JPH0745546A - Heat treatment device - Google Patents

Abstract

PURPOSE:To enhance the thermal responsibility of the title heat treatment device by a method wherein a temperature detecting sensor is arranged near treated bodies but on the part whereto no reaction product adheres at all. CONSTITUTION:Within the title heat treatment device 38 wherein treated bodies W is mounted on a treated body boat 10 mounted on a heat retaining cylinder 21 so as to be led into a treating vessel 8 for the heat treatment, a temperature detecting sensor 46 is arranged on an area 44 whereto a formed film hardly adheres e.g. an interval part 54 between an inner tube 4 and the heat retaining cylinder 21. Through these procedures, the thermal responsibility of the title heat treatment device can be enhanced thereby enabling the temperature detection to be performed precisely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment apparatus for heat treating a semiconductor wafer or the like.

[0002]

2. Description of the Related Art In general, a heat treatment apparatus is used as an apparatus for subjecting an object to be processed such as a semiconductor wafer to a predetermined heat treatment in a uniform temperature state to form a thin film on the surface or perform heat diffusion.

This type of heat treatment apparatus will be described with reference to FIG. 4. This heat treatment apparatus 2 has a processing container 8 consisting of a quartz inner tube 4 and an outer tube 6 arranged concentrically with the inner tube 4. A plurality of semiconductor wafers W, which are stacked in the quartz wafer boat 10 and are the objects to be processed, are removably accommodated in the elevator 12 by the elevator 12.

A stainless steel manifold 18 having a processing gas supply pipe 14 and a gas exhaust pipe 16 is connected to the lower portion of the processing container 8, and a stainless steel cap portion 20 is hermetically sealed at the lower end opening. It is possible. The wafer boat 10 is mounted on the cap portion 20 via a heat insulating cylinder 21 made of quartz for heat insulation. A heater part 22 for heating the container 8 is wound around the outer circumference of the processing container 8 along the height direction thereof, and an outer side of the heater part 22 is made of a stainless steel outer material via a heat insulating material 24. It is covered with the shell 26 and constitutes a heating furnace 28 as a whole.

Temperature control in the case of heat-treating a wafer is a very important factor, and therefore, in order to perform precise temperature control, a plurality of heating zones are arranged in the height direction of the processing container 8, for example, below the upper portion thereof. The heater section 22 is provided with temperature sensors, for example, external thermocouples 32A to 32E corresponding to the respective heating zones, and the detected values are divided into five zones. Based on this, the electric power of the heater portion 22 of each corresponding heating zone can be individually controlled.

Further, between the wafer W and the heater section 22,
Since there is a certain distance, the external thermocouple 32 of the heater section
The accurate temperature of the wafer is difficult to be reflected in A to 32E, and in order to compensate for this to some extent, an L-shaped quartz thermocouple tube 34 is formed between the inner tube 4 and the outer tube 6. It is arranged so as to be detachable from the manifold 18, in which a plurality of internal thermocouples 36A to 36A are provided corresponding to the heating zones.
6E is housed.

When performing a heat treatment on a wafer in such a heat treatment apparatus, for example, when the normal temperature wafer boat 10 and a large number of wafers W are loaded into the processing container 8 which is heated to about 400 ° C. in advance, the temperature inside the furnace is increased. However, after that, the power of the heater unit 22 is increased to raise the furnace temperature to a process temperature, for example, about 850 ° C. At this time, from the TOP (top) zone of the wafer boat 10 to the vicinity of the BTM (bottom) zone, specifically, the uppermost heating zone 30A.
Since the heat capacity is relatively small from 1 to the uppermost heating zone 30D at the bottom, the time required for temperature rise and temperature stabilization is relatively short, and control is easy. However, in comparison with the other zones, the BTM zone, more specifically, the lowermost heating zone 30E has a large heat capacity of the heat insulating cylinder 21 used as a heat insulating material and has a large heat radiation from the furnace opening.
The time required to raise the temperature and stabilize the temperature becomes relatively long.

