JP3058392B2 - Cooling system for low temperature processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-temperature processing apparatus, and more particularly to a cooling system for a low-temperature processing apparatus.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor processing apparatus,
In order to obtain a vertical pattern shape and a high selectivity, a low-temperature processing method for lowering the temperature of a reaction surface of an object to be processed, for example, a semiconductor wafer, is known. In such low-temperature processing,
It is important to accurately maintain the temperature of the reaction surface of the object within the allowable processing temperature range in order to improve the yield of products and perform delicate surface processing. In particular, recently, as the reaction surface temperature of the object to be processed is controlled to a lower temperature, the processing accuracy of the product is improved.

In order to obtain a stable cryogenic environment as described above, conventionally, as shown in FIG. 4, a refrigerant, for example, liquid nitrogen, is sent from a refrigerant source 100 to a cooling jacket in a susceptor by a motor 101, and its vaporization heat is The susceptor is cooled by the cooling method, and the reaction surface of the object to be processed is extremely cooled by the cooling heat transmitted from the cooled susceptor to the object. At this time, the refrigerant recovered from the cooling jacket is composed of a mixture of vaporized nitrogen gas and liquid nitrogen.
After completely vaporized by 2, exhaust was performed.

[0004]

However, in the conventional low-temperature processing apparatus, an extremely low temperature, for example, -150 ° C.
Since the refrigerant used to cool the susceptor to process the object to be processed was exhausted while having a cooling capacity enough to perform a heat exchange treatment by a vaporizer, the energy loss was large, so that This was causing the running cost to rise. Further, when a liquefied inert gas such as liquid nitrogen is used as a refrigerant, the exhaust gas has a high purity, so that it is necessary to find effective use of the exhaust gas from the viewpoint of energy saving.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the conventional low-temperature processing apparatus, and has as its object to make effective use of the recovered refrigerant used in the ultra-low-temperature processing apparatus. It is an object of the present invention to provide a new and improved cooling system for a low-temperature processing apparatus, which can reduce the running cost of the apparatus and also contributes to energy saving.

In order to solve the above problem, a liquefied inert gas is circulated in a first susceptor for mounting and fixing an object to be processed in a processing chamber of a first processing apparatus. And the heat of vaporization of the liquefied inert gas
A cooling system for the low-temperature processing apparatus including a first cooling circuit for cooling the first susceptor , wherein a refrigerant return path of the first cooling circuit is connected to a primary side of a heat exchanger;
The secondary side of the vessel is connected to a second cooling circuit for circulating and cooling a refrigerant in a second susceptor of a second processing apparatus for processing an object to be processed at a higher temperature than the first processing apparatus. It is characterized by having.

Further, a liquefied inert gas is circulated in a susceptor for mounting and fixing an object to be processed in a processing chamber of the processing apparatus, and the susceptor is heated by heat of vaporization of the liquefied inert gas. In the cooling system of the low-temperature processing apparatus provided with a cooling circuit for cooling the cooling system, the refrigerant return path of the cooling circuit is connected to a purge inert gas source via a recovery circuit for recovering the vaporized inert gas. It is characterized by having.

Further, a liquefied inert gas is circulated in a first susceptor for mounting and fixing an object to be processed in a processing chamber of the first processing apparatus. A cooling system for a low-temperature processing apparatus including a first cooling circuit for cooling a first susceptor by heat of vaporization of a gas includes a return path of the first cooling circuit connected to a heat exchanger, The primary side of the exchanger is connected to a purge inert gas source via a recovery circuit for recovering the heat-exchanged inert gas, and the secondary side of the heat exchanger has a higher temperature than the first processing apparatus. And a second cooling circuit for circulating and cooling the refrigerant in the second susceptor of the second processing apparatus for processing the object to be processed.

[0009]

According to the first aspect of the present invention, the liquefaction recovered from the refrigerant return path of the first cooling circuit and still having a high cooling capacity is achieved.
Inert gas is sent from the processing unit to the heat exchanger and sent to the heat exchanger.
Since it is possible to use the refrigerant circulating in the cooling circuit of Oite first processing device processing temperature is higher second processing unit than to cool, it is possible to effectively use the refrigerant, running costs And a low-energy cooling system can be constructed.

According to the second aspect of the present invention, particularly when the liquefied inert gas is used as the refrigerant, the inert gas recovered and vaporized from the processing apparatus is sent to the purge gas source, thereby the inert gas is removed. Can be used for purging various chambers such as a cassette chamber and a load lock chamber, so that a refrigerant can be used effectively, a running cost is low, and an energy-saving cooling system is constructed. Is possible.

