JP2007258561A - Protector and protection method of diffusion furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a protector and a protection method of a vertical diffusion furnace capable of reducing a damage when an earthquake occurs, with a simple structure. <P>SOLUTION: A P wave detector 51 informs a P wave analyzer 52 of the fact that P wave has arrived. The P wave analyzer 52, upon being informed of arrival of P waves from the P wave detector 51, predicts seismic intensity in the district where the vertical diffusion furnace 54 is installed at the time when S waves arrives in the future based on the waveform, amplitude of the arriving P waves, or the like. Then, whether the prediction result is equal to a seismic intensity 5 or higher or not is judged. If the result means seismic intensity 5 or higher, the fact is reported to an atmospheric pressure control unit 53. The atmospheric pressure control unit 53 lowers the atmospheric pressure inside the diffusion furnace when the prediction result is reported as 5 or higher of seismic intensity from the P wave analyzer 52. So, the atmospheric pressure in the diffusion furnace is lowered by decreasing the supplied amount of gas with no change of exhaustion level by a vacuum pump. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a protection device and a protection method for a diffusion furnace used for manufacturing a semiconductor device.

  In the process of manufacturing a semiconductor device, a vertical diffusion furnace is used when introducing impurities. Inside the vertical diffusion furnace, a furnace core tube into which a semiconductor wafer to be processed is inserted, a heater disposed around the core tube, and the like are provided. The semiconductor wafer is inserted into a core tube fixed to a quartz boat, and the quartz boat is placed on a base called a heat insulating cylinder.

  In the vertical diffusion furnace having such a structure, until now, no major problem has occurred during normal operation. However, if an earthquake with a large seismic intensity occurs, enormous damage will occur. For example, a quartz boat falls from a heat insulating cylinder and is damaged. Further, the quartz boat collides with the inner wall of the core tube and the quartz boat and / or the core tube is damaged. Further, the semiconductor wafer may fall from the quartz boat and break.

  And since the vertical diffusion furnace is part of the core in the factory that manufactures semiconductor devices, if the vertical diffusion furnace breaks down, production is delayed and production efficiency is greatly reduced. End up. For this reason, seismic countermeasures for vertical diffusion furnaces are important, and even if damage occurs, there is a demand for being able to recover as quickly as possible while keeping it as small as possible.

  Patent Document 1 discloses a vertical diffusion furnace in which countermeasures against earthquakes are taken. However, since a mechanically complicated configuration is employed, the time and cost required for the production increase.

JP-A-11-74205 JP 11-159571 A

  An object of this invention is to provide the protection apparatus and protection method of a diffusion furnace which can reduce the damage at the time of an earthquake with a simple structure.

  As a result of intensive studies to solve the above problems, the present inventor has come up with various aspects of the invention described below.

  The protection device for the diffusion furnace according to the present invention includes a detecting means for detecting the first wave of the earthquake, and when the first wave is detected by the detecting means, the contents of the first wave are analyzed, and the analysis result Analysis means for predicting whether the seismic intensity when the second wave following the first wave arrives is 5 or more. Furthermore, when the seismic intensity is predicted to be 5 or more by the analyzing means, an atmospheric pressure control means for reducing the atmospheric pressure in the diffusion furnace before the second wave arrives is provided.

  In the diffusion furnace protection method according to the present invention, when the first wave of the earthquake is detected, the contents of the first wave are analyzed, and the seismic intensity when the second wave following the first wave arrives from the analysis result is If it is predicted that the seismic intensity will be 5 or more, the atmospheric pressure in the diffusion furnace is reduced before the second wave arrives.

  According to the present invention, when a predetermined first wave is detected, the atmospheric pressure in the diffusion furnace is lowered before the second wave arrives, so that the adhesion between components is improved and collision and dropping due to vibration occur. It becomes difficult. As a result, the damage caused by the earthquake can be greatly reduced.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. FIG. 1 is a block diagram illustrating a protection device for a vertical diffusion furnace according to an embodiment of the present invention.

  The protection device 50 according to the present embodiment includes a P wave detection unit 51 that detects a first wave (P wave) of an earthquake, and a P wave analysis unit 52 that analyzes the P wave detected by the P wave detection unit. And the atmospheric pressure control part 53 which controls the atmospheric | air pressure in the vertical diffusion furnace 54 according to the analysis result by the P wave analysis part 52 is provided. Each of these units includes, for example, a computer (CPU) and a program stored in a ROM or the like accessible by the computer. When the P wave detection unit 51 detects the P wave, the P wave analysis unit 52 analyzes the waveform and amplitude and the seismic intensity when the second wave (S wave: Secondary wave) arrives after the P wave. Predict. This prediction is performed using not only the P wave itself but also a database or the like prepared in advance in consideration of the structure of the vertical diffusion furnace 54 and the structure of the ground in the area where the vertical diffusion furnace 54 is installed. Is called.

