JP2006086166A - Method for removing silicon-containing substance and removing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To promote cleaning reaction to improve the utilization factor of a cleaning gas and to greatly shorten a cleaning time in a step without plasma where a silicon-containing byproduct such as polysilane or the like generated during a thin-film formation step for a high-frequency plasma CVD method using a silane gas or the like is removed for cleaning. <P>SOLUTION: This method is used to remove a silicon-containing substance deposited at least in a reaction chamber 101 and/or piping 108 by introducing a cleaning gas, and it includes a step to move the silicon-containing substance to a place where the flow velocity of the cleaning gas is high from its deposition part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention removes silicon-containing by-products such as polysilane that remain on the surface of discharge space peripheral members, exhaust ducts, exhaust pipe inner walls, etc. in thin film formation processes such as high-frequency plasma CVD using silane gas. The present invention relates to a cleaning method and a cleaning apparatus.

As a means for removing by-products generated mainly in a discharge furnace in a thin film formation process such as a plasma CVD apparatus using a mixed gas containing silane gas, mainly polysilane, the cleaning method using dry etching includes a 7B group element. A gas such as CF 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 has an excellent advantage that the cleaning can proceed as long as it is in contact with the gas even if it is away from the electrode, and the polysilane can be removed. Furthermore, since the plasmaless cleaning method does not cause damage that causes the temperature of the member to rise due to plasma heating and cause excessive corrosion, a cooling means for protecting the member that is essential in cleaning using plasma, etc. The configuration tends to complicate the apparatus, and it is advantageous in terms of operation due to the procedural simplicity that the cleaning proceeds only by flowing gas, and is superior to the cleaning method using plasma.

As an example of further promoting this advantage and actively collecting and cleaning by-products in specific places other than the plasma discharge space, a trap device is placed in the middle of the gas processing section and exhaust pipe for forming a thin film, and the reaction product. Is trapped as a deposit, and ClF ₃ gas is separately supplied to the trap when the gas processing unit is not processed to remove the deposit (Patent Document 3).

  In another example of the trap, a louver-like member is provided in the plasma discharge space and / or in the vicinity of the plasma discharge space, and in some cases, the louver-like member is heated so that powder such as polysilane does not scatter in the vacuum processing container. Means for fixing is disclosed (Patent Document 4).

JP-A-1-231936 Japanese Patent Laid-Open No. 2-77579 JP 2001-189277 A Japanese Patent Laid-Open No. 11-80964

  However, silicon-containing by-products such as polysilane to be removed by cleaning adhere to locations such as the inner wall of the vessel, the inner side of the exhaust valve, the inner wall of the vacuum exhaust pipe, the inside of the vacuum pump, etc. located downstream from the discharge space during the thin film formation process At the same time, there is a tendency to deposit a larger amount more selectively at locations where the exhaust gas flow rate is relatively smaller than the others. For example, if the exhaust pipe has a bent shape, the inner wall on the inner circumference side of the pipe cross section, the part where the pipe diameter increases, that is, the part where the conductance increases, etc., becomes a lump and adheres to the inner wall It is piled up. On the other hand, a part where the flow velocity is intentionally reduced is provided in the middle of the exhaust piping system so that the flow is stagnant, that is, even when a trap part is provided, a large amount of polysilane accumulates and gradually grows in a lump. .

  When cleaning is started in such a situation, the cleaning is completed in a short time in a portion where a relatively small amount of polysilane is deposited, but in a portion where a large amount of polysilane is deposited, a collective amount presents a lump. The reaction with the cleaning gas occurred only in the vicinity of the surface of the lump, and there was a situation in which most of the cleaning gas was discharged unreacted without coming into contact with the polysilane.

