JP2004335500A - Cooling/heating temperature adjusting system for substrate of semiconductor product, or the like - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling/heating temperature adjusting system that can improve the working rate of a whole process by shortening the replacement time of a biasing electrode and, in addition, can reduce running cost and facility cost. <P>SOLUTION: A susceptor 4 is constituted so that it may be divided into an upper susceptor section 4a and a lower susceptor section 4b. The biasing electrode 3 is set up on the upper susceptor 4a, and a flow passage 12 for refrigerant is formed in the lower susceptor 4b. Consequently, temperature uniformity can be given exclusively to the upper susceptor 4a. When replacing the biasing electrode 3, in addition, the replacement work can be carried out without removing the flow passage 12 by only removing the upper susceptor 4a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a processing substrate (semiconductor) in a manufacturing process of a semiconductor wafer, a liquid crystal (LCD), an Electro-Luminescence (EL), a solar cell, and the like (hereinafter, these are referred to as “semiconductor products and the like”). The cooling / heating temperature control system used in the process of cooling / heating temperature control of a wafer, a glass substrate for liquid crystal, a substrate for EL, a substrate for solar cells, etc. By being configured to be able to be divided into an upper part having a lower electrode for generating plasma (an electrode for bias) and a lower part having a refrigerant flow path, the bias flow can be performed without separating the refrigerant flow path in the susceptor from the refrigerant circulation circuit. The replacement electrode is configured to be replaceable, thereby shortening the time required for replacement work, omitting the secondary refrigerant circulation circuit, and replacing only the primary refrigerant. Thus a cooling and heating temperature adjustment system capable of cooling and heating the susceptor.
[0002]
[Prior art]
Conventionally, when it is necessary to cool an object (load) in a manufacturing process of a semiconductor product or the like, a cooling / heating temperature control system has been used. The cooling / heating temperature control system includes a system based on a “two-stage cooling method” and a system based on a “single-stage cooling method”.
[0003]
In the temperature control system of the two-stage cooling method, a plurality of refrigerants (refrigerant refrigerant and brine) exist between a refrigerator as a cooling source and an object to be cooled. Of these, the refrigerator refrigerant is primarily referred to as “primary refrigerant” because it primarily mediates load cooling by the work of the refrigerator (evaporation process of the refrigeration cycle). , And mediates cooling of the load in a secondary manner (ie, indirectly cooling of the load by the primary refrigerant), and is therefore referred to as “secondary refrigerant”.
[0004]
On the other hand, the temperature control system using the single-stage cooling method directly controls the temperature of the load using only the primary refrigerant without using the secondary refrigerant.
[0005]
Incidentally, for example, in a plasma etching (dry etching) process of a semiconductor wafer, it is necessary to appropriately cool a wafer heated by plasma irradiation. Therefore, a dry etching apparatus for a semiconductor wafer usually has a temperature control system for cooling the wafer, as shown in FIG. 2 (a diagram showing a configuration example of a conventional general dry etching apparatus 21). .
[0006]
Here, the schematic configuration of the dry etching apparatus 21 shown in FIG. 2 and the operation of the temperature control system will be briefly described. The dry etching apparatus 21 includes a cooling / heating temperature control device 25 which is a main component of the temperature control system, an upper electrode 22 for plasma generation, an electrode 23 for bias, a susceptor 24, and the like.
[0007]
The susceptor 24 is composed of a susceptor upper part 24a and a susceptor lower part 24b. Of these, the susceptor upper part 24a is provided with a bias electrode 23 on its upper surface, and a refrigerant flow path 32 is formed inside. ing.
[0008]
In FIG. 2, W denotes a semiconductor wafer, and a helium gas layer (gas layer G) is formed between the susceptor upper portion 24a (bias electrode 23) and the semiconductor wafer W.
[0009]
The cooling / heating temperature controller 25 includes a refrigerator 26, a primary refrigerant pipe 27 (an inlet pipe 27a, an outlet pipe 27b), a heat exchanger 28, a pump 29, a heating electric heater 30, and a secondary refrigerant pipe 31 (an inlet pipe). A pipe 31a and an outlet pipe 31b) are provided.
