Coating apparatus – Gas or vapor deposition – Multizone chamber
Reexamination Certificate
1999-02-18
2001-06-26
Mills, Gregory (Department: 1763)
Coating apparatus
Gas or vapor deposition
Multizone chamber
Reexamination Certificate
active
06251192
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vacuum exhaust system for use in evacuating a processing chamber for advanced products such as semiconductor devices, for example.
2. Description of the Related Art
A conventional arrangement of a vacuum exhaust system used in semiconductor device manufacturing processes to evacuate a processing chamber for carrying out such process as etching and chemical vapor deposition (CVD) of semiconductor wafers is shown in
FIG. 8. A
main chamber (processing chamber)
10
is connected on both sides to auxiliary chambers (load lock chambers)
12
a
,
12
b
, for loading and unloading purposes through respective gates
14
. Each auxiliary chamber
12
a
,
12
b
is isolated from, or open to, the external environment by a gate
15
.
The main chamber
10
is connected to a vacuum pump
18
through an exhaust path
16
having a valve
20
, and each auxiliary chamber
12
a
,
12
b
is connected similarly to a vacuum pump
24
through an exhaust path
22
having a valve
26
. It has been customary to use rotary oil pumps for the vacuum pumps
18
,
24
, but lately, dry pumps are used primarily for this type of work.
In this type of apparatus, in order to access the main chamber
10
while it is under vacuum, loading or unloading of a workpiece into the main chamber
10
requires that an auxiliary chamber
12
be evacuated first, and the gate
14
opened next so as to avoid exposing the main chamber
10
to external atmosphere. This is done to prevent the main chamber
10
and associated piping from contamination as well as to improve productivity by shortening the time for re-starting.
In such conventional systems, a vacuum pump is provided for each chamber to evacuate individual chambers, therefore, working efficiency of each vacuum pump is low. If the number of main chambers
10
is increased in an effort to raise productivity, it leads to a problem that the number of vacuum pumps needs to be increased, leading ultimately to a large size facility and higher running costs. If an attempt is made to shorten the time for evacuating the auxiliary chambers, a higher capacity for each pump is required, thus aggravating the above problems even further.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a vacuum exhaust system to enable as much sharing of vacuum pumps as possible, to improve the operating efficiency of the vacuum exhaust system while reducing the system cost, or to quickly attain a vacuum in the auxiliary chambers without increasing the size of the vacuum pumps.
The object has been achieved in a vacuum exhaust system for evacuating a main chamber and at least one associated auxiliary chamber comprising: a first pumping section; a second pumping section disposed downstream of and in series with the first pumping section; a main exhaust passage communicating the main chamber with a suction port of the first pumping section; at least one auxiliary exhaust passage communicating the auxiliary chamber with a suction port of the second pumping section.
Accordingly, the main chamber can be evacuated with two pumping sections arranged in series, and the auxiliary chambers are evacuated with one of the pumping sections, thereby increasing the operating efficiency of each pumping section while keeping the capacity of each pump as small as practicable.
The first and second pumping sections may share a common drive motor. Accordingly, one multi-stage vacuum pump can manage the task of evacuating an entire processing system so that the number of vacuum pumps can be reduced compared with a case of providing a vacuum pump for each auxiliary chamber. However, the first pumping section and the second pumping section may be provided with individual drive sections.
The pumping sections may be controlled so as to obtain a minimum fluctuation in pressure, according to a pressure measured inside the main chamber. Accordingly, pressure changes can be held to a minimum in the main chamber which is an important chamber for processing advanced products such as semiconductor devices.
Another aspect of the invention is a vacuum exhaust system for evacuating a main chamber and a plurality of associated auxiliary chambers, the plurality of auxiliary chambers having a connecting passage connecting each other which can be opened or closed to equalize pressure in the auxiliary chambers. Accordingly, vacuum environment present inside an auxiliary chamber can be utilized to lower the pressure of another auxiliary chamber which may be at an atmospheric pressure so that evacuation time can be significantly reduced to improve the operating efficiency of the overall evacuation operation.
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Kawamura Takeshi
Niimura Yasuhiro
Armstrong Westerman Hattori McLeland & Naughton LLP
Ebara Corporation
MacArthur Sylvia R.
Mills Gregory
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