This situation will be described in more detail. For example, in a so-called low vacuum process in which the gas flow rate is about 1000 to 50000 cm ³ / min and the pressure is higher than 133 Pa, the gas flow property is a viscous flow region. The gas flow velocity distribution when flowing through the tube is maximum at the central portion of the cross section of the tube, and the velocity decreases in a quadratic function toward the periphery, and is almost zero near the inner wall. In other words, the number of gas molecules that pass through the pipe cross section per unit time means that the central part of the pipe cross section is the largest and decreases toward the inner wall of the pipe. For example, polysilane adhering to the inner wall surface portion is reduced. Even if the reaction was attempted while the gas was flowing, most of the cleaning gas passed through the central portion of the pipe where the flow velocity was large, and was discharged with little contribution to the cleaning reaction. This is an example of a straight pipe, but in general, the vacuum exhaust pipe is a combination of pipes having a curved part such as an elbow and pipes for converting the diameter difference of a reducer, etc. due to physical arrangement. It is often composed of. For example, when the flow direction changes in a piping part such as an elbow, the flow speed is larger on the outer periphery side of the curved part and the flow speed is smaller on the inner peripheral side of the curved part of the more complicated flow. The situation in which the cleaning gas is difficult to be supplied and passes through the outer peripheral side despite the fact that a large amount of polysilane is easily deposited on the peripheral side was the same as that of the straight pipe. Also, in piping such as reducers, especially when the diameter is converted from a small diameter to a large diameter, the gas flow velocity changes at the conversion location so that polysilane is likely to deposit on the inner wall of such location. However, since the flow of the cleaning gas mainly passes through the central portion of the pipe cross section as in the case of the straight pipe, it cannot be said that the cleaning reaction efficiency is good.

  Further, for example, when a louver-like member is appropriately provided at an appropriate position of the exhaust path in the thin film formation container or the vacuum exhaust pipe so that the gas flow does not flow linearly, the gas flow flows while being bent. As a result, it is possible to provide a portion where the gas flow can collide with the inner wall surface of the exhaust pipe as appropriate. However, this structure is approximately equivalent to the case where a large number of elbow parts are provided in the exhaust pipe, and a louver-like member. It is self-evident that the magnitude of the gas flow velocity occurs on the front and back of the above, and the above problem is not fundamentally eliminated.

Summarizing these events, the part where polysilane is likely to accumulate is the part where the gas flow rate is small, while the part where the supply amount of the cleaning gas is large is the part where the gas flow rate is large, and the two are contradictory parts. In particular, cleaning using ClF ₃ gas, which is performed while flowing gas without using plasma, has a problem that it is essentially inefficient. Furthermore, since ClF ₃ gas is highly corrosive, it is diluted to about 1% to 50% with an inert gas such as nitrogen gas for the purpose of protecting metal and resin components inside the device in actual operation. As a matter of course, the higher the dilution, the lower the collision probability of molecules, and the cleaning efficiency has to be further reduced.

  Performing the cleaning process in a state where the efficiency of using the clean gas is reduced is a problem in that the cleaning gas itself is wasted and at the same time the time until the cleaning is completed becomes long, and the apparatus downtime is shortened. there were. Therefore, it has been desired to find a means that can cause polysilane that is easily deposited in a place where the gas flow rate is small to react more efficiently with the cleaning gas, and to provide a means that can shorten the cleaning time.

  On the other hand, the pressure in the container and the pipe in the cleaning process are often performed at a relatively high pressure, for example, a pressure of 13.3 kPa or more, for the purpose of increasing the collision probability between gas molecules, and at a low flow rate. There was a certain effect in the sense that the removal time was shortened corresponding to the increased probability of collision between the deposited polysilane and the cleaning gas. However, even if the pressure is set high, it remains a so-called viscous flow region, and the essential problem that most of the cleaning gas easily passes through the center of the tube cross section has not been solved. This alone was not enough.

The configuration of the present invention that solves the above-mentioned conventional problems is as follows.
That is, the silicon-containing material removal method of the present invention is a method of removing at least the silicon-containing material deposited in the reaction chamber and / or the pipe by introducing a cleaning gas, and a step of moving the silicon-containing material. It is characterized by including.
Further, the step of moving the silicon-containing material is a step of moving the silicon-containing material from a deposition location of the silicon-containing material toward a location where the flow rate of the cleaning gas is larger.
Further, the silicon-containing material is moved by blowing a gas.
Further, the silicon-containing material is moved by physical means.

  Another method for removing silicon-containing materials of the present invention is a method of removing at least silicon-containing materials deposited in the reaction chamber and / or piping by introducing a cleaning gas, and stirring the silicon-containing materials. Including a process.

  Another method for removing a silicon-containing material of the present invention is a method of removing at least a silicon-containing material deposited in a reaction chamber and / or a pipe by introducing a cleaning gas, and pulverizing the silicon-containing material. Including a process.

