Title: Cooling apparatus and plasma processing apparatus having cooling apparatus
Abstract: a cooling apparatus 110 comprises a primary refrigerant circulating circuit which allows a primary refrigerant CW1 whose temperature is adjusted by a heat exchanger 138 to circulate through an electrode to adjust a temperature of the electrode, a secondary refrigerant circulating circuit which supplies a secondary refrigerant CW2 to the heat exchanger to adjust the temperature of the primary refrigerant, and a freezing circuit 140 which has a first heat exchanger 141 interposed in the secondary refrigerant circulating circuit and which adjust a temperature of the secondary refrigerant by a tertiary refrigerant. The temperature of the primary refrigerant is adjusted by the secondary refrigerant without adjusting the temperature using the freezing circuit. When a temperature of the primary refrigerant is set higher than that of the secondary refrigerant, the temperature of the primary refrigerant can be adjusted only by the secondary refrigerant. Only when the temperature of the primary refrigerant is set lower than that of the secondary refrigerant, the temperature of the secondary refrigerant is adjusted by the freezing circuit and thus, it is possible to save energy.
Patent Number: 7,000,416 Issued on 02/21/2006 to Hirooka, et al.
| Inventors:
|
Hirooka; Takaaki (Yamanashi, JP);
Furuya; Masao (Yamanashi, JP)
|
| Assignee:
|
Tokyo Electron Limited (Tokyo, JP)
|
| Appl. No.:
|
432888 |
| Filed:
|
November 29, 2001 |
| PCT Filed:
|
November 29, 2001
|
| PCT NO:
|
PCT/JP01/10430
|
| 371 Date:
|
May 29, 2003
|
| 102(e) Date:
|
May 29, 2003
|
| PCT PUB.NO.:
|
WO02/44634 |
| PCT PUB. Date:
|
June 6, 2002 |
Foreign Application Priority Data
| Nov 30, 2000[JP] | 2000-364339 |
| Current U.S. Class: |
62/259.2; 62/117; 62/185; 62/498; 62/434; 62/3.1; 62/3.2; 62/3.7; 219/120; 361/688; 361/689; 165/104.19 |
| Current Intern'l Class: |
F25D 23/12 (20060101); F25B 5/00 (20060101); F25B 21/02 (20060101); H05K 7/20 (20060101); F28D 15/00 (20060101) |
| Field of Search: |
62/2592,434,117,498,DIG.10,31-37,185
219/120
165/104.19
361/688,689
|
References Cited [Referenced By]
U.S. Patent Documents
| 5153405 | Oct., 1992 | Umeda.
| |
| 5376213 | Dec., 1994 | Ueda et al.
| |
| 6148626 | Nov., 2000 | Iwamoto.
| |
| 6247531 | Jun., 2001 | Cowans.
| |
| 6334311 | Jan., 2002 | Kim et al.
| |
| 6427462 | Aug., 2002 | Suenaga et al.
| |
| 6658861 | Dec., 2003 | Ghoshal et al.
| |
| 6705095 | Mar., 2004 | Thompson et al.
| |
| 2002/0020189 | Feb., 2002 | Namose.
| |
| Foreign Patent Documents |
| 61-38382 | Feb., 1986 | JP.
| |
| 05-039988 | Feb., 1993 | JP.
| |
| 07-201956 | Aug., 1995 | JP.
| |
| 11-183005 | Jul., 1999 | JP.
| |
| 11-294927 | Oct., 1999 | JP.
| |
| 2000-58514 | Feb., 2000 | JP.
| |
| 2000/-058517 | Feb., 2000 | JP.
