JPH07147249A - Cooling system of low temperature processor - Google Patents

Abstract

PURPOSE:To provide a cooling system of low temperature processor capable of effectively using a refrigent and the cold heat thereof. CONSTITUTION:A refrigerant fed to the first processor and exhausted after cooling down a susceptor 7 thereof is reused as the cooling source of a subcooling circuit 24 for cooling down another susceptor 7' of the second processor for processing it at higher temperature than the first processor while the evaporated refrigerant is reused as the purging gas source for the other chamber such as a cassette chamber, etc., so that the refrigerant and the cold heat thereof may be effectively reused thereby enabling the running cost of the title system to be cut down.

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 semiconductor processing equipment,
In order to obtain a vertical pattern shape and a high selection ratio, a low temperature processing method is known in which the temperature of the reaction surface of an object to be processed, for example, a semiconductor wafer, is lowered. In such low temperature treatment,
Accurately maintaining the temperature of the reaction surface of the object to be processed within the allowable processing temperature range is important for improving the yield of products and performing delicate surface processing. Particularly in recent years, 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, so that the processing temperature is being extremely lowered.

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 heat of vaporization is sent. Then, the susceptor was cooled, and the reaction surface of the object to be processed was made extremely cold by the cooling heat transferred from the cooled susceptor to the object to be processed. At that time, since the refrigerant recovered from the cooling jacket is composed of a mixture of vaporized nitrogen gas and liquid nitrogen, the vaporizer 10
It was completely vaporized by 2 and then evacuated.

[0004]

However, in the conventional low temperature processing apparatus, the temperature is extremely low, for example, -150 ° C.
The refrigerant used to cool the susceptor in order to process the object to be processed is exhausted while having a cooling capacity that requires heat exchange processing by a vaporizer, resulting in large energy loss and It was a cause of pushing up the running cost. Further, when a liquefied inert gas such as liquid nitrogen is used as the refrigerant, the exhaust gas has a high purity, and therefore it has been necessary to search for its effective use from the viewpoint of energy saving.

The present invention has been made in view of the above problems of the conventional low temperature processing apparatus, and an object of the present invention is to effectively use the recovered refrigerant used in the ultra low temperature processing apparatus. SUMMARY OF THE INVENTION It is an object of the present invention to provide a new and improved cooling system for a low-temperature treatment device that can be achieved and therefore contributes to a reduction in the running cost of the device and also meets the viewpoint of energy saving.

In order to solve the above problems, a cooling medium is circulated in a first susceptor for mounting and fixing an object to be processed in a processing chamber of a first processing apparatus according to claim 1 for cooling. In the cooling system of the low-temperature processing device including the first cooling circuit for, the refrigerant return path of the first cooling circuit is
It is characterized in that it is connected to a second cooling circuit for circulating and cooling a refrigerant in a second susceptor of a second processing apparatus that processes an object to be processed at a temperature higher than that of the first processing apparatus. There is.

According to a second aspect of the present invention, the liquefied inert gas is circulated in the susceptor for mounting and fixing the object to be processed in the processing chamber of the processing apparatus, and the susceptor is heated by the heat of vaporization of the liquefied inert gas. The cooling system of the low-temperature processing device having a cooling circuit for cooling the, the refrigerant return path of the cooling circuit is connected to the purge inert gas source through a recovery circuit for recovering the vaporized inert gas. It is characterized by being.

Furthermore, the liquefied inert gas is circulated in the first susceptor for mounting and fixing the object to be processed in the processing chamber of the first processing apparatus. In a cooling system of a low temperature processing apparatus having a first cooling circuit for cooling the first susceptor by heat of vaporization of gas, a return path of the first cooling circuit is connected to a heat exchanger, The primary side of the exchanger is connected to a purging inert gas source through a recovery circuit for recovering the heat-exchanged inert gas, and the secondary side of the heat exchanger has a higher temperature than that of the first processing device. Is connected to a second cooling circuit for circulating and cooling the refrigerant in the second susceptor of the second processing apparatus that processes the object.

[0009]

According to the first aspect of the present invention, the second treatment, which has a higher treatment temperature than the first treatment device, treats the refrigerant having a still high cooling capacity, which is recovered from the refrigerant return passage of the first cooling circuit. Since it can be used to cool the device, it is possible to effectively use the refrigerant, and it is possible to construct a cooling system with low running cost and energy saving.

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

According to the invention of claim 3, claim 2
Similarly to the invention described in 1, the liquefied inert gas is used as a refrigerant, is sent from the processing device to the heat exchanger, and the cooling circuit of the second processing device in which the processing temperature is higher than that of the first processing device in the heat exchanger. In addition to being used to cool the refrigerant that circulates, the inert gas that has been heat-exchanged and vaporized in the heat exchanger can be used as the purge gas, so that it is possible to further effectively use the refrigerant, and running. A lower cost and more energy efficient cooling system can be constructed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A case where a cooling circuit for a low temperature processing apparatus constructed 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 figure, the etching apparatus 1 has a substantially cylindrical airtight processing chamber 2 made of a conductive material such as aluminum, and an exhaust port 3 is provided near the bottom of the processing chamber 2. It is provided so that the inside of the processing chamber 2 can be evacuated to a desired depressurized atmosphere via an exhaust means (not shown) such as a vacuum pump.