[0010]
The secondary refrigerant is sent out from the pump 29, passes through the heat exchanger 28, the heating electric heater 30, the secondary refrigerant inlet pipe 31a, the refrigerant flow path 32, and the secondary refrigerant outlet pipe 31b, and returns to the pump 29 again. And circulates in the closed conduit (secondary refrigerant circuit 33).
[0011]
More specifically, when the secondary refrigerant passes through the heat exchanger 28, heat is exchanged by the primary refrigerant. Then, after the temperature is adjusted to the supply temperature by the heating electric heater 30, the temperature is supplied to the refrigerant flow path 32 provided in the upper part 24 a of the susceptor through the inlet pipe 31 a of the secondary refrigerant, and the heat of the semiconductor wafer W is removed. . The secondary refrigerant that has taken heat from the susceptor upper portion 24a is sent to the heat exchanger 28 again through the secondary refrigerant outlet pipe 31b, and is removed by the primary refrigerant.
[0012]
The primary refrigerant circulates in the primary refrigerant circulation circuit 34, takes heat from the secondary refrigerant in the heat exchanger 28, and removes heat taken from the secondary refrigerant by the work (refrigeration cycle) of the refrigerator 26. Discharge outside the refrigerator.
[0013]
As described above, the temperature control system of the dry etching apparatus 21 shown in FIG. 2 is based on the “two-stage cooling method” in which the load is indirectly controlled using the secondary refrigerant. In addition to the dry etching apparatus 21 illustrated in FIG. 2, most of the temperature control systems applied to the manufacturing process of semiconductor products and the like now employ a two-stage cooling method.
[0014]
In the temperature control system of the dry etching apparatus 21 as described above, the “cooling method of directly controlling the load with the primary refrigerant” (hereinafter, this cooling method is referred to as “simple one-stage cooling method”). In the case of adopting the dry etching apparatus 21, the equipment constituting the secondary refrigerant circulation circuit 33 excluding the refrigerant circuit 32 from the dry etching apparatus 21 (that is, the heat exchanger 28 pump 29, the heating electric heater 30, the secondary refrigerant pipe 31a and 31b) can be eliminated and the apparatus can be simplified, but this "simple one-stage cooling method" cannot be adopted in the temperature control system.
[0015]
This is because the bias electrode 23 installed on the susceptor upper portion 24a deteriorates during repeated plasma irradiation in the dry etching process and needs to be periodically replaced. Each time the electrode is replaced, it is necessary to collect the primary refrigerant, evacuate the primary refrigerant piping to dry and deaerate it, and refill the primary refrigerant. This is because the replacement work becomes more complicated, and after all, it is no different from the two-stage cooling method.
[0016]
[Problems to be solved by the invention]
As described above, at present, the two-stage cooling method is mainly used as a temperature control system applied in a manufacturing process of a semiconductor product or the like, but the temperature of the two-stage cooling method as shown in FIG. The key system has the following problems.
[0017]
In the cooling / heating temperature control system of the two-stage cooling method shown in FIG. 2, it is necessary to first collect the secondary refrigerant when the bias electrode 23 is periodically replaced. As shown in FIG. 2, since the bias electrode 23 is attached to the susceptor upper part 24 a, it must be removed together with the susceptor upper part 24 a from the etching apparatus 21 when replacing it. A refrigerant flow path 32 is formed inside the susceptor upper part 24a, and this refrigerant flow path 32 is connected to the secondary refrigerant pipe 31, and the secondary refrigerant circulates inside them. That is, the susceptor upper portion 24a cannot be removed from the etching device 21 unless the internal secondary refrigerant is recovered.
[0018]
Then, the recovery operation of the secondary refrigerant cannot be performed immediately from the state in which the temperature control device 25 is operating, and the following steps need to be performed extraly, which wastes time. . Specifically, first, the supply temperature setting of the secondary refrigerant is changed from “process temperature” to “around room temperature” while the temperature control device 25 is operating (without stopping). When the supply temperature of the secondary refrigerant reaches around room temperature, the temperature controller 25 is stopped, and the secondary refrigerant is recovered.
