JP2007271126A - Clean oven - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a clean oven having almost no heat loss, having high cleaning performance, and reducing a facility load. <P>SOLUTION: In the clean oven 1, a duct 11 provided in a furnace exterior and a furnace interior are connected to connect a connection B and a connection part C with mutually equal pressures of atmospheric gas, and the duct 11 is provided with a cooler 6 and a cooler fan 12 in an interior. Since the cooler 6 is provided in the furnace exterior, there is almost no heat loss, and since a damper is provided, there is no dust generation, and high cleaning performance is provided. Since the cooler fan 12 stops when supply of cooling water stops during heating, a duct for exhausting steam to a clean room exterior is unnecessary. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a clean oven for performing heat treatment of an object to be heat treated in a specific atmospheric gas.

  A clean oven is a device for heat-treating semiconductor devices, liquid crystal display devices, etc., in a furnace surrounded by heat insulating material, a processing chamber for storing the sample to be heat-treated, a heating means such as a heater, a fan, etc. Blower means and a filter are provided. The filter is provided at the entrance of the processing chamber, and the atmospheric gas heated to a high temperature and purified through the filter is sprayed on the sample and circulates in the furnace.

  In addition, a cooler (water-cooled fin cooler) is provided in the furnace for rapid cooling after heat treatment, and a damper (switching plate) is provided in the furnace to suppress heat loss during heat treatment. Conventionally, a clean oven in which the atmospheric gas flows has been proposed (see, for example, Patent Documents 1 and 2). For example, in heat treatment such as low-temperature polysilicon TFT (LTPS), nitrogen gas is usually introduced into the furnace, and the heat treatment is performed at 300 ° C. to 500 ° C. in a specific atmosphere with an oxygen concentration of 100 ppm or less. It is necessary to maintain the inside of the furnace in a specific atmosphere during the heat treatment until it is lowered and the sample is taken out. In the clean oven described above, the cooler is in the furnace, and the atmosphere gas in the furnace is cooled while confined, so that a specific atmosphere can be maintained in the furnace.

  7A and 7B are cross-sectional views showing the configuration of the clean oven 101 described in Patent Document 1. FIG. The clean oven 101 includes a heater 102, a fan 103, a filter 104, a cooler 106, and two dampers 107 a and 107 b in a furnace insulated from the outside, and a sample 105 is accommodated in a heat treatment chamber 108. The atmospheric gas heated by the heater 102 is sent to the heat treatment chamber 108 side by the fan 103, blown to the sample 105 through the filter 104, and circulates in the furnace.

  FIG. 7A shows a state during heating. Since the dampers 107a and 107b block the entrance of the cooling chamber 110, the atmospheric gas heated by the heater 102 hardly passes through the cooler 106. Heat loss can be suppressed. FIG. 7B shows a state at the time of cooling. After stopping energization of the heater 102, the damper 107a is rotated 90 ° clockwise, and the damper 107b is rotated 90 ° counterclockwise. The cooling chamber 110 is opened. As a result, the circulating atmosphere gas passes through the cooler 106 and can be cooled while maintaining a specific atmosphere in the furnace.

  FIG. 8 shows the configuration of the clean oven 201 described in Patent Document 2. The clean oven 201 includes a heater 202, a fan 203, a filter 204, a cooler 206, and two dampers 207a and 207b in a furnace insulated from the outside. A sample (not shown) to be heat-treated is placed in a heat-treatment chamber 208. Be contained. The atmospheric gas heated by the heater 202 is sent to the heat treatment chamber 208 side by the fan 203, blown to the sample through the filter 204, and circulates in the furnace through the rectifying plate 209.

FIG. 8 shows a state during heating. Since the dampers 207a and 207b are closed so that the atmospheric gas does not pass through the cooler 206, heat loss can be suppressed. During cooling, the damper 207a is rotated 90 ° clockwise and the damper 207b is rotated 90 ° counterclockwise, so that atmospheric gas passes through the cooler 206, and the furnace is cooled while maintaining a specific atmosphere. Is done.
Patent No. 3525074 (released on November 30, 2000) JP 2004-353928 A (released on December 16, 2004)

  However, the damper is usually a metal plate such as stainless steel and does not have a heat insulating structure. Therefore, in the conventional configuration, heat in the heating chamber is transferred from the damper to the cooler side, so that heat loss occurs.

