Horizontally supported planar surfaces – Power driven
Reexamination Certificate
2000-04-28
2002-01-01
Chen, Jose V. (Department: 3636)
Horizontally supported planar surfaces
Power driven
Reexamination Certificate
active
06334398
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a variable gap stop arrangement for a driving unit which, as one example, moves a semiconductor wafer to a desired height within a semiconductor processing chamber.
2. Discussion of the Background
In the processing of semiconductor wafers, the semiconductor wafers are at various times placed inside a process chamber, a deposition chamber, etc. In those chambers the semiconductor wafers are subjected to different processings.
For example, within an etching processing chamber a semiconductor wafer is placed on a semiconductor support element, such as a chuck which also serves as a lower electrode. Positioned above the chuck is an upper electrode. Further, positioned circumferentially around the chuck and the upper electrode is a rotating magnet. The chuck, the upper electrode, and the rotating magnet generate a plasma used to etch the semiconductor wafer placed on the chuck.
In such an etching processing chamber, the semiconductor wafer must be positioned at a certain distance from the upper electrode. To achieve that operation the chuck on which the semiconductor wafer is mounted is moved up and down within the processing chamber by a drive system to a desired height below the upper electrode.
FIG. 1
shows a background drive system to position a chuck at a desired height in a semiconductor processing chamber.
FIG. 1
shows a cylinder
10
on which a chuck (not shown) is mounted, and a semiconductor wafer (not shown) is in turn secured on the chuck.
In
FIG. 1
, three drive screws
12
are provided which when rotated drive the cylinder
10
up and down. Formed around the three drive screws
12
is a drive chain (not shown) to rotate the three drive screws
12
, and the drive chain is in turn is driven by a motor (not shown).
With the drive system of
FIG. 1
an operator of the semiconductor processing equipment can set a desired height of a semiconductor wafer within a process chamber. Then, the motor drives the drive chain to in turn drive the three drive screws
12
, which in turn move the cylinder
10
to a desired height within a semiconductor processing chamber. Further, various sensors and feedback systems can be employed to monitor the height of the chuck within the processing chamber to ensure that the chuck supports the semiconductor wafer at the desired height. Thus, utilizing the drive system for the cylinder
10
supporting a chuck as shown in
FIG. 1
allows a semiconductor wafer to be replaced at a variable height within a processing chamber.
However, the chain drive system of
FIG. 1
suffers from several drawbacks for semiconductor processing. First, semiconductor processing requires extremely precise operations and also requires a very high level of cleanliness. The chain drive of
FIG. 1
has a drawback in that it often generates vibrations within the semiconductor equipment which may be detrimental to the semiconductor equipment. Further, the chain drive may require lubricants which could result in contaminants finding their way into the semiconductor equipment, and any contaminants in semiconductor equipment may result in contaminating a semiconductor wafer being processed.
An alternative system for positioning a semiconductor support element is shown in FIG.
2
.
FIG. 2
shows a chuck
21
on which a semiconductor wafer is secured. The chuck
21
in turn is supported by a cylinder
22
which moves up and down to pass through an upper support bracket
27
and a lower support bracket
25
. The cylinder
22
also includes a lower base
26
attached thereto to move with the cylinder
22
. The cylinder
22
may be a pneumatically air driven cylinder which moves upward and downward based on a control of an airflow, in a standard way.
To ensure that the chuck
21
is at an appropriate height within a processing chamber, the lower base
26
includes three stop screws
24
. The stop screws
24
may have an adjustable height, as shown by the shadow line in FIG.
2
. When the cylinder
22
is moved upward to move a semiconductor wafer secured on the chuck
21
into a processing chamber, the stop screws
24
will abut against a bottom of the lower support bracket
25
to stop the cylinder
22
at an appropriate position, which as a result stops the chuck
21
at an appropriate height within the processing chamber. An operator of semiconductor equipment including the drive system of
FIG. 2
may manually adjust the positioning of the stop screws
24
(as shown by the dashed line in the front shown stop screw
24
) to adjust the height at which the chuck
21
stops within the processing chamber. With such a device, the movement of the cylinder
22
is only stopped by the stop screws
24
abutting against the lower support bracket
25
.
The benefits of the drive system of
FIG. 2
with respect to the drive system of
FIG. 1
is that the drive system of
FIG. 2
does not require a chain drive and thus avoids the vibration and potential contamination of the chain drive system. A drawback with the drive system of
FIG. 2
is that it is more difficult and cumbersome for an operator to adjust the height of the cylinder
22
within the processing chamber since performing such an adjustment requires an operator to manually and properly adjust the position of the stop screws
24
.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a novel drive system, which may find particular application in semiconductor processing equipment, which provides the benefits of allowing a height of an object support to be varied.
A further object of the present invention is to provide a novel drive system, which may find particular application in semiconductor processing equipment, which allows a height of an object support to be easily varied by an operator, and without generating vibration and contaminants.
A further object of the present invention is to provide a novel drive system, which may find particular application in semiconductor processing equipment, which can be implemented in semiconductor processing equipment which utilizes a pneumatic cylinder drive unit for driving a chuck on which a semiconductor wafer is placed.
To achieve the above and other objects, the present invention sets forth a novel variable gap stop device which can stop the movement of a drive unit, such as a pneumatically driven cylinder which moves a chuck on which a semiconductor wafer is secured in a semiconductor processing equipment. In the present invention the drive unit includes at least one positioning surface. A movable gap stop unit includes at least one stop surface, and in a preferred embodiment may include two or more different stop surfaces each at a different height. A cylinder with a rod moves the movable gap stop unit to position at least one of the stop surfaces to be in and out of alignment with the at least one positioning surface of the drive unit.
With such a structure and operation in the present invention, the at least one positioning surface of the drive unit can abut against one of the plural stop surfaces of the movable gap stop unit. Based on which of the plural stop surfaces the positioning surface of the drive unit abuts against, a height that the drive unit moves the positioning surface can be controlled, e.g. the height that the cylinder moves the chuck, and consequently the height of the chuck within a semiconductor processing chamber, can be controlled.
Thereby, the structure in the present invention provides an easily executable control such that an object, such as a semiconductor wafer, can be easily and efficiently positioned at variable heights within a device, such as a processing chamber.
REFERENCES:
patent: 4602555 (1986-07-01), Bushey
patent: 5054991 (1991-10-01), Kato
patent: 5323712 (1994-06-01), Kikuiri
patent: 5467720 (1995-11-01), Korenaga et al.
patent: 5685232 (1997-11-01), Inoue
patent: 5920938 (1999-07-01), Iwanaga et al.
patent: 6040909 (2000-03-01), Hasegawa et al.
patent: 6097492 (2000-08-01), Kondo et al.
Eason, Jr. James A.
Hamelin Tom
Kent Marty
Chen José V.
Tokyo Electron Limited
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