JPS6028634B2 - Double-sided polishing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for simultaneously forming both sides of a wafer, such as a single-crystal material widely used in the electronics industry, into a smooth surface (undistorted mirror surface) without a processed layer that is effective as an epitaxial growth substrate. The present invention relates to a double-sided polishing device that can perform finishing.

Figure 1 is a diagram for explaining an example of a conventional double-sided polishing device, in which a is a plan view with the polishing liquid removed;
-D sectional view.

In FIG. 1, 1 is a circular wafer which is a sample to be polished;
2 is a disk-shaped carrier that is thinner than the thickness of the wafer 1 and has concentric holes that can hold several wafers 1 at the same time; 3 and 4 are screws 5 that sandwich the outer circumference of the carrier 2 from both sides; 6 is a disc-shaped lower tray that is rotated at a constant speed by a motor or the like, and 7 is a disc-shaped holder that is rotated in the same way as the lower tray 6. 8 is an abrasive cloth adhered to the surfaces of the upper and lower receivers 6 and 7; 9 is a liquid polishing liquid containing ultrafine abrasive particles mixed with a chemical for etching the wafer 1; 10 is a ring-shaped plate attached to the carrier 2; A friction wheel 11 having a collar that holds an assembly consisting of holders 3 and 4 and is driven by a motor etc. has a similar shape to the friction wheel 10;
The carrier 2 is assembled so that it does not come into contact with the upper and lower abrasive cloths 8 by guide rollers that hold the assembly consisting of the carrier 2 and ring-shaped holders 3 and 4 at three points. 1
Reference numeral 2 is a cylindrical container fixed to the substrate 13 and capable of storing enough polishing liquid 9 to submerge the wafer 1, carrier 2, upper and lower trays 6 and 7, etc., and the lower tray 6 and the friction wheel 1 are filled with polishing liquid. The shaft of the guide roller 11 is fixed to the container 12, and is held via a ring 14 to prevent leakage.

Note that the rotation centers of the upper and lower trays 6 and 7 coincide with the center of the container 12, but the rotation center of the carrier 2 is assembled at an eccentric position.

The upper and lower trays 6, 7 and the friction wheel 10 may be rotated in the same direction with a certain speed difference, or the upper tray 7 and the friction wheel 10 may be rotated in the same direction with the lower tray 6.
The wafer 1 slides between the polishing cloths 8 on the upper and lower trays by rotating them in opposite directions, or by rotating the upper and lower trays 6 and 7 in the same direction and the friction wheel 10 in the opposite direction. Liquid 9 is supplied to both sides of the wafer to perform double-sided polishing.

However, in the double-sided polishing device as shown in Fig. 1, since the container is fixed, it is inconvenient to put in and take out the polishing liquid and to clean the inner surface of the container, and since the polishing liquid does not rotate, centrifugal force does not act on the polishing liquid itself. Foreign matter and large abrasive grains mixed in the polishing solution are present on the surface of the polishing cloth, so the machined surface does not become a distorted mirror surface, and since there are friction wheels and guide rollers in the polishing solution, corrosion-resistant materials are used. At the same time, it is necessary to prevent the rotation of the polishing liquid caused by the rotation of the upper and lower saucers and the carrier, to prevent uniform rotation due to slippage in the drive of the carrier, and to avoid chemicals when replacing the carrier or polishing cloth. It is difficult to work because the abrasive liquid comes into contact with the hands, and one of the friction wheels and guide rollers that hold the carrier must be disassembled, and the abrasive liquid leaks between the container, the lower pan shaft, and the friction axle. It has the disadvantage that it is difficult to completely prevent it.

An object of the present invention is to provide a double-sided polishing device that achieves good distortion-free mirror finishing and is capable of improving work efficiency by making it easy to replace and clean the container, carrier, and upper and lower polishers.

That is, the present invention has a holder configured to be able to support and drive the polishing liquid from the outside, a carrier whose outer peripheral portion is fixed by the holder and has a hole for holding the sample to be polished, and a carrier provided above and below with the carrier in between. It is equipped with two polishing machines and a rotatable container that accommodates these, a sample to be polished is placed in the carrier, and a polishing liquid is poured into the container to remove the carrier, the sample to be polished, and the two polishers. This is a double-sided polishing device that polishes both sides by immersing the disc and rotating the carrier, polishing disc, and container.

According to the present invention, a uniform centrifugal force is applied to the polishing liquid due to the rotation of the container storing the polishing liquid, and foreign matter and large abrasive grains in the polishing liquid are removed to the outer periphery and are uniformly distributed on the polishing machine. Processing is performed using fine particle abrasive grains, the container and lower polishing machine are removable, making cleaning and replacement easy, and the carrier can be attached and removed from outside the polishing solution, making work easier. There are advantages such as FIG. 2 is a diagram for explaining an embodiment of the double-sided polishing apparatus of the present invention, in which a is a plan view with the polishing liquid removed, and b is a plan view of A-○-A.
FIG.