  Also, during heat treatment, the ambient temperature differs between the damper cooler side and the furnace inside, so the thermal expansion of the damper changes between the cooler side face and the furnace inside face, and the damper increases with the temperature rise in the furnace. Will bend. Therefore, it is impossible to completely shut off the atmospheric gas in the furnace during the heat treatment so as not to flow to the cooler, resulting in a problem that heat loss cannot be eliminated.

  The damper is a mechanical mechanism that generates dust during opening and closing because of friction. In addition, the damper bends during heating and returns to its original state during cooling, but each part of the damper has a different heat capacity due to the difference in shape, so the temperature of each part when temperature changes is different, and the degree of bending is also different for each part. Different. As a result, friction between components occurs, and the damper generates dust not only during opening and closing operations but also during heating and cooling. Here, when a HEPA filter having a high collection efficiency is used as a filter in the furnace, the dust generated by the dust generated by the damper hardly flows into the heating chamber. However, since the HEPA filter has a low heat-resistant temperature, for example, a low-temperature polysilicon TFT (LTPS) ) And the like cannot be used for heat treatment at 300 ° C to 500 ° C. In that case, a heat-resistant filter having a heat-resistant temperature of about 500 ° C. is used, but the heat-resistant filter is inferior in collection efficiency compared to the HEPA filter. A part is sprayed on a sample, and the problem that the clean performance in a furnace deteriorates arises.

  Further, when the supply of cooling water to the cooler is stopped during operation at a high temperature, since the cooler is in the furnace, the water temperature in the cooler rises and vaporizes due to heat conduction, and the pressure in the cooler rises. Therefore, a safety valve is required for safety, but since the clean oven is used in a clean room, the steam discharged from the safety valve cannot be directly discharged into the clean room. Therefore, it is necessary to construct a dedicated duct for discharging the steam released from the safety valve to the outside of the clean room, and there is a problem that equipment burden arises.

  The present invention has been made in view of the above problems, and an object thereof is to realize a clean oven having high clean performance.

  Another object of the present invention is to realize a clean oven that further suppresses heat loss and consumes less power.

  Another object of the present invention is to realize a clean oven that does not require a dedicated duct for discharging steam to the outside of the clean room and has a low equipment burden.

  In order to solve the above problems, a clean oven according to the present invention includes a heating unit, an oven blowing means, and an oven filter in a furnace insulated from the outside, and the atmosphere gas heated by the heating unit, The oven blowing means is a clean oven that sprays the heat treatment product through the oven filter and circulates in the furnace, and a duct including a cooling unit and a cooling unit blowing means includes a first connection part in the furnace In the second connection portion, the first connection portion and the second connection portion are connected to each other, and the atmospheric gas in the furnace flows into the duct at the first connection portion by the cooling fan. The atmospheric gas in the duct flows into the furnace at the second connection portion by the cooler air blowing means, and in the first connection portion and the second connection portion. Pressure of 囲気 gas are equal to each other, the duct is characterized in that provided on the outside of the furnace.

  According to the above configuration, since no damper is provided in the duct, there is no problem of dust generation in the damper portion, and even if the filter in the furnace is not a high collection efficiency HEPA filter, high clean performance The effect that can be realized. Moreover, the duct provided with the cooling part is provided outside the furnace, and the pressure of the atmospheric gas in the first connection part and the second connection part is equal to each other, so that the cooling fan is operated at the time of cooling. Since the atmospheric gas in the furnace does not flow into the duct, there is an effect that there is almost no heat loss.

  In the clean oven according to the present invention, it is preferable that the driving of the cooling fan is stopped when the supply of the cooling water to the cooling unit is stopped.

  According to said structure, even if supply of the cooling water to a cooling part stops during a process, if the air blower for coolers is not driven, the atmospheric gas of the said 1st connection part and a 2nd connection part is not driven Since the pressures are equal to each other, the atmospheric gas in the furnace does not flow into the duct. Therefore, the cooling water is not vaporized, and a dedicated duct for discharging the steam to the outside of the clean room is not necessary, so that the burden on the facility can be reduced.

