That is, the gist of the present invention is: (1) a step of polishing the surface of the substrate before firing in the method for processing the surface of a brittle material substrate obtained by firing (hereinafter, also referred to as a lapping step before firing), A method of manufacturing a surface-processed substrate, characterized by comprising a step of grinding the surface by ductile mode processing, (2) Grinding by ductile mode processing is performed so as to form fan-shaped processing marks on the surface of the brittle material substrate. (1) The manufacturing method described in (3), the set cutting depth of the grindstone at the time of grinding by the ductility mode processing is 0.05 to 2
The production method according to (1) or (2) above, wherein the production method is 0 μm;
(4) The manufacturing method according to any one of (1) to (3), in which grinding is performed using a grinding device having a loop rigidity of 150 N / μm or more, (5) Ra (surface roughness) of the obtained surface-treated substrate is The manufacturing method according to any one of (1) to (4) above, which is 1 to 100Å, (6) The manufacturing method according to any one of (1) to (5) above, wherein the substrate material contains a thermosetting resin as a main component. (7) The flatness of the obtained surface-treated substrate is 1
The production method according to any one of (1) to (6), which is 0 μm or less, (8) The Ra (surface roughness) of the cured resin is 2 μm or less in the lapping step before firing.
~ (7) The manufacturing method according to any one of the above.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the production method of the present invention, 1) a step of obtaining a cured substrate (cured resin or the like), 2) a step of polishing the surface of the obtained cured substrate (a lapping step before firing), and 3) polishing. Step of firing the cured substrate to obtain a fired substrate, 4)
The surface of the obtained fired substrate may be ground by ductile mode processing to obtain a surface-treated substrate. The present invention is characterized in that, in the surface processing method of the brittle material substrate obtained by firing, a lapping step before firing and a step of grinding the surface by ductile mode processing are provided. The surface-processed substrate can be manufactured more efficiently without causing

Regarding Step 1) For example, the cured resin obtained in this step is a known thermosetting resin such as a phenol-modified furan resin or a furfuryl alcohol resin, which is commonly used in the production of carbon substrates. It is obtained by synthesizing and curing according to the method. The hardened substrate such as ceramics obtained in this step is made of inorganic powder P
It can be obtained by a known method such as a method in which an organic binder such as VA or methyl cellulose or a dispersant is mixed, well kneaded, and then cured at a temperature of several hundreds of degrees Celsius. As the inorganic powder, known materials such as alumina and zirconia are used. The dispersion medium may be water or alcohol. In the present invention, it is preferable that the substrate material contains a thermosetting resin as a main component.

Regarding step 2) The surface of the cured substrate obtained in step 1) is polished so that the flatness and Ra of the cured substrate are uniform, and the plate thickness unevenness (hereinafter, also referred to as thickness unevenness) of each cured substrate, between cured substrates To improve the average plate thickness variation. Specifically, the flatness is 20
μm or less is preferable, and 10 μm or less is more preferable. R
a is preferably 2 μm or less, and more preferably 0.1 μm or less. The plate thickness unevenness is preferably 20 μm or less, more preferably 5 μm or less. Average thickness variation is 2
It is preferably 0 μm or less, more preferably 10 μm or less.

The plate thickness variation means that the plate thickness at nine points is measured for each substrate in each group, and the difference between the maximum value and the minimum value thereof is calculated. The average value was obtained and used as the average thickness variation. The plate thickness was measured using a digital micrometer. Further, the polishing margin at the time of polishing is not particularly limited, and depends on the desired degree of flatness and the like, but is, for example, 50 to 30 per side.
0 μm is preferred. Further, Ra in the present specification is a value obtained by measurement under the following conditions using a stylus type surface roughness meter (manufactured by Tencor Corp .: model P2).

Measurement conditions Stylus tip radius: 0.6 μm (needle curvature radius) Stylus pressing pressure: 7 mg Measurement length: 250 μm × 8 places Tracing speed: 2.5 μm / sec Cutoff: 1.25 μm (low-pass filter)

As described above, by providing the lapping step before firing, it is possible to prevent warpage and undulation after firing and improve the accuracy of the dimensions of the finished substrate. Also,
As a result, the processing margin of the high-hardness fired substrate can be reduced, so that the grinding time can be shortened and the efficiency of manufacturing the surface-treated substrate can be improved. Further, in the case of a carbon substrate, the hardness thereof is Hv≈500, whereas the hardness of the cured resin is Hv≈50. Therefore, lapping before firing makes the polishing work shorter and cheaper. It can be carried out.