Therefore, in order to shorten the time required for temperature stabilization, it is necessary to increase the temperature rising rate as much as possible and to perform temperature control to stabilize the temperature without causing overshoot or the like. Therefore, the actual temperature control not only monitors the temperatures in the external thermocouples 32A to 32E provided in the heater unit 22, but also the internal thermocouple 36A provided in the furnace.
The temperature of ~ 36E is also monitored, and external thermocouples 32A-32E
Alternatively, the internal thermocouples 36A to 36E are controlled so that the internal thermocouples 36A to 36E reach the set temperature while controlling the temperature of the heater section by the detected values.

[0009]

However, in the processing apparatus as described above, the internal thermocouples 36A to 36E are provided between the inner tube 4 and the outer tube 6 in order to increase the temperature of the wafer and the temperature is compensated. However, in this case, it cannot be said that the distance between the internal thermocouples 36A to 36E and the wafer W is sufficiently close, and therefore the temperature responsiveness is not sufficient. . In particular, there is a problem in that the temperature response is poor in the bottom zone where the heat insulating cylinder 21 is arranged and the heat capacity is large, and it takes a lot of time to stabilize the entire wafer temperature.

Further, during heat treatment, for example, during film formation,
The processing gas introduced from the processing gas supply pipe 14 rises in the inner pipe 4, the reaction products are deposited on the wafer W surface, and the processed gas flows down between the inner pipe 4 and the outer pipe 6. Gas exhaust pipe 6
However, since the thermocouple tube 34 accommodating the internal thermocouples 36A to 36E is disposed on the downstream side of the processing gas flow, the reaction product is a thermocouple around the thermocouple tube 34 or to the manifold. It adhered to the tube attachment part, which caused a trouble of removing the thermocouple tube during maintenance of the internal thermocouple, and it was also a difficult task to clean and remove deposits that were damaged during removal or adhered to the tube wall. . Then, since the deposit adheres to the wall of the thermocouple tube as described above, this becomes a heat obstacle and makes it more difficult to measure the accurate temperature of the wafer. Furthermore, there is a problem in that a plurality of internal thermocouples, for example, five must be used, and the wires connected to the thermocouples become long, which inevitably leads to an increase in cost.

The present invention focuses on the above problems,
It was created to solve this effectively. An object of the present invention is to provide a heat treatment apparatus in which a temperature detection sensor is installed only in a place near the object to be processed and in which the response is most rate-determining, and in which a reaction product does not adhere to the temperature detection sensor to improve thermal responsiveness. To provide.

[0012]

In order to solve the above problems, the present invention introduces an object to be processed, which is accommodated in an object to be processed boat mounted on a heat retaining cylinder, into a processing container. In a heat treatment apparatus for performing heat treatment, a temperature detecting sensor for temperature control is provided in a film deposition non-adhesion area where a film is hardly deposited during heat treatment, which is a portion where a heat capacity is relatively large in a lower portion of the processing container. It was done.

[0013]

Since the present invention is configured as described above, since the temperature detecting sensor is arranged in the film deposition non-adhesive area formed by the gap formed between the heat retaining cylinder and the inner tube, this portion is It is on the upstream side of the process gas stream, so that reaction products do not adhere to the sensor. Also, since this sensor installation position is inside the inner tube, it will be closer to the object to be processed,
Therefore, it is possible to measure the temperature of the object to be processed with good thermal response and relatively accurately. Therefore, it is possible to quickly raise the temperature of the whole object to be processed to the process temperature and to stabilize the heat at an early stage.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a heat treatment apparatus according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a sectional view showing a heat treatment apparatus according to the present invention. The same parts as those of the conventional device shown in FIG. 4 are designated by the same reference numerals.