  Here, an outline of the vertical diffusion furnace 54 will be described. FIG. 2 is a schematic diagram showing the structure of the vertical diffusion furnace 54. In the vertical diffusion furnace 54, a quartz core tube 2, a quartz base (insulation cylinder) 3, and a heater 4 are provided inside the furnace wall 7. The base 3 is moved up and down in the furnace wall 7, and a quartz boat 12 is placed thereon. The quartz boat 12 is formed with support portions 12 a that support the semiconductor wafer 11 at three locations. Further, a supply pipe 5 to which raw materials and nitrogen gas are supplied and an exhaust pipe 6 connected to a vacuum pump or the like are connected to the lower portion of the furnace wall 7. The supply pipe 5 is provided with a source gas valve and a nitrogen gas valve, and the exhaust pipe 6 is also provided with a valve.

  Although not shown, a mechanism for moving the base 3 in the vertical direction is also provided, and the base 3 is in contact with a quartz member.

  Next, the operation of the protection device 50 will be described. The P wave detection unit 51 constantly monitors the arrival of the P wave, and notifies the P wave analysis unit 52 when the P wave arrives. When the P wave analysis unit 52 is informed that the P wave has arrived from the P wave detection unit 51, the vertical diffusion furnace 54 when the S wave arrives later from the waveform and amplitude of the incoming P wave. Predict the seismic intensity in the area where is installed. And it is judged whether a prediction result is seismic intensity 5 or more. As a result, when the result that the seismic intensity is 5 or more is obtained, the atmospheric pressure control unit 53 is notified of that. On the other hand, when the result that the seismic intensity does not become 5 or more, that is, the result that the seismic intensity becomes 4 or less is obtained, the process is terminated at that time.

  On the other hand, in the vertical diffusion furnace 54, the source gas and the nitrogen gas are supplied from the supply pipe 5 and the gas corresponding to the amount supplied by the vacuum pump connected to the exhaust pipe 6 is exhausted. That is, the atmospheric pressure in the furnace wall 7 is a normal pressure. Then, when the atmospheric pressure control unit 53 is informed of the prediction result that the seismic intensity is 5 or more from the P wave analysis unit 52, for example, by closing the valve for the source gas provided in the supply pipe 5, the furnace The pressure inside the wall 7 is reduced. That is, the atmospheric pressure in the furnace wall 7 is reduced by reducing the amount of gas supplied without changing the degree of exhaust by the vacuum pump. As a result, the degree of adhesion between the quartz boat 12 and the base 3 increases, and the degree of adhesion between the base 3 and the quartz member below it and the degree of adhesion between the semiconductor wafer 11 and the support portion 12a also increase. Accordingly, the quartz boat 12 is unlikely to fall from the base 3 even if it is attacked by a large shake. In addition, although there is some difference in natural frequency, the quartz boat 12 substantially swings following the base 3 and the core tube 2, so that the quartz boat 12 hardly collides with the inner wall of the core tube 2. Become. Furthermore, the semiconductor wafer 11 is also difficult to drop from the quartz boat 12.

  As described above, in this embodiment, when the predetermined P wave arrives, the atmospheric pressure in the furnace wall 7 is lowered to prepare for the arrival of the S wave, so that the earthquake damage can be greatly reduced even if the S wave arrives. Can do. Therefore, even if the seismic intensity is 5 or more, there is no damage at all, or the damage can be restored to an early level. As a result, even if the earthquake intensity is 5 or more, it is possible to remarkably shorten the stop period of the semiconductor device manufacturing factory. The reason why the seismic intensity of 5 is used as a criterion is that until now, no major damage has been reported if the seismic intensity is 4 or less.

  Further, in this embodiment, since nitrogen gas, which is an inert gas, is continuously supplied into the furnace wall 7 even when the atmospheric pressure is lowered, contamination of contaminants due to entrainment of outside air or the like can be suppressed. . Ar gas or the like may be supplied as an inert gas.

  In addition, it is not necessary to make the pressure | pressure drop by the atmospheric | air pressure control part 53 to the thing close | similar to a vacuum, What is necessary is just to reduce pressure to about 20%-50% of a normal pressure, for example. The pressure after the pressure reduction is preferably 200 hPa to 250 hPa. This is because if the pressure is reduced to less than 200 hPa, the quartz boat 12 or the like may be damaged due to excessive decompression. On the other hand, if it is higher than 250 hPa, there is a possibility that the effect of decompression may not be sufficiently obtained.

