JPH0788761A - Holding plate for polishing semiconductor substrate - Google Patents

Abstract

PURPOSE:To hold a workpiece substrate with no deformation thereof and further to prevent a recessed part from being generated in a substrate surface due to foreign matter sticking to a suction surface, in a polishing device for mirror polishing the semiconductor substrate of silicon wafer or the like. CONSTITUTION:In a holding plate 10 arranged on a rotary carrier 2 and secured by a metal ring 8 communicating with a suction hole 3 in the inside by providing suction hole paths 5 in the surface, many fine grooves 11 of 0.5mm to 1.0mm width and 0.5mm or more depth are engraved concentrically in a substrate suction side of the holding plate, and foreign matter sticking onto a substrate 1 is advanced into the fine grooves 11. Since foreign matter sticking onto a surface of the holding plate 10 is discharged into the fine grooves 11 by brushing or the like, in the sucked substrate, no partial hollow is generated at all due to the foreign matter or the like after polishing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing holding plate for sucking and supporting a semiconductor substrate used in a polishing apparatus for mirror-polishing a semiconductor substrate such as a silicon wafer. A holding plate for polishing a semiconductor substrate, in which a large number of narrow grooves each having a predetermined width and depth are provided to hold the same without deformation and prevent the formation of a recess on the substrate surface due to a foreign substance adhering to the suction surface. Regarding

[0002]

2. Description of the Related Art In the production of silicon wafers and the like, there are surface processing steps such as lapping and polishing in order to obtain a defect-free single crystal surface by scraping the surface breakdown layer. In this process, when the substrate is ground or polished, the wafer is fixed to the grinding and polishing device, so that the substrate is brought into contact with the surface of the holding plate held by the rotary carrier and suction-fixed. Examples include those that use porous ceramics, which is a hard material for grinding in general, and those that have a large number of holes formed in a metal plate or acrylic plate, which is a soft material for polishing that requires high-precision flatness. Was used.

[0003]

As shown in FIG. 3, an example using a metal holding plate is provided with a suction hole 6 in a thick metal holding plate 5 arranged on a rotary carrier 2 to form a rotary carrier. The substrate 1 is sucked and fixed by communicating with the suction holes 3 and the suction hole passages 4 on the second side, but the suction pores 6 appearing on the surface of the metal holding plate 5 cannot uniformly suck the entire surface of the substrate 1. However, there is a problem that the substrate 1 after polishing has a subtle undulation as shown in FIG.

The holding plate shown in FIG. 4 is made of porous ceramics, and the porous ceramics holding plate 7 is placed on the rotary base 2 having the suction hole passages 4, and the outer periphery of the porous ceramics holding plate 7 is sucked. A metal ring 8 is arranged for the purpose of closing the hole and for preventing cracking of the porous ceramics. By using porous ceramics, the entire surface of the substrate 1 can be evenly adsorbed, and subtle undulations can be resolved, but foreign matter 9 such as dust adheres to the back surface of the substrate 1 and the adsorption surface of the porous ceramics 7. As shown in FIG. 5, there is a problem that a recess is formed in the substrate 1 after processing. Therefore, the holding plate made of a hard material made of porous ceramics is generally not used for finish polishing of a silicon wafer because it causes depressions.

Further, a metal ring is arranged on the outer periphery of the porous ceramics holding plate for the purpose of closing the suction holes and for preventing cracks of the porous ceramics. There has been proposed a structure in which a sealing material made of aluminum is provided. However, by disposing the rubber seal material on the outer periphery of the holding plate, the rigidity as a polishing device for adsorbing and holding the semiconductor substrate and performing mirror polishing may be insufficient, and there is a concern that the polishing accuracy may be adversely affected. . In addition, the diameter of the holding plate should be approximately the same as the diameter of the semiconductor substrate to be processed to prevent leakage.
Since the semiconductor substrate is provided with a notch portion such as an orientation flat, there is a problem that a leak occurs from the portion and the suction force is reduced.

The present invention, in a polishing apparatus for mirror-polishing a semiconductor substrate such as a silicon wafer, holds a substrate to be polished without deforming it, and prevents the formation of a concave portion on the substrate surface due to a foreign substance adhering to the suction surface. An object of the present invention is to provide a substrate holding plate for polishing, and further to provide a substrate holding plate for polishing a semiconductor substrate having a structure capable of exhibiting a stable adsorption force.