| |
Primary Examiner: Jones; Melvin
Assistant Examiner: Zec; Filip
Attorney, Agent or Firm: Finnegan, Henderson, Farabow, Garrett & Dunner, LLP
Claims
What is claimed is:
1. A cooling apparatus comprising:
a primary refrigerant circulating circuit which allows a primary refrigerant
whose temperature is adjusted by a heat exchanger to circulate into an electrode
and adjusts a temperature of said electrode, and which has a first check valve
for allowing said primary refrigerant to flow into said electrode, a second check
valve allowing said primary refrigerant to flow out from said electrode, and a
purge valve capable of bringing said primary refrigerant into communication with
a purge gas path,
a secondary refrigerant circulating circuit which supplies a secondary refrigerant
to said heat exchanger to adjust a temperature of said primary refrigerant, and
a freezing circuit through which a tertiary refrigerant circulates said heat
exchanger being interposed in said secondary refrigerant circulating circuit, said
freezing circuit adjusting a temperature of said secondary refrigerant by said
tertiary refrigerant, a temperature detector for detecting temperatures of said
primary refrigerant and said secondary refrigerant, and a control system for actuating,
only when necessary, said freezing circuit in accordance with a detected temperature
value of at least one of said primary refrigerant and said secondary refrigerant,
wherein the freezing circuit is configured to not operate when the cooling apparatus
is in an energy-saving mode.
2. A cooling apparatus according to claim 1, wherein said control system is configured
to actuate said freezing circuit when a temperature of said primary refrigerant
is set lower than the detected temperature value of said secondary refrigerant.
3. A cooling apparatus according to claim 1, wherein said control system is configured
to detect an upstream temperature of said electrode of said primary refrigerant
circulating circuit, and adjust a flow rate of said secondary refrigerant which
circulates in the secondary refrigerant circulating circuit in accordance with
the detected temperature value.
4. A plasma processing apparatus having a cooling apparatus according to claim 1.
5. A plasma processing apparatus having a cooling apparatus according to claim 2.
6. A plasma processing apparatus having a cooling apparatus according to claim 3.
7. A cooling apparatus according to claim 1, wherein a second control system
is configured to prevent the freezing circuit from operating when the cooling apparatus
is the energy-saving mode.
8. A plasma processing apparatus having a cooling apparatus according to claim 7.
9. A cooling apparatus comprising:
a primary refrigerant circulating circuit which allows a primary refrigerant
whose temperature is adjusted by a heat exchanger to circulate into an electrode
and adjusts a temperature of said electrode, and which has a first check valve
for allowing said primary refrigerant to flow into said electrode, a second check
valve allowing said primary refrigerant to flow out from said electrode, and a
purge valve capable of bringing said primary refrigerant into communication with
a purge gas path,
a secondary refrigerant circulating circuit which supplies a secondary refrigerant
to said heat exchanger to adjust a temperature of said primary refrigerant, and
a freezing circuit through which a tertiary refrigerant circulates said heat
exchanger being interposed in said secondary refrigerant circulating circuit, said
freezing circuit adjusting a temperature of said secondary refrigerant by said
tertiary refrigerant, a temperature detector for detecting temperatures of said
primary refrigerant and said secondary refrigerant, and a control system for actuating,
only when necessary, said freezing circuit in accordance with a detected temperature
value of at least one of said primary refrigerant and said secondary refrigerant,
wherein a second control system is configured to prevent the freezing circuit
from operating when the cooling apparatus is an energy-saving mode.
10. A cooling apparatus according to claim 9, wherein said control system is
configured to actuate said freezing circuit when a temperature of said primary
refrigerant is set lower than the detected temperature value of said secondary refrigerant.
11. A cooling apparatus according to claim 9, wherein said control system is
configured to detect an upstream temperature of said electrode of said primary
refrigerant circulating circuit, and adjust a flow rate of said secondary refrigerant
which circulates in the secondary refrigerant circulating circuit in accordance
with the detected temperature value.
12. A plasma processing apparatus having a cooling apparatus according to claim 9.
13. A plasma processing apparatus having a cooling apparatus according to claim 10.
14. A plasma processing apparatus having a cooling apparatus according to claim 11.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a cooling apparatus and a plasma processing
apparatus having the cooling apparatus.
DESCRIPTION OF THE RELATED ART
Conventionally, in a producing procedure of a semiconductor device
or an LCD substrate, various processing apparatuses such as a plasma etching apparatus
are used. For example, a plasma etching apparatus brings predetermined processing
gas in a vacuum processing chamber into plasma state, and subjects a substrate
such as a semiconductor wafer or a glass substrate placed on a mounting stage to
etching processing. At the time of processing, the plasma etching apparatus maintains
the substrate at a predetermined temperature in order to restrain a temperature
rise of the substrate by the plasma or enhance the aspect ratio of the etching
or even up the etching shapes.
