JPH0543173B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a semiconductor heat treatment apparatus, in particular, to provide jet ports of cooling fluid pipes at different positions in the axial direction, and to detect each of the reaction tubes detected by a thermocouple. The present invention relates to a semiconductor heat treatment apparatus that enables uniform rapid cooling of a reaction tube by controlling the flow rate of a cooling fluid in accordance with the internal temperature of the section.

[Conventional technology]

Semiconductor substrates, such as silicon wafers, are placed in the reaction tube of semiconductor heat treatment equipment and heated to approximately 1300°C.
The material is then heated to a temperature of 100.degree. C. and subjected to heat treatment such as diffusion oxidation treatment. After the heat treatment, the silicon wafer is removed from the reaction tube and sent to the next process. 1300
If a silicon wafer that has been heated to a temperature of 0.degree. C. is suddenly brought into contact with the outside air after being removed from the reactor while still at a high temperature, it will be thermally deformed or internally strained, which is not desirable. Therefore, the silicon wafer is removed from the reaction tube after the internal temperature of the reaction tube is lowered to about 800° C. and the silicon wafer is cooled.

In a semiconductor heat treatment apparatus, a heat coil is disposed around a reaction furnace to heat a reaction tube, and a heat insulating material is disposed between the heat coil and the furnace body or around the outer periphery of the furnace body. Although this heat insulating material is effective for efficiently heating the reaction tube, it impedes natural heat dissipation from the reaction tube, making rapid cooling difficult. Therefore, it takes a long time to cool the reaction tube, resulting in a large time loss and lowering the heat treatment efficiency of the semiconductor heat treatment apparatus.

[Problem that the invention seeks to solve]

In order to shorten the cooling time, a configuration has been proposed in which a cooling fluid is forced to flow into the reactor body after a predetermined heat treatment is completed to forcibly cool the reactor. Forced cooling using a cooling fluid can rapidly cool the reaction tube, shorten the cooling time, and increase heat treatment efficiency.

In a semiconductor heat treatment apparatus, a semiconductor substrate such as a silicon wafer is disposed along the axial direction over substantially the entire length of a reaction tube. In order to apply uniform heat treatment to the silicon wafer, it is necessary to uniformly heat and cool the reaction tube, that is, the silicon wafer. In order to uniformly heat the reaction tube, a soaking tube is placed between the heat coil and the reaction tube. In addition, the heating coil can be divided into multiple sections, for example, 3 sections at the center and at both ends.
The current value flowing through each section is controlled. Uniform heating of the reaction tube is almost achieved by using a soaking tube or by controlling the current value.

However, in a configuration in which cooling fluid is forced to flow into the furnace body, the cooling fluid generally flows into the furnace body from one end of the furnace body, flows through the furnace body, and exits from the other end. In such a configuration, as the cooling fluid flows through the furnace body, heat is removed from the reactor and the like, and the cooling fluid itself is heated. Therefore, for example, the state of temperature drop does not match at the end of the reaction tube on the inflow side, the center of the reaction tube, and the end of the reaction tube on the outflow side, and the reaction tube cannot be cooled uniformly. Therefore, the silicon wafer is not uniformly cooled within the reaction tube, and a uniform heat treatment is not performed on the silicon wafer.

An object of the present invention is to provide a semiconductor heat treatment apparatus that can rapidly cool a reaction tube uniformly.

[Means for solving problems]

To achieve this objective, generally speaking, according to the present invention, the jet ports of the cooling fluid pipe are provided at different positions in the axial direction, and the internal temperature of each portion of the reaction tube is detected by a thermocouple. The flow rate of the cooling fluid is controlled accordingly.

[Effect]

