JPH0683956B2 - Silicon carbide ceramic top plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is a silicon carbide used for sticking a silicon wafer or Ga / As wafer used as an electronic component to finish a mirror surface with high surface accuracy. Regarding a ceramic top plate.

[Conventional technology]

The top plate is usually disc-shaped, and one surface of the work plate such as a wafer is pasted with wax or the like, and the lower surface plate is brought into contact with the wafer or the like as the lower surface and is mirror-polished with a polishing liquid. The surface of the top plate to which the above wafers are attached does not damage the wafers and increases the adhesive strength, so the surface roughness is 0 at Rmax.
It is necessary to polish to an appropriate smoothness of 05 to 5 μm.

Conventionally, stainless steel, glass, and alumina are often used as the material of the top plate, but when the attached wafer or the like is subjected to polishing, frictional heat generated causes a temperature difference between the top and bottom surfaces of the top plate. As a result, due to the difference in thermal expansion between the upper and lower surfaces, a warp in which the attaching surface of the wafer or the like becomes convex is not generated, and the lower surface plate surface does not come into proper contact, making it difficult to perform smooth polishing. In order to solve this, the amount of warpage is empirically taken into consideration to set the curvature of the lower surface plate, but as the demand for dimensional accuracy of the polished surface becomes more and more severe, Adjustment is becoming difficult.

Therefore, recently, it is a material that is lightweight, has excellent wear resistance and corrosion resistance, has a large thermal conductivity, a high elastic modulus, and a low Poisson's ratio.
Ceramic materials, especially silicon carbide ceramics, have come to be used because the warpage due to the difference in thermal expansion between the upper and lower surfaces is small.

[Problems to be Solved by the Invention]

However, when producing a top plate using silicon carbide ceramics as a material, when lapping the surface to which a wafer or the like is attached using a lapping plate, since the material is hard, the surface to which the wafer or the like can be stably attached is polished. It takes time and the processing cost is high.

In view of the above circumstances, an object of the present invention is to provide a top plate made of silicon carbide ceramics, which can easily obtain flatness suitable for sticking a wafer or the like even when using silicon carbide ceramics.

[Means for Solving the Problems]

In order to achieve the above object, in the silicon carbide ceramic top plate of the present invention, the surface of the central portion excluding the adhesive portion for adhering a workpiece such as a wafer is deeper than the upper surface of the adhesive portion. The depth is 0.05 to 1 mm.

In general, silicon carbide ceramic top plates are
The raw material silicon carbide is pulverized to, for example, 1 μm or less, a known sintering aid is added to the raw material silicon carbide, and a rubber press or the like is used.
It is produced by degreasing and sintering a product formed into a predetermined shape, and then grinding and polishing one surface with a lapping plate.In the silicon carbide ceramic top plate of the present invention, the above-mentioned production form is used. As shown in the plan view and the longitudinal sectional view of one embodiment in FIGS. 1 and 2, the surface of the central portion is slightly concave except the annular bonding portion 2 for bonding the workpiece 1 such as a wafer. Formed in shape 3.

Therefore, when this is degreased and sintered and the surface on which the concave shape is formed is ground, the central portion does not contact the lapping plate and the central portion with poor polishing efficiency has already been removed into the concave shape. Since it is not subject to polishing and only the ring-shaped adhesive portion 2 is polished, the polishing area is reduced, and the removal amount of the object to be polished by polishing is likely to be uniform at all points, and the surface to which a wafer or the like is attached is attached. The time for polishing to a predetermined smoothness is greatly shortened, and the polishing accuracy is improved. The depth of the concave shape is preferably shallow from the strength of the top plate so long as it does not contribute to polishing. Also,
If the depth is large, the polishing liquid and the polishing material will be accumulated, and in some cases, the polishing materials will easily aggregate with each other, and they may behave as polishing materials having an apparently large particle size, and scratches may occur on the wafer. Especially, 0.05 to 1 mm is suitable.