The polishing in the lapping process before firing is as follows.
For example, it can be carried out by a commonly used known free-abrasive method such as a method of using water and abrasive grains as a basic polishing material and a polishing liquid containing a polishing aid and the like. Examples of the abrasive grains include known diamond grains such as artificial diamond, γ-alumina, WA alumina, cerium oxide, and silica gel. The grain size of the abrasive grains is 1.0 to 30.0 μm
Those having a diameter of 1 to 10 μm are preferably used. Here, the particle size is preferably 1.0 μm or more from the viewpoint of shortening the polishing time, and is preferably 30.0 μm or less from the viewpoint of suppressing an increase in defects. The concentration of the abrasive grains in the polishing liquid may be 0.1 to 10% by weight. Examples of the polishing aid include known ones such as aluminum nitrate, aluminum sulfate, magnesium sulfate, aluminum chloride, iron chloride, iron nitrate and chromium oxide. The concentration of the polishing aid in the polishing liquid may be 0.1 to 10% by weight. Further, known polishing machines, carriers, pads, etc. which are commonly used can be used.

Further, the pressing pressure and the polishing time cannot be unequivocally stated because they differ depending on the material of the substrate, the thickness of the polishing margin, the kind of the polishing liquid, etc., but the pressing pressure is, for example, 20 to 20.
00 gf / cm ² , preferably 50-300 gf / cm
^{2. The} polishing time is 1 to 60 minutes, preferably 2 to 30 minutes. The hardness of the polishing pad mounted on the surface plate of the double-sided polishing machine is 40 to 100 (Shore A), preferably 60 to 1
00 (Shore A). When using a double-sided polishing device, the rotation speed of the lower platen of the double-sided polishing device is 10 to 100 r.
pm, preferably 20-60 rpm. The flow rate of the polishing liquid depends on the size of the apparatus, but is 9B (9
(Inch) size is 5 to 500 cc / min, preferably 10 to 50 cc / min.

Step 3) This step is a step of firing the cured substrate polished in step 2) to obtain a fired substrate. The firing method, conditions, etc. are not particularly limited, and may be the same known methods, conditions, etc. that are usually performed as in the manufacturing method without the lapping step before firing. Step 4) This step is a step of grinding the surface of the fired substrate obtained in step 3) by ductile mode processing to obtain a surface-treated substrate. By grinding the surface of the brittle material substrate by ductile mode processing, 1) because the amount of each abrasive grain biting into the substrate can be set to a ductility-brittleness transition point of the substrate or less,
The processing mode of the substrate can be controlled from brittle fracture to ductile (plastic) deformation center, and the generation of microcracks is suppressed. 2) Since free abrasive grains are not used, there is a risk of abrasive grains remaining on the substrate. 3) Excellent flatness and less surface roughness at the edge part seen with the loose abrasive method. 4) Wear of fixed abrasive is slight, so it is consumed compared to disposable free abrasive. Tool cost is significantly reduced, 5) there are few artistic technical elements, process control and full automation are easy, and 6) uniform grinding surface can be obtained regardless of whether or not there is unevenness in the material. is there.

In the present specification, "ductile mode machining" is a plastic-fluid removal process that does not cause cracks even in a brittle material, that is, a grinding process characterized by no damage to the material rather than brittle fracture (crushing). Means Such processing technology always makes the cutting depth of individual abrasive grains into the material ductile-
This is achieved by keeping the temperature below the brittle transition point. The means for achieving this is not particularly limited,
A commonly used known method can be used. For example, many materials generally used for magnetic recording medium substrates, silicon wafers, and the like such as carbon, glass, ceramics, and silicon have a ductility-brittleness transition point (dc) of 2 to 100 nm, and thus the ductile mode. The set cutting depth of the grindstone at the time of processing may be 0.05 to 20 μm, preferably 0.1 to 10 μm, and more preferably 0.1 to 5 μm. Here, the set cutting depth of the grindstone is preferably 0.05 μm or more from the viewpoint of device positioning accuracy, and 2 from the viewpoint of suppressing the grinding load and the occurrence of microcracks.
It is preferably 0 μm or less.

Further, by setting R on the shoulder of the outer periphery of the wheel (fixed abrasive grains) according to the set cutting depth of the grindstone, a ductile machined surface without microcracks can be obtained even if the set cutting depth of the grindstone is large. Therefore, it is more preferable.
The shape of R and the like may be set so that the cutting depth of each abrasive grain is smaller than dc of the material to be ground. For example, in the formula shown below,

[0020]

[Equation 1]

(Here, d _N is a cutting depth per one rotation of the substrate to be processed and is represented by the following equation.

