JPS61274876A - Semiconductor wafer measuring method in automatic surface grinder - Google Patents

Abstract

PURPOSE:To finish a semiconductor wafer into a high quality and accuracy mirror surface by measuring the upper surfaces of the wafer and a chuck with a two-point system integrated inprocess gauge while the wafer is vacuum adsorbed. CONSTITUTION:While a chuck 9 is rotated with high speed, a spindle 10 is automatically lowered. While a diamond grinding wheel 12 fixed to a cup wheel 11 on the lower end of the shaft 10 is fed for grinding, the working surface of a semiconductor wafer A vacuum adsorbed by the chuck 9 and the upper surface of the chuck 9 on a rotary table 8 are measured by an integrated inprocess gauge 13. Next, after an accurate predetermined thickness of the wafer is ground at a chuck position, the spindle 10 is lifted to release the wafer A from the grinding wheel 12, move the wafer to the next chuck position by the rotation of the rotary table 8 and carry out intermediate finish grinding while the working surface of the semiconductor A and the upper surface of the chuck 9 are measured by the similar gauge 13.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applicable to a surface grinding machine in which wide-diameter thin wafers sent out from a cartridge individually are accurately placed on a surface grinder, vacuum-adsorbed, and automatically ground. This invention relates to a method for measuring the thickness of a semiconductor wafer after grinding.

Today's continuous technological innovation is remarkable, and the development of cutting-edge technology has produced a large number of excellent product groups.

In particular, the development of electronic equipment equipped with computers, microcomputers, etc. of this type according to the present invention seems to be progressing rapidly, and efforts are being made to develop even more advanced applied technologies.

For this reason, semiconductor wafers are becoming wider and wider in order to achieve ultra-high quality, miniaturization, and mass integration of circuits.
There is a growing demand for ultra-thin devices.

Conventionally, semiconductor wafers are vacuum-adsorbed onto chucks at multiple locations on a rotary table formed by equally divided frames of an automatic surface grinding machine, and the chucks rotate together, causing a spindle shaft that rotates in the opposite direction to descend from above. During the grinding process, the thickness of the semiconductor wafer must be measured and the grinding condition must be constantly checked. A final check measurement is required to check whether the thickness of the wafer is finished, and the top surface of the semiconductor wafer and the top surface of the chuck of the checking mechanism are measured using separate measuring instruments, and the thickness of the wafer is measured by the difference between the two. Or, the thickness was determined by measuring only the top surface of the wafer and grinding it, but the temperature change on the wafer due to changes in the degree of wear of the diamond grinding wheel, the temperature difference after grinding, or the temperature change of the air in the surrounding atmosphere As a result, the conditions under which semiconductor wafers are measured change slightly, creating a problem in obtaining the thickness after grinding in microns.

Focusing on the above-mentioned reasons, the present invention has been developed to eliminate these problems at once as a result of extensive research, and to meet the demand for improving the precision of semiconductor wafers, which are becoming wider in diameter and ultra-thin. The aim is to develop and provide a method for measuring semiconductor wafers on a board.

A method for measuring a wafer in an automatic surface grinding machine for semiconductor wafers according to the present invention, which achieves the above object, will be explained below with reference to drawings of embodiments.

FIG. 1 is a general plan view of an entire embodiment for explaining the present invention, and FIG. 2 is a side view for explaining the main parts.

Semiconductor wafers A are delivered by a belt conveyor 1 from a cartridge B that stores a large number of semiconductor wafers A individually and can be raised and lowered. It is adsorbed, reversed, and transferred onto the surface of the preposition device 4. Then, the preposition device 4 performs accurate positioning and cleaning.
It is carried out by a jet of liquid, and an air suction pad 5 is attached to the tip.
The chuck position of the chuck 9 at six locations provided by the frame divided into six equal parts of the rotary table 8 of the surface grinding machine main body 7 is achieved by the wafer transfer arm 6, which is equipped with a wafer transfer arm 6 that can rotate horizontally, move forward and backward, and move up and down. It is guided accurately to 9a and is firmly vacuum-adsorbed. The rotary table 8 repeatedly rotates and stops in 1/6 increments at a constant low speed, and the chuck 9 has a mechanism that starts self-rotation at a predetermined rate when the rotary table 8 stops, and stops self-rotation while the rotary table 8 is rotating. be. Next is Chuck [9
A is moved to the position 9b by the rotation of the rotary table 8, and the spindle shaft 10 rotating from the upper part is automatically lowered, and the first rough grinding is started with the diamond grindstone 12 fixed to the cup wheel 11 at the lower end.