  Further, in the clean oven according to the present invention, a heating unit, an oven blowing unit, and an oven filter are provided in a furnace insulated from the outside, and the oven blowing unit converts the atmospheric gas heated by the heating unit into the oven. A clean oven in which a heat treatment product is sprayed through a filter for an oven and circulated in the furnace, and a duct including a cooling part and a damper is connected to the first connection part and the second connection part in the furnace at a first connection. The atmosphere gas in the furnace flows into the duct at the first connection portion only when the damper is opened, and the atmosphere gas in the duct is connected to connect the part and the second connection part. Only when the damper is opened, it flows into the furnace at the second connection portion, and the pressures of the atmospheric gases at the first connection portion and the second connection portion are different from each other. The duct is characterized in that provided on the outside of the furnace.

  According to the above configuration, dust is generated in the damper portion. By closing the damper during the heat treatment, the atmospheric gas in the furnace can be prevented from flowing into the duct, and the cooler is connected to the outside of the furnace. Therefore, there is an effect that almost no heat loss can be eliminated. In addition, since the atmospheric gas pressure at the first connection portion and the second connection portion is different, it is possible to flow the atmospheric gas into the duct simply by opening the damper during cooling, and the air blower means for the cooler in the duct is unnecessary. There is an effect that there is.

  In the clean oven according to the present invention, it is preferable that the damper is further provided between the cooling part and the second connection part, and the valve part of the damper is made of rubber.

  According to the above configuration, since the damper valve portion is made of rubber, it is possible to reliably prevent the atmospheric gas in the furnace from flowing into the duct when the damper is closed, thereby further eliminating heat loss. There is an effect that can be. Moreover, since dust generation in the damper can be further reduced as compared with a metal damper, there is an effect that the atmosphere in the furnace can be further cleaned.

  In the clean oven according to the present invention, it is preferable that the duct further includes a duct filter, and the duct filter is provided between the damper and the second connection portion.

  According to said structure, since the filter for ducts collects the dust which generate | occur | produced with the damper, there exists an effect that the atmosphere in a furnace can be further cleaned.

  In the clean oven according to the present invention, the duct filter is more preferably a HEPA filter.

  According to said structure, since the HEPA filter has very high collection efficiency, there exists an effect that the dust which generate | occur | produced with the damper hardly flows in into a furnace.

  In the clean oven according to the present invention, it is more preferable to close the damper when the supply of cooling water to the cooling unit is stopped.

  According to said structure, even if supply of the cooling water to a cooling part stops during heat processing, if the damper is closed, the atmospheric gas in a furnace will not flow in in a duct. Therefore, the cooling water is not vaporized, and a dedicated duct for discharging the steam to the outside of the clean room is not necessary, so that the burden on the facility can be reduced.

  As described above, the clean oven according to the present invention includes a heating unit, an oven blowing means, and an oven filter in a furnace insulated from the outside, and the atmosphere gas heated by the heating unit is used for the oven. A clean oven in which a blowing means sprays the heat-treated product through the oven filter and circulates in the furnace, and a duct including a cooling part is provided in the first connection part and the second connection part in the furnace. The first connection portion and the second connection portion are connected to each other, and the duct is provided outside the furnace.

  Therefore, since the damper is not provided in the duct, the problem of dust generation at the damper portion does not occur, and high clean performance can be realized even if the filter in the furnace is not a HEPA filter with high collection efficiency. Moreover, since the duct provided with the cooling unit is provided outside the furnace, heat loss can be suppressed and power consumption can be reduced.

Embodiment 1
An embodiment of the present invention will be described below with reference to FIGS.

  FIG. 1 is an AA arrow view showing the configuration of the clean oven 1 according to the first embodiment, and FIG. 2 is a cross-sectional view of the clean oven 1. The clean oven 1 is formed in a box shape by a top wall 1a, a side wall 1b and a bottom wall 1c made of a heat insulating wall, and a door 1d made of a heat insulating wall is attached. A heater 2 (heating unit), an oven fan 3 (oven blowing means), and a filter 4 (oven filter) are provided in the furnace. The heater 2 is attached to the inside of the top wall 1a and heats atmospheric gas in the furnace. The oven fan 3 is attached to the inside of the side wall 1b opposite to the door 1d and is operated by the oven fan drive motor 3a. The filter 4 is provided in the lower part of the oven fan 3, and the sample 5 (heat-treated product) is accommodated between the filter 4 and the door 1d.