[0019]
The reason why the supply temperature setting of the secondary refrigerant is first changed to “around room temperature” in this way is to prevent condensation from occurring in the secondary refrigerant circulation circuit 33. For example, when the process temperature set for efficiently manufacturing semiconductor products and other industrial products is −10 ° C., the cooling / heating temperature controller 25 can be used without changing the supply temperature of the secondary refrigerant. Is stopped, and after the secondary refrigerant is recovered, if the secondary refrigerant inlet pipe 31a and the like are cut off from the refrigerant flow path 32, the exposed air may cause condensation on the inner surface of the secondary refrigerant inlet pipe 31a and the like. There is.
[0020]
If water is mixed in the secondary refrigerant, chemical and physical changes occur during use, which hinders continuous stable operation.Therefore, when refilling the secondary refrigerant, dew condensation water will be present in the pipeline. It is not preferable that it remains. For this reason, when recovering the secondary refrigerant, a step for adjusting the temperature of the secondary refrigerant circulation circuit 33 to around room temperature in advance is required to prevent dew condensation.
[0021]
As described above, in the cooling / heating temperature control system based on the two-stage cooling method shown in FIG. 2, when the bias electrode 23 is replaced, the recovery operation of the secondary refrigerant is required, and the recovery operation of the secondary refrigerant is performed. Requires a step for preventing dew condensation, and as a result, it takes a very long time to complete the replacement of the bias electrode 23.
[0022]
In addition, the recovery operation of the secondary refrigerant must be performed carefully and carefully so that the secondary refrigerant does not remain in the secondary refrigerant circulation circuit 33. This is because if the secondary refrigerant remains, the secondary refrigerant may leak out when the susceptor upper portion 24a is removed. Since the leaked secondary refrigerant may have high volatility in some cases, there is a possibility that the global environment as well as the working environment is polluted by fluorine or the like which is one of the substances constituting the secondary refrigerant.
[0023]
Further, when the secondary refrigerant is recovered, after the susceptor upper portion 24a having the new bias electrode 23 is mounted, it is necessary to refill the secondary refrigerant. During the refilling operation, gas may be mixed into the secondary refrigerant circulation pipeline 33. In such a case, the secondary refrigerant is circulated for a certain time to completely remove the gas that has entered. It is necessary to degas.
[0024]
Insufficient degassing in the secondary refrigerant circuit 33 causes gas pockets. Such gas pockets are formed as a layer at the highest position of the refrigerant flow path 32 provided inside the upper susceptor 24a. Probability of formation is highest. If such a gas layer is formed, the heat transfer resistance increases, so that a predetermined heat transfer capability cannot be obtained, and a temperature distribution occurs in the wafer to be cooled. Can also occur.
[0025]
Also, in order to reduce manufacturing costs, semiconductor wafers have become larger in diameter, and accordingly, the amount of heat removal has been required to be increased. In order to meet the demand for reinforcement, it is necessary to increase the amount of secondary refrigerant supplied to the susceptor, increase the size of the pump, and further increase the size of refrigerators and heaters for cooling and heating the secondary refrigerant. It becomes. As a result, there is a problem that equipment costs and running costs increase.
[0026]
For this reason, in a semiconductor wafer etching apparatus, cooling / heating can shorten the replacement time of a bias electrode, improve the operation rate of the entire process, and reduce running costs and equipment costs. The development of a temperature control system is desired.
[0027]
[Means for Solving the Problems]
The cooling / heating temperature control system of the present invention is configured so that the susceptor can be divided into an upper susceptor and a lower susceptor in order to solve the above-mentioned problems of the related art, and a bias electrode is installed on the upper susceptor. The refrigerant flow path is formed in the lower part of the susceptor. With such a configuration, the upper portion of the susceptor can be provided with temperature uniformity exclusively. Further, when replacing the bias electrode, only the upper part of the susceptor needs to be removed, and the replacement operation can be performed without removing the coolant channel. Therefore, the operation of recovering the refrigerant is not required, and the gas is not mixed into the refrigerant circuit.