In Figure 2, 1' is the wafer, 2' is the carrier, 3',
4' is a ring-shaped holder; 7' is an upper tray; 8' is an abrasive cloth; 9' is a polishing liquid;
Three supports 16 are used to hang the assembly consisting of the ring-shaped holders 3' and 4' and hold it so that it does not touch the surface of the upper and lower polishing cloths 8'. A top plate ig having three arms 18 for fixing is a support rod 21 that is fixed to the top plate 16 with a thumbscrew 20 and holds the top plate 16 at a position divided into three equal parts on the outer circumference of the top plate 16; 22 is an intermediate bearing for holding the bottom plate 21 via a bearing 23 so that the bottom plate 21 can be rotated; 24 is a V-belt 25 that connects the bottom plate 21; It is a belt pulley that is driven by a motor, and is rotated at a constant speed by a motor or the like. 26 is a base, 27 is a structure that is rotated by a motor or the like and has a disk at the tip, and the lower side has a round protrusion in the center of the disk and a pin 28 at a corner position, and 29 is placed on the lower moat 27. 301 is a circular removable lower saucer which is integrally attached by a protrusion in the center of the rotary container 29 and a pin 28' located at an eccentric position. , the upper saucer 7', the lower saucer 30, and the rotating container 2
The rotation centers of the three parts 9 are aligned, but the rotation center of the carrier 2' is assembled at an eccentric position, and the rotation center of the carrier 2'
The wafer 1' in the carrier slides between the polishing cloths 8' by the rotation of the carrier.

The wafer 1' can be moved between the polishing cloths 8' even if the carrier 2' performs a reciprocating motion, an oscillating arc motion, etc. instead of an eccentric rotation motion. The double-sided polishing in Figure 2 is the first
As in the case of the figure, upper saucer 7', belt wheel 24, lower koji 27
The three parts may be rotated at a speed difference in the directions of the arrows in the figure, or the upper tray 7' and the belt pulley 24 may be rotated in the same direction and the lower shaft 27 in opposite directions, or the upper tray 7' and the lower tray 27 may be rotated in the same direction and the lower shaft 27 in opposite directions. This is done by rotating the belt pulley 24 in the same direction in the opposite direction, but in the present invention, the container rotates, the lower shaft, the container, and the lower tray are detachable, and the carrier is driven from outside of the polishing liquid. As a result, all of the problems of the conventional device mentioned above can be solved, and excellent distortion-free double-sided polishing can be achieved, as well as cleaning of dirt caused by adhesion of polishing liquid, replacing polishing cloth and carrier, and loading and unloading of polishing liquid and wafer. It is extremely effective as a distortion-free double-sided polishing device with excellent workability. By configuring the polishing machine as in this embodiment, in which the polishing cloth is provided on the tray, double-sided polishing with less strain on the sample to be polished can be achieved.

In the above embodiments, a structure in which the assembly consisting of the carrier 2' and the ring-shaped holders 3' and 4' is suspended by three supports 15, and a structure in which the top plate 16 is held by three support rods 19 are exemplified. A similar effect can be obtained with a structure made of several pillars or a cylindrical ljing having holes or notches. Further, in the above embodiment, the method of rotating the upper tray 7' was illustrated, but polishing can also be achieved by fixing the upper tray 7' and rotating the lower shaft 27 and the belt pulley 24 in the same direction or in opposite directions at a certain speed difference. It is possible.

As described above, according to the present invention, it is possible to easily manufacture the device, and it is possible to create a strain-free double-sided polishing device that has no functional problems and has durability, and is also convenient to handle.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing an example of a conventional strain-free double-sided polishing device, in which a is a plan view with the polishing liquid removed and a part of the upper tray and part of the polishing cloth cut away, and b is a plan view of A-8. FIG. 2 is a cross-sectional view taken along the line C-D, and FIG. Plan view of cutaway state, b is A-○-A
FIG. In the figure, 1 and 1' are wafers, 2 and 2' are carriers, and 3 and 3
', 4, 4' are link-shaped holders, 5, 5', 17 are screws, 6 is a lower saucer, 7, 7' are upper saucers, 8, 8' are abrasive cloths,
9 and 9' are abrasive liquid, 10 is a friction wheel, 11 is a guide loft, 12 is a fixed container, 13 is a base plate, 14 is a ○ ring, 15 is a column, 16 is a top plate having three arms 18, 1
9 is a support rod, 20 is a thumbscrew, 21 is a bottom plate, 22 is a hollow bearing, 23 is a bearing, 24 is a belt pulley, 25 is a V-belt, 26 is a base, 27 is a lower shaft, 28, 28' are pins. ,
29 is a rotating container, and 30 is a removable lower tray. Sai 2
Illustration soup l illustration 2 illustration

Claims (1)

[Scope of Claims] 1. A holder configured to be able to support and drive the polishing liquid from the outside, a carrier whose outer periphery is fixed by the holder and has a hole for holding the sample to be polished, and a carrier that is held in the upper and lower portions with this carrier in between. It is equipped with two polishing machines installed in the carrier, and a rotatable container that accommodates the polishing machines.The sample to be polished is placed in the carrier, and the polishing liquid is injected into the container. A double-sided polishing device characterized in that two polishing discs are immersed, and these carriers, polishing discs, and container are rotated to perform double-sided polishing. 2. The double-sided polishing apparatus according to claim 1, wherein the two polishing machines have a structure in which a polishing cloth is provided on the surface of a saucer.