Wafer holding hand

Details Wafer holding hand Wafer holding hand

2000-01-06

2001-04-17

Gibson, Jr., Robert W. (Department: 3634)

Supports: racks

Special article

Platelike

C118S728000, C206S454000, C414S941000

Reexamination Certificate

active

06216883

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a wafer holding hand and transporting it during semiconductor manufacturing process.
BACKGROUND ART
FIG. 11
is a top view showing an example of a conventional wafer holding hand.
FIG. 12
is a side view showing the wafer holding hand shown in FIG.
11
. The wafer holding hand
200
holds a plurality of wafers W, and it is constituted so that fingers
201
are laminated. A vacuum hole
202
is provided in the center of each finger
201
. Moreover, an air passage
203
for letting the air pass which is interconnected with the vacuum hole
202
is formed in the finger
201
. Adsorption surface
204
of the finger
201
is finished smoothly so that the wafer W is easily adsorbed. The fingers
201
are laminated with spacers
205
in between and are fixed and supported by a frame
206
. When the wafer W is placed on the finger
201
and air is sucked, a vacuum is created in the gap between the adsorption surface
204
and the wafer W, and both of them adsorb to each other. The adsorbed state between the wafer W and the adsorption surface
204
is released by stopping the suction of the air.
FIG. 13
is a top view showing another example of a conventional wafer holding hand.
FIG. 14
is a side view of the wafer holding hand shown in FIG.
13
. The wafer holding hand
300
has projections
302
along the shape of the wafer W on fingers
301
. A slope
303
towards an inner side is provided on the projection
302
. The wafer W is held by the projection
302
at the peripheral edge. A plurality of fingers
301
are laminated with spacers
304
in between and are fixed and supported by a frame
305
. When the wafer W is placed on the finger
301
, it moves along the slope
303
of the projection
302
to a predetermined position and held there.
However, in the wafer holding hand
200
shown in
FIGS. 11 and 12
, when the air suction is stopped, particles flow backward from the vacuum holes
202
. Therefore, there is a possibility that a rear surface of the wafer W which contacts with the adsorption surface
204
, and the wafer W on the down-stream side of the air current are contaminated. Moreover, there is a problem that the wafer W cannot be located properly on the finger
201
.
In the wafer holding hand
300
shown in
FIGS. 13 and 14
, the wafer W is positioned by the projection
302
, but since the wafer W is supported only by placing it on the projection
302
, the wafer W can be transported only in the horizontal direction. Moreover, there is a problem that the transporting speed cannot be increased in order to prevent the wafer W from jumping out.
In addition, in the wafer holding hands
200
and
300
, as a number of the fingers
201
and
301
and a number of the spacers
205
and
304
increase, a dimensional tolerance is accumulated. As a result, a tolerance of a distance between the bottommost finger and the topmost finger becomes larger, and thus mounting accuracy of the hand cannot be obtained.
Therefore, it is an object of the present invention to provide a wafer holding hand which is capable of preventing contamination of a wafer and simultaneously transporting the wafer freely, and capable of preventing drop of hand mounting accuracy.
DISCLOSURE OF THE INVENTION
The present invention provides a hand for holding a wafer comprising a plurality of plate-shaped fingers which are laminated; two fixed clamps provided at the tips of said finger, said fixed clamps having an approximately hook shape or approximately drum shape; a movable clamp provided on the fixed side of said finger, which movable clamp having an approximately drum shape or approximately hook shape; an elastic member for holding said movable clamp; and a slider for sliding said elastic member and said movable clamp, wherein said slider is moved and a wafer is sandwiched and held by said movable clamp and constrictions of said two fixed clamps.
Namely, when the wafer is placed on the finger and the movable clamp is moved, the wafer is fixed by the fixed clamp and a constriction of the movable clamp. In such a manner, the wafer is held at three points with the help of the fixed clamps and the movable clamp. Since the movable clamp is supported by the elastic member, a pressure required for holding the wafer is changed by a slider moving amount. In this structure, since the wafer can be held securely, it can be transported on a processing line freely. Moreover, since air is not directly used, the wafer can be prevented from being contaminated.
In addition, in the present invention, a predetermined number of the fingers are fixed to a bracket, and the fingers are mounted to a frame by means of the brackets so that a plurality of the fingers are overlapped.
Namely, when the fingers are mounted to the frame by means of the brackets, an increase in an accumulated dimensional tolerance of the fingers can be suppressed.
In addition, in the present invention, the elastic member is formed from two plate springs, and the plate springs are provided parallel with each other between the slider and the movable clamp.
Namely, when the two plate springs are provided, they move like a link, and thus a force applying direction of the movable clamp can be kept approximately constant.
In addition, in the present invention, the elastic member is provided for each of the fingers.
If a common elastic member is used for a plurality of wafers, when dimensions of the wafers are scattered and a number of wafers is small, an excessive holding force is applied to the wafers. Therefore, the elastic member is provided for each of the fingers so that an excessive holding force is prevented from being applied to the wafers.


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