Lid latch mechanism for clean box

Details Lid latch mechanism for clean box Lid latch mechanism for clean box

2000-04-27

2002-01-15

Ellis, Christopher P. (Department: 3651)

Material or article handling

Apparatus for moving material between zones having different...

For carrying standarized mechanical interface type

C414S217000, C414S937000, C414S938000, C414S939000

Reexamination Certificate

active

06338604

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a lid latch mechanism for a clean box for transferring and reserving various articles to be processed such as semiconductor wafers in a clean condition in a process for manufacturing semiconductors, electronic part related products, optical discs or the like.
2. Related Background Art
Recently, in a manufacturing process that requires a high level clean environment such as a semiconductor device manufacturing process, a method such as a mini-environment or a local clean space where an entire factory is not kept clean but only the ambient environment for products is kept under a clean condition has been adopted. In brief, only the interior of the respective processing apparatus is kept clean, which is used in the manufacturing process, and the transfer and reservation of the articles to be processed between the respective processing apparatus (clean apparatus) are performed by using containers (i.e., clean boxes) whose interior is kept clean.
The clean box is a substantially rectangular box body opened at one surface, and has a plate-like door (i.e., lid) for closing the opening. In the case where the article to be processed such as a semiconductor wafer received in the clean box is loaded into a processing apparatus, the loading operation is performed through an additional device called a load port, mounted on the processing apparatus. The load port is a device mounted on the processing apparatus for opening and closing the lid of the clean box while keeping the clean box and the interior of the processing apparatus under the clean condition and for making it possible to transfer the article to be processed such as a semiconductor wafer housed in the clean box into the interior of the processing apparatus. The load port is sometimes called an opener because it opens the lid of the clean box.
The clean boxes are categorized into two types in accordance with the types of the associated load ports, i.e., a bottom down type which is opened at the bottom surface, for taking out the housed article in the downward direction of the box and a side open type which is opened at a side surface of the clean box for taking out the housed article in the sideway.
An example of the bottom down type clean box is shown in
FIGS. 1A and 1B
.
FIG. 1A
is a side elevational cross-sectional view of the clean box and
FIG. 1B
is a plan view of the lid (door).
As shown in
FIG. 1A
, a clean box
100
is composed of a substantially square-shaped box body
101
opened at one side surface (a bottom surface in case of the bottom down type clean box shown in
FIGS. 1A and 1B
) and a lid
102
for closing the opening of the box body
101
. A shelf-like carrier
103
for holding the stacked semiconductor wafers to be received in the box at an equal interval is fixed above the lid
102
in the example shown in
FIGS. 1A and 1B
. A flange portion
101
a
expanded outwardly is provided around the bottom surface opening of the box body
101
into which the lid
102
is inserted/engaged.
An annular groove
110
for vacuum suction is formed in a circumferential edge portion of the surface (upper surface) facing the box body
101
of the lid
102
in the example shown in
FIGS. 1A and 1B
. O-rings used as elastic seal members are mounted along the inside and the outside of the annular groove
110
along the annular groove
110
, respectively. Under the condition that the lid
102
closes the opening of the clean box body
101
in
FIG. 2
, the suction space formed by the annular groove
110
and the flanged portion
101
a
of the box body
101
, i.e., a space of an interior of the annular groove
110
closed at its upper portion by the flanged portion
101
a
of the box body
101
is evacuated to thereby suck the lid
102
to the box body
101
. The evacuation is performed from the back side of the lid by a means (not shown) through a gas passage
112
provided in communication with the annular groove
110
. For instance, the vacuum suction method using such a suction groove is described in Japanese Patent Application Laid-Open No. 10-321696.
In such type clean box, there is provided a mechanical latch for preventing the falling off of the lid since there is a fear that the lid would be fallen off in the case where the vacuum suction is broken down due to leakage at the seal portion or the like.
Also, in a conventional clean box where the above-described vacuum suction groove is not provided, a seal member such as an O-ring is mounted so as to surround the opening of the box on the lid
102
or the box body flange portion
101
a.
Also in this case, although the latch mechanism for latching the lid to the box body is provided, the function of the latch mechanism is not only to prevent the lid from falling off but also to fix the lid to the body under the sealed condition by depressing the lid to the box body and deforming the seal member (O-ring) between the box body and the lid.
An example of the conventional lid latch mechanism to be used for both the clean box provided with the above-described vacuum suction annular groove and the clean box provided with no annular groove is shown in FIG.
2
.
FIG. 2
is a bottom view of the lid of the clean box
100
shown in
FIGS. 1A and 1B
.
The latch mechanism has a circular rotary cam plate
201
provided rotatably substantially at a center of the interior of the lid
102
. Two cam grooves
201
a
and
201
b
are formed in the rotary cam plate
201
. The latch mechanism also has slidable latch members
203
and
204
. The latch members
203
and
204
are slidable up and down under the guidance of guide members
206
and
207
. Cam pins
205
and
206
are implanted in the latch members
203
and
204
, respectively, and the cam pins
205
and
206
are engaged with the cam grooves
201
a
and
201
b
of the rotary cam plate
201
, respectively.
As shown in
FIG. 2
, the respective cam grooves
201
a
and
201
b
are formed into a shape such that a distance from the center of the rotary cam plate
201
is changed depending on the circumferential position thereof. The latch members
203
and
204
are moved up and down in
FIG. 2
in response to the clockwise and counterclockwise rotation of the rotary cam plate
201
in accordance with the cam shape. Thus, in response to the rotational position of the rotary cam plate
201
, the respective tip end portions
203
a
and
204
a
may take positions retracted and projected with respect to the circumference of the lid
102
.
In the case where the lid is mounted on the clean box body
101
, when the rotary cam plate
201
is rotated in the counterclockwise direction of
FIG. 2
so that the tip end portions
203
a
and
204
a
of the latch members are projected from the circumference of the lid
102
, the tip end portions are engaged with tabs or holes (not shown) formed in the clean box body
101
to thereby latch the lid
102
to the clean box body
101
. Inversely, when the rotary cam plate
201
is fully rotated clockwise, the latch members
203
and
204
are slid to the innermost position indicated by two-dot-and-dash lines in FIG.
2
. In this case, the tip end portions
203
a
and
204
a
of the latch members are retracted from the circumference of the lid to thereby release the engagement with the clean box body.
A latch drive portion
209
is provided at the center of the rotary cam plate
201
for rotatably driving the cam plate
201
. A pair of circumferential holes
201
c
are formed in the latch drive portion
209
.
A mechanism for opening/closing the above-described latch is provided in the load port for transferring the article to be processed within the clean box to the processing apparatus. A latch opening/closing mechanism having two pins that engage with the circumferential holes
201
c
of the above-described latch drive portion
209
of the latch mechanism is provided in the load port table on which the clean box
100
is laid on the load port. The pins are driven to rotate the latch drive portion
209
to thereby open/

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