Handling: hand and hoist-line implements – Utilizing fluid pressure – Venturi effect
Reexamination Certificate
2000-07-07
2003-06-17
Jillions, John M. (Department: 3654)
Handling: hand and hoist-line implements
Utilizing fluid pressure
Venturi effect
C294S907000, C414S941000
Reexamination Certificate
active
06578891
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a substrate holder which is mounted on a substrate transfer apparatus, such as a robot, for holding and transferring a thin substrate such as a semiconductor wafer. The present invention also relates to a substrate transfer apparatus using the above-mentioned substrate holder.
FIGS.
1
(
a
)-
1
(
b
) show an arrangement of a conventional substrate holder of the above-mentioned type.
FIG. 1
a
is a plan view and FIG.
1
(
b
) is a side view. As shown in FIG.
1
(
a
), the conventional substrate holder comprises a substrate support member
100
including a base portion
101
and finger portions
102
extending from the base portion
101
in a bifurcated form. Each finger portion
102
includes a vacuum opening
103
at a forward end portion thereof Further, a vacuum passage
104
extends through the finger portion
102
so as to communicate with the opening
103
. The respective vacuum passages
104
of the finger portions
102
join at the base portion
101
and communicate with an opening
105
which in turn communicates with a vacuum system (not shown).
In the above-mentioned substrate holder, a substrate is held by means of suction. Illustratively stated, a thin substrate (not shown), such as a semiconductor wafer, is provided in the holder so that a central portion of a backside of the substrate abuts against the vacuum openings
103
of the finger portions
102
. A vacuum pressure is applied through the openings
103
, thus holding the substrate on the finger portions
102
. In FIG.
1
(
a
), reference numeral
106
denotes a bolt opening. The substrate holder is fixed to a forward end of a robot (not shown) by passing bolts through the openings
106
.
As mentioned above, in the conventional substrate holder, the central portion of the backside of the substrate is suctioned onto the finger portions
102
. Therefore, a problem arises, such that when breakage of a vacuum source occurs during transfer of a substrate, a vacuum pressure cannot be applied to the substrate, with the result that the substrate is likely to fall from the substrate holder and break. Further, particles floating in air are collected at the portion of the substrate to which the vacuum pressure is applied, leading to contamination of the substrate. These particles adversely affect the manufacture of chips for semiconductors and therefore the amount thereof should be minimized.
Further, when the speed of transfer (the speed of movement of the substrate holder) is increased so as to achieve a reduction in tact time, a force which horizontally moves the substrate becomes large, so that the substrate mounted on the holder is displaced. Therefore, the substrate cannot be delivered accurately to a target position, so that there is a risk of damage to the substrate.
In recent years, in semiconductor manufacturing apparatuses, it has been strongly desired to prevent contamination of semiconductor substrates. Conventionally, preventing only contamination of a patterned surface was satisfactory, but with a recent tendency to reduce wiring line widths of devices, contamination of the backside of a substrate has also become problematic. In a conventional substrate holder in which a suction is utilized, contaminants are collected at a portion of the substrate to which vacuum is applied from the holder, leading to a high risk of contamination.
As a measure to obviate the above-mentioned problem of contamination, it is considered to employ a recessed type substrate holder comprising a substrate support member having a recessed area for placing a semiconductor substrate therein. However, when a semiconductor substrate is removed from a cassette case, the semiconductor substrate is not always positioned at a regular position in the cassette case, that is, a position where the center of the substrate and the center of the cassette case coincide with each other. That is, the substrate can be displaced from the regular position in the cassette case. In this case, when use is made of a substrate holder having a portion formed in a certain configuration for receiving a substrate, such as the above-mentioned conventional substrate holder, defective transfer due to displacement of the substrate is likely to occur.
SUMMARY OF THE INVENTION
In view of the above, the present invention has been made. It is an object of the present invention to provide a substrate holder which is free from the above-mentioned problems. The substrate holder of the present invention is capable of suppressing contamination of a substrate due to particles, eliminating the risk of breakage of a substrate falling from the holder, receiving a substrate accurately even when it is displaced from a regular position and delivering the substrate accurately to a regular position. It is another object of the present invention to provide a substrate transfer apparatus using the above-mentioned substrate holder.
In accordance with the present invention, there is provided a substrate holder for holding and transferring a thin substrate, comprising a substrate support member having a recessed area for receiving a thin substrate therein and substrate mount portions formed in the recessed area in the vicinity of a circumferential edge thereof. The substrate mount portions are adapted to be engaged with an outer circumferential portion of a substrate placed in the recessed area. The substrate holder also includes a substrate detector for detecting presence or absence of the substrate in the recessed area.
In the substrate holder, there is little risk of displacement of the substrate and breakage of the substrate due to falling from the holder. Further, only the outer circumferential portion of the backside of the substrate abuts against the substrate mount portion, so that it is possible to suppress contamination of the substrate due to deposition of particles at a portion of the backside of the substrate which does not abut against the substrate mount portion.
The substrate detector may comprise at least one detection means selected from a first detection means and a second detection means and a second detection means. The first detection means includes a substrate detecting portion which is formed in the recessed area in the vicinity of a circumferential edge thereof. The substrate detecting portion has surface with which the outer circumferential portion of the backside of the substrate received in the recessed area is engaged, and a fluid passage is provided in the substrate holder and has an opening formed in the stated surface of the substrate detecting portion. The first detection means is adapted to detect presence or absence of the substrate by detecting a pressure in the stated opening. The second detection means is a non-contact type which detects presence or absence of the substrate in the recessed area without making contact with the substrate.
In the substrate holder, a fluid such as clean air or N
2
gas is flowed at a low rate through the opening of the fluid passage to the outside. The presence or absence of the substrate is detected by detecting whether or not a change in pressure occurs due to closing of the opening by the substrate. Differing from the conventional technique in which the presence or absence of the substrate is detected according to a change in vacuum pressure, in the substrate holder, there is no possibility of contamination of a substrate due to collection of particles floating in air. Further, when the detector is a non-contact type, such as a photoelectric sensor, the detector detects the presence or absence of the substrate in the recessed area without making contact with the substrate. This enables rapid detection of displacement of the substrate during transfer and is advantageous in preventing breakage of the substrate due to it falling from the holder. Further, when the opening of the fluid passage is connected to a vacuum source during transfer of the substrate, lifting of the substrate (hence displacement of the substrate) can be prevented. In this case, a high v
Ito Kenya
Sakurai Kunihiko
Suzuki Hiroo
Togawa Tetsuji
Wakabayashi Satoshi
Ebara Corporation
Jillions John M.
Wenderoth , Lind & Ponack, L.L.P.
LandOfFree
Substrate holder and substrate transfer apparatus using the... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Substrate holder and substrate transfer apparatus using the..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Substrate holder and substrate transfer apparatus using the... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3155088