According to the third aspect of the present invention,
Similarly to the inventions described in 1 and 2, the second processing apparatus uses a liquefied inert gas as a refrigerant and sends it from the processing apparatus to the heat exchanger, where the processing temperature of the heat exchanger is higher than that of the first processing apparatus. It can be used to cool the refrigerant circulating in the cooling circuit of the above, and the inert gas vaporized by heat exchange in the heat exchanger can be used as a purge gas, so that the refrigerant can be used more effectively. In addition, a running system with lower running cost and a more energy-saving cooling system can be constructed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A case where a cooling circuit of a low-temperature processing apparatus according to the present invention is applied to a plasma etching apparatus will be described below with reference to the accompanying drawings.

First, an etching apparatus 1 to which the method of the present invention can be applied will be briefly described with reference to FIG. As shown in the drawing, the etching apparatus 1 has a substantially cylindrical airtight processing chamber 2 made of a conductive material, for example, aluminum, and an exhaust port 3 is provided near the bottom of the processing chamber 2. The processing chamber 2 is configured to be evacuated to a desired reduced-pressure atmosphere via an exhaust unit (not shown), for example, a vacuum pump.

Further, a substantially columnar mounting table 4 is accommodated at substantially the center of the processing chamber 2 so as to maintain an electrically insulating state from the bottom of the processing chamber 2. An object to be processed, for example, a semiconductor wafer W can be mounted on the upper surface of the mounting table 4. The mounting table 4 includes a substantially cylindrical susceptor support 5 made of, for example, aluminum and a susceptor 7 made of, for example, aluminum, which is detachably provided on the support 5 with a bolt 6.

The susceptor support 5 is provided with a refrigerant storage section, for example, a cooling jacket 8 for circulating a refrigerant, for example, liquid nitrogen. The cooling jacket 8 is provided with a coolant supply passage 9 and a coolant discharge passage 10. A coolant, for example, liquid nitrogen is supplied from a cooling circuit 11 configured as described later through the coolant supply passage 9 to the cooling jacket 8. 8, the refrigerant is circulated through the jacket, discharged through the refrigerant discharge path 10, and returned to the cooling circuit 11, so that the refrigerant can be effectively used as described later.

The susceptor 7 has a disk shape having a convex portion at the center, and a fixing means for mounting and fixing the semiconductor wafer W on the mounting surface of the central convex portion, for example, an electrostatic device. A chuck 12 is provided. This electrostatic chuck 12
Is formed by sandwiching a conductive film 13 such as a copper foil between two polyimide films, for example.
By applying a high voltage from the DC high voltage source 14 to
By generating Coulomb force on the chuck surface, it is possible to suction-hold the semiconductor wafer W on the mounting surface.

Further, the heat transfer gas supply means 1 is provided on the connection surface of each component of the mounting table 4, the back surface of the mounted semiconductor wafer W and the chuck surface of the electrostatic chuck 12, respectively.
5, it is possible to supply a heat transfer medium, for example, helium gas, etc., so that cold heat can be quickly transmitted from the cooling jacket 8 in the susceptor 7 to the semiconductor wafer W. I have.

Further, at the peripheral edge of the upper end of the susceptor 7,
An annular focus ring 1 surrounding the semiconductor wafer W
6 are arranged. The focus ring 16 is made of an insulating material that does not attract reactive ions, and makes the reactive ions incident only on the semiconductor wafer W installed inside, thereby improving the efficiency of the etching process.

A high-frequency power supply 18 is connected to the susceptor 7 via a matching capacitor 17 so that a high frequency of, for example, 13.56 MHz can be applied to the susceptor during processing. Acts as a lower electrode, generates a glow discharge with the upper electrode, forms a reactive plasma in the processing chamber, and is configured to be capable of etching the object to be processed with the plasma flow. I have.

A temperature control heater 29 is provided between the susceptor 7 and the susceptor support 5, and power is applied to the temperature control heater 29 from a power supply 30 via a filter 31 to supply a heating source. By acting as
The amount of cold transmitted to the semiconductor wafer W from the cooling jacket 8 provided in the susceptor support 5 can be adjusted optimally.

A grounded upper electrode 20 is provided above the susceptor 7. The inside of the upper electrode 20 is hollow, and a large number of small holes 21 are formed in the surface facing the semiconductor wafer W, which is the object to be processed. The processing gas, for example, an etching gas such as CF ₄ sent through a mass flow controller (not shown) can be uniformly introduced into the processing chamber.

As described above, the plasma etching apparatus 1 to which the cooling system of the low-temperature processing apparatus configured according to the present invention can be applied.