[0007]

According to the present invention, a polishing holding plate for sucking and supporting a semiconductor substrate is attached to a rotating rotary carrier for polishing, and a carrier body has suction holes for vacuum sucking the substrate. In a polishing holding plate used for a semiconductor substrate polishing apparatus, the holding plate is made of porous ceramics and has a width dimension of 0.5 mm to the substrate suction side of the holding plate.
A holding plate for polishing a semiconductor substrate, wherein a plurality of fine grooves having a depth of 1.0 mm and a depth of 0.5 mm or more are provided. Further, the present invention also proposes a holding plate for polishing a semiconductor substrate, characterized in that the fine grooves are arranged concentrically in the above structure. Further, in the invention, in the above structure, the average pore diameter of the porous ceramics is more than 10 μm and 50 μm or less, the porosity is 30% to 50%, and 3 mm from the outer peripheral edge of the holding plate.
A polishing plate for holding a semiconductor substrate is also proposed, in which the average pore size of the porous ceramics in the range of 10 mm is set to 10 μm or less, and the average pore size of the other porous ceramics is set to 20 μm to 50 μm. .

In the present invention, the holding plate made of porous ceramics has an outer dimension slightly larger than the outer dimension of the substrate to be processed, and a plurality of fine grooves are formed on the surface thereof, for example, concentrically. However, in order to store the foreign matter adhering to the suction surface in the groove, the groove dimension must be at least 0.5 mm in both width and depth. Since the accuracy of the local flatness of the surface may deteriorate, the groove width is 0.5 mm
Limited to 1.0 mm. The upper limit of the groove depth is not particularly limited, but it need not be too deep. Further, the distance between the adjacent fine grooves is not particularly limited, but does not reduce the strength of the holding plate and does not deteriorate the accuracy of the local flatness of the surface of the substrate to be processed, depending on the width and depth of the groove. It is preferable to select a narrow groove pitch in a range, for example, when the groove width is 0.5 mm, select a narrow groove pitch of at least 0.5 mm and arrange a large number of narrow grooves.

In the present invention, the characteristic of the porous ceramic itself of the holding plate is that the average pore diameter is 10 μm.
m and 50 μm or less, and porosity of 30% to 50%
When the average pore diameter is 10 μm or less and the porosity is less than 30%, the vacuum adsorption efficiency is poor, and when the average pore diameter exceeds 50 μm and the porosity exceeds 50%, vacuum adsorption becomes difficult. At the same time, the fine groove pitch cannot be reduced, which is not preferable. More preferably, the average pore size is 15
μm to 25 μm, and the porosity is about 40%.

In the present invention, as a structure capable of exhibiting a stable suction force, 3 mm to 10 m from the outer peripheral edge of the holding plate.
The average pore diameter of porous ceramics in the range of m is 1
The average pore size of the other porous ceramics is 20 μm to 50 μm, and the porous ceramics having an average pore size of 10 μm or less are used on the outer peripheral portion of the holding plate when the average pore size exceeds 10 μm. This is because a leak occurs at the time of suction, and if the width is less than 3 mm from the outer peripheral edge of the holding plate, there is no leak preventing effect, and if it exceeds 10 mm, the suction force is reduced, which is not preferable, and a width of 4 to 5 mm is most preferable.

[0011]

A holding plate for polishing a semiconductor substrate according to the present invention comprises:
Having a slightly larger outer dimension than the outer dimension of the substrate to be processed, and by engraving a plurality of narrow grooves having a specific dimension on its surface, for example, concentrically, in mirror polishing, no subtle waviness occurs, Both the flatness and the parallelism of the polishing substrate can be processed to 1 μm or less, and the generation of recesses on the surface of the substrate due to the foreign matter adhering to the suction surface is prevented, which has the effect of improving the processing accuracy of the substrate. Further, by arranging the porous ceramics having an average pore diameter of 10 μm or less in a ring shape on the outer peripheral portion of the holding plate, a leak is not generated from the orientation flat portion and the suction force does not decrease, and a stable suction force is obtained. Can be demonstrated.

