Material or article handling – Chamber of a type utilized for a heating function and... – Charging of chamber
Reexamination Certificate
1996-06-04
2001-11-20
Werner, Frank E. (Department: 3652)
Material or article handling
Chamber of a type utilized for a heating function and...
Charging of chamber
C454S187000, C432S239000, C118S719000, C414S217000, C414S416080, C414S937000, C414S939000, C414S940000, C414S936000, C414S754000, C414S283000, C414S416030
Reexamination Certificate
active
06318944
ABSTRACT:
TECHNICAL BACKGROUND
The present invention relates to a semiconductor fabricating apparatus for producing a semiconductor device by depositing a thin film on a silicon wafer or by subjecting the latter to an impurity diffusion treatment, etc., to a method for modifying the positional displacement of a wafer in a wafercassette within the semiconductor fabricating apparatus, and to a method for transferring the wafer cassette.
Referring to
FIGS. 9 and 10
, a conventional semiconductor fabricating apparatus will now be described.
The apparatus includes a housing
1
in which a cassette transfer unit
2
is provided at a front side thereof for achieving the transfer of a wafer cassette
11
between the apparatus and an external transfer system. Behind the cassette transfer unit
2
, there is provided a cassette transfer device
3
. Provided behind the cassette transfer device
3
is a cassette storage
4
. A buffer storage
5
is disposed upwardly of the cassette storage
4
. Behind the buffer storage
5
, there is provided a clean unit
6
. Disposed at a rear upper part of the housing
1
is a vertical reaction furnace
7
. Below the reaction furnace
7
, there is provided a boat elevator
9
for introducing into and withdrawing from the furnace
7
a boat
8
. Between the boat elevator
9
and the cassette storage
4
, there is provided a wafer transfer device
10
. Reference numeral
25
designates a clean unit.
The cassette transfer device
3
is supported on a drive portion
24
which can move upward, downward and in a horizontal direction. The cassette transfer device
3
includes a cassette loader
13
which is designed to rotate about a horizontal axial center
15
by approximately 90°. The cassette loader
13
also includes a cassette transfer plate
16
capable of back and forth movements and a cassette receiver
17
disposed perpendicularly to the cassette transfer plate
16
.
Each of the cassette storage
4
and the buffer storage
5
has plural rows of cassette shelves (three rows of three shelves shown in the figures) . The number of the shelves is at least greater than the number of wafer cassettes required for single batch processing.
The wafer transfer device
10
comprises a rotary stage
18
which can move upward and downward and rotate and a wafer chuck
19
capable of advancing and retracting movements mounted on the rotary stage
18
. The wafer chuck
19
includes plural chuck plates
20
arranged vertically.
The boat elevator
9
includes a boat receiver plate
21
which can move upward and downward for supporting the boat
8
thereon.
The reaction furnace
7
is comprised of a cylindrical heater
22
and a reaction tube
23
located internally of the heater
22
and forming a reaction chamber which is sealingly closed by the full insertion of the boat
8
.
The wafer cassette
11
loading wafers
12
is transferred from the external transfer system to the cassette transfer unit
2
in an upwardly-oriented position. Then, the transferred wafer cassette
11
is held by the cassette transfer device
3
and transferred from the cassette transfer unit
2
to the cassette storage
4
after it is rotated by 90° to be brought to a horizontal position.
The wafer transfer device
10
effects the transfer of the wafers
12
between the cassette storage
4
and the boat
8
.
By the upward and downward movements and rotation of the rotary stage
18
, the wafer chuck
19
is brought to oppose the wafer cassette
11
to be transferred. Then, by the forward and backward movements of the wafer chuck
19
, the wafers
12
are chucked by the chuck plate
20
. Thereafter, the chucked wafers
12
are sequentially loaded onto the boat
8
through the upward and downward movements and rotation of the rotary stage
18
and the forward and backward movements of the wafer chuck
19
. Within a predetermined range at the upper and lower portions of the boat
8
, there are provided dummy wafers as well as monitor wafers at predetermined intervals.
When the loading of the wafers onto the boat
8
is completed, the boat elevator
9
introduces the boat
8
into the reaction furnace
7
for treatment of the wafers.
The treated wafers are loaded back onto the wafer cassette backwardly following the wafer cassette transfer procedure described above, whereafter the wafer cassette is taken out again following backwardly the wafer cassette transfer procedure. The dummy wafers are used repeatedly. Thus, no transfer operations are conducted with respect to the dummy wafers when the semiconductor fabricating apparatus is in operation.
In the described conventional semiconductor fabricating apparatus, the cassette storage
4
and the buffer storage
5
are both arranged to accommodate the wafer cassettes
11
in horizontally-oriented positions.
Further, as described above, the dummy wafers are used repeatedly within the semiconductor fabricating apparatus and thus undergo repeated transfer operations between the boat
8
and the wafer cassettes in the cassette storage
4
. As a result, it is likely that the dummy wafers are positionally displaced with respect to the wafer cassette
11
due to transfer errors and vibrations to occur during transfer of the wafers
12
. Such positional displacement of the dummy wafers may accumulates and exceed the tolerable level.
If such positional displacement of the wafers exceeds the tolerable level, such troubles as impossibility of wafer transfer, damaging of the wafers and down-fall of the boat may result. This may further lead to the stoppage of the apparatus, thus lowering the serviceability ratio of the apparatus. Apart from this, since cleanliness within the semiconductor fabricating apparatus significantly affects the treatment quality of the wafers, improved cleanliness within the apparatus has been desired.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a semiconductor fabricating apparatus wherein the positional displacement of dummy wafers relative to wafer cassettes, which results from the repeated use of the dummy wafers, is prevented by modifying such displacement at a predetermined time to thereby avoid such accidents as failures to transfer wafers and dummy wafers, damaging of the wafers and down-fall of boats and hence to increase the rate of operation of the apparatus. Another object of the present invention is to provide a semiconductor fabricating apparatus wherein a cassette storage and a buffer storage have increased accommodation capacity. Still another object of the present invention is to provide a semiconductor fabricating apparatus in which a stream of uniform clean air flows through the apparatus to prevent inside air from remaining therein, whereby cleanliness within the apparatus is improved. According one aspect of the present invention, there is provided a semiconductor fabricating apparatus which comprises a plurality of cassette shelves capable of loading wafer cassettes in upwardly-oriented positions. In a preferred form of the invention, the semiconductor fabricating apparatus further comprises a cassette transfer unit, a cassette transfer device and a storage in order seen from the front side of an internal of a housing, wherein the cassette shelves capable of loading wafer cassettes in upwardly-oriented positions are provided upwardly of the cassette transfer unit. According to another aspect of the present invention, there is provided a semiconductor fabricating apparatus comprising a vertical reaction furnace, a boat for holding plural wafers in a multi-layered fashion and being loaded into the vertical reaction furnace, a storage disposed at a location corresponding to the boat for storing at least one of the wafer cassettes, a wafer transfer device for transferring the wafer between the storage and the boat, a cassette transfer unit for transferring the wafer cassettes between the apparatus and outside thereof, a cassette transfer device for transferring the wafer cassettes between the cassette transfer unit and the storage, and a plurality of cassette shelves disposed within a r
Ohba Shigeo
Shimeno Kazuhiro
Tometsuka Kouji
Kokusai Electric Co. Ltd.
Morrison & Foerster / LLP
Werner Frank E.
LandOfFree
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