JP2006161937A - Liquefied gas supply method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that liquefied gas is liable to be reliquefied in a supply system pipe during greatly changing its flow amount, particularly, suddenly reducing it when cleaning a device while supplying the liquefied gas being gasified. <P>SOLUTION: This liquefied gas supply method comprises using a first heating means for increasing the temperature of a container to gasify the liquefied gas filled in the container, passing gas via a diluted gas mixer connected to the container with a first pipe having a second heating means and a mixed gas flow amount detecting means through at least one of a plurality of branch valves connected to the flow amount detecting means with a second pipe having a third heating means, and introducing the gas to a plurality of portions of a vacuum treatment device via at least one of a plurality of third pipes connected to the plurality of branch valves, respectively. The quantity of heat generated by each of the first heating means, the second heating means and the third heating means is controlled depending on a value measured by the gas flow amount detecting means or on the number of the plurality of branch valves being opened. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is for removing a by-product such as polysilane which remains deposited on the surface of the peripheral member of the discharge space, the exhaust duct, the exhaust pipe inner wall, etc., in a thin film forming process such as a high-frequency plasma CVD method using silane gas or the like. The present invention relates to a liquefied gas supply method using a liquefied gas as a cleaning gas in a cleaning process.

As a means for removing by-products generated mainly in a discharge furnace of a plasma CVD apparatus using a mixed gas containing silane gas, mainly polysilane, etc., in a cleaning method by dry etching, a gas containing a 7B group element, for example, CF A gas such as ₄ or NF ₃ was introduced into the processing apparatus and plasma was generated to excite, decompose, and clean the gas. However, with this method, it has been difficult to clean the member in the plasma discharge region, that is, at a position away from the power application electrode.

As a cleaning method that does not depend on plasma discharge to solve this problem, a plasmaless cleaning method using a gas such as ClF ₃ as a highly reactive gas containing a group 7B element has been performed (for example, Patent Document 1). 2). This method was an excellent cleaning method in which the cleaning progresses as long as it is in contact with gas even if it is away from the electrode, and the polysilane can be removed. Furthermore, in the plasmaless cleaning method, problems due to temperature rise of the members are unlikely to occur, so it is possible to suppress damage to the members due to this, and it is configured by separately providing cooling means etc. for member protection Therefore, it can be said that it is superior to the cleaning method using plasma.

By the way, ClF ₃ has a boiling point of about 11.8 ° C., is liquid at room temperature, and is filled in a container. The filling pressure is about 0.05 MPa (instrument indication value) and a low pressure. Therefore, it is easier to handle gasification once it is introduced into the vacuum device while controlling the flow rate. As the gasification means, using a heat source such as an electric heater, hot air, or hot water, the filling container itself is heated to raise the liquid temperature. In general, the gasification is performed. As a means for controlling the amount of heat generated by the heat source, temperature control such as PID control using an indication value of a temperature probe such as a thermocouple is generally used. As another example, a method of detecting the gasified pressure and adjusting the amount of heat generated by the heat source according to the value is performed (for example, see Patent Document 3).

As another heating control method, in order to prevent re-liquefaction of once gasified ClF ₃ , heating means is provided so that a temperature gradient gradually increases along the downstream direction of the gas flow. (For example, refer patent document 4).

JP-A-1-231936 Japanese Patent Laid-Open No. 2-77579 JP 2002-228093 A Japanese Patent No. 2909364

However, ClF ₃ has a boiling point of room temperature or lower, and even if the liquid is heated, the gasified pressure can only rise to about 0.2 MPa at most. When the supply pipe internal pressure slightly fluctuates (increases), or when diluted with a gas such as N ₂ , a large amount of dilution gas is often flowed, so the dilution gas pressure is relatively high. Therefore, it is easily affected by the pressure fluctuation and liquefaction easily occurs. For example, when the total flow rate of ClF ₃ is flown at a constant value during the cleaning process, the flow is not particularly caused, so that a relatively sufficient effect can be obtained by using the conventional method. However, in view of the actual operation status of the apparatus cleaning process, cleaning is often performed while supplying ClF ₃ from a set of supply systems to a plurality of locations via a plurality of branch pipes. If, for example, 10 places are supplied as the plurality of supply places, the supply is not always continued from the start to the end in every cleaning process. This is because it was judged by some means that the cleaning was completed in the middle of the cleaning process, and the supply was sequentially stopped even in the middle of the process. This is because gases such as HCl and HF generated by the decomposition of ClF ₃ exhibit strong corrosive properties, and continuing to flow past the state where the object to be cleaned is removed may cause unnecessary damage to device components, particularly metal components. This is because there is no reason to manage the stainless steel and aluminum materials having relatively corrosion resistance with the minimum exposure time. Furthermore, ClF ₃ is not inexpensive, and is also from the viewpoint that it is required to be operated so as not to flow unnecessarily from the viewpoint of material cost reduction. In operation based on such a background, as described above, a change procedure for reducing the number of a plurality of supply points as appropriate during the cleaning process is routinely performed. It can be said that there were frequent fluctuations such as sudden declines. In this way, when the supply request amount changes with time, particularly when it decreases in a stepwise manner, when the supply request amount of ClF ₃ is considered, There was a time when the amount of heating heat applied for gasification was relatively excessive due to the rapid decrease. This is because the temperature control means using a conventional thermocouple and the control means for detecting the gasification pressure and adjusting the heat quantity have poor control system responsiveness. Regarding the former, for example, even if the temperature of the container wall surface or the liquid itself is measured, the response of the temperature indication value with respect to the applied heat amount is low, and a time difference of several minutes to ten or more minutes occurs on the time axis. Regarding the latter, although the responsiveness is improved and superior to the former, the container or the liquid temperature rises corresponding to the applied heat amount, and the corresponding liquid amount is reflected as the pressure after being gasified Considering that, a time difference of about several minutes on the time axis had to occur.

