JPH07201758A - Opening variable valve device for reduced pressure heat-treating furnace - Google Patents

Abstract

PURPOSE:To contrive the reduction in facility cost and the space for facilities and the simplification of the control of the device by a method wherein the opening and shutting of an exhaust system, a strong vacuum control, a slow vacuum and a weak vacuum control are made possible by one valve. CONSTITUTION:An opening variable valve device 20, which is provided in an exhaust system of a vacuum heat-treating furnace, has a valve seat 27 formed in a valve chamber 26, this valve seat 27 is provided with a valve disc 28 in a seating and separation adjustable manner. Peripheral wall parts 28a and 27a are respectively formed on these of the valve disc 28 and the valve seat 27 so as to oppose to each other in the direction to intersect orthogonally the direction of movement of the valve disc 28 and a gap 37 for fine adjustment is provided between these parts 28a and 27a. Accordingly, the opening and shutting of the exhaust system, a strong vacuum control, a slow vacuum and a weak vacuum control become possible by one valve and the reduction in facility cost and the space for facilities and the simplification of the control of the device are contrived.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable opening valve device for a reduced pressure heat treatment furnace.

[0002]

2. Description of the Related Art As a low pressure heat treatment furnace, a low pressure CVD (Chemic
There is known a reduced pressure heat treatment furnace used for treatment such as al Vaper Deposition). As shown in FIG. 7, the depressurized heat treatment furnace 1 is connected to an unillustrated processing gas supply system for supplying a processing gas into the furnace and an exhaust system 18 for creating a depressurized atmosphere in the furnace. In order to perform pressure control such as first performing vacuum substitution inside the furnace, performing slow vacuum so as not to wind up particles at that time, and then maintaining the inside of the furnace at a predetermined processing pressure, this exhaust system 18 The following configuration is adopted.

The exhaust system 18 has a pipe 19 having a predetermined pipe diameter (inner diameter) of, for example, about 80 mm. The pipe 19 has a main opening / closing valve 43 which is an angle valve, a main pressure control valve 44 which is a butterfly valve, and a pressure reducing valve. The pump 21 is provided in order. Also, a bypass pipe 45 having a small pipe diameter of, for example, about 9 mm that bypasses the main opening / closing valve 43 is connected to the pipe 19, and an auxiliary opening / closing valve 46 formed of an angle valve and an auxiliary pressure control formed of a needle valve are connected to the bypass pipe 45. The valve 47 is provided in order. The main and auxiliary on-off valves 4
Reference numerals 3 and 46 are provided with a valve seat 27 formed in the valve chamber 26 as shown in FIG. 8 and a valve body 28 provided on the valve seat 27 so that seating and separation movement can be adjusted. Since it is difficult to control the pressure by adjusting a minute gap between the valve 27 and the valve body 28, it is dedicated for on / off (opening / closing).

The inside of the furnace is treated at a predetermined processing pressure, for example, 40
When controlling to about 0 Torr, first, the main opening / closing valve 43
Is closed, the main pressure control valve 44, the auxiliary opening / closing valve 46 and the auxiliary pressure valve 47 are opened, and the inside of the furnace is pressurized to a predetermined pressure by, for example, slow vacuum via the bypass pipe 45 having a small diameter.
After reducing the pressure to about rr, then opening the main opening / closing valve 43, closing the auxiliary opening / closing valve 46 and the auxiliary control valve 47, and performing vacuum decompression inside the furnace by strong depressurization via the pipe 19, for example, about 0.5 Torr, and then processing While supplying gas into the furnace, the main opening / closing valve 43 is closed again, the auxiliary opening / closing valve 46 is opened, and the auxiliary pressure valve 4 is opened.
7, the inside of the furnace is slightly decompressed, for example, 400 Torr
A control method of controlling to a certain degree is adopted. When the pressure inside the furnace is controlled to be strongly depressurized, for example, to about 1 Torr, the pressure is controlled by the main pressure control valve 44 without switching the valve after the vacuum replacement.

[0005]

However, in the exhaust system of the decompression heat treatment furnace, the bypass pipe and the exhaust pipe for performing the pressure control as described above, that is, the opening / closing of the exhaust system, the strong decompression control, the slow vacuum and the weak decompression control are provided. There are problems that a large number of valves are required, the equipment cost and the equipment space are increased, and the control becomes complicated.

Therefore, an object of the present invention is to solve the above-mentioned problems and to perform opening / closing of an exhaust system, strong decompression control, slow vacuum and weak decompression control with one valve, thereby reducing equipment cost and equipment space. Another object of the present invention is to provide a variable opening valve device for a reduced pressure heat treatment furnace which can simplify control.