As shown in the drawing, the heat treatment apparatus 38 has a processing container 8 which is formed into a cylindrical shape by using, for example, quartz, the upper end portion of which is closed and the lower end portion of which is open. An outer cylinder 6 made of quartz and having a ceiling with an open upper end, and a cylindrical inner cylinder 4 having a cylindrical upper end and being concentrically arranged inside, for example, having an open upper end. Then, in the inner tube 4, a plurality of processing target boats made of, for example, quartz, for example, semiconductor wafers W stacked on the wafer boat 10 in a vertical direction at a predetermined pitch are removably accommodated. Has been done.

A heater part 22 is provided on the outer periphery of the processing container 8 so as to be coaxially wound, for example, in a spiral shape, and the outer periphery of the heater part 22 is made of, for example, stainless steel via a heat insulating material 24. A cylindrical outer shell 26 made of steel is provided to form a heating furnace 28 as a whole.

A plurality of heating zones of the heating furnace 28 are provided in the height direction of the processing container 8 for precise temperature control, for example, the first to fifth heating zones 3 from the upper side to the lower side.
The heater section 22 is provided with temperature sensors, for example, external thermocouples 32A to 32E corresponding to each heating zone, and the heater section of each corresponding heating zone is divided into 0A to 30E. The electric power of 22 can be controlled individually. Therefore, the heater portion 22 is also divided into five parts corresponding to the heating zones, which are represented by 22A to 22E in the figure.

A cylindrical manifold 18 made of, for example, stainless steel is connected to the lower end of the processing container 8. An annular flange portion 18A is formed on the upper end portion of the manifold 18, and the lower end flange portion 6A of the outer pipe 6 is airtightly supported on the flange portion 11 via an O-ring 40, for example.

The manifold 18 has an inner protruding portion 1
The lower end of the inner pipe 4 is supported by 8B, while a processing gas supply pipe 14 for introducing a processing gas is connected to the manifold 18 with its tip extending to the inner side of the inner pipe 4. A gas exhaust pipe 16 connected to a vacuum pump (not shown) is connected between the outer pipe 6 and the inner pipe 4 so as to communicate with each other.

The wafer boat 10 is mounted on a heat retaining tube 21 made of, for example, quartz, which exhibits a heat insulating function, and the heat retaining tube 21 hermetically seals the lower end opening of the manifold 10 through an O-ring 42. It is rotatably supported by a cap portion 20 made of, for example, stainless steel that seals as much as possible. The cap portion 20 is held by an elevating mechanism, for example, an elevator 12, so that the wafer boat 10 can be loaded / unloaded into / from the inner pipe 4.

A temperature detecting sensor 46 for temperature control is provided in the film deposition non-adhesion area 44 in the lower part of the processing container 8 where the film deposition during heat treatment is difficult to adhere. Specifically, the temperature detection sensor 46 includes an L-shaped sensor glass tube 50 having a diameter of about 9 mm and a bottom thermocouple 52 housed in the sensor glass tube 50. 50 is installed in a gap 54 formed between the inner wall of the inner pipe 4 and the outer wall of the heat insulating cylinder 21, and the base end thereof is supported in a through hole 56 of the manifold 10 in an airtight manner through an O-ring 58, for example. I am letting you.

In this case, the bottom thermocouple 52 is positioned horizontally opposed to the outer thermocouple 32E of the heating zone 30E at the bottom end of the bottom zone. The gap portion 54 is a portion immediately after the processing gas is introduced, reaction products have not yet been formed, and is close to the wafer, and is a position where the wafer temperature can be accurately detected with good thermal response. . Here, the gap between the outer pipe 6 and the inner pipe 4 and the gap between the inner pipe 4 and the wafer boat 10 are both set to about 20 mm.

The temperature at the bottom thermocouple 52 is detected by the bottom detection unit 60, and its output is input to the control unit 62 which is, for example, a microcomputer. In addition, each external thermocouple 32A to 32E provided in the heater unit 22
Is detected by the external thermocouple detection unit 64, and the output is input to the control unit 62. The control unit 62 uses various control methods based on these input values, and the divided heater units 22A to 2A through the heater driving unit 66.
2E is controlled individually. In this case, above the bottom zone, the internal thermocouple used in the apparatus shown in FIG. 4 is omitted, but this portion has a heat capacity higher than that of the area where the bottom thermocouple 52 is provided. Is relatively small, and because of this, the thermal response is also good, so that accurate temperature control is possible without using an internal thermocouple.