[0022]

[Equation 2]

Further, f is the lateral feed amount of the wheel per one rotation of the substrate to be processed, Δ is the set cutting depth, R is the radius of curvature of the shoulder on the outer circumference of the wheel, d _g is the cutting depth of each abrasive grain,
a abrasive grains interval, V _w the workpiece substrate peripheral velocity, V _s is the wheel peripheral velocity, and D is the wheel diameter. ) D _g <d
It may be set to be c.

By the way, the set cutting depth of the grindstone is 0.
In order to achieve the ductile mode processing in the range of 05 to 20 μm, the grinding device, the abrasive grains, etc. must satisfy the following conditions. 1) Design and manufacture of a grinding wheel spindle with extremely high dynamic rigidity.
Radial and axial movement errors are 100 nm or less. 2) Design and manufacture of extremely high dynamic rigidity work support and motion system. Based on empirical rules, the loop stiffness between the processing machine tool and the workpiece is 150 N / μm (static stiffness) or more. 3) Dressing of abrasive binder to ensure high precision truing and moderate porosity of the wheel. Furthermore, it is desirable that the cutting edge height distribution of the individual abrasive grains on the wheel is not more than dc.

Therefore, the grinding machine is not particularly limited as long as it satisfies the above conditions. From the viewpoint of a combination of a work table and a wheel (fixed abrasive grains) of a grinding device, for example, 1) a mode in which a firing substrate is set on a rotary work table and grinding is performed using a straight wheel, 2) a firing substrate is placed on a reciprocating work table. Examples include a mode in which they are set and grind using a straight wheel, and 3) a mode in which a baked substrate is set on a rotary work table and grinding is performed using a cup wheel. In the present invention, any of the aspects can be used, but (i)
Since grinding can be performed so that the processing marks are formed in a fan shape, the generation of microcracks due to the intersection of the processing marks is suppressed, and (ii) the substrate to be processed and the wheel working surface make a line contact. Therefore, the damage to the substrate to be processed and the wheel at the time of processing is remarkably improved, so that the embodiment of 1) is preferably used.

As a specific example of the apparatus of the aspect 1),
Ultra-precision surface grinding machine (HPG- manufactured by Nisshin Kikai Co., Ltd.)
2A) and the like. Ultra-precision surface grinding machine (HPG-
2A) was developed for the purpose of ductile mode processing of brittle materials and has the following characteristics. 1) Radial and axial movement accuracy is 100 nm or less 2) Loop rigidity between the machine tool and the workpiece is 170 N / μ
m (static rigidity) 3) Truing accuracy is 100 nm Therefore, this ultra-precision surface grinding device (HPG-2A)
Satisfies all of the above device conditions.

In order to form a fan-shaped machining mark using this apparatus, for example, the substrate (workpiece) to be processed is placed on the workpiece mounting face plate (worktable) of the work spindle so that the work spindle rotation center is not included. , That is, r ₂ ≧
The face plate may be eccentrically attached so as to satisfy the relationship of r ₁ , the face plate may be rotated, a minute cut may be made in the straight wheel, and the wheel may be laterally fed along the face plate. Even if the eccentricity is 0, that is, even if the work is attached to the center of the work table, machining marks that do not intersect can be added, but in that case, only one work can be attached, resulting in low productivity.
Not preferred. According to the method of the present invention, a plurality of works can be attached, which is advantageous in terms of productivity and reduction of grinding cost.

"Fan-shaped" of fan-shaped processing marks in the present specification
Is a substantially concentric shape as schematically shown in FIG. The center of the concentric circle may be on the substrate or may be outside the substrate. Preferably, the radius r of the substrate
The relationship between ₁ and the radius r _{2 of the} processing mark satisfies r ₂ ≧ r ₁ , and is more preferably ₁₀₀ r from the viewpoint of workability of mounting a substrate to be processed (work) and processing accuracy of the apparatus.
_It satisfies the relationship of ₁ ≧ r ₂ ≧ 2r ₁ .

Grinding in step 4) will be described with reference to FIG. Here, FIG. 2 is a schematic configuration diagram of an ultra-precision surface grinding device (HPG-2A). This apparatus is a rotary plane processing machine that performs traverse grinding using the outer circumference of a straight wheel. The NC controls two axes. That is, X axis (traverse feed of work table) and Z
Positioning of the shaft (wheel feed).