  What happens when the time difference is large is that there is an imbalance between the amount of heat input and the amount of liquid to be gasified, and the amount of heat that should be consumed for gasification is excessive. As a result, the place where the excess amount of heat was used was used to raise the container temperature and liquid temperature. This results in overturning the desirable situation where the temperature should be gradually increased along the downstream direction of the gas flow, which is also a conventional example, that is, a location where the temperature becomes higher on the upstream side occurs. It means being forced to re-liquefy.

  Therefore, it has been found that the conventional method, that is, heating control such as gasification pressure and temperature gradient, is not sufficient to keep it flowing stably for a long time while controlling so as not to reliquefy in the pipe. In other words, even when sudden pressure fluctuations occur, especially when supply requirements are suddenly reduced, it is possible to control the amount of heating heat applied by the heating means as quickly as possible after detecting the pressure change more positively. Realization of supply means that can be reflected has been desired.

In order to solve the conventional problems described above, the present inventors have found the following means.
That is, the present invention gasifies the liquefied gas filled in the container using the first heating means for raising the temperature of the container, and the first piping having the container and the second heating means. At least one of a plurality of branch valves connected by a second pipe having a mixed gas flow rate detecting means and a third heating means via a dilution gas mixer and a mixed gas flow rate detecting means connected by In the liquefied gas supply method of introducing gas to a plurality of locations of the vacuum processing apparatus via at least one or more of the plurality of third pipes respectively connected to the plurality of branch valves. The amount of heat generated by the first heating unit is controlled in accordance with a measurement value of the mixed gas flow rate detection unit.
According to the present invention, the liquefied gas filled in the container is gasified using the first heating means for raising the temperature of the container, and the gas is first pipe having the container and the second heating means. At least one of a plurality of branch valves connected by a second pipe having a mixed gas flow rate detecting means and a third heating means via a dilution gas mixer and a mixed gas flow rate detecting means connected by In the liquefied gas supply method of introducing gas to a plurality of locations of the vacuum processing apparatus via at least one or more of the plurality of third pipes respectively connected to the plurality of branch valves. The amount of heat generated by the second heating unit is controlled in accordance with a measurement value of the mixed gas flow rate detection unit.
According to the present invention, the liquefied gas filled in the container is gasified using the first heating means for raising the temperature of the container, and the gas is first pipe having the container and the second heating means. At least one of a plurality of branch valves connected by a second pipe having a mixed gas flow rate detecting means and a third heating means via a dilution gas mixer and a mixed gas flow rate detecting means connected by In the liquefied gas supply method of introducing gas to a plurality of locations of the vacuum processing apparatus via at least one or more of the plurality of third pipes respectively connected to the plurality of branch valves. The amount of heat generated by the third heating unit is controlled in accordance with a measurement value of the mixed gas flow rate detection unit.
Further, according to the present invention, the liquefied gas filled in the container is gasified using a first heating means for raising the temperature of the container, and the gas is first pipe having the container and the second heating means. At least one or more of a plurality of branch valves connected by a second pipe having a mixed gas flow rate detecting means and a third heating means via a dilution gas mixer and a mixed gas flow rate detecting means connected by In the liquefied gas supply method of introducing gas to a plurality of locations of the vacuum processing apparatus via at least one or more of the plurality of third pipes respectively connected to the plurality of branch valves. The amount of heat generated by the third heating unit is controlled according to the number of the plurality of branch valves that are open.

  By using the method of the present invention, it is possible to prevent reliquefaction in the supply system pipe when the apparatus cleaning is performed while supplying the liquefied gas while gasifying, when the flow rate is greatly changed, particularly when the flow rate is rapidly decreased. As a result, effective use of the cleaning gas and reduction of damage to the device members are achieved, and there are effects such as operation costs and reduction of device downtime.