Next, a temperature control method carried out based on the apparatus constructed as described above will be explained. First, the upper part except the heating zone 30E at the bottom end is
There is little heat dissipation when the furnace opening is opened, and the object to be processed and the wafer boat that accommodates it are preheated in the lower zone, so the temperature change is small, and the heat capacity of the object to be processed is also small, so the time required for temperature stabilization is short. So each external thermocouple 32A ~
Temperature control using only 32D is performed.

On the other hand, the lowermost heating zone 30E
Has a relatively large heat capacity because the heat retaining cylinder 21 is arranged, and the thermal response is not good. For that purpose, fine temperature control is performed using the opposite sides of the external thermocouple 32E and the bottom thermocouple 52. Considering the temperature characteristics in the furnace, the temperature between the heater portion 22 and the vicinity of the wafer is, for example, 5 ° C.
It is inevitable that a certain temperature difference will occur. Therefore, prior to actual heat treatment, a thermocouple tube having a plurality of test thermocouples such as the internal thermocouple shown in FIG. 4 is inserted into the tubes of the wafer boat 40 and the inner tube 4 from below. , The temperature difference between each test thermocouple and the corresponding external thermocouple is obtained to create a temperature profile, and this temperature difference is input to the control unit 62 as a correction value.

Therefore, the wafer temperature in the heating zones 30A to 30D other than the heating zone 30E at the lowermost end is obtained by the following equation, and the temperature is controlled based on the temperature control block diagram shown in FIG. Wafer temperature (set temperature) = external thermocouple temperature + correction value (test thermocouple temperature−external thermocouple temperature) In contrast, in the heating zone 30E at the lowermost end,
By using the detected values of the external thermocouple 32E and the thermocouple 52 for the bottom side, for example, control as shown in FIG. 3 is performed.

The heating furnace 28 is preheated by the heater section 22 in advance to a relatively high temperature, for example, about 400 ° C. within a temperature range in which a natural oxide film is hardly formed on the wafer, and a large number of semiconductor wafers W are The wafer boat 10 accommodated at a predetermined pitch is loaded into the processing container 8 preheated by the elevator 12, and the lower end opening of the manifold 18 is closed by the cap portion 20 to seal the inside of the processing container 8. Then, when the power of the heater unit 22 is increased to raise the temperature of the wafer W to a process temperature, for example, 850 ° C. and becomes stable, a predetermined process gas is supplied from the process gas supply pipe 14 and a vacuum pump (not shown) is supplied. To evacuate the processing container 8 to a predetermined pressure, for example 0.5 Torr
The heat treatment, for example, a film forming process is performed while maintaining the temperature to a certain degree. In this case, the processing gas introduced into the furnace from the processing gas supply pipe 14 rises in the gap 54 between the heat insulating cylinder 21 and the inner pipe 4 and flows into the wafer region in a uniform temperature state, where it reacts. A product is formed and a film is formed on the wafer surface. The processing gas that has risen in the inner pipe 4 makes a U-turn at the ceiling portion of the container to flow between the inner pipe 4 and the outer pipe 6, and flows down between these to exhaust the gas exhaust pipe 1
It will be discharged from the container 6 through the container.

Here, the temperature inside the furnace is constantly detected by each thermocouple provided in the heating furnace 28, and the detected temperature is controlled via the bottom detecting section 60 and the external thermocouple detecting section 64. Input to the unit 62, the control unit 62 controls the power of the heater unit 22 via the heater driving unit 66 based on the set temperature. This control consists of 5 divided heating zones 3
In order to independently control each of the heaters 0A to 30E, the temperature of each of the divided heater units 22A to 22E is individually controlled.