  Further, as shown in FIG. 1, in the clean oven 1, a duct 11 (duct) is connected at a connection portion B (first connection portion) and a connection portion C (second connection portion) near the oven fan 3 in the furnace. Therefore, the pressures of the atmospheric gases in the connection part B and the connection part C are equal. The duct 11 is made of stainless steel having a thickness of about 1.0 mm and a diameter of about 125 mm, and a cooler 6 (cooling unit) and a cooler fan 12 (cooler blower) are provided inside the duct 11. . The cooler fan 12 is operated by a cooler fan drive motor 12a. The length of the duct 11 from the connection point in the furnace to the cooler 6 is about 1090 mm. The cooling water is supplied from the water supply pipe 6a, passes through the cooler 6, and is discharged from the drain pipe 6b. The water supply pipe 6a is provided with a flow rate switch 6c to control the flow rate of the cooling water.

  At the time of heating and heat treatment, as shown in FIG. 2, the atmospheric gas heated by the heater 2 passes through the filter 4 by the oven fan 3 and is sprayed onto the sample 5. After passing through the sample 5, the atmospheric gas is heated again by the heater 2 and circulates in the furnace. At this time, nitrogen gas or the like for making the inside of the furnace into a specific atmosphere is introduced from an inlet (not shown) provided in the vicinity of the cooler 6 in the duct 11 and through the duct 11 connected to the inside of the furnace. Create a specific atmosphere in the furnace.

  During the heating and the heat treatment, the cooler fan 12 is stopped. At this time, since the pressures of the atmospheric gases in the connection part B and the connection part C are equal, even if a damper for controlling the inflow / outflow of the atmospheric gas is not provided in the duct 11, Atmospheric gas does not flow into the duct 11. For this reason, there is no heat loss during heating and heat treatment, and power consumption can be reduced.

  Further, unlike the conventional clean oven, it is not necessary to provide a damper for preventing atmospheric gas in the furnace from passing through the cooler, so that the problem of dust generation in the damper does not occur.

  Therefore, even if the filter 4 in the furnace is a heat-resistant filter having a lower collection efficiency than the HEPA filter, a cleaner atmosphere can be provided with a simple structure. Therefore, clean heat treatment is possible even in heat treatment of a low-temperature polysilicon TFT (LTPS) or the like in which a HEPA filter cannot be used for the filter 4 in the furnace due to high temperature.

  At the time of cooling, as shown in FIG. 1, the energization to the heater 2 is stopped and the cooler fan 12 is operated. The atmosphere gas in the furnace flows into the duct 11 from the connection portion B, passes through the cooler 6, is cooled, and is sent out to the connection portion C by the cooler fan 12. Since the duct 11 is shielded from the outside air, the atmospheric gas in the furnace can be cooled while maintaining a specific atmosphere.

  Here, when supply of the cooling water to the cooler 6 is stopped during cooling, the supply stop is detected by the flow switch 6c, and the cooler fan 12 is stopped based on the detection. When the cooler fan is stopped, the pressure of the atmosphere gas in each of the connection portion B and the connection portion C is equal, so that the high temperature atmosphere gas in the furnace does not flow into the duct 11.

  At this time, only the portion of the duct 11 from the connecting portion B to the cooler 6 and the atmosphere gas inside the duct 11 are heated at a high temperature in the duct 11, but the cooler 6 is outside the furnace. The heat capacity of the vessel 6 is sufficiently larger than the heat capacity of the portion of the duct 11 where the temperature is high and the atmospheric gas inside. For this reason, even if supply of cooling water stops, there is no possibility that the temperature of the cooling water in the cooler 6 will rise and vaporize.

  Therefore, there is no need for a safety valve, and there is no need to construct a dedicated duct for exhausting the vaporized cooling water out of the clean room.

  Next, a modification of the first embodiment is shown in FIGS.