Further, a substantially column-shaped mounting table 4 is housed in substantially the center of the processing chamber 2 so as to maintain an electrically insulated 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 is composed of, for example, a substantially columnar susceptor support 5 made of aluminum, and a susceptor 7 made of aluminum, which is detachably provided on the support 5 with bolts 6.

The susceptor support 5 is provided with a coolant container, for example, a cooling jacket 8 for circulating and circulating a coolant, for example, liquid nitrogen. The cooling jacket 8 is provided with a refrigerant supply path 9 and a refrigerant discharge path 10, and a refrigerant, for example liquid nitrogen, is supplied from the cooling circuit 11 configured as described later via the refrigerant supply path 9 to the cooling jacket. It is possible to effectively use the refrigerant as will be described later, by introducing the refrigerant into the inside of the jacket 8, circulating the inside of the jacket, discharging it through the refrigerant discharge path 10 and returning it to the cooling circuit 11 again.

The susceptor 7 is in the shape of a disk having a convex portion in the center thereof, and a fixing means for mounting and fixing the semiconductor wafer W on the mounting surface of the central convex portion, for example, electrostatic. 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.
By applying a high voltage from the DC high voltage source 14 to
It is possible to generate a Coulomb force on the chuck surface and suck and hold the semiconductor wafer W on the mounting surface.

Further, the heat transfer gas supply means 1 is provided on the connection surfaces of the respective constituent members of the mounting table 4, the back surface of the mounted semiconductor wafer W and the chuck surface of the electrostatic chuck 12, respectively.
It is possible to supply a heat transfer medium, for example, helium gas or the like via 5, and the cold heat can be quickly transferred from the cooling jacket 8 in the susceptor 7 to the semiconductor wafer W. There is.

Further, on 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 the reactive ions, and the reactive ions are incident only on the semiconductor wafer W placed inside to improve the efficiency of the etching process.

A high frequency power source 18 is connected to the susceptor 7 via a matching capacitor 17, and 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 capable of etching the object to be processed by the plasma flow. There is.

A temperature adjustment heater 29 is provided between the susceptor 7 and the susceptor support 5, and electric power is applied to the temperature adjustment heater 29 from a power source 30 via a filter 31 to generate a heating source. By acting as
It is possible to optimally adjust the amount of cold heat transferred to the semiconductor wafer W from the cooling jacket 8 provided in the susceptor support 5.

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. A processing gas sent through a mass flow controller (not shown), for example, an etching gas such as CF ₄ 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 constructed according to the present invention can be applied is constructed.

Next, with reference to FIG. 1, a cooling system connected to the ultra low temperature processing apparatus 1 configured as described above will be described. As illustrated, the cooling jacket 8 in the susceptor 7 can be supplied with a refrigerant such as liquid nitrogen through a refrigerant supply passage 9. The liquid nitrogen cools the susceptor 7 to, for example, −150 ° C.,
By transferring the cold heat 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 a mixture of nitrogen gas and liquid nitrogen, which is the refrigerant discharge path 10.
And is sent to the primary side of the heat exchanger 23. The refrigerant discharge path 10 and the refrigerant supply path 9 are communicated with each other by a bypass path 25 in which an electromagnetic valve 24 is inserted.
By controlling the opening degree of the solenoid valve 24 in accordance with the signal from 6, the amount of refrigerant supplied to the cooling jacket 8 can be adjusted.

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

As described above, according to the present invention, for example,
The first to process the object by cooling it to an ultra low temperature of 150 ℃
Since the refrigerant used in the treatment apparatus of 1, that is, the ultra-low temperature treatment apparatus 1, for example, liquid nitrogen at -196 ° C is still present as nitrogen gas at -50 ° C, for example, even after being recovered from the first treatment apparatus 1. For example, the second processing apparatus that cools the object to be processed at a low temperature of 0 ° C., that is, the low-temperature processing apparatus 1 ′ has a sufficient cooling capacity, and the cooling heat of the exhaust gas is heat-exchanged. The refrigerant can be effectively used by transmitting it to the sub-cooling circuit 24 of the second processing apparatus 1 ′ via the container 23.

Further, in the heat exchanger 23, the nitrogen gas deprived of the cold heat by the secondary cooling circuit 24 on the secondary side is sent to the evaporator 28 via the nitrogen gas recovery pipe 27, and the remaining liquid nitrogen content is completely vaporized. Then, it is sent to the accumulator 30 via the booster pump 29 and stored in the accumulator 30. Since the stored nitrogen gas has a high purity, it is possible to supply the nitrogen gas for purging the cassette chamber, the load lock chamber, or the pump as needed.

When the cooling circuit as shown in FIG. 1 is constructed based on the present invention as described above, the first processing device,
That is, the refrigerant used for cooling the ultra low temperature processing device is
It can be used to cool down the processing equipment, that is, the low temperature or room temperature processing equipment, and the vaporized refrigerant can be used as the purging gas, so the refrigerant can be used much more effectively than the conventional system. It is possible to construct a system with low running cost and energy saving.