Since the cooling fluid is jetted out from the jetting port of the cooling fluid pipe, the reaction tube is rapidly cooled. In addition, since the cooling fluid pipe jet ports are provided at different positions in the axial direction,
The reaction tubes are constantly cooled by fresh cooling fluid, either directly or indirectly via the soaking tubes, thus making possible uniform rapid cooling. In particular, the present invention not only provides each section of the reaction tube with fresh cooling fluid from a cooling fluid pipe, but also corresponds to the internal temperature of each section of the reaction tube detected by the thermocouple. The flow rate of the cooling fluid is controlled manually or automatically by a central control means. Under such flow rate control, the state of decrease in internal temperature in each part of the reaction tube can be easily made the same, and uniform rapid cooling of the reaction tube can be accurately performed.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 1, a semiconductor heat treatment apparatus 10 according to the present invention includes a reaction tube 12 in which a semiconductor substrate (not shown) to be heat treated is housed.
The reaction tube is arranged vertically within the furnace body 14.
An introduction section 15 provided at the lower end of the furnace body 14
A process gas is then introduced into the reaction tube 12 . Since the reaction tube 12 is heated, the heating coil 1
6 are arranged around the reaction tube. Reaction tube 12
In general, the center is more likely to be heated than the ends. Therefore, in order to uniformly heat the reaction tube,
The heating coil 16 is divided into a plurality of sections, for example, three sections 16A to 16C (see FIG. 2), and the current value supplied to each section is controlled by a current control means 17 (see FIG. 2). has been done. The heating coil 16 is not limited to three divisions, but may be divided into a larger number of divisions. Furthermore,
A soaking tube 18 is disposed between the reaction tube 12 and the heating coil 16 so as to uniformly transfer the heat from the heating coil to the reaction tube.

A plurality of thermocouples 20 for detecting the internal temperature of the reaction tube 12 are housed within the protection pipe 22 and extend in the axial direction of the reaction tube. Protective pipe 22
is fixed to the inner periphery of the reaction tube 12, and the thermocouple 20 is inserted into the protection pipe from the open end of the protection pipe located outside the lower end of the reaction tube. On the other hand, the end of the protection pipe 22 located inside the reaction tube 12 is
It is closed to prevent outside air etc. from entering the inside of the reaction tube. A thermocouple 20 detects the temperature inside the reaction tube 12 at a position adjacent to the closed end of the protection pipe 22 .

As shown in FIG. 1, four protection pipes 22 containing thermocouples 20 are fixed in the reaction tube 12 in the embodiment, and the length of the protection pipes in the reaction tube is as follows.
It varies depending on the part of the reaction tube that the thermocouple detects. In the embodiment, two thermocouples 20B-1 and 20B-2 are connected to the reaction tube 1 at the center.
Thermocouples 20A and 20C detect the internal temperature of reaction tube 12 at the upper and lower ends. Of course, if necessary, add 20 thermocouples.
You may increase or decrease the number, arrangement, etc. As can be understood from FIG. 2, the temperature detected by thermocouples 20B-1 and 20B-2 is
Detects the heating state of 6B and connects thermocouples 20A and 20C.
detects the heating state of the upper and lower sections 16A and 16, respectively.

As shown in FIG. 1, a heat insulating material 24 is disposed within the furnace body 14 adjacent to the periphery of the heating coil 16 to prevent heat radiation from the heating coil to the outside. A plurality of cooling fluid pipes 26, eight in this embodiment, connect the heat soaking tube 18 and the heating coil 16.
It extends into the furnace body from the lower end of the furnace body.
Cooling fluid pipe 26 may be disposed in other locations, such as between soaking tube 18 and reaction tube 12.

Here, the reaction tube 12 is generally made of quartz glass having fine holes. Therefore, unless measures are taken such as coating the side surfaces of the reaction tube or making the side walls thicker, there is a risk that the cooling fluid will permeate the side walls of the reaction tube and flow into the reaction tube. Therefore, it is necessary to utilize cooling fluids of high purity. However, in a configuration in which the soaking tube 18 is disposed between the heating coil 16 and the reaction tube 12 and the cooling fluid pipe 26 is provided between the heating coil 16 and the soaking tube 18, the soaking tube acts as a barrier. This eliminates the need for high purity cooling fluids.

The tip of the cooling fluid pipe 26 is open, and cooling fluid, such as air, is spouted from the open end. As can be seen from FIGS. 2 and 3 in addition to FIG. are provided at different positions in the axial direction so as to be indirectly cooled through the cooling. Specifically, the length of the cooling fluid pipe 26 within the reactor body is 8
Four cooling fluid pipes 26A, 26B, 26C, and 26D, two of which are the same and different from each other, are as follows:
When viewed from above the semiconductor heat treatment apparatus 10, cooling fluid pipes having short lengths are sequentially arranged clockwise at equal intervals in the circumferential direction. The longest cooling fluid pipe 26A of the next group is located next to the shortest cooling fluid pipe 26D. In the present invention, the jet ports of the cooling fluid pipe 26 are provided at different positions in the axial direction, and each part of the reaction tube 12 is cooled with a separate cooling fluid. Therefore, each part of the reaction tube 12 is always cooled with fresh, unheated cooling fluid, rather than with cooling fluid that has been heated by removing heat from the surroundings. Therefore, each portion of the reaction tube 12 is rapidly cooled uniformly.