The design features of this machine are as follows: T-axis plane arrangement of X-axis and Z-axis, closed loop positioning system without screws, 10 nm laser scale, VV sliding guide surface, low thermal expansion cast iron, standard straightness. Straightness in-process correction by a gauge. The performance is characterized by contour processing at a command resolution of 10 nm. The position of the correction wheel is X
By controlling with Z, it is possible to obtain a desired accurate shape. Further, in order to grind the processing marks into a fan shape using the present apparatus, the substrate to be processed may be mounted on a work table as shown in FIG. 3, for example.

In order to grind brittle materials without cracking (ductile mode grinding), it is necessary to keep the cutting depth of each abrasive grain at a ductile-brittle transition point (dc value) or less. For that purpose, a high-rigidity and high-precision processing machine is required. This device has a grinding wheel shaft of 1300N / μm by itself
As described above, the worktable shaft alone satisfies the above-mentioned conditions at a 1000 N / μm or more and a loop rigidity of 150 N / μm or more. The run-out in the thrust direction of the work table, the radial run-out of the grinding wheel shaft, and the peripheral run-out of the grinding wheel after truing are all 100 nm or less. Positioning of the X axis and the Z axis is controlled by a laser scale having a resolution of 10 nm, and a minute cut of 100 nm or less can be given.

Further, by performing the grinding in the ductile mode processing by using electrolytic in-process dressing (hereinafter referred to as ELID), it is possible to perform the grinding with higher accuracy and higher efficiency. Specifically, in the grinding device, the fixed abrasive is a metal bond wheel (the abrasive is fixed on the outer periphery of a straight wheel with a metal binder), and the electrode is installed so as to cover a part of the outer periphery of the wheel, An ELID type ductile working can be achieved by supplying an aqueous solution coolant containing an electrolyte between the outer peripheral surface of the wheel and the substrate to be processed, applying a positive electric field to the wheel side, and grinding while rotating both the substrate and the wheel.

The fixed abrasive grains (wheel) used for grinding in step 4) are not particularly limited,
Known materials that are commonly used are used, but substrate materials,
Degree of intermediate grinding, machining allowance (set cutting depth of grindstone)
Depending on the type, the type, shape, grain size, bonding agent, and wheel shape of the abrasive grains will differ, so it cannot be generally stated. For example, using the above grinding machine (HPG-2A), the substrate is a carbon substrate, the degree of intermediate grinding is Ra 100 nm, and the processing allowance is 20 μm.
In the case of m / one side, industrial diamond abrasive grains are used as the abrasive grains (the average grain size of the abrasive grains is 1 to 5 μm, more preferably 1 to 5 μm).
2.5 μm), and a metal or the like is used as the bonding agent. When the ELID method is used, the bonding agent is Fe.
It is preferable to use a simple substance such as (cast iron), Cu, Ni, or an alloy containing one or more of these. Further, other conditions in this case, such as the grinding wheel peripheral speed, the feed speed, the work table rotation speed, and the like are not particularly limited, and may be a commonly used known degree.

As described above, a surface-treated substrate in which the generation of microcracks is suppressed can be obtained. Further, Ra of the obtained surface-treated substrate is 1 to 300Å, more preferably 1 to 200Å, particularly preferably 1 to 100Å. From the viewpoint of grinding productivity, 1 Å or more is preferable, and from the viewpoint of achieving ductile mode processing, 300 Å or less is preferable.
Further, Rp (protrusion height) / Ra of the substrate is preferably 2-10, more preferably 2-8, particularly preferably 2-4. Wheel truing (shape modification)
It is preferably 2 or more from the viewpoint of reducing the management load of the process, and 10 or less from the viewpoint of maintaining the ductile mode processing. Rp is a stylus type surface roughness meter (manufactured by Tencor Co.,
It can be measured under the same conditions as Ra described above using model P2). When the surface-treated substrate is used as a magnetic recording medium, the flatness of the obtained surface-treated substrate is preferably 10 μm or less, and more preferably 5 μm or less, from the viewpoint of the flying running stability of the magnetic head.

[0035]

EXAMPLES The present invention will be described below in more detail with reference to Production Examples, Examples and Comparative Examples, but the present invention is not limited to these Examples and the like.