[0028]
In addition, it is preferable that a primary refrigerant pipe connected to a refrigerator is directly connected to a refrigerant flow path provided at a lower part of the susceptor so as to directly supply a primary refrigerant (refrigerant refrigerant such as HFC). . In such a configuration, unlike the conventional temperature control system, it is not necessary to dispose a secondary refrigerant circulation circuit, which can be omitted, and the supply temperature is supplied to the refrigerant flow path formed in the lower part of the susceptor. By directly supplying the primary refrigerant whose temperature has been controlled, the heat transfer resistance between the semiconductor wafer to be cooled and the refrigerant (primary refrigerant) is reduced as compared with the conventional temperature control system using the two-stage cooling method. be able to.
[0029]
Further, by forming a layer of a gas having good thermal conductivity, for example, a helium gas layer between the object to be cooled and the upper part of the susceptor and between the upper part of the susceptor and the lower part of the susceptor, the object to be cooled is formed. More preferably, the heat transfer resistance between the first refrigerant and the primary refrigerant is reduced.
[0030]
Then, by reducing the heat transfer resistance between the object to be cooled and the refrigerant, the set temperature of the supplied primary refrigerant can be increased. Since the required power of the refrigerator decreases as the set temperature (that is, the evaporation temperature) increases, the running cost of the temperature control system can be reduced.
[0031]
Also, the heat transfer method of the primary refrigerant is boiling heat transfer in a phase change during evaporation, and the heat transfer method of the secondary refrigerant is liquid phase heat transfer without a phase change. The coefficient is more than twice the heat transfer coefficient of the secondary refrigerant, and if the temperature control system using the single-stage cooling method and the temperature control system using the two-stage cooling method set the same supply temperature of the refrigerant, In the temperature control system using the cooling method, the heat transfer area required for heat removal can be made smaller than that in the temperature control system using the two-stage cooling method. Therefore, the size of the susceptor can be reduced, which contributes to a reduction in equipment cost.
[0032]
Furthermore, in the present invention, since the secondary refrigerant circulation circuit is not required and the configuration is omitted, the equipment cost and the running cost can be reduced, and the device size can be reduced at the same time.
[0033]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a semiconductor wafer dry etching apparatus 1 to which a cooling / heating temperature control system according to the present invention is applied. This etching apparatus 1 also basically has a cooling / heating temperature adjustment apparatus 5 which is a main component of the temperature adjustment system, an upper electrode 2 for plasma generation, an electrode 3 for bias, and It is composed of a susceptor 4 and the like.
[0034]
The susceptor 4 includes a susceptor upper portion 4a and a susceptor lower portion 4b, and the bias electrode 3 is disposed on an upper surface of the susceptor upper portion 4a. However, unlike the conventional one, the coolant channel 12 is formed not in the susceptor upper part 4a but in the susceptor lower part 4b.
[0035]
The cooling / heating temperature control device 5 includes a refrigerator 6 and a primary refrigerant pipe 7 (an inlet pipe 7a and an outlet pipe 7b), and is not a two-stage cooling method as shown in FIG. This constitutes a temperature control system of the "single-stage cooling method" in which the load is directly temperature-controlled only by the refrigerant.
[0036]
In FIG. 1, W denotes a semiconductor wafer, and a helium gas is introduced between the upper part 4a of the susceptor (the bias electrode 3) and the semiconductor wafer W to form a helium gas layer (gas layer G1). ) Is formed, and a helium gas layer (gas layer G2) is also formed between the susceptor upper portion 4a and the susceptor lower portion 4b.
[0037]
In this dry etching apparatus 1, the primary refrigerant adjusted to the process temperature by the refrigerator 6 is supplied to the refrigerant flow path 12 provided in the lower part 4b of the susceptor via the primary refrigerant inlet pipe 7a, and the semiconductor wafer W Is performed.
