JPH01135464A - Polishing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a polishing apparatus for polishing the surface of a material to be polished, such as a semiconductor wafer.

``Prior Art'' As semiconductor devices such as semiconductors and GaAs devices become highly integrated and pattern sizes become miniaturized, semiconductor wafers (hereinafter simply referred to as ``wafers'') are required to have highly accurate flatness. Therefore, it is necessary to obtain highly accurate flatness even in the borizing process, which is a wafer surface polishing process.

Incidentally, as such a wafer polishing apparatus, one shown in FIG. 2 is conventionally known.

In FIG. 2, reference numeral 1 is a surface plate, 2 is a gear rear plate, and 3 is a pressure plate attached to the upper part of the carrier plate 2.

The surface plate 1 is a rotating plate having a circular shape in plan view, and a polishing cloth is attached to the upper surface of the surface plate 1 to form a polishing surface 1a. This surface plate l is connected to a drive device (not shown) and is rotatable about an axis O. A polishing liquid supply pipe 4 is provided above the center of the surface plate l for supplying a polishing liquid in the form of slurry, which is a mixture of abrasive grains and alkaline liquid, to the center of the polishing surface 1a of the surface plate l.

The carrier plate 2 is a circular plate made of metal such as stainless steel, ceramics, or glass, and both surfaces thereof are polished to have a flat surface. As shown in FIG. 3, on one side of the carrier plate 2, one or more (four in this figure) wafers 5, 5, etc. are arranged at equal intervals in the circumferential direction when viewed from above. Fixed. Methods for fixing this wafer 5 to the carrier plate 2 include a wax method in which the wafer 5 is attached to one side of the carrier plate 2 by applying wax to one side of the wafer 5, and a method such as vacuum suction or water bonding. There is a waxless method of adhesion. The carrier plate 2, on which the wafer 4 is fixed by these methods, is placed on the surface plate 1 with the surface on which the wafer 5 is fixed facing downward.

One or more carrier plates 2 placed on the surface plate 1 are arranged on one surface plate l (only l is shown in the figure). These carrier plates 2.2...
are located at equal intervals in the circumferential direction when viewed from above.

Reference numeral 3 denotes a pressure plate which is circular in plan view, and a cylindrical recess is formed on the lower surface of the pressure plate 3, and the flat part thereof serves as a pressure surface 6 for pressing the carrier plate 2. It becomes. This pressurizing surface 6 is a flat surface. The upper part of the carrier plate 2 is fitted into the cylindrical recess, and the upper surface of the carrier plate 2 and the pressurizing surface 6 are in close contact with each other.

A pressure shaft 7 is connected to the center of the upper part of the pressure plate 3, and the pressure plate 3 is swingable and rotatable with respect to the pressure shaft 7.

To polish the wafer 5 using the polishing apparatus as described above, first, use a pneumatic cylinder, a 4-gauge cylinder, etc. (a dead weight type is also acceptable), and apply pressure connected to the upper part of the press plate 3. By pressing the shaft 7 downward, the wafer 5 is pressed against the polishing surface 1a of the surface plate 1. In this state, the polishing liquid is supplied from the polishing liquid supply pipe 4 to the center of the polishing surface 1a of the surface plate I, and the surface plate I is rotated in the direction of the arrow in FIG. 2 about the axis O. In this case, the relative speed at the contact surface between each wafer 5 fixed on the carrier plate 2 and the polishing surface 1a of the surface plate l increases as the distance from the axis 0 of the surface plate l increases, so that the carrier plate 2
Among the wafers 5 fixed to the surface plate 1, a larger relative speed is given to the wafer 5 that is in contact with the polishing surface 1a of the surface plate 1 on the outside of the surface plate 1, and the carrier plate 2 is moved along with the pressure plate 3 as shown in FIG. is rotated in the direction of the arrow.

Further, the polishing liquid supplied to, for example, the center of the polishing surface 1a of the surface plate L rotates together with the polishing surface 1a of the surface plate I due to the twisting force of the polishing surface 1a of the surface plate L. It flows radially outward on the polishing surface la and is supplied to the lower surface of the wafer 5. In this way, the lower surface of the wafer 5 is rubbed on the polishing surface ia of the surface plate l and mechanochemically polished by the polishing liquid.

"Problems to be Solved by the Invention" By the way, such a conventional polishing apparatus has the following problems.

That is, the frictional heat generated by the friction between the wafer 5 and the polishing surface 1a of the surface plate 1 generates heat in the t-wafer 5, and this heat is conducted to the carrier plate 2.
I also have a fever. Since the top surface of the carrier plate 2 is in close contact with the pressure surface 6 of the pressure plate 3, the heat from the top of the carrier plate 2 is conducted to the pressure plate 3, creating a temperature difference between the top and bottom of the carrier plate 2. Yes, carrier plate 2
Since thermal distortion occurs in the carrier plate 2, the flatness of the upper and lower surfaces of the carrier plate 2 deteriorates.

In addition, heat is conducted from the upper surface of the carrier plate 2 to the pressure surface 6 of the pressure plate 3, and the lower part of the pressure plate 3 also generates heat, causing thermal distortion on the pressure surface 6. Since this differs depending on the material, shape, etc., uneven pressure is applied to the carrier plate 2 being pressed by the pressing surface 6.

If the wafer 5 is polished under the above conditions, the lower surface of the wafer 5 will not be polished uniformly, and therefore the required flatness will not be obtained.