Of course, it is sufficient that the cooling fluid pipes 26 are configured to cool each portion of the reaction tube 12 by spraying a separate fresh cooling fluid, and the number of cooling fluid pipes may vary depending on the number of cooling fluid pipes.
Combinations, arrangements, etc. are not limited to the examples.

Additionally, the present invention provides a closed loop control system to ensure uniform rapid cooling of the reaction tubes 12. That is, as shown in FIG. 2, the cooling fluid pipes having the same length are connected to each other, and the flow rate of the cooling fluid sent to the cooling fluid pipes is controlled by the flow rate control means 28. The flow rate control means 28 includes, for example, throttle valves 29A to 29D whose throttle amount is regulated by a pulse motor, and the operation of the pulse motor is controlled by a central control means 30. The central control means 30 are also connected to the heating coil current control means 17 and the thermocouple 20. Note that the throttle valves 29A to 29D of the flow rate control means may be manually controlled without providing the central control means 30.

After the heat treatment is completed, the supply of current to the heating coil 16 is cut off, and in order to cool the reaction tube 12, cooling fluid is flowed from the cooling fluid pipe 26 around the soaking tube 18, that is, around the reaction tube 12. Reaction tube 12
The internal temperature of each part of is continuously detected by thermocouples 20, and the central control means 30 is informed of the temperature drop based on the signals from the thermocouples. The central control means 30 acts so that the internal temperatures of the upper, middle, and lower ends of the reaction tube 12 are lowered in the same manner. That is, for example, if the temperature drop at the upper end of the reaction tube 12 is slower than elsewhere, the central control means 30 will control the cooling fluid pipe 26A.
Flow control means 28 is signaled to increase the flow rate of cooling fluid delivered to the flow control means 28 . Flow rate control means 28
Based on the sent signal, the controller drives the pulse motor to reduce the throttle of the throttle valve 29A and increase the amount of cooling fluid flowing into the cooling fluid pipe 26A. Then, the upper end of the reaction tube 12 is strongly cooled through the soaking tube 18, so that the upper end is cooled in the same state as the others. Conversely, for example, if the temperature drop at the lower end of the reaction tube 12 occurs more rapidly than elsewhere, the central control means 30 controls the flow rate control means so as to throttle the throttle valve 29D and reduce the flow rate passing therethrough. 28.

In order to uniformly cool each section of the reaction tube 12, the flow rate of the cooling fluid ejected from the cooling fluid pipe 26 is controlled, or the corresponding section of the heating coil is heated, with or without controlling the flow rate. , the current control means 17 may be controlled by the central control means 30. For example, if the temperature drop at the lower end of the reaction tube 12 occurs more rapidly than elsewhere, the section 16C of the heating coil 16 is energized in response to a signal from the central control means 30. Then, the lower end of the reaction tube 12 is indirectly heated via the soaking tube 18, and the temperature drop is alleviated.

The present invention is not limited to diffusion furnaces, but can be applied to semiconductor heat treatment equipment for various heat treatments such as CVD processing. Further, in the embodiment, the reaction tubes are arranged vertically, but the present invention may be applied to a semiconductor heat treatment apparatus in which the reaction tubes are arranged horizontally. Furthermore, instead of indirectly heating and cooling the reaction tube via the soaking tube, the soaking tube may be removed and the reaction tube may be directly heated and cooled.

〔Effect of the invention〕

As described above, according to the semiconductor heat treatment apparatus according to the present invention, the reaction tube is disposed within the furnace body, and the heat coil having a plurality of sections is disposed between the furnace body and the reaction tube in the axial direction of the reaction tube. is installed to heat the reaction tube. A plurality of thermocouples are arranged to be able to detect the internal temperature of each portion of the reaction tube corresponding to the section of the heating coil. Furthermore, a plurality of cooling fluid pipes extend in the axial direction between the reaction tube and the furnace body, and cool the reaction tube by jetting cooling fluid from jet ports located at different positions in the axial direction. The flow control means is
The flow rate of the cooling fluid supplied to each cooling fluid pipe is controlled in accordance with the internal temperature of the reaction tube detected by the thermocouple.