Generally, a cooling mechanism provided on a mounting stage manages a
temperature of the substrate. The cooling mechanism sends a refrigerant (e.g.,
Galden: trade name) into a refrigerant circulating passage disposed in the mounting
stage, and refrigerant absorbs heat to cool the substrate. A refrigerant in a refrigerant
tank whose temperature is adjusted by a freezing circuit is sent into a refrigerant
circulating passage by a pump, and the refrigerant returned from the refrigerant
circulating passage is adjusted in temperature by the freezing circuit and sent
into the refrigerant tank. A temperature of the refrigerant sent into the refrigerant
tank or the refrigerant circulating passage from the refrigerant tank is monitored
and the temperature is controlled such that the temperature becomes equal to a
predetermined value.
When a refrigerant for cooling an electrode of the processing apparatus is adjusted
in temperature by the freezing circuit, the freezing circuit is operated in association
with the temperature control, and the freezing circuit keeps operating irrespective
of whether there is a load as long as a temperature setting is not changed.
In accordance with the processing procedure, a temperature of the substrate is
set to a low value (e.g., set in a range of -10° C. to +60° C.) or to
a high value (e.g., in a range of +30° C. to +100° C.). When the refrigerant
is excessively cooled such as when the temperature is adjusted to a high value
after a low value, a temperature is adjusted such that refrigerant cooled by the
freezing circuit is again heated by a heater in some cases. In such a case, electricity
is consumed twice by the freezing circuit and the heater, which hinders energy-conservation.
SUMMARY OF THE INVENTION
The present invention has been accomplished in view of the above problem of the
conventional electrode cooling apparatus of the processing apparatus. It is an
object of the invention to provide a new and improved electrode cooling apparatus
of a processing apparatus capable of save energy without directly adjusting a temperature
of a refrigerant (e.g., Galden: trade name) which cools an electrode of the processing
apparatus by the freezing circuit.
To achieve the above object, the present invention provides a cooling apparatus
and a plasma processing apparatus having the cooling apparatus comprising a primary
refrigerant circulating circuit which allows a primary refrigerant whose temperature
is adjusted by a heat exchanger to circulate into an electrode and adjusts a temperature
of said electrode, and which has a first check valve for allowing said primary
refrigerant to flow into said electrode, a second check valve allowing said primary
refrigerant to flow out from said electrode, and a purge valve capable of bringing
it into communication with a purge gas path, a secondary refrigerant circulating
circuit which supplies a secondary refrigerant to said heat exchanger to adjust
a temperature of said primary refrigerant, a freezing circuit through which a tertiary
refrigerant circulates said heat exchanger being interposed in said secondary refrigerant
circulating circuit, said freezing circuit adjusting a temperature of said secondary
refrigerant by said tertiary refrigerant, a temperature detector for detecting
temperatures of said primary refrigerant and said secondary refrigerant, and a
control system for actuating, only when necessary, said freezing circuit in accordance
with a detected temperature value of at least one of said primary refrigerant and
said secondary refrigerant.
According to such a structure, a temperature of the primary refrigerant
(e.g., Galden: trade name) which cools the electrode of the processing apparatus
is adjusted by the secondary refrigerant (e.g., cooling water) without adjusting
the temperature using the freezing circuit. Therefore, when a temperature of the
primary refrigerant is set higher than that of the secondary refrigerant, the temperature
of the primary refrigerant can be adjusted only by the secondary refrigerant. Only
when the temperature of the primary refrigerant is set lower than that of the secondary
refrigerant, the temperature of the secondary refrigerant is adjusted by the freezing
circuit. Therefore, it is possible to save energy remarkably as compared with the
conventional technique in which the freezing circuit is always actuated and the
temperature is adjusted by the heater. A range of controllable temperature is not
changed by variation in environment such as season.