For example, when the temperature is raised from 400 ° C. during preheating to 850 ° C. which is the process temperature, heating zones 30A to 30D above the lowermost heating zone 30E are taken.
2 has a relatively small heat capacity and therefore has a good thermal response, and is controlled as shown in FIG. That is, with respect to the values detected by the external thermocouples 32A to 32D of the heating zones 30A to 30D, a correction value obtained in advance corresponding to each zone, for example, −5 ° C. (generally higher than that of the heater unit). The temperature of the wafer is assumed to be about 5 ° C. lower), and the corrected value is compared with the set temperature of the wafer to obtain the difference value. Then, a new manipulated variable is calculated based on the calculated difference value, and the corresponding divided heater unit is controlled. In this case, temperature control is performed so that the difference value always maintains zero.

As described above, since the heating zones other than the lowermost heating zone have a relatively small heat capacity and a good thermal response, even if the temperature control using only the external thermocouples 32A to 32D is performed, the heating zones are overheated. It is possible to stabilize the process temperature at an early stage without generating a chute or the like. Therefore, the time required to raise the temperature to the process temperature and stabilize the temperature is short.

On the other hand, the bottom heating zone 30E
In the above, detailed control is performed using not only the external thermocouple 32E but also the detected temperature value of the bottom thermocouple 52. That is, the furnace temperature is controlled so that the temperature detected by the external thermocouple and the temperature detected by the bottom thermocouple are mixed at a fixed ratio (ratio) so that the temperature matches the set temperature. The goodness of convergence to the final target temperature, the goodness of the bottom thermocouple 52 located inside, the good followability with respect to the set value, and the good response of the furnace temperature control to the rapid change of the internal temperature. It is a combination of both advantages and can improve temperature recovery during wafer loading.

As shown in FIG. 3, a correction value obtained in advance corresponding to this heating zone is added to the temperature value detected by the external thermocouple 32E, and the corrected value and the bottom thermocouple are added. The temperature value detected at 52 is mixed with a predetermined ratio (ratio) to obtain a mixed value. And
The mix value thus obtained is compared with the set temperature to obtain a difference value between them, and a new manipulated variable is obtained based on the difference value to control the split heater section 22E.

For example, when the wafer W at room temperature is loaded, the temperature drops sharply. Therefore, at this point, the power of the lowermost divided heater section 22E is set to be slightly higher than that of the other sections, and the heating rate is increased. When the temperature is raised to a certain level, the power is set to obtain a normal heating rate to prevent overheating. The time until the temperature of the entire furnace stabilizes is controlled by the rate of temperature stabilization on the bottom side, which has a relatively large heat capacity. Thus, only the lowermost heating zone 30E, which has a relatively large heat capacity, is provided inside. Since the temperature control is performed based on the detection values of the bottom thermocouple 52 and the external thermocouple 32E, the time required for temperature rise and temperature stabilization in this portion can be greatly shortened, and therefore the temperature stabilization of the entire furnace can be achieved. It is possible to shorten the time required until, and it is possible to improve the throughput.

Further, since the bottom thermocouple 52 is located in the lower portion of the inner tube 4 and in the gap 54 between the heat insulating cylinder 21 and the inner wall of the inner tube 4, the bottom thermocouple 52 is located upstream of the process gas flow. In addition, since the temperature is low, reaction products are not formed, and there are many unreacted gases, almost no deposits are attached to the glass tube 50 for sensor that accommodates the bottom thermocouple 52. Therefore, even if the film forming process is repeated, almost no deposits are attached, so that the temperature of the wafer W can always be detected accurately, and not only accurate temperature control can be performed but also the pipe mounting portion However, since the deposit does not adhere, the sensor glass tube 50 can be easily removed and maintenance can be easily performed.

Further, as described above, the adhesion of the reaction products is very small, so that the cleaning at the time of maintenance can be easily performed, and the number of wires for the thermocouple is as small as one, and the cleaning operation can be further performed. It will be easy. Furthermore, the glass tube for sensor 5
Since 0 is provided inside the inner tube 4, unlike the conventional device, the glass tube for sensor 50 can be removed without removing the inner tube 4 during maintenance. Moreover, since the number of thermocouples used can be significantly reduced, the cost can be reduced.