[0038]
The primary refrigerant that has taken heat in the lower part 4b of the susceptor passes through the primary refrigerant outlet pipe 7b, is adjusted to the supply temperature in the refrigerator 6, and is supplied again to the refrigerant channel 12 through the primary refrigerant inlet pipe 7a. You.
[0039]
Here, a procedure for replacing the bias electrode 3 in the dry etching apparatus 1 will be described. First, the setting of the supply temperature of the primary refrigerant is changed to room temperature (temperature at which no dew condensation occurs). When the supply temperature reaches around this room temperature, only the susceptor upper part 4a provided with the bias electrode 3 is removed from the etching apparatus 1.
[0040]
After removing the susceptor upper part 4a, a new susceptor upper part 4a is installed, a helium gas layer G2 is formed between the susceptor upper part 4a and the susceptor lower part 4b, and the supply temperature setting of the primary refrigerant is changed to "process temperature" (replacement work). Done). By the way, the total work time required for the single-stage cooling method is about 15 minutes, and the total work time required for the two-stage cooling method is at least about 30 minutes. It only takes time.
[0041]
As described above, the setting of the supply temperature of the primary refrigerant is first changed before removing the susceptor upper part 4a to be replaced, in order to avoid the occurrence of dew condensation on the surface of the susceptor lower part 4b and to prevent the deterioration of the electric heat resistance. It is. More specifically, if only the susceptor upper part 4a is removed, the surface of the susceptor 4b is exposed. At this time, if the primary refrigerant supplied to the refrigerant flow channel 12 remains at a low temperature, the exposed susceptor Dew condensation may occur on the surface of the lower part 4b. If the new susceptor upper part 4a is installed without removing the dew, the dew water is gasified by the heat generated by the plasma irradiation in the helium gas layer G2 formed between the susceptor upper part 4a and the susceptor lower part 4b. There is a possibility that the heat transfer resistance is deteriorated in the initial stage. The gasified water is purged together with the helium gas so that it can be finally removed.However, in order to ensure safety in the early stages of the process, changing the set temperature avoids the formation of condensation. It is desirable to do.
[0042]
As described above, the cooling / heating temperature control system of the present invention is configured by a one-stage cooling method, has a structure without a secondary refrigerant circulation circuit, and has a refrigerant flow path 12 including the bias electrode 3. The cooling / heating temperature controller 5 is formed not in the susceptor upper part 4a but in the susceptor lower part 4b, and it is not necessary to disconnect the refrigerant flow path 12 from the refrigerant pipe 7 when replacing the bias electrode 3. Therefore, the operation of replacing the bias electrode 3 can be performed extremely simply.
[0043]
Hereinafter, examples of the present invention will be described. In the dry etching apparatus 1 of FIG. 1 to which the cooling / heating temperature control system according to the present invention is applied, a thermal load of 4500 W is generated on a semiconductor wafer having a diameter of 300 mm, and the heat load is cooled by the temperature control system, and each part (coolant) , The susceptor upper part, the electrodes, and the wafer). The result is shown in FIG. The graph of FIG. 3 shows, as a comparative example, a temperature measurement value of the temperature control system of the conventional two-stage cooling method in addition to a temperature measurement value of the temperature control system of the one-stage cooling method according to the present invention.
[0044]
As shown in this graph, in the temperature control system of the conventional two-stage cooling method, the supply temperature of the secondary refrigerant was set to -10C. As a result, the surface temperature of the semiconductor wafer became 67.2 ° C.
[0045]
Then, in the temperature control system of the one-stage cooling method according to the present invention, the supply temperature of the primary refrigerant was adjusted such that the surface temperature of the semiconductor wafer was 67.2 ° C. As a result, when the supply temperature of the primary refrigerant was set to -1.4 ° C, the surface temperature of the semiconductor wafer became 67.2 ° C. From this test result, it can be seen that in the temperature control system of the single-stage cooling method of the present invention, the supply temperature of the refrigerant can be set 8.6 ° C. higher than in the case of the conventional temperature control system of the two-stage cooling method. I understood.