Further, it is preferable that said control system is configured to actuate
said freezing circuit when a temperature of said primary refrigerant is set lower
than the detected temperature value of said secondary refrigerant. Since it is
possible to control the amount of heat of the flow rate of the primary refrigerant
or the secondary refrigerant while performing the feed back control such that the
temperature follows the target adjusted temperature, it is possible to manage the
temperature of the substrate more strictly.
It is preferable that said control system is configured to detect an upstream
temperature of said electrode of said primary refrigerant circulating circuit,
and adjust a flow rate of said secondary refrigerant which circulates in the secondary
refrigerant circulating circuit in accordance with the detected temperature value.
Since it is possible to control the amount of heat or the flow rate of the secondary
refrigerant or the tertiary refrigerant while performing the feed back control
such that the temperature follows the target adjusted temperature, it is possible
to manage the temperature of the substrate more strictly.
Further, it is preferable that the primary refrigerant circulating circuit
comprises a first check valve which allows the primary refrigerant to flow into
the electrode, a second check valve which allows the primary refrigerant to flow
out from the electrode, and a purge valve which is connected to a downstream side
of the first check valve and which is capable of bringing the primary refrigerant
circulating circuit into communication with a purge gas path. At the time of over
load of the primary refrigerant, if the primary refrigerant circulating circuit
is brought into communication with the purge gas path, it is possible to easily
control the flow rate of the primary refrigerant. By removing the primary refrigerant
in the primary refrigerant circulating circuit using the purge gas, it is possible
to easily perform maintenance of the electrode.
As described above, the present invention is especially effective when the temperature
of the primary refrigerant is set higher than that of the secondary refrigerant.
That is, when the target adjusted temperature of the electrode is, for example,
30° C. to 100° C., it is possible to adjust the temperature of the primary
refrigerant only by the secondary refrigerant, it is unnecessary to actuate the
freezing circuit, and it is possible to save energy.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic sectional view of an etching apparatus and a cooling apparatus.
FIG. 2 is a flowchart for explaining temperature control of a refrigerant of
the etching apparatus shown in FIG. 1.
FIG. 3 is a table for collectively explaining adjustable temperatures at the
time of low temperature setting and high temperature setting, and operations of
a primary refrigerant, a secondary refrigerant and a freezing circuit.
FIG. 4 are diagrams for explaining vertically arranged a plurality of cooling apparatuses.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of a cooling apparatus and a plasma processing apparatus
having the cooling apparatus according to the present invention will be explained
in detail with reference to the accompanying drawings below. In the specification
and the drawings, constituent elements having substantially the same functions
are designated with the same symbols, and redundant explanation will be omitted.
(1) Structure of a Plasma Etching Apparatus
100
First, a plasma etching apparatus
100 will be explained as one example
of a processing apparatus with reference to FIG. 1.
A lower electrode
106 on which a semiconductor wafer (simply wafer, hereinafter)
W can be placed is disposed in a processing chamber
104 formed in a hermetic
processing container
102. Refrigerant circulating passages
108 for
cooling the wafer W through the lower electrode
106 to maintain a temperature
of the wafer W at a predetermined value are disposed in the lower electrode
106.
A cooling apparatus
110 is connected to the cooling circulating passages
108. The cooling apparatus
110 supplies a primary refrigerant (e.g.,
Galden: trade name) CW
1 which is adjusted in temperature into the refrigerant
circulating passages
108, and recovers the primary refrigerant CW
1
which circulates in the refrigerant circulating passages
108 and again adjusts
its temperature. A structure of the cooling apparatus
110 and control of
temperature of the primary refrigerant CW
1 will be described later.
Upper electrodes
112 which are opposed to a placing surface of the lower
electrode
106 are disposed in the processing chamber
104. With such
a structure, if high frequency electric power output from a high frequency power
supply
114 is applied to the lower electrode
106 through a matching
device
116, processing gas which was introduced into the processing chamber
104 from a processing gas supply source G
118 through a flow-rate
adjusting valve MFC
120 and a large number of gas discharging holes
112a
formed in the upper electrodes
112 is brought into plasma state. With
the plasma, the wafer W whose temperature is maintained on the lower electrode
106 is subjected to the etching processing. Gas in the processing chamber
104 is exhausted from an exhausting system
122.