  Another method for removing silicon-containing materials of the present invention is a method for removing at least silicon-containing materials deposited in a reaction chamber and / or piping by introducing a cleaning gas, wherein the silicon-containing materials are vibrated. Including a step of providing.

  Another method for removing a silicon-containing material of the present invention is a method of removing at least a silicon-containing material deposited in a reaction chamber and / or a pipe by introducing a cleaning gas, and stirring the cleaning gas It is characterized by including.

  In addition, the silicon-containing material removal method of the present invention is characterized in that the pressure in the reaction chamber and / or the piping is set to 13.3 kPa or more.

The apparatus for removing silicon-containing material according to the present invention is an apparatus for introducing at least a silicon-containing material that has accumulated in the reaction chamber and / or the piping to remove the silicon-containing material, and has means for moving the silicon-containing material. It is characterized by.
Further, the means for moving the silicon-containing material is a means for moving the silicon-containing material by blowing a gas.
Further, the means for moving the silicon-containing material is a means for physically moving.

  Another apparatus for removing a silicon-containing material of the present invention is an apparatus that introduces a cleaning gas to remove at least the silicon-containing material deposited in the reaction chamber and / or piping, and stirs the silicon-containing material. It has the means.

  Further, another silicon-containing material removal apparatus of the present invention is an apparatus for introducing at least a silicon-containing material deposited in a reaction chamber and / or a pipe to remove the silicon-containing material, and pulverizes the silicon-containing material. It has the means.

  Another apparatus for removing silicon-containing material according to the present invention is an apparatus for introducing at least a silicon-containing material deposited in a reaction chamber and / or piping by introducing a cleaning gas, which vibrates the silicon-containing material. It has the means to give.

  Another apparatus for removing a silicon-containing material of the present invention is an apparatus for introducing and removing at least a silicon-containing material deposited in a reaction chamber and / or a pipe, and a means for stirring the cleaning gas. It is characterized by having.

  By using the removal method and the removal apparatus of the present invention, when performing apparatus cleaning without plasma, even if there is a silicon-containing material accumulated in a lump collected at a small flow velocity, the removal reaction can be efficiently promoted. As a result, the cleaning time can be greatly shortened, the cleaning gas can be effectively used, and the damage to the apparatus members can be reduced, resulting in operational costs and apparatus downtime.

  FIG. 1 shows an example of the present invention. A supply gas pipe 103 is connected to the thin film formation container 101 that can be kept in a vacuum via a supply valve 102, and gas can be introduced into the container. The exhaust valve 107 is opened and the vacuum exhaust pipe 108 is used for vacuum. It is discharged to the exhaust pipe 110 by the pump 109. In this case, for example, if a valve whose opening degree can be adjusted is used as the exhaust valve 107 or a vacuum pump having a function capable of adjusting the motor rotation speed is used as the vacuum pump 109, the inside of the container or the exhaust pipe is brought to a desired pressure. Adjustment can be maintained.

A high-frequency applying electrode 106 connected to a high-frequency power source (not shown) is installed in the thin film forming container 101, so that plasma discharge can be performed in a space between the substrate holder / counter electrode 104 that can hold the substrate 105. ing. For example, by using such a mixing device configured in a mass flow controller or the like (not shown) to adjust the gas flow rate, silane gas and hydrogen gas respectively 500 cm ³ / min, through a 2,000 cm ³ / min flow while mixing the feed gas pipe 103 Flow into the container, adjust the pressure in the container to 133 Pa using the exhaust valve 107, apply 800 W of RF (13.56 MHz) power to the high frequency application electrode 106 to generate plasma, and use a glass plate as the substrate 105. An amorphous silicon thin film was formed on the surface. After such a thin film forming process is continued for 50 hours, polysilane adheres to and deposits on the inner wall of the container 101, the inner walls of the exhaust valve 107 and the vacuum exhaust pipe 108, and the trap 111, and in particular, a large amount of deposits 112 and 113 are present. Polysilane was deposited in bulk.

A cleaning process was performed in this state. For example, by using a mixing device or the like which is constituted by a mass flow controller or the like (not shown) to adjust the gas flow rate, ClF ₃ gas and nitrogen gas each 2,000 cm ³ / min, and mixed while passing 20,000 cm ³ / min feed Flow into the container through the gas pipe 103, fully open the exhaust valve 107, and adjust the pressure in the container and the vacuum exhaust pipe to 13.3 kPa or more by adjusting the rotation speed of the vacuum pump using an inverter (not shown). Then, the mixed gas was allowed to flow for cleaning.