  Moreover, the protection device according to the present invention can be applied not only to the vertical diffusion furnace but also to the protection of the horizontal diffusion furnace.

  Hereinafter, various aspects of the present invention will be collectively described as supplementary notes.

(Appendix 1)
A protection device for protecting the diffusion furnace from earthquakes,
Detection means for detecting the first wave of the earthquake;
When the first wave is detected by the detection means, the contents of the first wave are analyzed, and the seismic intensity when the second wave following the first wave arrives is predicted from the analysis result. Analysis means;
When the seismic intensity is predicted to be 5 or more by the analysis means, atmospheric pressure control means for lowering the atmospheric pressure in the diffusion furnace before the second wave arrives;
A device for protecting a diffusion furnace, comprising:

(Appendix 2)
The apparatus for protecting a diffusion furnace according to appendix 1, wherein the atmospheric pressure control means supplies an inert gas into the diffusion furnace when the atmospheric pressure is lowered.

(Appendix 3)
The apparatus for protecting a diffusion furnace according to appendix 2, wherein the atmospheric pressure control means supplies nitrogen gas as the inert gas.

(Appendix 4)
The apparatus for protecting a diffusion furnace according to any one of appendices 1 to 3, wherein the atmospheric pressure control means reduces the atmospheric pressure in the diffusion furnace to 200 hPa to 250 hPa.

(Appendix 5)
A protection method for protecting a diffusion furnace from earthquakes,
An analysis step for analyzing the contents of the first wave when the first wave of the earthquake is detected, and predicting whether the seismic intensity when the second wave following the first wave arrives is 5 or more from the analysis result;
When the seismic intensity is predicted to be 5 or more in the analysis step, a pressure control step for reducing the pressure in the diffusion furnace before the second wave arrives;
A method for protecting a diffusion furnace, comprising:

(Appendix 6)
The method for protecting a diffusion furnace according to appendix 5, wherein an inert gas is supplied into the diffusion furnace when the atmospheric pressure is decreased in the atmospheric pressure control step.

(Appendix 7)
The diffusion furnace protection method according to appendix 6, wherein nitrogen gas is supplied as the inert gas in the atmospheric pressure control step.

(Appendix 8)
The method for protecting a diffusion furnace according to any one of appendices 5 to 7, wherein, in the atmospheric pressure control step, the atmospheric pressure in the diffusion furnace is reduced to 200 hPa to 250 hPa.

It is a block diagram which shows the protection apparatus of the vertical diffusion furnace which concerns on embodiment of this invention. 3 is a schematic diagram showing the structure of a vertical diffusion furnace 54. FIG.

Explanation of symbols

2: Reactor core tube 3: Base 4: Heater 5: Supply pipe 6: Exhaust pipe 7: Furnace wall 11: Wafer 12: Quartz boat 12a: Supporting part 50: Protection device 51: P wave detection part 52: P wave Analysis unit 53: Barometric pressure control unit 54: Vertical thermal diffusion furnace

Claims (5)

A protection device for protecting the diffusion furnace from earthquakes,
Detection means for detecting the first wave of the earthquake;
When the first wave is detected by the detection means, the contents of the first wave are analyzed, and the seismic intensity when the second wave following the first wave arrives is predicted from the analysis result. Analysis means;
When the seismic intensity is predicted to be 5 or more by the analysis means, atmospheric pressure control means for lowering the atmospheric pressure in the diffusion furnace before the second wave arrives;
A device for protecting a diffusion furnace, comprising:   The apparatus for protecting a diffusion furnace according to claim 1, wherein the atmospheric pressure control means supplies an inert gas into the diffusion furnace when the atmospheric pressure is lowered.   The apparatus for protecting a diffusion furnace according to claim 2, wherein the atmospheric pressure control means supplies nitrogen gas as the inert gas. A protection method for protecting a diffusion furnace from earthquakes,
An analysis step for analyzing the contents of the first wave when the first wave of the earthquake is detected, and predicting whether the seismic intensity when the second wave following the first wave arrives is 5 or more from the analysis result;
When the seismic intensity is predicted to be 5 or more in the analysis step, a pressure control step for reducing the pressure in the diffusion furnace before the second wave arrives;
A method for protecting a diffusion furnace, comprising:   The method for protecting a diffusion furnace according to claim 4, wherein, in the atmospheric pressure control step, an inert gas is supplied into the diffusion furnace when the atmospheric pressure is lowered.

Images