FIG. 1 shows an example of the liquefied gas supply method of the present invention.
The liquefied gas filling container 100 is provided with a first heating means 101 and connected to a first control power supply 111. As a heating means, a flexible sheath heater type band heater was wound around the outer periphery of the container conductor. However, other methods include halogen lamp heating and hot air heating that can be heated in a non-contact manner, and pipes around the container. Means such as heating by feeding the wound hot water are conceivable, but there is no particular limitation as long as it is a structure that emphasizes responsiveness including the adhesion between the heating means and the container. As the liquefied gas, ClF ₃ is suitable, but is not particularly limited as long as it is a compound capable of cleaning silicon-based byproducts such as polysilane.

  One end of the first pipe 105 having the second heating means 102 is connected to the liquefied gas filling container 100, and the other end is connected to the inlet of the flow rate detecting means 104. As the flow rate detection means, a mass flow controller that also has a flow rate adjustment function was used. However, a mass flow meter or the like may be used in addition to these, and any means that can measure the flow rate value in real time and output the value externally can be used. It is not limited to.

A dilution gas pipe 121 is joined from the N ₂ filling container 120 to the inlet portion of the flow rate detection means 104, and the N ₂ gas flow rate and the ClF ₃ dilution ratio can be appropriately set by using a mixing control means (not shown). is there. The diluent gas may be argon, helium or the like, and is not particularly limited as long as it is an inert gas that does not contain moisture.

  One end of the second pipe 106 having the third heating means 103 is connected to the outlet of the flow rate detecting means 104, the other end is branched into 10 systems, and the branched pipes are each configured by an automatic valve. A plurality of branch valves 131 to 140 are installed and connected to a plurality of supply points 141 to 150 (not shown) on the downstream side thereof to supply gas.

  The pipe heating means may be the same as the container heating means, but the heat conductivity between the pipe and the heating means is good to ensure better adhesion because the shape is uneven compared to the container. An aluminum metal wool or a synthetic silicon resin paste material may be filled.

  A valve control system 114 for controlling the open / closed state of the plurality of branch valves 131 to 140 is installed. Information is input to the overall control system 115 in real time via the control signal line 116 and the flow rate value from the flow rate detection means 104 and the number of open valves from the valve control system 114, respectively. In accordance with the determined control routine, a command is sent to the first control power supply 111, the second control power supply 112, and the third control power supply 113, and the first heating means 101, the second heating means 102, This can be reflected in the control of the three heating means 103. As a control routine, for example, when the open valve ratio (= [number of open valves] / [number of all branch valves]) is constant and the flow rate value of the flow rate detection means is reduced by 10%, the heating means heat generation amount is reduced by 5%. On the other hand, when the flow rate value of the flow rate detection means is a constant value and the open valve rate is reduced by 15%, the heating means heat generation amount is reduced by 5%, and the flow rate value is 5%. If the open valve rate decreases simultaneously by 5%, the heating means heat generation may be reduced by 12%, but the degree of each is not uniquely determined, and the environment (temperature) Confirmation experiments based on preconditions according to individual cases such as humidity, air conditioning operation status, heating pipe length, cabinet size, and mixing box size) If selected data to individual well is not particularly limited to the above values.

  The liquefied gas supply method of the present invention will be described below with specific examples, but the gist of the present invention is not limited to these descriptions.

[Example 1]
When the supply method shown in FIG. 1 is used and the method for controlling the amount of heat generated by each of the first, second, and third heating means is changed to the method of Experiment 1 and Experiment 2 shown below, ClF ₃ (N ₂ The mixture gas flow rate is set to 50,000 cm ³ / min (normal), all the branch valves 131 to 140 are opened, and the gas is allowed to flow through all of the supply points 141 to 150 in a steady state. Supplied when the cleaning is continued for 10 minutes while maintaining the state, and then the flow rate setting value of the flow rate detection means 104 is used to operate the flow rate setting value to a half value to rapidly reduce the flow rate and continue cleaning for 10 minutes It was compared whether reliquefaction occurred inside the pipe. In the liquefaction confirmation method, after the gas flow is temporarily stopped, the inside of the first pipe and the second pipe is evacuated, and it takes 5 minutes or more to reach 1 Pa. Judged that it occurred.

(Experiment 1)
When the value of the flow rate detection means 104 is halved in the control of the heat generation amount of each of the first heating means, the second heating means, and the third heating means, the generated heat quantity change (100% output) confirmed in advance by experiments → changed to 60% output) and reflected in the heat control.
(Experiment 2)
PID temperature control using a thermocouple was performed to control the amount of heat generated by each of the first heating means, the second heating means, and the third heating means.
Table 1 shows the determination results of reliquefaction in Experiment 1 and Experiment 2.