  FIG. 3 is an AA arrow view showing the configuration of the clean oven 20 according to a modification of the first embodiment, and FIG. 4 is a cross-sectional view of the clean oven 20. The connection position in the duct and the furnace may be anywhere as long as the pressure of the atmospheric gas is equal to each other. In the clean oven 20, the duct 11 is connected to the connection part D (first connection part) and the connection part E (first connection part) below the accommodation position of the sample 5. 2 connection portions), and the pressures of the atmospheric gases at the connection portions D and E are equal. The configuration and operation of the clean oven 20 are substantially the same as those of the clean oven 1 except for the connection position between the duct and the furnace. In FIGS. 3 and 4, the same members as those in the clean oven 1 are denoted by the same reference numerals. A description of the configuration and operation will be omitted.

[Embodiment 2]
Another embodiment of the present invention will be described below with reference to FIGS.

  FIG. 5 is a cross-sectional view of the clean oven 30 according to the second embodiment. The inside of the clean oven 30 is substantially the same as the clean oven 1 and the clean oven 20 according to the first embodiment, and the same members as those in the clean oven 1 and the clean oven 20 are denoted by the same reference numerals.

  In the clean oven 30, the position between the oven fan 3 and the filter 4 (connection portion F / first connection portion) and the position between the heater 2 in the furnace and the oven fan 3 (connection portion G / second connection portion). The duct 31 is connected so as to connect the connecting portion). Inside the duct 31, a cooler 6 and a motor damper 32 (damper) are provided, and the cooling water is supplied from the water supply pipe 6a and is discharged from the drain pipe 6b through the cooler 6. The drain pipe 6b is provided with a flow rate switch 6c to control the flow rate of the cooling water.

  The pressure of the atmospheric gas in the connection part F and the connection part G is different from each other, and the pressure in the connection part F is higher than that in the connection part G. Therefore, unlike the duct 11 in the first embodiment, a motor damper 32 is provided in the duct 31 on the outlet side of the cooler 6, and atmospheric gas in the furnace flows into the duct 31 during heating and heat treatment. Is preventing. On the other hand, when the motor damper 32 is opened, the atmospheric gas in the furnace flows into the duct 31 from the connection portion F and is sent out into the furnace through the cooler 6 at the connection portion G. The flow can be controlled by opening and closing the motor damper 32. Therefore, unlike the duct 11 in the first embodiment, the cooler fan is not provided in the duct 31.

  During heating and heat treatment, the motor damper 32 is closed, and the atmospheric gas in the furnace does not flow into the duct 31. By opening the motor damper 32 at the time of cooling, the atmospheric gas in the furnace flows from the connection portion F, and flows back into the furnace at the connection portion G through the cooler 6 and the motor damper 32.

  Here, since the motor damper 32 is on the outlet side of the cooler 6, the temperature of the atmospheric gas passing through the motor damper 32 is low. Therefore, the valve portion of the motor damper 32 can be made of rubber such as silicon rubber having low heat resistance, and the flow of atmospheric gas in the duct 31 can be reliably blocked. Further, since the valve portion of the motor damper 32 is made of rubber, dust generation at the motor damper 32 is small, and the influence on the cleanliness in the furnace is small.

  Further, when the supply of the cooling water to the cooler 6 is stopped during cooling, the supply stop is detected by the flow switch 6c, and the motor damper 32 is closed based on the detection. Thereby, the atmospheric gas in the furnace does not flow into the duct 31.

  At this time, only the portion of the duct 31 from the connecting portion F to the cooler 6 and the atmosphere gas inside the duct 31 are heated at a high temperature in the duct 31, but the cooler 6 is outside the furnace. The heat capacity of the vessel 6 is sufficiently larger than the heat capacity of the portion of the duct 31 where the temperature is high and the atmospheric gas inside. For this reason, even if the supply of the cooling water is stopped, the temperature of the cooling water in the cooler 6 does not rise and vaporize.

  Therefore, in the duct 31, as in the case of the duct 11 in the first embodiment, a safety valve is not necessary, and it is not necessary to implement a dedicated duct for exhausting the evaporated cooling water to the outside of the clean room.

  Next, the case where the influence on the cleanliness in the furnace due to the dust generated by the motor damper 32 is a problem will be described.