(2) Structure of Cooling Apparatus
110
Next, the structure of the cooling apparatus (simply cooling apparatus, hereinafter)
110 for the lower electrode
106 of the plasma etching apparatus
100
will be explained. The cooling apparatus
110 is roughly divided into three
circuits, i.e., a circulating circuit of a primary refrigerant which adjust a temperature
of the lower electrode
106, a circulating circuit of a secondary refrigerant
which adjusts a temperature of the primary refrigerant, and a freezing circuit
(circulating circuit of a tertiary refrigerant) which adjusts a temperature of
a secondary refrigerant.
First, the circulating circuit of the primary refrigerant will be explained.
The primary refrigerant (e.g., Galden: trade name) CW
1 whose temperature
is adjusted is accumulated in a refrigerant tank
124. A heater
126
for adjusting a temperature of the primary refrigerant CW
1 is provided in
the refrigerant tank
124. The primary refrigerant CW
1 in the refrigerant
tank
124 is pressurized by a pump
130, and is sent to the refrigerant
circulating passage
108 in the lower electrode
106 through a refrigerant
supply pipe
132. A first temperature detector Th
1 for detecting a
temperature of the primary refrigerant CW
1 whose temperature is adjusted
in the refrigerant tank
124, and a first check valve
133 which allows
the primary refrigerant CW
1 to flow into the lower electrode
106
from the cooling apparatus
110 are interposed in the refrigerant supply
pipe
132.
If a flow rate of the primary refrigerant CW
1 flowing through the refrigerant
supply pipe
132 is monitored and its value is fed-back to the pump
130
and the pump
130 is controlled in an inverter manner, it is possible to
always supply the constant primary refrigerant CW
1 to the refrigerant circulating
passage
108. It is also possible to give an alarm when the flow rate of
the primary refrigerant CW
1 is reduced due to leakage of the primary refrigerant
CW
1 from a joint portion. If an immersion type volute pump which embeds
an impeller in the refrigerant tank
124 is used as the pump
130,
it becomes unnecessary to seal a driving section (motor) and the reliability can
be enhanced.
The first temperature detector Th
1 detects a temperature of the primary
refrigerant CW
1 whose temperature is adjusted in the refrigerant tank
124.
A detected temperature value detected by the first temperature detector Th
1
is transmitted to a first control system (not shown). The first control system
controls the driving operation of a secondary refrigerant circulating circuit which
adjust a temperature of the primary refrigerant CW
1 in accordance with the
detected temperature value detected by the first temperature detector Th
1.
Since it is possible to control an amount of heat or flow rate of the primary refrigerant
CW
1 or the secondary refrigerant CW
2 while feed-back controlling
such that the temperature follows a target adjusted temperature, it is possible
to further strictly manage the temperature of the substrate.
The primary refrigerant CW
1 which circulated through the refrigerant circulating
passage
108 is returned into the cooling apparatus
110 through the
refrigerant discharging pipe
136. A second check valve
137 which
permits the primary refrigerant CW
1 to flow into the cooling apparatus
110
from the lower electrode
106 is interposed in the refrigerant discharging
pipe
136. Heat of the primary refrigerant CW
1 returned to the cooling
apparatus
110 is exchanged with the secondary refrigerant (e.g., cooling
water) CW
2 by the heat exchanger
138 and then the primary refrigerant
CW
1 is accumulated in the refrigerant tank
124 again.