Production Example 1 500 parts by weight of furfuryl alcohol, 400 parts by weight of 92% formaldehyde and 30 parts by weight of water were dissolved by stirring at 80 ° C. Then, a mixed solution of 520 parts by weight of phenol, 9.5 parts by weight of calcium hydroxide and 45 parts by weight of water was added dropwise with stirring, and the mixture was reacted at 80 ° C. for 3 hours. Thereafter, 80 parts by weight of phenol and the above-mentioned phenol / calcium hydroxide / water mixture were further added dropwise, and reacted at 80 ° C. for 2 hours. After cooling to 30 ° C., the mixture was neutralized with a 30% aqueous solution of p-toluenesulfonic acid. This neutralized product is dehydrated under reduced pressure to
70 parts by weight of water is removed and furfuryl alcohol 500 is added.
Parts by weight were added and mixed, and the insoluble matter in the resin was filtered with a membrane filter. The amount of water that the resin could contain was 35% by weight.

To 100 parts by weight of this thermosetting resin, 0.5 parts by weight of a mixed solution of 70% by weight of paratoluenesulfonic acid, 20% by weight of water and 10% by weight of cellosolve was added and sufficiently stirred. Next, this mixture was poured between two glass plates (with a gap of 2 mm) and left at about 80 ° C. for 48 hours for curing. After curing, it was taken out from between two glass plates to obtain a plate-shaped cured resin. Next, this plate-shaped cured resin was processed into a predetermined donut shape using a laser cutter. The surface of the obtained doughnut-shaped thermosetting material was subjected to lapping by the free abrasive grain method. Do here,
The main conditions for the lapping process before firing are as follows.
As the double-sided polishing machine, a 9B5L double-sided polishing machine manufactured by Speed Farm was used. The abrasive grains were # GC4000 (GC: silicon carbide), and the concentration thereof was 12% by weight in the polishing liquid. Pressing pressure: 60 gf / cm ² Polishing liquid supply rate: 100 cc / min Lower surface plate rotation speed: 30 rpm A cast iron surface plate was used as the surface plate. Polishing allowance is 300 per side
μm.

After that, in an organic material firing furnace, under a nitrogen atmosphere, 2
Heated to 700 ° C at a ramp rate of ~ 5 ° C / hr. Then, it is heated and calcined to 1200 ° C. at a temperature rising rate of 5 to 20 ° C./hour, held at this temperature for 2 hours, then cooled, and has a diameter of 1.8.
An inch carbon substrate was obtained. The carbon substrate thus obtained had Ra of 0.1 μm and an average plate thickness variation of 3 μm.
3 μm, thickness unevenness 6.7 μm, density 1.5 g / cm ³ ,
The Vickers hardness was 650 and the structure was amorphous. After that, the chamfer processing machine SG-T manufactured by Shiba Giken was used to cut and align the inner and outer diameters to predetermined dimensions, and then chamfer (45
°) (hereinafter referred to as chamfer processing).

Production Example 2 A carbon substrate was obtained in the same manner as in Production Example 1 except that GC # 1500 was used as the abrasive grains. The obtained carbon substrate had Ra of 0.17 μm, average plate thickness variation of 42 μm,
The thickness was 13 μm, the density was 1.5 g / cm ³ , the Vickers hardness was 650, and the structure was amorphous. After this,
Chamfer processing was performed.

Production Example 3 The mixture of thermosetting resin, p-toluenesulfonic acid, water and cellosolve prepared in Production Example 1 was poured into a disc-shaped mold having a thickness of 2 mm, and degassed under reduced pressure. Then, it was heated and cured at 50 ° C. for 3 hours and at 80 ° C. for 2 days. This thermosetting product was processed into a predetermined donut shape, and then heated to 700 ° C. in a nitrogen atmosphere in a nitrogen atmosphere at a heating rate of 2 to 5 ° C./hour. Then 1200 at a heating rate of 5 to 20 ° C./hour
After heating to ℃ and firing, and holding at this temperature for 2 hours, it was cooled to obtain a carbon substrate having a diameter of 1.8 inches. The carbon substrate thus obtained had an Ra of 1.5 μm, an average thickness variation of 140 μm, a thickness variation of 18.5 μm, a density of 1.5 g / cm ³ , a Vickers hardness of 650, and an amorphous structure.

Production Example 4 The donut-shaped thermosetting product obtained in Production Example 1 was heated to 70 ° C. in a nitrogen atmosphere in an organic firing furnace at a temperature rising rate of 2 to 5 ° C./hour.
Heated to 0 ° C. Then, it was heated and calcined to 1200 ° C. at a temperature rising rate of 5 to 20 ° C./hour, held at this temperature for 2 hours and then cooled to obtain a carbon substrate having a diameter of 1.8 inches.
The obtained substrate was subjected to lapping processing by the loose abrasive grain method. Here, as a polishing machine, 9 manufactured by Speed Farm
Using a B5L type double-side polishing machine, the abrasive grains are one of crushed silicon carbide abrasive grains, GC (green silicon carbide abrasive) # 15.
00 (concentration 4% by weight) was used, and the surface plate was a cast iron surface plate. Pressing pressure: 60 gf / cm ² Polishing liquid supply: 100 cc / min Lower platen rotation speed: 50 rpm The polishing allowance was 300 μm per side. The obtained carbon substrate had Ra 0.4 μm and average plate thickness variation 6 μ.
m, thickness unevenness 0.5 μm, density 1.5 g / cm ³ , Vickers hardness 650, and the structure was amorphous. Then, chamfer processing was performed.