The present invention accurately measures the thickness of the semiconductor wafer A to be ground during or after the grinding. Grinding is started with a predetermined amount of cutting margin by the amount of protrusion at an arbitrary slow speed, and the cutting amount of the diamond grinding wheel 12 fixed to the cup wheel 11 at the lower end of the shaft 10, but during accurate rough grinding, Alternatively, the top surface of the semiconductor wafer A is firmly vacuumed by the chuck 9 in order to measure the thickness of the semiconductor wafer after grinding.

That is, the machining surface and the upper surface of the chuck 9 during machining provided at several locations on the rotary table 8 are measured by an integrated in-process gauge 13.

After grinding to an accurate predetermined thickness at the chuck position 9b, the spindle shaft 10 rises and the wafer A is released from the grinding wheel 12, and the rotary table 8 rotates to the chuck position 9.
c, and further performs semi-finish grinding using the method described above. Then, finish grinding is performed in the same way at the chuck position [9d, but also at chuck positions 9c and 9d.
Of course, the measurement can be performed using the semiconductor wafer measurement method of the present invention.

Next, the ultra-thin semiconductor wafer A that has been ground is cleaned at the chuck position 9e, and then moved to the storage transfer arm, which is equipped with a suction pad 14 of the storage transfer arm at the tip and can rotate horizontally and move forward and backward, and can be raised and lowered. 15, and transferred to the cleaning and drying device 16, and after cleaning and drying, the storage frame of the storage cartridge C is placed on the storage belt conveyor 19 by the storage reversal arm 18 equipped with the air suction pad 17 of the storage reversal arm. This is an automatic surface grinding machine that has a structure in which each item is stored in an orderly manner.

The above explanation is an explanation of the grinding process for one semiconductor wafer, but when wafer A is transferred from cartridge B to belt conveyor 1 to Bri position 5, the next wafer is transferred from cartridge B to belt conveyor 5. 1 and waits for the previous wafer to be transferred to the chuck position 9a of the rotary table 8.The structure has automatic feeding and automatic rotation mechanisms that can repeatedly and continuously perform these operations, such as waiting for the previous wafer to be transferred to the chuck position 9a of the rotary table 8. At each of the positions 9a to 9f of the chang 99 provided in 8, operations are performed simultaneously and continuously. That is, chuck position l 9
The wafer that has been ground in e is transferred to the cleaning/drying device 16, placed on the storage conveyor 19 by the storage transfer arm 18, and stored in the storage cartridge C, but the chuck 9 of the rotary table 8 is in the chuck position. At 9f, cleaning is performed and preparations are made for the next wafer grinding.

In other words, the wafer is transferred from the cartridge to the belt conveyor to the reversing arm to the preposition to the chuck position 9a to the chuck position 9b to the chuck position 9C to the chuck position 9d to the chuck position 9e to the storage transfer arm to the cleaning/drying device to the storage reversing arm. This is an automatic surface grinding machine that transports, grinds, and stores one after another from a storage belt conveyor to a storage cartridge. In this embodiment, the rotary table is composed of frames divided into six equal parts, but the number of equal parts can be set arbitrarily depending on the processing process, method, etc.

The measurement method using the two-point in-process gauge integrated with the present invention is an epoch-making method that meets the current demands for ultra-thinness, wide diameter, and high precision. It is possible to obtain a high-quality, high-precision mirror surface regardless of the temperature difference between the semiconductor wafer and the chuck, the temperature change due to the degree of wear of the diamond grinding wheel, or the change in outside temperature, and its contribution is immeasurable. There are things that can be done that can have an extremely meaningful effect.

[Brief explanation of the drawing]

FIG. 1 is a plan view for explaining one embodiment of the present invention, and FIG. 2 is a side view of the main parts thereof. A-wafer, B-cartridge, C-storage cartridge. 1-belt conveyor, 2-suction bat, 3-transfer arm, 4-preposition, 5-air suction bat, 6-transfer arm, 7-plane grinder body, 8-rotary table, 9-chuck, 9a, 9b , 9c, 9d, 9e, 9
f-chuck position, 10-spindle shaft, 11-cup wheel, 12-diamond grindstone, 13-in-process gauge, 14-air suction butt of transfer arm for storage, 15-transfer arm for storage, 16-washing and drying device ,
17-Air suction bat of inversion arm for storage, 18-Inversion arm for storage, 19-belt conveyor for storage.

Claims (1)

[Scope of Claims] A flat surface formed by a frame divided into multiple equal parts, where a plurality of semiconductor wafers are vacuum-adsorbed by a chuck mechanism, chucked onto a rotary table that repeatedly rotates and stops at a constant low speed, and is automatically ground. The grinding machine is a grinding machine that uses a two-point in-process gauge that integrates the top surface of the wafer and the top surface of the chuck with the semiconductor wafer being vacuum-adsorbed during or after the grinding process. A method for measuring a semiconductor wafer in an automatic surface grinding machine.