The present invention was made in view of the above circumstances, and an object thereof is to provide a polishing device that can reduce thermal distortion of a carrier plate and uniformly press the carrier plate.

[Means for Solving the Problems] In order to achieve the above object, the polishing device of the present invention has an annular body made of a soft elastic material interposed between the pressing surface of the pressing plate and the upper surface of the carrier plate. It is something.

"Embodiment" An embodiment of the polishing apparatus of the present invention will be described below with reference to FIG.

In FIG. 1, the same components as in FIG. 2 are given the same reference numerals.

Reference numeral 8 denotes a pressure plate that is circular in plan view, and a cylindrical recess is formed on the lower surface of the pressure plate 8, and the flat part thereof serves as a pressure surface 9 for pressing the carrier plate 2. It becomes. Four annular grooves 10 are formed concentrically in this pressure surface 9 at required intervals. An O-ring +1 (annular body) made of a soft elastic material such as rubber is attached to one of the annular grooves 10, and the lower part thereof protrudes from the pressure surface 9. The upper part of the carrier plate 2 is fitted into the cylindrical recess. In this case, an O-ring 11 is interposed between the upper surface of the carrier plate 2 and the pressurizing surface 9.

The pressure plate 8 is connected to a pressure shaft 12 at the center of its upper part, and is swingable and rotatable with respect to the pressure shaft 12.

The rest of the structure is similar to that of a conventional polishing device.

To polish the wafer 5 using the polishing apparatus as described above, first, use a pneumatic cylinder, a hydraulic cylinder, etc.
The wafer 5 is pressed against the polishing surface 1a of the surface plate 1 by pressing the press shaft 12 connected to the upper part of the press plate 8 downward. In this state, the surface plate 6 is rotated in the direction of the arrow in FIG. 1 about the axis O while supplying polishing liquid from the polishing liquid supply pipe 4 to the polishing surface 1a of the surface plate l. In this case, the carrier plate 2 is rotated together with the pressure plate 8 in the direction of the arrow in FIG. 1, as in the conventional case. In this way, wafer 5
The lower surface of the plate is rubbed on the polishing surface la of the surface plate 1 and mechanochemically polished by the polishing liquid.

In the above-mentioned polishing apparatus, since the O-ring 11 is interposed between the pressure surface 9 of the pressure plate 8 and the upper surface of the carrier plate 2, the pressure surface 9 of the pressure plate 8 and the carrier plate 2
Since the contact area with the top surface of the holder is small, heat conduction can be reduced. Therefore, the temperature difference between the upper and lower portions of the carrier plate 2 can be reduced, and thermal distortion of the carrier plate 2 can be reduced.

Furthermore, the carrier plate 2 and pressure plate 8 slightly generated
Although the thermal distortions are not the same thermal distortions, they are circularly symmetrical because the carrier plate 2 and the pressure platen 8 are circularly symmetrical, and the pressure can be applied by an O-ring made of a soft elastic material that has a similar symmetry. This allows the carrier plate 2 to be pressed uniformly and with good reproducibility.

As a result of the above, the lower surface of the wafer 5 can be uniformly polished, and therefore the required flatness can be obtained.

In addition, since a plurality of annular grooves 10 (four in the above embodiment) are provided in which the O-rings 11 are attached, O-rings 11 with different diameters can be attached to other annular grooves depending on the situation, such as changing the pressing force. There is an advantage that it can be done.

In the above embodiment, 1 g of the O-ring 11 was attached, but a plurality of O-rings 11 may be attached.

"Effects of the Invention" As explained above, in the polishing apparatus of the present invention, the annular body made of a soft elastic material is interposed between the pressure surface of the pressure plate and the upper surface of the carrier plate. Because the contact area between the pressure surface and the top surface of the carrier plate is small,
Heat conduction can be reduced. Therefore, the temperature difference between the upper and lower portions of the carrier plate can be reduced, and thermal distortion of the carrier plate can be reduced.

Furthermore, the slight thermal strain that occurs on the carrier plate and the pressure plate is not the same thermal strain, but because the carrier plate and the pressure plate are circularly symmetrical, they are circularly symmetrical, and the soft elastic material has similar symmetry. The carrier plate can be stably pressed by pressing with an annular body consisting of the carrier plate, and if the diameter of the annular body is selected depending on the rigidity of the carrier plate, uniform pressing can be achieved.

By doing the above, the lower surface of the wafer can be uniformly polished, and therefore the required flatness can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the polishing apparatus of the present invention, FIG. 2 is a sectional view showing a conventional polishing apparatus, and FIG. 3 is a bottom view of a carrier plate to which a wafer is fixed. be. l... Surface plate, la... Polished surface, 2...
...Carrier plate, 5...Wafer (
(material to be polished), 8...pressure plate, 9...pressure surface, 11...0 ring (annular body).

Claims (1)

[Claims] A carrier plate, on which the material to be polished is fixed on the lower surface, is pressed by a pressure plate against a surface plate whose upper surface is a polishing surface, and the surface plate is rotated to separate the surface of the material to be polished and the surface plate. In a polishing device that polishes the surface of a workpiece by supplying a polishing liquid to the polishing surface of the surface plate while applying relative motion to the polishing surface, the pressure surface of the pressure plate and the upper surface of the carrier puto are A polishing device characterized by having an annular body made of a soft elastic material interposed therebetween.