  From the above results, it was demonstrated that the method of Experiment 1 using the present invention can prevent reliquefaction even when the gas flow rate is suddenly reduced.

[Example 2]
In the case where the supply method shown in FIG. 1 is used and the control method of the heat generation amount of each of the first, second, and third heating means is changed to the method of Experiment 3 and Experiment 4 shown below, ClF ₃ (N ₂ The mixture gas flow rate is set to 50,000 cm ³ / min (normal), all the branch valves 131 to 140 are opened, and the gas is allowed to flow through all of the supply points 141 to 150 in a steady state. When cleaning is continued for 10 minutes while maintaining the state, and the flow rate is rapidly reduced by closing five valves 132, 134, 136, 138, 140 among the branch valves 131 to 140, and cleaning is continued for 10 minutes. We compared whether reliquefaction occurred inside the pipe. In the liquefaction confirmation method, after the gas flow is temporarily stopped, the inside of the first pipe and the second pipe is evacuated, and it takes 5 minutes or more to reach 1 Pa. Judged that it occurred.

(Experiment 3)
When the number of open valves of the branch valve is halved to control the amount of heat generated by each of the first heating means, the second heating means, and the third heating means, the amount of generated heat that has been confirmed in advance by experiments (100% output) → changed to 65% output) and reflected in the heat control.
(Experiment 4)
PID temperature control using a thermocouple was performed to control the amount of heat generated by each of the first heating means, the second heating means, and the third heating means.
Table 2 shows the determination results of reliquefaction in Experiment 3 and Experiment 4.

  From the above results, it was demonstrated that the method of Experiment 3 using the present invention can prevent reliquefaction even when the gas flow rate is suddenly reduced.

It is a liquefied gas supply piping diagram for explaining the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Liquefied gas filling container 101 1st heating means 102 2nd heating means 103 3rd heating means 104 Mixed gas flow rate detection means 105 1st piping 106 2nd piping 111 1st control power supply 112 2nd control Power supply 113 Third control power supply 114 Valve control system 115 Overall control system 116 Control signal line 120 N ₂ filling container 121 Dilution gas piping 131-140 Multiple branch valves 141-150 Multiple supply locations

Claims (4)

  The liquefied gas filled in the container is gasified by using the first heating means for raising the temperature of the container, and the gas is diluted by the first pipe having the container and the second heating means. Passing through the gas mixer and the mixed gas flow rate detection means, at least one of the plurality of branch valves connected by the second pipe having the mixed gas flow rate detection means and the third heating means is opened and passed. In the liquefied gas supply method for introducing gas into a plurality of locations of the vacuum processing apparatus via at least one of the plurality of third pipes respectively connected to the plurality of branch valves, the first heating A liquefied gas supply method characterized in that the amount of heat generated by the means is controlled in accordance with the measured value of the mixed gas flow rate detecting means.   The liquefied gas filled in the container is gasified by using the first heating means for raising the temperature of the container, and the gas is diluted by the first pipe having the container and the second heating means. Passing through the gas mixer and the mixed gas flow rate detection means, at least one of the plurality of branch valves connected by the second pipe having the mixed gas flow rate detection means and the third heating means is opened and passed. In the liquefied gas supply method of introducing gas into a plurality of locations of the vacuum processing apparatus via at least one of the plurality of third pipes respectively connected to the plurality of branch valves, the second heating A liquefied gas supply method characterized in that the amount of heat generated by the means is controlled in accordance with the measured value of the mixed gas flow rate detecting means.   The liquefied gas filled in the container is gasified by using the first heating means for raising the temperature of the container, and the gas is diluted by the first pipe having the container and the second heating means. Passing through the gas mixer and the mixed gas flow rate detection means, at least one of the plurality of branch valves connected by the second pipe having the mixed gas flow rate detection means and the third heating means is opened and passed. In the liquefied gas supply method of introducing gas into a plurality of locations of the vacuum processing apparatus via at least one of the plurality of third pipes respectively connected to the plurality of branch valves, the third heating A liquefied gas supply method characterized in that the amount of heat generated by the means is controlled in accordance with the measured value of the mixed gas flow rate detecting means.   The liquefied gas filled in the container is gasified by using the first heating means for raising the temperature of the container, and the gas is diluted by the first pipe having the container and the second heating means. Passing through the gas mixer and the mixed gas flow rate detection means, at least one of the plurality of branch valves connected by the second pipe having the mixed gas flow rate detection means and the third heating means is opened and passed. In the liquefied gas supply method of introducing gas into a plurality of locations of the vacuum processing apparatus via at least one of the plurality of third pipes respectively connected to the plurality of branch valves, the third heating A liquefied gas supply method characterized in that the amount of heat generated by the means is controlled according to the number of the plurality of branch valves that are open.

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