JPH09201764A - Substrate polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To polish a substrate at a high accuracy of flatness and parallelism, as well as to maintain the substrate flat. SOLUTION: This polishing device is composed by providing a polishing pad 5 held on a turntable 4; a porous member 3 to suck and hold a substrate 1; and a substrate holder 2 to fix the porous body 3; and to carry out the polishing of the substrate 1 while moving the polishing pad 5 and the substrate 1 relatively, as well as pressure contacting both members oppositely. In this case, the diameter d of the porous member 3 prescribed by filling a seal material to the porous member 3, which is used to suck and hold the substrate 1, is made less than the diameter D of the substrate 1. Consequently, the substrate 1 can be finished at a high accuracy of flatness and parallelism less than a submicron.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate polishing apparatus, and more particularly to a substrate polishing apparatus that suction-holds a substrate on a porous material fixed to a substrate holder.

[0002]

2. Description of the Related Art In recent years, precision parts are required to have higher precision, and a substrate polishing apparatus for polishing the flatness and parallelism of the surface of precision parts to submicron or less plays an important role. In particular, the diameter of wafers used for semiconductor substrates is increasing, and it is important to hold substrates such as wafers in a substrate polishing apparatus. In view of this, there is a vacuum suction method in which a substrate is suction-held on a porous material fixed to a substrate holder.
This will be described with reference to FIG.

2A is a schematic side sectional view of the substrate polishing apparatus, and FIG. 2B is a schematic side view of the substrate 1 after polishing. The substrate polishing apparatus includes a turntable 4 to which a polishing pad 5 is fixed and which is rotated in the direction of an arrow in the drawing by a driving force from the outside, a porous material 3 and a porous material 3 which suction-hold a substrate 1 as a workpiece. While being firmly fixed, the substrate 1 is urged and pressed against the polishing pad 5 with an air cylinder or the like (not shown), and the substrate holder 2 that is rotated in the direction of the arrow in the figure by a driving force from the outside is roughly configured. The polishing slurry 7 is dropped from the nozzle 6 near the center of rotation of the pad 5, and the dropped polishing slurry 7 is substantially uniformly dispersed on the polishing pad 5 by the centrifugal force generated by the rotation of the turntable 4. Then, the turntable 4 and the substrate holder 2 are both rotated, and the substrate 1 is polished by a sliding movement of the substrate 1 and the polishing pad 5 via the polishing slurry 7.

Conventionally, the means for holding the substrate 1 on the porous material 3 has a suction surface 3c of the porous material 3 made of porous ceramics or the like having a diameter smaller than that of the substrate 1, and a diameter of the substrate 1 of the porous material 3. The substrate 1 and the sealing surface 2b of the substrate holder 2 which is larger than the suction surface 3c and which is flush with the suction surface 3c and is made of a material such as stainless steel that does not allow air to pass through. The vacuum pump (not shown) discharges air from the suction hole 2a at the center of the substrate 1, and the suction surface 3c and the sealing surface 2b hold the substrate 1.

However, since the hardness of the porous material 3 is different from that of the substrate holder 2 in the step of polishing the suction surface 3c and the sealing surface 2b to finish them on the same plane, the porous material 3
2A, the outer peripheral portion of the suction surface 3c does not become flush with the sealing surface 2b of the substrate holder 2 and tends to be recessed in a tapered shape. If such a tapered recess is present on the suction surface 3c that holds the substrate 1 by suction, the substrate 1 bites into the tapered recess, and the reaction thereof causes a tapered warp in the outer peripheral portion. Therefore, the polishing rate at the outer peripheral portion of the substrate 1 becomes large, and there is a possibility that the polishing surface 1a of the substrate 1 cannot be polished to a flat surface as shown in FIG.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a substrate polishing apparatus for holding a substrate flat and polishing it with high precision in flatness and parallelism.

[0007]

In order to solve the above problems, in a substrate polishing apparatus of the present invention, a polishing pad held by a turntable, a substrate pressed against the polishing pad,
In a substrate polishing apparatus having a porous material for sucking and holding a substrate and a substrate holder for fixing the porous material, the polishing pad and the substrate are pressed against each other, and the substrate is polished while moving relative to each other. The diameter of the porous material substrate, which is defined by filling the sealing material with the sealing material, for suction holding is less than or equal to the diameter of the substrate.