[0046]
As described above, in the temperature control system using the single-stage cooling method, the supply temperature of the refrigerant can be set higher than that in the temperature control system using the two-stage cooling method. While the susceptor is cooled by cooling the (secondary refrigerant) and the liquid phase heat transfer of the cooled brine, in the single-stage cooling method, the susceptor is directly cooled by the boiling heat transfer of the refrigerator refrigerant (primary refrigerant). This is because the heat transfer resistance of the single-stage cooling method is smaller than half the heat transfer resistance of the two-stage cooling method.
[0047]
In the case where an inverter refrigerator is used in the temperature control system of the present invention, if the supply temperature of the primary refrigerant is set to −10 ° C. (the same conditions as in the comparative example), if the calorific value to be removed is 4500 W, refrigeration is performed. According to the performance table of the machine manufacturer, the power consumption was 7.07A. Moreover, when it was set to -1.4 ° C, it was 5.63A. Therefore, according to the temperature control system of the present invention, the energy consumption is reduced by 1.44 A.
[0048]
In the temperature control system using the two-stage cooling method, a refrigerator and a refrigerator refrigerant are used to cool brine as a secondary refrigerant, and the cooled brine is used to cool and heat the susceptor. In some cases, the brine is heated and controlled by an electric heater for heating. On the other hand, in the case of the single-stage cooling method as in the present invention, since the susceptor is directly cooled and heated by the refrigerator refrigerant, the secondary refrigerant, the secondary refrigerant circulation pump, and the electric heater for heating temperature adjustment become unnecessary. The initial equipment costs, annual maintenance costs, and running costs can be reduced accordingly.
[0049]
In this example, the temperature control system according to the present invention was used for 2000 hours or more. However, since the lower part of the susceptor did not cause any trouble, it was confirmed that the lower part of the susceptor had sufficient durability. Was.
[0050]
【The invention's effect】
As described above, the present invention reduces the time required for replacing the bias electrode by reviewing the structure of the susceptor, and directly supplies the refrigeration refrigerant, which is the primary refrigerant, to the susceptor. In addition, it is possible to provide a single-stage cooling / heating temperature control system that saves energy and has a small installation area.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a semiconductor wafer etching apparatus 1 to which a cooling / heating temperature control system according to the present invention is applied.
FIG. 2 is a configuration diagram of a conventional general etching apparatus 21 to which a cooling / heating temperature control system of a two-stage cooling method is applied.
FIG. 3 is a graph showing the results of temperature measurement performed on the cooling / heating temperature control system according to the present invention.
[Explanation of symbols]
1,21: dry etching equipment,
2, 22: upper electrode for plasma generation,
3, 23: bias electrode,
4, 24: susceptor,
4a, 24a: upper part of susceptor,
4b, 24b: lower part of susceptor
5, 25: Cooling / heating temperature controller,
6, 26: refrigerator,
7, 27: primary refrigerant pipe,
7a, 27a: inlet piping,
7b, 27b: outlet piping,
28: heat exchanger,
29: Pump,
30: electric heater for heating,
31: secondary refrigerant pipe,
31a: inlet piping,
31b: outlet piping,
12, 32: refrigerant flow path,
33: secondary refrigerant circuit,
34: primary refrigerant circulation circuit,
G, G1, G2: gas layer,
W: Semiconductor wafer

Claims (3)

The susceptor is configured so that it can be divided into a susceptor upper part and a susceptor lower part,
A bias electrode is placed on the susceptor,
A cooling / heating temperature control system, wherein a coolant passage is formed in a lower portion of the susceptor. The cooling / heating temperature control system according to claim 1, wherein a primary refrigerant pipe is connected to a refrigerant flow path provided below the susceptor so as to directly supply the primary refrigerant. The helium gas layer is formed between the object to be cooled and the upper part of the susceptor, and between the upper part of the susceptor and the lower part of the susceptor, wherein the helium gas layer is formed. Cooling / heating temperature control system.

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