Production Example 5 A carbon substrate was obtained in the same manner as in Production Example 4 except that # GC280 was used as the lapping abrasive grains. The carbon substrate obtained had an Ra of 2.3 μm and an average plate thickness variation of 35.0 μ.
m, thickness unevenness 1.1 μm, density 1.5 g / cm ³ , Vickers hardness 650, and the structure was amorphous. Then, chamfer processing was performed.

Production Example 6 Production Example 4 except that GC # 4000 was used as the lapping grains.
The following carbon substrate was obtained by the same method as described above. Ra: 0.1 μm Average plate thickness variation: 5.5 μm Thickness unevenness: 0.5 μm

Production Example 7 97% by weight of alumina having an average particle size of 0.6 μm, PVA2.
6% by weight, CMC (carboxymethyl cellulose) 0.
Proper water and methyl alcohol were added to a 4 wt% compounding system, thoroughly mixed and dispersed, and then degreasing was performed at 200 ° C. for 4 hours. Then, lapping treatment was performed with GC # 4000 abrasive grains in the same manner as in Production Example 1. The polishing allowance was 300 μm. Then, it was heated and baked at a temperature rising rate of 20 to 40 ° C./hour to 1500 ° C. under atmospheric pressure, kept at this temperature for 1 hour, and then cooled to obtain an alumina substrate having a diameter of 1.8 inches. The alumina substrate thus obtained had a Ra of 0.08μ.
m, the average plate thickness variation was 25 μm, and the thickness unevenness was 7 μm.

Production Example 8 A fired substrate was obtained in the same manner as in Production Example 7 except that lapping was omitted after degreasing. The obtained fired substrate was GC # 4.
Lapping treatment was performed with 000 abrasive grains in the same manner as in Production Example 1. The obtained substrate had Ra: 0.05 μm average plate thickness variation: 7 μm and thickness unevenness: 0.6 μm.

Example 1 Both surfaces of the carbon substrate that had been subjected to the lapping process before firing, obtained in Production Example 1, were ground by ductile mode processing to obtain a surface-processed substrate. The main processing conditions are as follows. Grinding machine: Ultra-precision horizontal surface grinding machine (HPG-2A manufactured by Nisshin Kikai Seisakusho Co., Ltd.) Work table diameter: 200 mm Work table rotation speed: 530 rpm Grinding wheel peripheral speed: 1260 m / min Grinding wheel feed speed: 60 mm / min

Abrasive grain type / count: # 20,000 diamond (average grain size of about 1.2 μm) (Shinto Brator Co., Ltd. iron-based bond stone, SD2000
Only 0N100FX3) is used. Coolant: manufactured by Yushiro Kagaku, ELIDNO. 2% of 35
Aqueous solution ELID power supply: Shinto Breta Co., Ltd., pulse power supply ED
P-10A Initial truing: # 200 diamond (average particle size: about 75 μm) (manufactured by Oriental Diamond Tool Laboratory Co., Ltd .:
SD200Q75M) Initial dressing: 3A x 15 minutes (voltage: maximum 60V setting) Pulse (rectangular wave) cycle: 4 microseconds (voltage: maximum 60V setting)

The shoulder of the grinding wheel is precision trued so that the # 2000 wheel has a generatrix shape as shown in FIG. 4, and the cutting depth of each abrasive grain is less than the ductility-brittleness transition point (about 50 nm) of the carbon substrate. Was set to be. The substrate was fixed by a vacuum chuck method using a plurality of vacuum suction holes provided on a work table. Next, the set cutting depth of the grindstone was set to 3 μm, three-pass grinding was performed, and then 0.2
One pass grinding was performed with a thickness of μm, and this was performed on both sides.
Note that FIG. 5 shows a mounting structure of the ELID electrode. When the obtained surface-processed substrate was observed with an optical microscope, it had fan-shaped processing marks. No crossing of the processing marks was observed.

