Ultrasonic wafer blade vibration detecting

Details Ultrasonic wafer blade vibration detecting Ultrasonic wafer blade vibration detecting

2002-04-26

2004-03-23

Kwok, Helen (Department: 2856)

Measuring and testing

Vibration

Sensing apparatus

C702S056000, C324S207250

Reexamination Certificate

active

06708565

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to rotating or spinning blades, such as may be found in robots used in conjunction with semiconductor fabrication equipment, and more particularly to detecting vibration of such blades.
BACKGROUND OF THE INVENTION
Robots are increasingly being used in many different applications, including semiconductor device fabrication. A robot can be generally and non-restrictively defined as a stand-alone hybrid computer system that performs physical and computational tasks. It is a multiple-motion device with one or more arms and that is capable of performing many different tasks. It can be designed similar to human form, although most industrial robots do not resemble people at all. Robots are used extensively in manufacturing, including semiconductor device fabrication.
FIG. 1
shows a robot
100
that is used in conjunction with semiconductor device fabrication. The robot
100
includes a process chamber
102
, the sidewalls of which meet at a base at the bottom to form a cavity
104
. A blade assembly
108
is positioned at the bottom of the base of the chamber
102
, and rotates around an axis of rotation
106
at the center of the base of the chamber
102
. The blade assembly
108
has a primary wafer blade
110
, an auxiliary wafer blade
112
, a straight wing
114
, and an angled wing
116
. The wafer blades
110
and
112
each have a base portion and a tip portion, the latter which is extensible from the center of the base of the chamber
102
to the sidewall of the chamber
102
. The blade assembly
108
is used to transfer semiconductor wafers among different wafer orientation chambers, such as may include the chambers
118
a
,
118
b
,
118
c
, and
118
d
. The robot
100
may be a Centura robot as is available from Applied Materials, Inc., of Santa Clara, Calif.
A potential problem with the robot
100
is when the primary blade
110
begins to vibrate, moving up and down besides just rotating. This is shown in FIG.
2
. From the center
106
, the blade
110
should be located as is indicated in FIG.
2
. However, when it vibrates, it moves up and down, from and to the positions
202
and
204
. The vibration of the wafer blade
110
can have disadvantageous consequences. A semiconductor wafer may slide out, or may be damaged by the vibrating blade
110
, since it is typically located only 1.5 millimeters from the blade
110
. Furthermore, vibration may indicate that the robot
100
is becoming damaged, such as the bearings thereof that control the movement of the primary blade
110
.
Therefore, there is a need for detecting blade vibration. Such blade vibration detection should ensure that semiconductor wafers are not damaged. Such blade vibration detection should also provide an early warning that the robot of which the blade is a part is becoming damaged. For these and other reasons, there is a need for the present invention.
SUMMARY OF THE INVENTION
The invention relates to detecting blade vibration via ultrasonic waves. The blade may be part of a robot that is used in conjunction with semiconductor device fabrication. A process chamber is provided that has a sidewall and a base defining a cavity contained therein. A rotatable blade is mounted at a center of the cavity that has a base portion and a tip portion extensible from the center to the sidewall of the process chamber. One or more ultrasonic sensors are mounted on the base adjacent to the sidewall. Ultrasonic waves are sent and received toward and reflected by the tip portion of the wafer blade to determine the tip portion's position. In this way, vibrational movement of the blade can be detected.
Embodiments of the invention provide for advantages over the prior art. If vibration exceeds specifications, then the blade can be stopped, or an operator can be notified that the blade should be stopped. This prevents damage to semiconductor wafers, as well as to the blade or the robot itself. Furthermore, detection of vibration provides an early warning that the robot may be becoming damaged, and thus should be investigated. Still other aspects, embodiments, and advantages of the invention will become apparent by reading the detailed description that follows, and by referring to the accompanying figures.


REFERENCES:
patent: 4518917 (1985-05-01), Oates et al.
patent: 4573358 (1986-03-01), Luongo
patent: 4887468 (1989-12-01), McKendree et al.
patent: 4896537 (1990-01-01), Osborne
patent: 4951500 (1990-08-01), Twerdochlib et al.
patent: 5206816 (1993-04-01), Hill et al.
patent: 5996415 (1999-12-01), Stanke et al.

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