Next, a cooling system connected to the ultra-low temperature processing apparatus 1 configured as described above will be described with reference to FIG. As shown in the figure, a coolant such as liquid nitrogen can be supplied to a cooling jacket 8 in the susceptor 7 through a coolant supply passage 9. The susceptor 7 is cooled to, for example, -150 ° C. by the liquid nitrogen,
By transmitting the cold to the semiconductor wafer,
It is possible to realize ultra-low temperature processing of the object to be processed. The liquid nitrogen that has been heat-exchanged in the cooling jacket 8 is converted into a mixture of nitrogen gas and liquid nitrogen as a refrigerant discharge passage 10.
And sent to the primary side of the heat exchanger 23. The refrigerant discharge path 10 and the refrigerant supply path 9 are connected by a bypass path 25 in which an electromagnetic valve 24 is inserted.
By controlling the opening of the solenoid valve 24 in accordance with the signal from the controller 6, the amount of refrigerant supplied to the cooling jacket 8 can be adjusted.

On the secondary side of the heat exchanger 23, for example, a sub-cooler for cooling the susceptor 7 'of the low-temperature or normal-temperature processing apparatus 1' for processing an object to be processed at a higher temperature than the ultra-low temperature processing apparatus 1 is provided. A cooling circuit 24 is connected. The sub-cooling circuit 24 includes a temperature control unit 25 for controlling the temperature of the refrigerant cooled by the heat exchanger 23, and the susceptor 7 that supplies the refrigerant, which has been adjusted to an appropriate temperature by the temperature control unit, through the refrigerant supply path 9 '. Pump 26 for sending to 'inside refrigerant passage 8'
And a refrigerant discharge path 10 'for recovering the refrigerant after heat exchange in the refrigerant supply path 9' and cooling the susceptor 7 'to, for example, room temperature of 0 ° C.

Thus, according to the present invention, for example,
The first method for processing by cooling an object to be processed to an extremely low temperature of 150 ° C.
, The refrigerant used in the ultra-low temperature processing apparatus 1, for example, liquid nitrogen at −196 ° C. is present as nitrogen gas at −50 ° C. even after being recovered from the first processing apparatus 1. For example, the second processing apparatus that cools the object to be processed at a low temperature of 0 ° C. to perform the processing, that is, the low-temperature processing apparatus 1 ′ has a sufficient cooling capacity, and the cooling heat of the exhaust gas is subjected to heat exchange. By transmitting the refrigerant to the sub-cooling circuit 24 of the second processing apparatus 1 'via the vessel 23, the refrigerant can be effectively used.

The nitrogen gas deprived of heat by the secondary side sub-cooling circuit 24 in the heat exchanger 23 is sent to an evaporator 28 via a nitrogen gas recovery pipe 27, and the remaining liquid nitrogen is completely vaporized. After that, it is sent to the accumulator 30 via the boosting pump 29 and is stored in the accumulator 30. Since the stored nitrogen gas has a high purity, the nitrogen gas can be supplied to a cassette chamber, a load lock chamber, or a purge in a pump as needed.

As described above, when the cooling circuit as shown in FIG. 1 is configured based on the present invention, the first processing device,
That is, the refrigerant used for cooling the ultra-low temperature processing device is
It can be used for cooling of processing equipment, that is, low-temperature or normal-temperature processing equipment, and the vaporized refrigerant can be used as a purge gas. And a low running cost, energy saving system can be constructed.

Next, an embodiment in which the cooling circuit 11 constructed according to the present invention is applied to a multi-chamber type processing apparatus 50 will be described with reference to FIG. As shown in the figure, the multi-chamber processing apparatus 50 includes a load cassette chamber 54 and a load cassette chamber 5 centered on a load lock chamber 53 in which a transfer arm 51 and an alignment table 52 are installed.
5, ultra-low temperature etching device 56, room temperature CVD device 57,
The natural oxide film removing devices 58 are connected to each other via gate valves.

The semiconductor wafer loaded into the loading cassette chamber 54 via the gate valve 59 is
After being introduced into the load lock chamber 53 by the transfer arm 51 through the
1 through the susceptor 62 in the cryogenic etching apparatus 56
Placed on Liquid nitrogen is supplied from the cooling circuit 11 to the coolant reservoir (not shown) in the susceptor 62 via the supply path 63 to cool the susceptor 62 to a predetermined processing temperature, for example, −.
The semiconductor wafer can be cooled to 150 ° C., and the semiconductor wafer can be etched with high anisotropy in an ultra-low temperature state by heat transfer therefrom.

The liquid nitrogen partially vaporized in the refrigerant reservoir is returned to the cooling circuit 11 via a discharge path 64, and the liquid nitrogen recovered there is supplied to cassette chambers 54, 55 via purge gas supply pipes 65, 66. And used to purge the interior of the room where pressure reduction and release to the atmosphere are repeated. On the other hand, the refrigerant returned from the ultra-low temperature etching apparatus 56 but still having a sufficient cooling capacity is used for cooling the secondary refrigerant circulating in the sub-cooling circuit by the heat exchanger, and the cooled secondary refrigerant is used here. The next refrigerant is supplied to the room temperature CVD device 57 through the pipes 67 and 68.
The susceptors 69 and 70 are sent to the susceptor 69 and the susceptor 70 in the natural oxide film removing device 58, and are used to cool the susceptors 69 and 70 to a desired temperature.