Example 2 Both sides of the carbon substrate that had been subjected to lapping before firing obtained in Production Example 1 were ground by ductile mode processing under the same conditions as in Example 1 except for the following conditions. Abrasive grain type / count: Only # 12000 diamond (average grain size of about 1.2 μm) (Shinto Brator Co., Ltd. iron-based bond grindstone, SD12000N100FX3) is used. When the obtained surface-treated substrate was observed with an optical microscope,
It had a fan-shaped processing mark. No crossing of the processing marks was observed.

Example 3 Both sides of the carbon substrate which had been subjected to the lapping process before firing obtained in Production Example 2 were ground by ductile mode processing under the same conditions as in Example 1 except for the following conditions. Abrasive grain type / count: # 8000 diamond (average grain size of about 2.5 μm) (Shinto Brator Co., Ltd. iron-based bond grindstone,
Only SD8000N100NFX3) is used. When the obtained surface-treated substrate was observed with an optical microscope,
It had a fan-shaped processing mark. No crossing of the processing marks was observed.

Example 4 Both sides of the carbon substrate, which was obtained in Production Example 2 and which had been subjected to lapping before firing, were ground by ductile mode processing under the same conditions as in Example 3 except for the following. Abrasive grain type / count: # 6000 diamond (average grain size of about 1.8 μm) (Shinto Brator Co., Ltd. iron-based bond grindstone,
Only SD6000N100NFX3) is used. When the obtained surface-treated substrate was observed with an optical microscope,
It had a fan-shaped processing mark. No crossing of the processing marks was observed.

Example 5 A vertical surface grinder (manufactured by Co., Ltd.) was used as a grinder on both sides of the carbon substrate which had been subjected to lapping before firing and which was obtained in Production Example 1.
Grinding was performed under the following conditions using a cup-type grindstone using VPG manufactured by Nisshin Kikai Seisakusho. Worktable diameter: 250 mm (9 on the outside of the substrate)
Sheet set) Work table rotation speed: 350 rpm Whetstone peripheral speed: 1200 m / min Abrasive grain type / count: # 8000 diamond (average grain size 1.8 μm) (Fuji Die Co., Ltd., cast iron bond whetstone, SD8000N100M) Whetstone Set cut depth: 1 μm / min The machining allowance of 10 μm was removed under the above conditions.

Example 6 The same procedure as in Example 4 was carried out on both sides of the pre-fired lapping alumina substrate obtained in Production Example 7.

Comparative Example 1 The carbon substrate obtained in Production Example 1 was subjected to finish polishing by a known method using free abrasive grains to obtain a surface-treated substrate. The main polishing conditions are as follows. The polishing liquid was supplied as a slurry by adding a predetermined amount of abrasive grains and a polishing aid to water. Polishing machine: 9B5P type double-side polishing machine manufactured by Speed Farm Co., Ltd. Abrasive grains: artificial diamond (particle size 0.5 μm, manufactured by Fujimi Incorporated, DIATEC WAM2.
0: 0.15% by weight in polishing liquid)

Polishing aid: Aluminum nitrate (1% by weight in the polishing liquid) Pressing pressure: 150 gf / cm ² Lower platen rotation speed: 30 rpm Polishing liquid flow rate: 40 rpm Carrier: 10 μm Carrier: Epoxy glass material Pad: Hard pad (Rodale Nitta) Manufactured by C14A) When the obtained surface-treated substrate was observed with an optical microscope,
It had a fan-shaped processing mark. No crossing of the processing marks was observed.

Comparative Example 2 Both surfaces of the carbon substrate obtained in Production Example 4 and subjected to lapping after firing were ground by ductile mode processing under the same conditions as in Example 3 to obtain a surface-treated substrate. When the obtained surface-processed substrate was observed with an optical microscope, it had fan-shaped processing marks. No crossing of the processing marks was observed.

Comparative Example 3 Both surfaces of the carbon substrate obtained in Production Example 6 were ground in the same manner as in Example 2 to obtain a surface-treated substrate. When the obtained surface-processed substrate was observed with an optical microscope, it had fan-shaped processing marks. No crossing of the processing marks was observed.

Comparative Example 4 Both surfaces of the carbon substrate, which was obtained in Production Example 5 and which was subjected to lapping after firing, were ground by ductile mode processing under the same conditions as in Example 1 to obtain a surface-treated substrate. When the obtained surface-treated substrate was observed with an optical microscope, many pits and the like generated by lapping remained, and the surface-treated substrate had many defects. It took several times longer to process until this disappeared. Therefore, it can be said that such a method has poor productivity.

