Conveyance arm device

Details Conveyance arm device Conveyance arm device

1999-08-10

2001-10-16

Cherry, Johnny D. (Department: 3652)

Handling: hand and hoist-line implements

Contact lens applicator

C294S902000

Reexamination Certificate

active

06302459

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority benefit of Taiwan application serial no. 88200047, filed Jan. 4, 1999, the full disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a conveyance apparatus. More particularly, the present invention relates to a conveyance arm device which has a function to eliminate or dispel static electricity accumulated during wafer conveyance.
2. Description of Related Art
Static electricity is a major source of wafer damage during the wafer fabrication process and after the wafer is fabricated. People walking on a carpet in a relatively high humidity ambience carry from hundreds to thousands of volts of static electricity. In an ambience with a relatively low humidity, the static voltage on the human body may be over ten thousand volts. When these charged carriers contact with wafers, the static electricity is discharged to the wafers, and thus, damages the wafers. In complementary metal-oxide semiconductor (CMOS) fabricating processes, the problem caused by the static electric discharge is especially serious.
A wafer fab is required to be a clean, dirtless environment, usually with a relatively low humidity. However, a high static electricity voltage is often generated in a wafer fab. Therefore, the equipment for wafer fabrication is usually designed to be conductive, so as to minimize the damage caused by accumulated static charges.
But many fabricating devices are still made of insulators under the consideration of fabrication cost, convenience of operation, and possibility of scratching wafers. It is known that the accumulated static electricity damages the wafers and affects the yield of the products.
FIG. 1
shows a conventional conveyance arm device used in a furnace in a wafer fab for conveying wafers. The conveyance arm device comprises a conductive seat
12
and a tweezer
10
. One end of the tweezer
10
is connected to the conductive seat
12
. The tweezer
10
is vacuumed in order to dispose the wafers onto the tweezer
10
firmly without causing vibration or falling from the tweezer
10
during conveyance. The operation of the conducting seat
12
is controlled to drive the tweezer
10
, so that the wafers are conveyed to a predetermined place by the tweezer. Generally, the tweezer
10
that conveys the wafers is made of quartz (SiC) to protect wafers from being scratched. Since quartz is not a conductor, the static charges thereon can not be timely discharged or dispelled. In addition, the wafer boat used to carry the wafers is also made of quartz. Thus, static charges are continuously accumulated, and particles in the ambience are easily absorbed onto the wafers to cause a static voltage as high as 4000V to 10000V; thus, the wafers are easily damaged, and the yield is lowered.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a conveyance arm device to convey wafers. The conveyance arm device comprises a conducting seat, at least a tweezer, and at least film. The conducting seat drives the tweezer to convey the wafers. The tweezer has a circumference comprising a first end and a second end, and a first surface and a second surface between the first and the second ends. The first end and a first part of the second surface lie on the conducting seat, while the second end is suspended. The wafers are disposed on the first surface near the second end of the tweezer. The conducting film is adhered onto a second part of the second surface and the second end of the tweezer. That is, the conducting film on the tweezer extends from the conducting seat to the second end of the tweezer to dispel static electricity accumulated thereon.
The invention effectively dispels the static electricity accumulated onto the wafers by adding a conducting film on the tweezer.
Additionally, the conducting film and the tweezer of the conveyance arm device may be replaced by a conducting glass plate. The conducting glass plate has one end connected to the conducting seat and the other end suspended in air so that the static electricity is dispelled more effectively.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.


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patent: 287638 (1987-12-01), None
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