[0012]

【Example】

Embodiment 1 A holding plate 10 according to the present invention shown in FIG. 1 is arranged on a rotary carrier 2 provided with a suction hole passage 4 on its surface and communicated with an internal suction hole 3, and is fixed by a metal ring 8. It
The holding plate 10 has an average pore diameter of 20 μm and a porosity of 40.
% Porous ceramics with a width of 1.
A large number of fine grooves 11 having a depth of 0 mm and a depth of 0.5 mm are concentrically formed. When the substrate 1 is brought into contact with the holding plate 10 and the vacuum pump is operated, the back surface of the substrate 1 comes into close contact with the surface of the porous ceramic holding plate 10. By inserting a large number of concentric thin grooves 11 on the surface of the holding plate 10, foreign matters attached to the substrate 1 enter the fine grooves 11, and foreign matters attached to the surface of the holding plate 10 are finely grooved by brushing or the like. Since it was discharged into 11, the absorbed substrate did not have any partial depression due to foreign matters after polishing.

Embodiment 2 A holding plate 20 according to the present invention shown in FIG. 2 is arranged on a rotary carrier 2 and fixed by a metal ring 8. The holding plate 20 has a porous structure having an average pore diameter of 10 μm on the outer peripheral portion thereof. A ring portion 21 made of ceramics and having a width of 5 mm was fitted, and the other adsorption portion 22 had an average pore diameter of 38 μm and a porosity of 40.
% Porous ceramic material is used. Further, although not shown, the same thin grooves as those in the first embodiment are provided on the surface of the holding plate 20. When the substrate was placed on the holding plate 20 and sucked, the orientation flat portion of the substrate was located on the ring portion 21 and there was no leakage from the portion, and no decrease in suction force was observed.

[0014]

The holding plate for polishing a semiconductor substrate according to the present invention uses porous ceramics to prevent the generation of subtle undulations due to non-uniform adsorption and to engrave fine grooves of specific dimensions on the surface of the porous ceramics. By doing so, it is possible to prevent the occurrence of dents on the substrate due to foreign matter, etc., and also to exert a stable suction force, and to process the flatness and parallelism of the polishing substrate to less than 1 μm, thereby improving the processing accuracy of the substrate. be able to.

[Brief description of drawings]

FIG. 1A is a vertical cross-sectional explanatory view showing the structure of a holding plate according to the present invention together with a polishing rotary holder, and B is a vertical cross-sectional explanatory view showing the structure of narrow grooves of a holding plate.

FIG. 2 is a vertical cross-sectional explanatory view showing another structure of the holding plate according to the present invention together with a polishing rotary holder.

FIG. 3 is a vertical cross-sectional explanatory view showing a substrate polishing holding plate using a conventional thick metal holding plate.

FIG. 4 is a vertical cross-sectional explanatory view showing a conventional substrate polishing holding plate using porous ceramics.

5A and 5B are schematic diagrams showing a state of a substrate when the metal holding plate of FIG. 3 is used, where A is at the time of adsorption and B is after polishing.

FIG. 6 is a schematic diagram showing a state of a substrate when the porous ceramics of FIG. 4 is used, where A is at the time of adsorption and B is after polishing.

[Explanation of symbols]

 1 Substrate 2 Rotation Carrier 3 Suction Hole 4 Suction Hole Path 5 Metal Holding Plate 6 Suction Pore 7 Porous Ceramics Holding Plate 8 Metal Ring 9 Foreign Material 10, 20 Holding Plate 11 Narrow Groove 21 Ring Part 22 Adsorption Part

Claims (4)

[Claims] 1. A polishing substrate used for polishing a semiconductor substrate, wherein a polishing holding plate for sucking and supporting a semiconductor substrate is attached to a polishing rotary carrier, and a carrier body has suction holes for vacuum-sucking the substrate. In the holding plate for use, the holding plate is made of porous ceramics, and has a width dimension of 0.5 mm to 1.0 mm and a depth dimension of 0.5 on the substrate suction side of the holding plate.
A holding plate for polishing a semiconductor substrate, characterized in that a plurality of fine grooves of mm or more are arranged. 2. The holding plate for polishing a semiconductor substrate according to claim 1, wherein the fine grooves are arranged concentrically. 3. The average pore diameter of porous ceramics is 1
It is more than 0 μm and 50 μm or less, and the porosity is 30% to 5
The holding plate for polishing a semiconductor substrate according to claim 1 or 2, wherein the content is 0%. 4. The average pore diameter of the porous ceramics within the range of 3 mm to 10 mm from the outer peripheral edge of the holding plate is 10 μm.
The holding plate for polishing a semiconductor substrate according to claim 1 or 2, wherein the average pore diameter of the porous ceramics other than the above is set to 20 m to 50 m.