The method for determining the progress or completion of the cleaning can be determined by monitoring the temperature of the outer wall of a member such as a pipe because the reaction between the ClF ₃ gas and polysilane is accompanied by considerable heat generation. That is, when the cleaning starts, the outer wall temperature rises from around room temperature to 40 ° C. or higher and continues to rise while the cleaning reaction is taking place. After the polysilane is removed, the outer wall temperature begins to drop and finally reaches the final temperature. Shows the process of returning to room temperature. In this way, the progress in one part is observed in each part of the exhaust pipe path, the temperature of the outer wall on the upstream side of the cleaning gas flow starts to rise first, and the temperature rise part gradually moves toward the downstream side. It becomes the situation like this. Ultimately, it was determined that the cleaning of the entire system was completed when the temperature of the portion where the temperature rose until the end returned to room temperature.

  Since the amount of polysilane deposited was small at the portion where the gas flow rate during the thin film formation was large, the temperature rising time was returned to room temperature after the lapse of about 80 minutes and cleaning was completed. On the other hand, since the progress of the reaction is slow at places such as the depositing places 112 and 113 where a large amount of polysilane is present, it is effective to promote the reaction by taking measures such as moving, stirring and crushing the polysilane. For example, when a stirrer 114 using a rotary blade is installed in the trap, the handle is rotated periodically while flowing the cleaning gas, and the deposition site 113, that is, polysilane accumulated in the trap is stirred, and then contacted with the cleaning gas. The amount of polysilane to be increased can be increased to promote the reaction. In this case, the rotary blade is used, but any means capable of physically stirring the accumulated polysilane may be used, and the present invention is not particularly limited thereto. As another means, for example, it is possible to stir by applying vibration energy by attaching or contacting a vibrator such as a vibration means using an ultrasonic oscillator, a vibrator, a diaphragm or the like to a place to be stirred. In addition, the fixed projection 117 or the thin film is stored in a predetermined position where the amount of polysilane deposited is relatively small in the cleaning gas flow path so as not to disturb the gas flow, and appropriately protrudes into the gas flow path during cleaning. It is also possible to agitate the cleaning gas by providing an obstacle such as the movable protrusion 118. Furthermore, a member having a function capable of reciprocating movement such as a movable projection 118 is provided in a portion where the flow velocity in the exhaust pipe is small, that is, in the vicinity of a polysilane deposition portion, and the polysilane is moved by being operated as appropriate during etching. It is also possible to make it. At this time, the shape of the protrusion may be a round bar shape, a prismatic shape, a long plate shape, or the like, but is not particularly limited as long as it has a shape and structure that do not significantly disturb the gas flow.

  As another example, a gas pipe 115 is provided in the vicinity of the deposition location 112 of the vacuum exhaust pipe 108, and nitrogen gas whose pressure is adjusted to 0.1 MPa, for example, is connected to the upstream via a valve 116, and cleaning is performed. The pressure in the vicinity of the deposition site 112 may be suddenly changed by instantaneously ejecting nitrogen gas by opening and closing the valve 116 appropriately. It becomes possible to move the polysilane deposited by the injection of nitrogen gas to a portion having a high gas flow rate while pulverizing and blowing off, thereby further promoting the cleaning reaction. Further, the cleaning gas itself is agitated by the injection of the nitrogen gas, whereby the unreacted cleaning gas comes into efficient contact with the polysilane, thereby further promoting the cleaning reaction. In this case, nitrogen gas is used, but any other inert gas such as argon gas or helium gas may be used as long as it is inactive in this system. The gas pressure to be supplied is 0.1 MPa in this case, but it is not particularly limited as long as it is set in accordance with the form of each device.

  In addition to the above, the timing at which the polysilane is moved, diffused, and pulverized is also effective when the cleaning is temporarily stopped before the cleaning is started. In other words, the location where the gas flow rate is large is often known in advance for a specific device, and it is not difficult to predict. Therefore, after the thin film formation process, the polysilane is moved to such a location in advance. Alternatively, cleaning may be started. Further, as described above, a temperature detecting means is provided at a predetermined place or part to be cleaned to detect the temperature of each part. Further, it is more effective to move, stir and grind the polysilane based on the detected temperature.