Next, an embodiment in which the cooling circuit 11 constructed according to the present invention is applied to the multi-chamber type processing apparatus 50 will be described with reference to FIG. As shown in the figure, this multi-chamber type processing apparatus 50 has a load lock chamber 53 in which a transfer arm 51 and an alignment table 52 are installed, with a loading cassette chamber 54 and an unloading cassette chamber 5 as the center.
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 transferred to the gate valve 60.
After being introduced into the load lock chamber 53 by the transfer arm 51 via the and aligned, the gate valve 6
1 through the susceptor 62 in the ultra-low temperature etching apparatus 56.
Placed on. Liquid nitrogen is supplied from a cooling circuit 11 to a coolant reservoir (not shown) in the susceptor 62 via a supply passage 63, and the susceptor 62 is treated at a predetermined processing temperature, for example, −.
It is possible to cool the semiconductor wafer to 150 ° C., and heat transfer from the semiconductor wafer enables highly anisotropic etching of the semiconductor wafer in an ultralow temperature state.

The liquid nitrogen partially vaporized in the refrigerant reservoir is returned to the cooling circuit 11 via the discharge passage 64, and the liquid nitrogen recovered therein is returned to the cassette chambers 54, 55 via the purge gas supply pipes 65, 66. And is used to purge the interior of the chamber, which is repeatedly depressurized and released to the atmosphere. On the other hand, the refrigerant returned from the ultra-low temperature etching device 56 but still having a sufficient cooling capacity is used to cool the secondary refrigerant circulating in the sub-cooling circuit in the heat exchanger, and is cooled here. The next refrigerant passes through the pipes 67 and 68, and the room temperature CVD device 57
It is sent to the susceptor 69 inside or the susceptor 70 inside the natural oxide film removing device 58 and used to cool each susceptor 69, 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 by the transfer arm 51 through the gate valve 61, and then transferred into the other processing chambers 57 and 58 through the gate valves 71 and 72. After performing a predetermined process in a predetermined temperature atmosphere, the gate valve 73
After being sent to the unloading cassette chamber 55 via the pressure riser, it is further discharged into the atmosphere through the gate valve 74.

As described above, the cooling system constructed according to the present invention is applied to the multi-chamber type processing apparatus as shown in FIG. 3 so that the refrigerant and its cooling capacity can be used efficiently. Therefore, it is possible to construct a system with low running cost and excellent energy saving. However, it is needless to say that the present invention is not limited to the multi-chamber type processing apparatus and can be applied to a system including a plurality of individual type processing apparatuses.

In the above embodiment, an example in which the cooling system constructed according to the present invention is applied to a low temperature plasma etching apparatus is shown as an example, but the method of the present invention is not limited to such an apparatus, and a CVD apparatus, Ashing device,
When inspecting a sputtering device or an object to be processed at a low temperature, for example, it can be applied to 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 equipment can be used as a cold heat source of the cooling circuit of other processing equipment that processes the object at a higher temperature than the processing equipment, and also the cassette chamber etc. Since it can also be used as a gas source of the purging gas for other chambers, the refrigerant and its cold heat can be remarkably effectively used as compared with the conventional system. As a result, it becomes possible to construct a low-temperature processing system with low running cost and energy saving.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an outline of a cooling system of a low-temperature treatment apparatus configured according to 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 type processing apparatus to which the present invention can be applied.

FIG. 4 is a configuration diagram showing an outline of a cooling system of a conventional low temperature processing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Processing apparatus 2 Processing chamber 4 Mounting table 5 Susceptor support 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 Boost pump 30 accumulator

Claims (3)

[Claims] 1. A low-temperature processing apparatus comprising a first cooling circuit for circulating and cooling a refrigerant in a first susceptor for mounting and fixing an object to be processed in a processing chamber of the first processing apparatus. In the cooling system, the refrigerant return path of the first cooling circuit circulates the refrigerant in the second susceptor of the second processing device that processes the object to be processed at a temperature higher than that of the first processing device to cool the object. A cooling circuit for a low-temperature processing device, which is connected to a second cooling circuit for operating the cooling circuit. 2. A cooling for cooling a susceptor by 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 heat of vaporization of the liquefied inert gas. In a cooling system for a low-temperature processing apparatus having a circuit, the refrigerant return path of the cooling circuit is connected to a purging inert gas source through a recovery circuit for recovering vaporized inert gas. , Low temperature processing equipment cooling system. 3. 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 liquefied inert gas heats vaporization of the liquefied inert gas. In a cooling system for a low-temperature processing apparatus including a first cooling circuit for cooling a first susceptor, a return path of the first cooling circuit is connected to a heat exchanger, and a primary side of the heat exchanger is a heat exchanger. It is connected to a purging inert gas source through a recovery circuit for recovering the exchanged inert gas, and the secondary side of the heat exchanger processes the object at a higher temperature than that of the first processing device. 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 the second susceptor of the second processing device.