It is preferable that a conductive Teflon hose is used as at least a portion
of
the refrigerant supply pipe
132 or the refrigerant discharging pipe
136
which connects the cooling apparatus
110 and the plasma etching apparatus
100 with each other. That is, insulative Teflon hose, rubber hose, stainless
hose and the like are conventionally used as a hose (pipe) for guiding perphloro
carbon fluid such as the Galden or Florinate (trade name). However, the insulative
Teflon hose has a problem that static electricity is generated by friction between
Teflon and the PerFluoro Carbon fluid and a pin hole is adversely formed in the
hose. If the rubber hose is used, however, there is a problem that plasticizer
is deposited from the hose by the PerFluoro Carbon fluid, the hose is hardened
and the hose is pulled off. On the other hand, the stainless hose has a problem
that pipe friction coefficient is large. Thereupon, in this embodiment, using a
conductive Teflon hose (e.g., R276 produced by Tokatsu Industry Inc.) in which
Teflon including carbon is incorporated in a stainless tube, thereby preventing
electric charge by friction with respect to the PerFluoro Carbon fluid, and solving
the problem that the pin hole is formed in the hose. In this manner, the refrigerant
supply pipe
132 and the refrigerant discharging pipe
136 are formed
of Teflon having excellent heat insulating coefficient in a high heat-insulation
manner and in a flexible manner.
A second temperature detector Th
2 for detecting a temperature of the primary
refrigerant CW
1 after its heat is exchanged with the secondary refrigerant
CW
2 by the heat exchanger
138 is provided upstream of the refrigerant
tank
124. In this manner, the amount of heat or the flow rate of the primary
refrigerant CW
1 or the secondary refrigerant CW
2 can be controlled
in a feed-back control manner such that the temperature of the refrigerant follows
the target adjusted temperature. Therefore, it is possible to manage the temperature
of the substrate more strictly.
A purge valve
135 capable of bringing the refrigerant supply pipe
132
into communication with a purge gas path is provided downstream of the first check
valve
133. Air or N
2 gas is used as the purge gas. By bringing
the refrigerant supply pipe
132 into communication with the purge gas path,
purge is carried out by air and N
2 gas. With this structure, at the
time of over load of the primary refrigerant CW
1, it is possible to easily
control the flow rate of the primary refrigerant CW
1 by bringing the refrigerant
supply pipe
132 into communication with the purge gas path. By temporarily
removing the primary refrigerant CW
1 in the refrigerant supply pipe
132,
the refrigerant circulating passage
108 and the refrigerant discharging
pipe
136, it is possible to easily perform maintenance of the lower electrode
106.
FIG. 2 is a flowchart of detaching and attaching operation of the lower electrode
106 at the time of maintenance of the lower electrode
106.
First, the purge valve
135 is opened to bring the refrigerant supply
pipe
132 into communication with the purge gas (step S
1). It is judged
whether most of the primary refrigerant CW
1 is removed from the refrigerant
supply pipe
132, the refrigerant circulating passage
108 and the
refrigerant discharging pipe
136 (step S
2). If YES, purge is carried
out for a given time using a timer (step S
3). With this, it is possible
to completely remove the primary refrigerant CW
1 is removed from the refrigerant
supply pipe
132, the refrigerant circulating passage
108 and the
refrigerant discharging pipe
136.
If the primary refrigerant CW
1 is completely removed from the primary
refrigerant
circulation path, the communication between the refrigerant supply pipe
132
with the purge gas is stopped (step S
4). Then, the lower electrode
106
is detached from the processing chamber
104 (step S
5). Predetermined
maintenance (or exchange) of the lower electrode
106 is performed (step
S
6) and then, the lower electrode
106 is again attached (step S
7).
In this manner, it is possible to easily perform the maintenance of the lower electrode
106.
One of the features of this embodiment is that the apparatus has the secondary
refrigerant circulating circuit which supplies the secondary refrigerant CW
2
to the heat exchanger
138 and adjusts a temperature of the primary refrigerant
CW
1. The circulating circuit of the secondary refrigerant which adjusts
the temperature of the primary refrigerant CW
1 will be explained below.
The flow rate of the secondary refrigerant (e.g., cooling water) CW
2 is
controlled by an adjusting valve
139. A heat exchanger
138 and a
later-described first heat exchanger (evaporator)
141 in the freezing circuit
140 are interposed downstream of the adjusting valve
139. After heat
exchange is performed between the secondary refrigerant CW
2 and the primary
refrigerant CW
1 by the heat exchanger
138, heat exchange between
the secondary refrigerant CW
2 and the tertiary refrigerant CW
3 is
further performed by a first heat exchanger
141. A third temperature detector
Th
3 which detects a temperature of the secondary refrigerant CW
2
after the heat exchange with the tertiary refrigerant CW
3 is performed by
the first heat exchanger
141 is interposed downstream of the first heat
exchanger
141.