  After performing the thin film forming process for 50 hours as described above, an experiment for confirming the effect of the present invention was performed by changing the following conditions while flowing the cleaning gas under the same conditions as described above.

(Experiment 1) Cleaning was performed at the deposition site 112 while injecting nitrogen gas from the gas pipe 115 by the method described above. Nitrogen gas was continuously injected for 5 seconds, and this was repeated every 10 minutes.

(Experiment 2) In the deposition location 113, cleaning was performed while rotating the stirrer (rotary blade) 114 by the method described above. The rotation of the rotary blade was performed 5 times continuously, and this was repeated every 10 minutes.

(Experiment 3) Cleaning was performed without performing any nitrogen gas injection or rotating blade rotation performed in Experiments 1 and 2 above.

  The time from the start to the end of cleaning under these conditions was measured and compared. Each cleaning time was 230 minutes in Experiment 1, 210 minutes in Experiment 2, and 370 minutes in Experiment 3.

  From this result, the method of the present invention performed in Experiment 1 and Experiment 2 was shortened in time compared with the conventional method performed in Experiment 3, and the effect of the present invention was proved.

It is a schematic diagram which shows an example of the reaction chamber and piping system which implemented the removal method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Thin film formation container 102 Supply valve 103 Supply gas piping 104 Substrate holder and counter electrode 105 Substrate 106 High frequency application electrode 107 Exhaust valve 108 Vacuum exhaust piping 109 Vacuum pump 110 Exhaust pipe 111 Trap 112 Deposition location 113 Deposition location 114 Stirrer 115 Gas piping 116 Valve 117 Fixed projection 118 Mobile projection

Claims (16)

  A method for removing at least silicon-containing material deposited in a reaction chamber and / or piping by introducing a cleaning gas, the method comprising a step of moving the silicon-containing material.   2. The silicon-containing material according to claim 1, wherein the step of moving the silicon-containing material is a step of moving the silicon-containing material from a deposition location of the silicon-containing material toward a location where the flow rate of the cleaning gas is larger. How to remove things.   The method for removing a silicon-containing material according to claim 1 or 2, wherein the silicon-containing material is moved by blowing a gas.   The method for removing a silicon-containing material according to claim 1 or 2, wherein the silicon-containing material is moved by physical means.   A method for removing at least silicon-containing material deposited in a reaction chamber and / or piping by introducing a cleaning gas, the method comprising a step of stirring the silicon-containing material.   A method for removing at least silicon-containing material deposited in a reaction chamber and / or piping by introducing a cleaning gas, the method comprising a step of pulverizing the silicon-containing material.   A method of removing at least silicon-containing material accumulated in a reaction chamber and / or piping by introducing a cleaning gas, and including a step of applying vibration to the silicon-containing material. .   A method for removing at least silicon-containing material deposited in a reaction chamber and / or piping by introducing a cleaning gas, the method comprising a step of stirring the cleaning gas.   The method for removing a silicon-containing material according to any one of claims 1 to 8, wherein the pressure in the reaction chamber and / or the piping is set to 13.3 kPa or more.   An apparatus for removing at least silicon-containing material deposited in a reaction chamber and / or piping by introducing a cleaning gas, and having means for moving the silicon-containing material.   11. The apparatus for removing a silicon-containing material according to claim 10, wherein the means for moving the silicon-containing material is a device that moves the silicon-containing material by blowing a gas.   11. The apparatus for removing a silicon-containing material according to claim 10, wherein the means for moving the silicon-containing material is a means for physically moving the silicon-containing material.   An apparatus for removing at least silicon-containing material accumulated in a reaction chamber and / or piping by introducing a cleaning gas, and having means for stirring the silicon-containing material.   An apparatus for removing at least silicon-containing material deposited in a reaction chamber and / or piping by introducing a cleaning gas, and having means for pulverizing the silicon-containing material.   An apparatus for removing at least silicon-containing material deposited in a reaction chamber and / or piping by introducing a cleaning gas, and having means for applying vibration to the silicon-containing material .   An apparatus for removing at least silicon-containing material accumulated in a reaction chamber and / or piping by introducing a cleaning gas, and having means for stirring the cleaning gas.

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