The object to be processed, which has been processed in the ultra-low temperature etching apparatus 56, is carried out again through the gate valve 61 by the transfer arm 51 and is carried into the other processing chambers 57, 58 through the gate valves 71, 72. After a predetermined process is performed in a predetermined temperature atmosphere, the gate valve 73
After being pressurized and sent to the unloading cassette chamber 55 via the gate valve 74, it is further discharged to the atmosphere via the gate valve 74.

As described above, the cooling system configured according to the present invention can efficiently utilize the refrigerant and its cooling capacity by applying to the multi-chamber type processing apparatus as shown in FIG. Therefore, a system excellent in low running cost and energy saving can be constructed. However, it is needless to say that the present invention is not limited to the multi-chamber type processing apparatus, but can be applied to a system including a plurality of individual type processing apparatuses.

In the above embodiment, an example is shown in which the cooling system constructed according to the present invention is applied to a low-temperature plasma etching apparatus as an example. However, the method of the present invention is not limited to such an apparatus, but includes a CVD apparatus, Ashing device,
In the case of inspecting a sputter apparatus or an object to be processed at a low temperature, the present invention can be applied to, for example, a sample mounting table of an electron microscope or a cooling mechanism of a sample mounting table for evaluating semiconductor materials and elements.

[0034]

As described above, according to the present invention,
The liquid nitrogen used to cool the susceptor of the ultra-low temperature processing device can be used as a cooling source for the cooling circuit of another processing device that processes the object to be processed at a higher temperature than the processing device, and a cassette chamber. Since it can also be used as a gas source for purging gas in other chambers, it is possible to use the refrigerant and its cold heat significantly more effectively than the conventional system. As a result, a low-temperature processing system with low running cost and energy saving can be constructed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically illustrating a cooling system of a low-temperature processing device configured based on the present invention.

FIG. 2 is a schematic sectional view of a low-temperature etching apparatus to which the present invention can be applied.

FIG. 3 is a schematic configuration diagram of a multi-chamber processing apparatus to which the present invention can be applied.

FIG. 4 is a configuration diagram schematically illustrating a cooling system of a conventional low-temperature processing apparatus.

[Explanation of symbols]

 Reference Signs List 1 processing apparatus 2 processing chamber 4 mounting table 5 susceptor support base 7 susceptor 8 cooling jacket 9 refrigerant supply path 10 refrigerant discharge path 11 cooling circuit 23 heat exchanger 24 sub-cooling circuit 24 temperature controller 26 pump 28 evaporator 29 booster pump 30 accumulator

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/3065 H01L 21/205

Claims (3)

(57) [Claims] 1. A first liquefied inert in the susceptor for placing fixing the object to be processed in a processing chamber of the first processing unit
By circulating sex gas, the heat of vaporization of the liquefied inert gas
In a cooling system for a low-temperature processing apparatus having a first cooling circuit for cooling a first susceptor, a refrigerant return path of the first cooling circuit is provided on a primary side of a heat exchanger.
The second side of the heat exchanger is connected to a second susceptor of a second processing apparatus for processing an object to be processed at a higher temperature than the first processing apparatus. A cooling system for a low-temperature processing device, wherein the cooling system is connected to a cooling circuit. 2. A cooling system for circulating a liquefied inert gas in a susceptor for mounting and fixing an object to be processed in a processing chamber of a processing apparatus, and cooling the susceptor by heat of vaporization of the liquefied inert gas. In a cooling system of a low-temperature processing device provided with a circuit, a refrigerant return path of the cooling circuit is connected to a purge inert gas source via a recovery circuit for recovering a vaporized inert gas. , Low-temperature processing equipment cooling system. 3. A liquefied inert gas is circulated in a first susceptor for placing and fixing an object to be processed in a processing chamber of a first processing apparatus, and the liquefied inert gas is circulated by heat of vaporization of the liquefied inert gas. In a cooling system for a low-temperature processing apparatus provided with a first cooling circuit for cooling one susceptor, a return path of the first cooling circuit is connected to a heat exchanger, and a primary side of the heat exchanger has heat. It is connected to a purge inert gas source via a recovery circuit for recovering the exchanged inert gas, and the secondary side of the heat exchanger processes the workpiece at a higher temperature than the first processing apparatus. A cooling system for a low-temperature processing device, wherein the cooling system is connected to a second cooling circuit for circulating and cooling a refrigerant in a second susceptor of the second processing device.