In addition, instead of providing a concave shape in the central part, if a concave shape is used as a hole that penetrates the top plate, the same effect can be obtained for polishing the surface of the adhesive part, but the strength of the entire top plate decreases. , The life will be shortened after repeated use. Also,
Since the polishing liquid and the polishing material accumulate in the holes, scratches may occur on the wafer, which is not preferable.

Example 1 Carbon, boron, and aluminum powders were added and mixed as a sintering aid to a powder obtained by crushing silicon carbide ceramics to a size of 1 μm or less, and produced by a rubber press.

This molded product is sintered at 2000 ℃, diameter 300mm, thickness 13m
A top plate having a diameter of 60 mm and a depth of 0.5 mm was produced.

The concave surface is treated with a diamond slurry having a particle size of 30 μm for 3 hours, a diamond slurry having a particle size of 9 μm for 5 hours, a diamond slurry having a particle size of 6 μm for 4 hours, and a diamond slurry having a particle size of 3 μm for 4 hours. total
Polished for 16 hours.

As a result, the polished surface had a roughness of 0.1 μm and a flatness of 1 μm.

Example 2 Similar to Example 1, a green press was used for forming.

This molded product is sintered at 2000 ℃, diameter 300mm, thickness 13m
A top plate with a diameter of 100 mm and a depth of 0.5 mm was produced.

The concave surface is treated with a diamond slurry having a particle size of 30 μm for 3 hours, a diamond slurry having a particle size of 9 μm for 4 hours, a diamond slurry having a particle size of 6 μm for 3 hours, and a diamond slurry having a particle size of 3 μm for 3 hours. total
Polished for 13 hours.

As a result, the polished surface had a roughness of 0.1 μm and a flatness of 0.8 μm.

Example 3 Similar to Example 1, a green press was used for forming.

This molded product is sintered at 2000 ℃, diameter 380mm, thickness 13m
A top plate having a diameter of 60 mm and a depth of 0.5 mm was produced.

This concave surface is treated with a diamond slurry having a particle size of 30 μm for 3 hours, a diamond slurry having a particle size of 9 μm for 5 hours, a diamond slurry having a particle size of 6 μm for 5 hours, and a diamond slurry having a particle size of 3 μm for 4.5 hours, Polished for a total of 17.5 hours.

As a result, the polished surface had a roughness of 0.1 μm and a flatness of 1.2 μm.

Comparative Example 1 Without forming a concave shape in the central portion, a diamond slurry having a particle size of 30 μm was used for 3 hours, a diamond slurry having a particle size of 9 μm was used for 5 hours, and a diamond slurry having a particle size of 6 μm was used for 6 hours.
Example 1 was repeated except that the diamond slurry having a particle size of 3 μm was used for 10 hours and the total polishing time was 24 hours. As a result, the surface roughness after polishing was 0.1 μm,
The flatness was 3 μm, and the central portion had a high shape.

〔The invention's effect〕

As described above, the silicon carbide ceramics top plate of the present invention can easily provide highly accurate flatness, the time required for polishing is significantly shortened, and the cost is reduced. Since the processing accuracy is improved without accumulating the polishing liquid and the polishing material in the concave shape and scratches on the wafer, it is possible to meet the demand for high dimensional accuracy for the polished surface of the wafer, etc. Is extremely large.

[Brief description of drawings]

1 and 2 are views of a formed product of a silicon carbide ceramic top plate according to the present invention, FIG. 1 is a plan view, and FIG. 2 is a sectional view taken along the line II-II in FIG. Is. 1 ... Workpiece such as wafer, 2 ... Toroidal bonded portion, 3 ... Concave shape at center.

Claims (1)

[Claims] 1. A surface of a central portion of one surface excluding an adhesive portion having a surface roughness Rmax for adhering a workpiece such as a wafer of 0.05 to 5 μm, has a depth of 0.05 with respect to an upper surface of the adhesive portion. ~ 1 mm
A top plate made of silicon carbide ceramics characterized by having a concave shape.