If necessary, a central control means is also provided, which receives signals from the thermocouples regarding the internal temperature of each section of the reaction tube and sends control signals to the flow rate control means. .

In this way, since the cooling fluid is jetted out from the spout of the cooling fluid pipe, the reaction tube is rapidly cooled. In addition, since the cooling fluid pipe jet ports are provided at different positions in the axial direction, the reaction tubes are constantly cooled by fresh cooling fluid, either directly or indirectly through the soaking tube. , Therefore, uniform rapid cooling is possible.

In addition to supplying fresh cooling fluid from the cooling fluid pipe to each section of the reaction tube, the flow rate of the cooling fluid is also adjusted in response to the internal temperature of each section of the reaction tube detected by the thermocouple. , manually or automatically by central control means. Under such flow rate control, the state of decrease in internal temperature in each part of the reaction tube can be easily made the same, and uniform rapid cooling of the reaction tube can be accurately performed.

The above-mentioned embodiments are for illustrating the present invention, and are not intended to limit the present invention in any way, and any modifications, modifications, etc. made within the technical scope of the present invention are also included in the present invention. Needless to say.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a semiconductor heat treatment apparatus according to the present invention, FIG. 2 is a schematic control system diagram in the semiconductor heat treatment apparatus, and FIG. 3 is a partial perspective view of the semiconductor heat treatment apparatus showing the arrangement of cooling fluid pipes. It is a diagram. 10: Semiconductor heat treatment equipment, 12: Reaction tube, 1
4: Furnace body, 16: Heat coil, 16A, 16
B, 16C: Heat coil section, 17:
Current control means, 20, 20A, 20B-1, 20
B-2, 20C: Thermocouple, 26, 26A, 26
B, 26C, 26D: Cooling fluid pipe, 28: Flow rate control means, 29A, 29B, 29C, 29D:
Throttle valve, 30: central control means.

Claims (1)

[Scope of Claims] 1. A reaction tube disposed within the furnace body, and a heat coil having a plurality of sections and disposed in the axial direction of the reaction tube between the furnace body and the reaction tube to heat the reaction tube. , a plurality of thermocouples corresponding to the sections of the heat coil, respectively arranged to be able to detect the internal temperature of each part of the reaction tube, and a plurality of thermocouples each extending in the axial direction of the reaction tube between the reaction tube and the furnace body; A plurality of cooling fluid pipes eject cooling fluid from jet ports located at different positions in the axial direction to cool the reaction tube, and the flow rate of the cooling fluid supplied to each cooling fluid pipe is measured based on the reaction detected by the thermocouple. A semiconductor heat treatment apparatus comprising: a flow rate control means for controlling the internal temperature of each part of the pipe; 2. The semiconductor heat processing apparatus according to claim 1, wherein the soaking tube is disposed between the heat coil and the reaction tube, and the cooling fluid pipe is located between the soaking tube and the reaction tube. 3. A reaction tube arranged inside the furnace body, a heat coil having multiple sections and arranged in the axial direction of the reaction tube between the furnace body and the reaction tube to heat the reaction tube, and a section of the heat coil. A plurality of thermocouples are arranged to detect the internal temperature of each part of the reaction tube, and thermocouples extend in the axial direction of the reaction tube between the reaction tube and the furnace body, and are located at different positions in the axial direction. Cooling fluid is ejected from a certain spout to cool the reaction tube, and the flow rate of the cooling fluid supplied to each cooling fluid pipe is detected by the thermocouple in each part of the reaction tube. a flow rate control means for controlling the internal temperature of each section of the reaction tube according to the internal temperature;
A semiconductor heat treatment apparatus comprising: central control means that receives a signal from a thermocouple and sends a control signal to the flow rate control means to control the operation of the flow rate control means. 4. The semiconductor heat processing apparatus according to claim 3, wherein the soaking tube is disposed between the heating coil and the reaction tube, and the cooling fluid pipe is located between the soaking tube and the reaction tube. 5. The semiconductor heat treatment apparatus according to claim 3 or 4, wherein the central control means is configured to be able to control the amount of current flowing through each section of the heating coil.