In the heat exchanger
138, a temperature of the primary refrigerant CW
1
is adjusted by the secondary refrigerant CW
2. That is, the secondary refrigerant
CW
2 having a predetermined flow rate which is cooled by the freezing circuit
140 is allowed to circulate in the secondary refrigerant circulating circuit,
heat of the primary refrigerant CW
1 is absorbed by the secondary refrigerant
CW
2 when it passes through the heat exchanger
138, and the temperature
of the primary refrigerant CW
1 is adjusted to the predetermined temperature.
The temperature of the primary refrigerant CW
1 can appropriately be changed
by adjusting the circulating amount of the secondary refrigerant CW
2 by
the adjusting valve
139 interposed in the secondary refrigerant circulating
circuit. If the flow rate of the secondary refrigerant CW
2 is increased,
the temperature of the primary refrigerant CW
1 is reduced, and if the flow
rate of the secondary refrigerant CW
2 is reduced, the temperature of the
primary refrigerant CW
1 is increased.
The third temperature detector Th
3 detects a temperature of the secondary
refrigerant CW
2 immediately after its temperature is adjusted by the first
heat exchanger
141. The detected temperature value detected by the third
temperature detector Th
3 is transmitted to a second control system (not
shown). The second control system control the drive of the freezing circuit
140
in accordance with the detected temperature value by the third temperature detector
Th
3. In this manner, the amount of heat or the flow rate of the secondary
refrigerant CW
2 or the tertiary refrigerant CW
3 can be controlled
in a feed-back control manner such that the temperature of the refrigerant follows
the target adjusted temperature. Therefore, it is possible to manage the temperature
of the substrate more strictly.
Next, the freezing circuit (tertiary refrigerant circulating circuit)
140
which adjusts a temperature of the secondary refrigerant CW
2 will be explained.
The freezing circuit
140 comprises a first heat exchanger (evaporator)
141 for adjusting a temperature of the secondary refrigerant CW
2,
a second heat exchanger (condenser)
142, and a heat-exchange path
144
for circulating the tertiary refrigerant (e.g., Freon) CW
3 which receives
and delivers heat between the first and second heat exchangers
141 and
142
through the first and second heat exchangers
141 and
142. A pump
(compressor)
148 and an open/close valve (expansion valve)
150 are
interposed in the heat-exchange path
144.
A temperature sensor is provided downstream of the pump
148, a temperature
of the tertiary refrigerant CW
3 is monitored, thereby finding the contamination
of the second heat exchanger
142 and the leakage or excessive cooling of
the refrigerant. It is preferable to use a refrigerant having a low GWP (Global
Warming Potential) value such as HFC-407C as the tertiary refrigerant CW
3.
In the freezing circuit
140 having such a structure, the first heat exchanger
141 is interposed in the secondary refrigerant circulating circuit, and
a temperature of the secondary refrigerant CW
2 is adjusted by the tertiary
refrigerant CW
3. That is, the tertiary refrigerant CW
3 having a predetermined
flow rate which is cooled in the second heat exchanger
142 is allowed to
circulate in the heat-exchange path
144 so that the heat of the secondary
refrigerant CW
2 is absorbed by the tertiary refrigerant CW
3 when
it passes through the first heat exchanger
141, and the temperature of the
secondary refrigerant CW
2 is adjusted to the predetermined temperature.
The temperature of the secondary refrigerant CW
2 can appropriately be changed
by adjusting the pumpage of the pump
148. If the flow rate of the tertiary
refrigerant CW
3 is increased, the temperature of the secondary refrigerant
CW
2 is reduced, and if the flow rate of the tertiary refrigerant CW
3
is reduced, the temperature of the secondary refrigerant CW
2 is increased.
FIG. 3 collectively show the above-described adjustable temperature at the time
of low temperature setting and high temperature setting, and operations of the
primary refrigerant CW
1, the secondary refrigerant CW
2 and the freezing
circuit
140.
