Incremental offset measurement instrument

Details Incremental offset measurement instrument Incremental offset measurement instrument

2002-07-23

2004-08-10

Fulton, Christopher W. (Department: 2859)

Geometrical instruments

Gauge

With support for gauged article

C033S833000

Reexamination Certificate

active

06772528

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an incremental offset measuring instrument for accurately determining dimensions of objects, thereby reducing product loss during manufacturing processes.
2. Description of the Prior Art
Please refer to FIG.
1
.
FIG. 1
is a typical view of a prior art guide ring
10
and a wafer
15
to-be-polished. As shown in
FIG. 1
, the wafer
15
is subject to a typical polishing process in order to remove a layer of material from the wafer surface. During the polishing process, the wafer
15
is protected and restrained by the guide ring
10
. In an ideal case, the diameter of the wafer
15
is equal to the inner diameter of the guide ring
10
so that the water
15
can be fittingly placed in the guide ring
10
. It is known that large space between the wafer peripheral and the guide ring
10
can cause sever collision or even drop off of the wafer
15
during the polishing process.
However, a very small space between the wafer peripheral and the guide ring
10
and collision are usually inevitable during mass production. Frequent collision of wafers results in incremental offset of the inner diameter of the guide ring
10
. A step cross section of the guide ring
10
is observed due to incremental offset of the inner diameter of the guide ring
10
. Referring to
FIG. 2
, the cross section of the guide ring
10
without a step cross section is shown. Referring to
FIG. 3
, the cross section of the guide ring
10
a
with a step cross section is shown. When the step difference
12
exceeds a predetermined value, the wafer
15
is subject to sliding out of the guide ring
10
during the polishing process and may be broken. Consequently, it is an important task of measuring friction loss of the guide ring
10
and the step difference
12
.
Referring to FIG.
4
and
FIG. 5
, a typical way to the measurement of the step difference
12
of the guide ring
10
is according to experience of an operator. When measuring, the operator uses his nail of a finger as a measuring tool, thereby determining if the guide ring
10
can be used in the next polishing process or not. However, the prior art method is not accurate and cannot obtain quantified data that can be used as a basis for effective management of wafer polishing process.
SUMMARY OF THE INVENTION
It is therefore a primary object of the present invention to provide an incremental offset or step difference measuring instrument for accurately measuring the step difference of a guide ring.
Another object of the present invention is to provide an incremental offset or step difference measuring instrument for accurately measuring the step difference of a guide ring and obtaining quantified data that are used as a basis of a wafer polishing management standard.
Still another object of the present invention is to provide an incremental offset or step difference measuring instrument for accurately measuring the step difference of a guide ring thereby determining the lifetime of the guide ring and decreasing the cost of production.
Still another object of the present invention is to provide an incremental offset or step difference measuring instrument for accurately measuring the step difference of a guide ring thereby avoiding a dropped wafer from damaging pricey semiconductor equipment.
According to the claimed invention, an incremental offset measuring instrument is provided. The incremental offset measuring instrument includes a main base; a specimen seat mounted on the main base for resting a specimen; a measuring tool assembly for measuring the specimen; and a movable assembly mounted on the main base, wherein the movable assembly carries the measuring tool assembly, thereby achieving the goal of measuring the specimen.
It is to be understood that both the forgoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed. Other advantages and features of the invention will be apparent from the following description, drawings and claims.


REFERENCES:
patent: 4166323 (1979-09-01), Maag
patent: 4251922 (1981-02-01), Perlotto
patent: 4679330 (1987-07-01), Williams
patent: 5419056 (1995-05-01), Breitenstein
patent: 5539992 (1996-07-01), Woodhouse

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