According to the above-mentioned means, since the adsorption surface of the porous material for adsorbing and holding the substrate is polished to a flat surface in the step of polishing to finish the surface, the substrate adsorbed and held on the adsorption surface is not warped. There is no possibility of occurrence, and the polishing surface of the substrate is brought into pressure contact with the polishing pad held by the turntable at a uniform pressure on the plane, and has the effect of polishing at a uniform polishing rate.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIG. Note that components in the figure that have the same structure as the conventional technology are denoted by the same reference numerals. The schematic structure of the substrate polishing apparatus is the same as that described with reference to FIG.

FIG. 1A is a schematic side sectional view of the substrate polishing apparatus, and FIG. 1B is a schematic side view of the substrate 1 after polishing. The substrate holder 2 made of stainless steel or the like is fixed with a porous material 3 made of porous ceramics or the like having a diameter larger than the diameter D of the substrate 1 and substantially the same diameter as the substrate holder 2. . The porous material 3 has a central portion having a diameter d that is less than or equal to the diameter D of the substrate 1, a porous portion 3a that is a portion through which air can pass, and a portion that cannot pass air. Sealing material filling portion 3b forming the outer peripheral portion of the material 3
It is composed of As a means for producing the sealing material filled portion 3b which is a portion where air cannot pass, a mask having a diameter d equal to or smaller than the diameter D of the substrate 1 is formed at the center of the adsorption surface 3c of the porous material 3 and exposed. There is a method in which a low-viscosity adhesive or the like is infiltrated into the outer peripheral portion and hardened to form a portion through which air cannot pass, the mask is removed, and finally the suction surface 3c is highly precisely flat-polished.

When the substrate 1 is brought into close contact with the suction surface 3c and air is exhausted from a suction hole 2a at the center of the substrate holder 2 by a vacuum pump (not shown), the substrate 1 is sucked flat on the suction surface 3c. Since it is held, there is no possibility that a taper-shaped warp will occur in the outer peripheral portion of the substrate 1. Therefore, the substrate 1 is brought into pressure contact with the polishing pad 5 held on the turntable 4 at a uniform pressure and is polished at a uniform polishing rate. As shown in FIG. Can be flat-polished with high precision.

[0012]

As described in detail above, according to the present invention, it is composed of a porous portion having a diameter equal to or smaller than that of a substrate and a portion through which air can pass, and a sealing material filling portion which is a portion through which air cannot pass. Since the porous material is the same material, the suction surface that suction-holds the substrate can be made flat by precision polishing, and a taper warp occurs on the outer periphery of the suction-held substrate on this suction surface. There is no fear of doing it. Therefore, the polishing surface of the substrate is brought into pressure contact with the polishing pad held on the turntable in a plane at an equal pressure, and is polished at a uniform polishing rate, so that the substrate has a highly accurate flatness and parallelism of submicron or less. The substrate polishing apparatus can be finished.

[Brief description of drawings]

1A and 1B show an embodiment of the present invention, FIG. 1A is a schematic side sectional view of a substrate polishing apparatus, and FIG. 1B is a schematic side view after polishing a substrate.

2A and 2B show a conventional example, FIG. 2A is a schematic side sectional view of a substrate polishing apparatus, and FIG. 2B is a schematic side view after polishing a substrate.

[Explanation of symbols]

 1 Substrate 1a Polishing Surface 2 Substrate Holder 2a Suction Hole 3 Porous Material 3a Porous Part 3b Sealing Material Filling Part 3c Adsorption Surface 4 Turntable 5 Polishing Pad 6 Nozzle 7 Polishing Slurry

Claims (2)

[Claims] 1. A polishing pad held on a turntable, a substrate pressed against the polishing pad, a porous material for sucking and holding the substrate, and a substrate holder for fixing the porous material. While bringing the polishing pad and the substrate into pressure contact with each other,
A substrate polishing apparatus that polishes the substrate while relatively moving the substrate, wherein the diameter used for sucking and holding the porous material is equal to or less than the diameter of the substrate. 2. The porous material has a diameter which is defined by filling the porous material with a sealing material and which is provided for suction-holding of the porous material. The substrate polishing apparatus according to.