According to the embodiment as explained above, a temperature of the primary
refrigerant CW
1 which cools the lower electrode
106 is adjusted by
the secondary refrigerant CW
2 without directly adjusting the temperature
by the freezing circuit. Therefore, when the temperature of the primary refrigerant
CW
1 is set to a value higher than that of the secondary refrigerant CW
2,
e.g., when the target adjusted temperature of the lower electrode
106 is
set to 30° C. to 100° C., it is possible to adjust the temperature of
the primary refrigerant CW
1 only with the secondary refrigerant CW
2.
Only when the temperature of the primary refrigerant CW
1 is set to a value
lower than that of the secondary refrigerant CW
2, the temperature of the
secondary refrigerant CW
2 is adjusted by the freezing circuit
140.
Therefore, it is only necessary to actuate the freezing circuit
140 only
when it is required, and it is possible to save energy. A range of controllable
temperature is not changed by variation in environment such as season.
Further, since the amount of heat or flow rate of the refrigerant is controlled
in accordance with the detected temperature value by the temperature detectors
Th
1 to Th
3, it is possible to manage the temperature of the wafer
W more strictly.
Further, since the primary refrigerant circulating circuit is provided with
the first check valve
133, the second check valve
137 and the purge
valve
135, it is possible to easily control the circulation amount of the
primary refrigerant CW
1 in the primary refrigerant circulating circuit,
and it is possible to easily control the primary refrigerant CW
1 at the
time of over load, and to perform maintenance of the lower electrode
106 easily.
Although the preferred embodiment of a cooling apparatus and a plasma processing
apparatus having the cooling apparatus according to the present invention has been
explained above with reference to the drawings, the invention is not limited to
the embodiment. It is apparent that a person skilled in the art can reach various
examples of change of modification within a range of the technical idea described
in claims, and it should be understood that there various examples naturally belong
to the technical range of present invention.
For example, although a temperature of the primary refrigerant is controlled
based on a temperature of the electrode (lower electrode
106) in the above
embodiment, the present invention is not limited to such a structure. For example,
the temperature of the primary refrigerant may be controlled based on a temperature
of the substrate (wafer W).
Although the adjustable temperature range of the cooling apparatus is -10°
C. to +100° C. in the above embodiment, a plurality of cooling apparatuses
having different adjustable temperature ranges may be disposed. In this case, as
shown in FIGS. 4A and B, it is preferable to set power (electric power and cooling
water) to be supplied to the cooling apparatuses in accordance with the number
of processing chambers. That is, if the apparatus has one processing chamber (not
shown), as shown in FIG. 4A, one set of system of the power is prepared, and the
power is supplied from a lower (low temperature) cooling apparatus
110-
1
to an upper (high temperature) cooling apparatus
110-
2 through a
power supply section
160. If the apparatus has two processing chambers (not
shown), as shown in FIG. 4B, if two sets of power system respectively corresponding
to the lower cooling apparatus
110-
1 and the upper cooling apparatus
110-
2 are prepared, it is possible to perform maintenance for each
processing chamber, which is convenient. By disposing the cooling apparatuses vertically
as shown in FIGS. 4A and B, it is possible to reduce the installing space.
As explained above, according to the present invention, the primary refrigerant
(e.g., Galden: trade name) for cooling the electrode of the processing apparatus
is adjusted in temperature only by the secondary refrigerant (e.g., cooling water)
without adjusting the temperature by the freezing circuit. Therefore, when the
temperature of the primary refrigerant is set to a value higher than the secondary
refrigerant, the temperature of the primary refrigerant can be adjusted by the
secondary refrigerant only. Only when the temperature of the primary refrigerant
is set lower than that of the secondary refrigerant, the temperature of the secondary
refrigerant is adjusted by the freezing circuit. Therefore, it is possible to save
energy remarkably as compared with the conventional technique in which the freezing
circuit is always actuated and the temperature is adjusted by the heater. A range
of controllable temperature is not changed by variation in environment such as season.
The present invention can be utilized for various processing apparatuses such
as plasma etching apparatuses used for producing procedure of the semiconductor
device and the LCD substrate.
*