  FIG. 6 is a cross-sectional view of the clean oven 40 according to the second embodiment. The clean oven 40 is configured to further include a HEPA filter 41 on the exit side of the motor damper 32 in the clean oven 30, and the configuration other than the HEPA filter 41 is the same as the configuration of the clean oven 30.

  As described above, there is some dust generation in the motor damper 32, but the dust generated in the motor damper 32 is collected by the HEPA filter 41. The HEPA filter 41 has a collection efficiency of 99.97% or more at 0.3 μm at the time, and the influence of dust generation by the motor damper 32 on the cleanliness in the furnace is almost negligible. In addition, since the atmospheric gas which passes through the HEPA filter 41 is immediately after passing through the cooler 6, the temperature is low, and the HEPA filter 41 having low heat resistance is not damaged.

  Further, as in the clean ovens 1 and 20 of the first embodiment, a cooler fan may be provided in the duct, which makes it easier to control the flow of the atmospheric gas in the duct.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The clean oven according to the present invention can be suitably applied to heat treatment of a low temperature polysilicon TFT (LTPS) or the like.

FIG. 3 shows an embodiment of the present invention and is a view taken along the line AA of FIG. 1 is a cross-sectional view illustrating a configuration of a clean oven 1 according to an embodiment of the present invention. FIG. 5 shows the embodiment of the present invention and is a view taken along the line AA of FIG. 1 is a cross-sectional view illustrating a configuration of a clean oven 20 according to an embodiment of the present invention. 1 is a cross-sectional view illustrating a configuration of a clean oven 30 according to an embodiment of the present invention. 1, showing an embodiment of the present invention, is a cross-sectional view showing a configuration of a clean oven 40. FIG. (A) And (b) shows a prior art and is sectional drawing which shows the structure of the clean oven 101. FIG. FIG. 9 is a cross-sectional view illustrating a configuration of a clean oven 201 according to a conventional technique.

Explanation of symbols

1,20,30,40 Clean oven 2 Heater (heating part)
3 Oven fan (Oven blowing means)
4 filter (filter for oven)
5 Sample (heat-treated product)
6 Cooler (cooling part)
11.31 Duct (duct)
12 Cooler fan (cooler blower)
32 Motor damper (damper)
41 HEPA filter

Claims (7)

A heating unit, an oven blowing means and an oven filter are provided in a furnace insulated from the outside, and the atmosphere gas heated by the heating unit is blown onto the heat-treated product through the oven filter by the oven blowing means, A clean oven that circulates in the furnace,
A duct including a cooling unit and a blower for cooler is connected to connect the first connection unit and the second connection unit in the first connection unit and the second connection unit in the furnace,
Atmospheric gas in the furnace flows into the duct at the first connecting portion by the cooler air blowing means, and atmospheric gas in the duct flows into the furnace at the second connecting portion by the cooler air blowing means. And
The atmospheric gas pressures in the first connection part and the second connection part are equal to each other,
A clean oven, wherein the duct is provided outside the furnace.   2. The clean oven according to claim 1, wherein when the supply of cooling water to the cooling unit is stopped, the driving of the cooling fan is stopped. A heating section, an oven blowing means and an oven filter are provided in a furnace insulated from the outside, and the atmosphere gas heated by the heating section is blown onto the heat-treated product by the oven blowing means through the oven filter, A clean oven that circulates in the furnace,
A duct including a cooling part and a damper is connected to connect the first connection part and the second connection part in the first connection part and the second connection part in the furnace,
The atmospheric gas in the furnace flows into the duct at the first connecting portion only when the damper is opened, and the atmospheric gas in the duct enters the furnace at the second connecting portion only when the damper is opened. Flow into
The atmospheric gas pressures in the first connection part and the second connection part are different from each other,
A clean oven, wherein the duct is provided outside the furnace.   The clean oven according to claim 3, wherein the damper is provided between the cooling part and the second connection part, and a valve part of the damper is made of rubber. The duct further comprises a duct filter,
The clean oven according to claim 3 or 4, wherein the duct filter is provided between the damper and the second connection portion.   The clean oven according to claim 5, wherein the duct filter is a HEPA filter.   The clean oven according to any one of claims 3 to 6, wherein when the supply of cooling water to the cooling unit is stopped, the damper is closed.

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