Wafer suction pad

Details Wafer suction pad Wafer suction pad

2000-07-10

2001-08-28

Banks, Derris H. (Department: 3723)

Abrading

Work holder

Vacuum

C451S289000

Reexamination Certificate

active

06280308

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a wafer suction pad, specifically a wafer suction pad for holding an extremely thin wafer by suction to transport it.
2. Description of Related Art
In a chamfering machine, which handles a wafer immediately after being sliced from an ingot, the wafer can be held by certain points by suction with a suction pad and transported, because the wafer is very thick.
The necessity has arisen to use the wafer for an IC card, and a planarization apparatus such as a back grinder, which grinds the reverse (opposite to the obverse, on which electronic devices are formed) of the wafer so as to make the wafer thin, processes the wafer as extremely thin as 30 &mgr;m like paper. If the extremely thin wafer is held at certain points by suction in the planarization apparatus, then cracks and chips are usually generated.
In consideration of the above disadvantage, the wafer is held and transported by suction with a suction pad whose sucking face is substantially the same as the size of the wafer in the planarization apparatus of that type.
Yet, in the conventional suction pad, the suction pad must be changed every time the size of the wafer to be processed changes; hence, the working efficiency is lowered.
Japanese Patent Publication No. 2-46331 and Japanese Patent Application Laid-open No. 8-1464 disclose a worktable to hold a wafer in process by suction. In the worktable, annular grooves are formed on a face to suck the wafer, and a suction area of the air can be selected in accordance with the outer diameter of the wafer to be held. However, neither of them discloses applying the grooves to the suction pad that is provided with an arm for transportation.
SUMMARY OF THE INVENTION
The present invention has been developed in view of the above-described circumstances, and has as its object the provision of the wafer suction pad that can appropriately hold wafers of different sizes.
In order to achieve the above-described objects, the present invention is directed to a wafer suction pad which is provided to a transporting arm of a transporting device and holds a wafer by suction, the wafer suction pad comprising: a pad body having a sucking face, the wafer being held on the sucking face, a plurality of annular grooves being concentrically formed on the sucking face; a plurality of air intake lines, each of the plurality of the air intake lines communicating with a corresponding one of the plurality of the annular grooves on the sucking face of the pad body; an air suction device which sucks air; a plurality of valves, each of the plurality of the air intake lines connecting with the air suction device via a corresponding one of the plurality of the valves; and a changing device which changes opening and closing of each of the plurality of the valves in accordance with an outer diameter of the held wafer.
According to the present invention, the annular grooves are concentrically arranged on the wafer sucking face of the wafer suction pad, so that air is sucked selectively in accordance with the outer diameter of the wafer to be held. Thus, by changing the suction area of the air every time the size of the wafer changes, wafers of various sizes can be appropriately held by suction by the wafer suction pad.


REFERENCES:
patent: 4448404 (1984-05-01), Ogawa et al.
patent: 4667944 (1987-05-01), Althouse
patent: 5324012 (1994-06-01), Aoyama et al.
patent: 5888127 (1999-03-01), Piper et al.
patent: 61-182738 (1986-08-01), None
patent: 2-46331 (1990-10-01), None
patent: 8-1464 (1996-01-01), None

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