Comparative Example 5 A surface-processed substrate was obtained by the same method as in Example 5 on both surfaces of the carbon substrate obtained in Production Example 6 which was not subjected to lapping before firing. When the obtained surface-processed substrate was observed with an optical microscope, it had fan-shaped processing marks. No crossing of the processing marks was observed.

Comparative Example 6 A surface-treated substrate was obtained in the same manner as in Example 6 on both sides of the alumina substrate obtained in Production Example 8. When the obtained surface-processed substrate was observed with an optical microscope, it had fan-shaped processing marks. No crossing of the processing marks was observed.

Ra, Rp (protrusion height), processing time, and flatness of the surface-treated substrates obtained in the above Examples, Reference Examples and Comparative Examples were measured to calculate Rp / Ra. R
p is a stylus surface roughness meter (manufactured by Tencor Corp., model P
2) was used and measured under the same conditions as Ra described above. The flatness was measured by ZYGO (model: Mark-4). In the present specification, Ra, Rp, and flatness were measured by scanning the stylus in a direction orthogonal to the shape of the processed trace (direction in which roughness etc. is maximum). The processing time was calculated by dividing the total polishing time required for mirror finishing including the lapping step before and after firing by the number of processed sheets. In addition, the surface of the surface processed substrate is observed with an optical microscope and an SEM (scanning electron microscope), and grinding progresses in a ductile mode to leave a smooth machining mark, or progresses in a brittle mode, resulting in a non-smooth state. It was confirmed whether the surface was rough or had microcracks remaining. Further, the number of defects per surface was determined by observing with an optical microscope and measuring the number of defects of about 10 μm or more. The results are shown in Tables 1 and 2.

[0062]

[Table 1]

[0063]

[Table 2]

The following was found from Tables 1 and 2. It was found that Examples 1 to 6 in which the pre-baking lap was performed can shorten the total processing time as compared with the cases in which the post-baking lap was performed (Comparative Examples 2 to 6). Comparative Example 1
Had a large number of defects because the surface processing was performed by finish polishing.

[0065]

EFFECTS OF THE INVENTION According to the present invention, lapping is performed in advance before firing to reduce surface roughness, variation in plate thickness, and thickness unevenness, thereby greatly reducing the burden of finish grinding, resulting in excellent productivity. , It became possible to provide a low-cost surface-treated substrate.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a fan shape.

FIG. 2 is a schematic configuration diagram of an apparatus for carrying out an example of the manufacturing method of the present invention.

3 is a schematic diagram showing a state in which a substrate to be processed is set on a work table in the grinding apparatus of FIG.

FIG. 4 is a schematic diagram showing a generatrix shape of a shoulder portion of a grinding wheel.

FIG. 5 is a schematic diagram showing a mounting structure of an ELID electrode.

[Explanation of symbols]

 1 Work Table 2 Grinding Wheel 3 Correction Wheel 4 Chuck 5 Slide Base 6 Spindle / Hydrostatic Bearing 7 Low Expansion Material 8 Coolant Supply Unit 9 Workpiece (Working Substrate) 11 Clearance Adjusting Screw 12 Insulator 13 Electrode 14 Grindstone 21 Abrasive Grains Coating layer NC Numerical control device PI Proportional / integral control device a Pressure control servo valve b Pressure oil source c Hydraulic actuator d Laser scale (resolution 10 nm)

Claims (8)

[Claims] 1. A method for processing a surface of a brittle material substrate obtained by firing, a step of polishing the surface of the substrate before firing (hereinafter, also referred to as a lapping step before firing), and a step of grinding the surface by ductile mode processing. A method for manufacturing a surface-treated substrate, comprising: 2. The manufacturing method according to claim 1, wherein the grinding by the ductile mode processing is performed so as to form a fan-shaped processing mark on the surface of the brittle material substrate. 3. The manufacturing method according to claim 1, wherein the set cutting depth of the grindstone at the time of grinding by ductile mode processing is 0.05 to 20 μm. 4. The manufacturing method according to claim 1, wherein grinding is performed using a grinding machine having a loop rigidity of 150 N / μm or more. 5. The method according to claim 1, wherein the surface-treated substrate obtained has an Ra (surface roughness) of 1 to 100 Å. 6. The manufacturing method according to claim 1, wherein the substrate material contains a thermosetting resin as a main component. 7. The obtained surface-treated substrate has a flatness of 10 μm.
It is m or less, The manufacturing method in any one of Claims 1-6. 8. The manufacturing method according to claim 1, wherein Ra (surface roughness) of the cured resin is 2 μm or less in the lapping step before firing.