In the above embodiment, the temperature control method in the lowermost heating zone 30E has been described as a control method in which the ratio of two thermocouples is mixed, but the present invention is not limited to this. The set temperature is compared with the detected temperature of the internal bottom thermocouple 52 to obtain a difference value, the set temperature is added to the difference value to obtain a new set value, and the new set value and the external thermocouple 32E are obtained. Needless to say, a so-called cascade control method may be used, in which control is performed so that the detected temperatures of 1 are matched.

In the above embodiment, the case where the heating zone is divided into five has been described as an example. However, the present invention is not limited to this, and the present invention can be applied to a case where the heating zone is divided into less than five or more. obtain. Further, although the apparatus of the above-described embodiment has a structure that rotates the wafer boat 10, the present invention can of course be applied to an apparatus that does not rotate the wafer boat 10.

[0038]

As described above, according to the heat treatment apparatus of the present invention, the following excellent operational effects can be exhibited. Since the temperature detection sensor is provided in the film deposition non-adhesion area where the film deposition is difficult to deposit during heat treatment, which is a part of the lower part of the processing vessel where the heat capacity is relatively large, the generated reaction product does not deposit and the removal is easy. In addition to the above, cleaning is facilitated and maintainability can be improved.
Also, almost no deposit adheres to the temperature sensor,
Moreover, since the thermal response can be improved, the temperature of the object to be processed can be accurately detected, the heat recovery can be performed quickly, and the time required for temperature stabilization can be shortened, thus improving the throughput. be able to.
Furthermore, since the number of thermocouples used can be reduced, the cost can be reduced accordingly.

[Brief description of drawings]

FIG. 1 is a sectional view showing a heat treatment apparatus according to the present invention.

FIG. 2 is a temperature control block diagram of a heating zone other than the heating zone at the lowermost end of the apparatus shown in FIG.

FIG. 3 is a temperature control block diagram of a heating zone at the bottom end of the apparatus shown in FIG.

FIG. 4 is a sectional view showing a conventional heat treatment apparatus.

[Explanation of symbols]

 4 Inner Tube 6 Outer Tube 8 Processing Container 10 Wafer Boat (Processing Object Boat) 18 Manifold 21 Heat Keeping Tube 22 Heater Section 22A-22E Split Heater Section 30A-30E Heating Zone 32A-32E External Thermocouple 38 Heat Treatment Device 44 Deposition of Film Area 46 Temperature detection sensor 50 Sensor glass tube 52 Bottom thermocouple 54 Gap 60 Bottom detection unit 62 Control unit 64 External thermocouple detection unit 66 Heater drive unit W Semiconductor wafer (processing target)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshimitsu Shibata 1-24-1 Machiya, Shiroyama-cho, Tsukui-gun, Kanagawa Tokyo Electron Tohoku Co., Ltd. Sagami Business Office (72) Toshiaki Miyazo, Shiroyama-cho, Tsukui-gun, Kanagawa 1-24-1 Machiya Tokyo Electron Tohoku Co., Ltd. Sagami Business Office

Claims (2)

[Claims] 1. A heat treatment apparatus for performing heat treatment by introducing a treatment target object accommodated in a treatment target boat mounted on a heat retaining cylinder into a treatment container, wherein a heat capacity of a lower portion of the treatment container is relatively high. A heat treatment apparatus characterized in that a temperature detection sensor for temperature control is provided in a film deposition non-adhesion area where a film is hardly deposited during heat treatment in a large area. 2. The processing container has a double tube structure of an inner tube and an outer tube, and the film deposition non-adhesion area is a gap portion formed between the heat retaining cylinder and the inner tube. The heat treatment apparatus according to claim 1, wherein the heat treatment apparatus is a heat treatment apparatus.