Cleaning and liquid contact with solids – Apparatus – For work having hollows or passages
Reexamination Certificate
1999-02-19
2001-10-23
Coe, Philip R. (Department: 1746)
Cleaning and liquid contact with solids
Apparatus
For work having hollows or passages
C015S104030, C015S104050, C137S238000, C137S240000, C137S242000
Reexamination Certificate
active
06305392
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to processing liquid delivery systems for processing chambers, and more specifically to the removal of processing liquid from a processing liquid delivery line of a processing liquid delivery system.
BACKGROUND OF THE INVENTION
Many semiconductor processes such as chemical vapor deposition (CVD) employ vaporized processing liquids. These vaporized processing liquids are generated and supplied to a processing chamber via a processing liquid delivery system comprising an interconnection of pipes, valves, flow regulators and vaporizing mechanisms. Typically a separate vaporizing mechanism is provided for vaporizing each processing liquid, and is coupled to a source of processing liquid and a source of carrier gas. Although a number of vaporizing mechanisms exist (e.g., bubblers, injection valves, etc.), most conventional processing liquid delivery systems employ a plurality of injection valves for vaporizing processing liquids to be delivered to a processing chamber.
A typical injection valve comprises a processing liquid inlet for receiving a pressurized processing liquid, a carrier gas inlet for receiving a pressurized inert carrier gas, and an outlet for delivering a vaporized processing liquid/carrier gas mixture. The injection valve is heated such that when the processing liquid is injected into the carrier gas, the heat and the pressure difference between the two sides of the injection valve cause the processing liquid to vaporize.
Over time injection valves may clog or fail (e.g., due to deposit formation within the injection valve from the interaction of processing liquid with other processing chemicals or with the injection valve itself) and must be replaced. However, the process of injection valve replacement is complicated when the processing liquid vaporized by the injection valve reacts deleteriously with air (e.g., with moisture, oxygen, etc.) to form by-products (e.g., solid films such as oxides) that can damage the processing liquid delivery system or the processing chamber, contaminate subsequently processed semiconductor wafers or harm humans or the environment (e.g., are toxic).
To prevent deleterious processing liquid formation during injection valve replacement, if possible, processing liquid is purged from all processing liquid delivery lines that will be exposed to atmosphere when the clogged injection valve is removed. However, as described with reference to
FIG. 1
, within conventional processing liquid delivery systems the purging process is difficult, particularly when processing liquids with strong adhesive properties such as metal-organics (e.g., tetrakis(dimethylamino)titanium (TDMAT)) must be purged from processing liquid delivery lines.
FIG. 1
is schematic view of a conventional processing liquid delivery system
11
(“conventional system
11
”) for delivering vaporized processing liquid to a processing chamber
12
. The conventional system
11
comprises a source of processing liquid
13
operatively coupled (i.e., coupled either directly or indirectly so as to operate) to an injection valve
15
via a processing liquid delivery line
17
. Note that the processing liquid delivery line
17
is shown broken to indicate that the source of processing liquid
13
may be a substantial distance (e.g., about 10-15 feet) from the injection valve
15
.
Disposed along and forming a part of the processing liquid delivery line
17
are a first isolation valve
19
, a second isolation valve
21
, a liquid flow meter
23
and a third isolation valve
25
. The first isolation valve
19
is positioned near the source of processing liquid
13
, the third isolation valve
25
is positioned near the injection valve
15
, the liquid flow meter
23
is positioned near the third isolation valve
25
, and the second isolation valve
21
is positioned near the liquid flow meter
23
, as shown. A large number of other isolation valves typically are present along the processing liquid delivery line
17
but are omitted for clarity.
The conventional system
11
also comprises a source of purging gas
27
(e.g., nitrogen, argon, or some other gas which does not react with the processing liquid) operatively coupled to the processing liquid delivery line
17
via a purging gas line
29
, and a pump
31
(e.g., a mechanical pump) operatively coupled to the processing liquid delivery line
17
via a pump line
33
. Disposed along and forming a part of the purging gas line
29
is a purge valve
35
, and disposed along and forming a part of the pump line
33
is a pump valve
37
.
During normal operation of the conventional system
11
, the first isolation valve
19
, the second isolation valve
21
and the third isolation valve
25
are open to allow processing liquid to flow from the source of processing liquid
13
to the injection valve
15
at a rate controlled by the liquid flow meter
23
. The purge valve
35
and the pump valve
37
are closed to prevent processing liquid from being purged by the source of purging gas
27
and from being pumped by the pump
31
.
If the injection valve
15
subsequently becomes clogged and must be replaced, the injection valve
15
is isolated from the source of processing liquid
13
by closing the first isolation valve
19
. Assuming the processing liquid is a metal-organic substance such as TDMAT, the injection valve
15
cannot be directly disconnected from the conventional system
11
without posing a substantial health risk to the technician removing the injection valve
15
and without posing a substantial damage risk to the conventional system
11
. TDMAT, for instance, reacts with moisture in the air to form by-products that are harmful to humans (e.g. amines) and solid films (e.g., oxides) that will contaminate the entire conventional system
11
. Processing liquid, therefore, must be purged from the processing liquid delivery line
17
prior to removing the injection valve
15
.
To purge processing liquid from the processing liquid delivery line
17
, while the first isolation valve
19
is closed and the second isolation valve
21
and the third isolation valve
25
are open, the purge valve
35
and the pump valve
37
are opened. Purging gas thereby flows from the source of purging gas
27
, through the purging gas line
29
, through the processing liquid delivery line
17
and through the pump line
33
to the pump
31
. The purging gas dislodges processing liquid particles from the surfaces of the processing liquid delivery line
17
, and the dislodged particles are pumped from the processing liquid delivery line
17
via the pump
31
. Pump/purge cycles (wherein the purge valve
35
is closed for a time period while the pump
31
continues to pump processing liquid and purging gas from he processing liquid delivery line
17
, followed by a time period wherein the purge valve
35
is opened so as to introduce more purging gas to the processing liquid delivery line
17
) may be performed to aid in processing liquid removal from the processing liquid delivery line
17
.
For processing liquids having strong adhesive properties (e.g., metal-organics), the pump/purge process described above does not effectively removing processing liquid from the processing liquid delivery line
17
to a level sufficient to prevent deleterious by-product formation when the injection valve
15
is disconnected from the conventional system
11
. This is particularly true for TDMAT.
One approach to improving the purging effectiveness of the conventional system
11
is to employ thermal methods which heat the relevant processing liquid path to desorb processing liquid therefrom. Thermal methods, however, can damage rubber parts (e.g., valve seats), and can lead to decomposition of the processing liquid, generating particles and the problems associated therewith. Rubber parts, with added expense, can be designed to withstand thermal desorption temperatures. Decomposition, on the other hand, is unavoidable because processing liquid desorption and processing liquid decomposition may occur in the sa
Jackson Michael
Mandrekar Tushar
Tolia Anish
Applied Materials Inc.
Coe Philip R.
Dugan & Duan
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