Method to reduce the particles in load-lock chamber

Details Method to reduce the particles in load-lock chamber Method to reduce the particles in load-lock chamber

1999-04-06

2001-08-14

Gulakowski, Randy (Department: 1746)

Cleaning and liquid contact with solids

Processes

Using sequentially applied treating agents

C134S022120, C134S034000, C422S007000, C422S009000, C422S010000, C438S905000

Reexamination Certificate

active

06273962

ABSTRACT:

FIELD OF THE INVENTION
The present invention relations to a process chamber environment improvement, and more-particularly to a method to reduce the corrosive particle and/or corrosion in the load-lock chamber.
BACKGROUND OF THE INVENTION
Semiconductor devices are built from a number of different layers deposited sequentially. Hence the lithography techniques and etching process are two vital processes cooperate with deposition used to fabricate the desired pattern and so does a primitive or further device structure.
After the device wafers are processed with a photoresist layer and lithographed to obtain a desired photoresist pattern, the wafers are readied for etching. In an embodiment, the etching process is conducted in a Lam-Alliance series TCP 9400 process system, as shown in the FIG.
1
. It includes two load-lock chambers
10
, an orientation chamber
18
, a transfer module chamber
15
and a number of etching chambers
20
. The detailed arrangement of the load-lock chamber
10
is shown in the FIG.
2
. In
FIG. 2
the wafers had been loaded into a cassette
25
from a process chamber (not shown) before the cassette
25
was transfer to a load-lock chamber
10
. The load-lock chamber
10
includes a vacuum pump (not shown) to suck a level of vacuum coming down to about 90 mm torr before the wafers are proceeded to etch. While the vacuum level is about balance to that of the transferred module
15
, then a gate
35
of the load-lock chamber
10
is opened. After that, a wafer transfer arm
30
of the transfer module chamber
15
removes a single semiconductor wafer which is within a cassette
25
to an etching chamber
20
for processing i.e. removes the unmasked portions of the wafer via a orientation process in the orientation chamber
18
. Generally, the etching techniques consist of dry and wet etching methods. The Lam-Alliance series process system includes several dry etch chambers
20
. For performing a dry etching, the environment of the etching chamber
20
is set to maintain to an apt low pressure in accordance with the process requirement. Before the wafer is transferred into the etching chamber
20
, the N
2
purge to a vacuum level, which is the same vacuum as the transferred module
15
. After the etching process is achieved, the purge process to the same vacuum as the transferred module
15
, and then the transfer arm
30
withdraws the etched wafer to the original cassette
25
in the load-lock chamber
10
. A second wafer follows sequentially to proceed the etching process. The cassette
25
will not transferred from the load-lock chamber
10
to another process chamber till all wafers are etched away. In an embodiment, each batch of wafers is about twenty-five pieces of wafers.
After etching process is achieved, the gate
35
is closed and N
2
gas is flowed via an N
2
-purge tube
40
into the load-lock chamber
10
to vent the vacuum to the surrounding atmosphere. An another gate
38
of the load-lock chamber
10
is then opened and another transferred arm (not shown) withdraws the cassette
25
to proceed further processes. It is found that some of the corrosive particulate disperse onto the space and walls of the load-lock chamber, and cause the corrosion to occur before a regular cleaning the load-lock chamber
10
commences. The interval between regular cleaning is about processing two thousands piece of wafers, generally. For solving above corrosion and particulate/contamination issue, a conventional approach is by shortening the duty cycle. However, it will pull down the throughput. The invention provides an efficient method to solve above issues.
SUMMARY OF THE INVENTION
A method for preventing corrosion and particulate in a load-lock chamber is disclosed. The load-lock chamber is adjourning at least one etching chamber and a wafer transferred module, each time the wafer transferred module transfer a wafer in a cassette, which is in the load-lock chamber into the etching chamber to etch. After that, the etched wafer is withdrawn to the cassette. The load-lock chamber comprises a N
2
-purge tube with a outlet setting in the load-lock chamber for venting the pressure in the load-lock chamber to its surrounding atmosphere. The method comprises at least either step of coupling heating means to the N
2
-purge tube or heating N
2
gases before injecting into the N
2
-purge tube so that the temperature of the N
2
-purge tube is at least not lower than the temperature of the environment in the load-lock chamber. The higher temperature of N
2
-purge would efficiently prevent any residue etching gases carried by the etching chamber trapped thereon.


REFERENCES:
patent: 5378283 (1995-01-01), Ushikawa
patent: 6110232 (2000-08-01), Chen et al.

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