[0007]

In order to achieve the above object, the invention of claim 1 is a variable opening valve device provided in an exhaust system of a decompression heat treatment furnace, comprising a valve seat formed in a valve chamber. A valve element provided so that seating and separating movement of the valve seat can be adjusted, and a peripheral wall portion formed so as to face the valve body in a direction orthogonal to the moving direction of the valve body, It is characterized in that a fine adjustment gap provided between these peripheral wall portions is provided.

Further, the invention of claim 2 is based on the invention of claim 1, so that the cross-sectional area of the fine adjustment gap is gradually increased in the at least one peripheral wall portion in accordance with the valve opening movement of the valve body. It is characterized in that it is formed to be inclined.

Further, the invention of claim 3 is based on the invention of claim 1, and the peripheral wall portion is formed by gradually increasing the diameter in the valve opening movement direction of the valve element, and the diameter of the peripheral wall portion on the large diameter side is increased. It is characterized in that the fine adjustment gap is formed such that the dimension in the moving direction of the valve body is larger than that on the small diameter side.

[0010]

According to the invention of claim 1, the valve body is seated on the valve seat (when the valve is closed), the valve body is separated from the valve seat (when the valve is open), and the valve body has a fine adjustment gap. Exhaust with a single valve because each state can be obtained: movement within stroke (during slow vacuum and weak pressure reduction control) and movement of valve body outside stroke of fine adjustment gap (during strong pressure reduction control) It is possible to open / close the system, perform strong decompression control, slow vacuum and weak decompression control, and reduce equipment cost and equipment space and simplify control.

According to the second aspect of the present invention, since the cross-sectional area of the fine adjustment gap is gradually increased as the valve body is opened, the pressure control in a wide range can be performed by the small movement of the valve body in the weak pressure reducing control. It is possible to reduce the size of the device.

According to the third aspect of the present invention, the peripheral wall portion is formed such that its diameter is gradually increased in the valve opening movement direction of the valve body, and the fine adjustment gap on the large diameter side is formed on the small diameter side. Since the valve body is formed to have a larger dimension in the moving direction than the above, the control range in the weak depressurization control is further increased, and precise pressure control suitable for processing can be performed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. First, a decompression heat treatment furnace to which the variable opening valve device of the present embodiment is applied will be described. As shown in FIG. 2, the reduced pressure heat treatment furnace 1 is a semiconductor wafer W which is an object to be processed.
It is a vertical furnace configured to be suitable for performing a film forming process by low pressure CVD, and is horizontally provided with a base plate 2 made of, for example, stainless steel having a circular opening 2a in the center.

A short cylindrical manifold 3 made of, for example, stainless steel, having a flange portion 3a at the upper end is detachably attached to the lower portion of the base plate 2 by bolting so that the axial center of the manifold 3 is aligned with the opening portion 2a. A reaction tube 4 made of a heat-resistant material such as quartz is provided as the processing furnace 1 on the manifold 3. This reaction tube 4
Has a double pipe structure in which an inner pipe 5 whose upper and lower ends are open and an outer pipe 6 which is closed at its upper end and has an outwardly facing flange 6a are concentrically arranged.

The outer pipe 6 is airtightly supported on the upper end flange portion 3a of the manifold 3 through an O-ring 7 made of a material having heat resistance and corrosion resistance, such as fluorine rubber, as a sealing means. Is supported by a small-diameter step portion 3b formed in the inner periphery of the manifold 3 at a substantially middle portion in the height direction. An inlet port 8 to which a processing gas supply system for communicating the inside of the inner tube 5 with the outside (outside the furnace) and introducing a processing gas from a processing gas supply source (not shown) into the reaction tube 4 is connected to the manifold 3. And an outlet port 9 connected to an exhaust system 18 described later for communicating the annular space 4a between the inner pipe 5 and the outer pipe 6 with the outside (outside the furnace) to exhaust and depressurize the inside of the reaction pipe 4. Is provided.

Around the reaction tube 4, there is arranged a heating part 11 formed by forming a heating wire 10 such as a kathal wire in a coil shape for heating the inside of the reaction tube 4 to a high temperature, for example, about 800 to 1200 ° C. The outer circumference of the heating portion 11 is covered with an outer shell (not shown) via a heat insulating material 12. The heating unit 11, the heat insulating material 12, and the outer shell are supported on the base plate 2.

Below the manifold 3, a lid 13 made of, for example, stainless steel, which opens and closes the lower surface opening thereof, is provided so as to be able to move up and down by an elevating mechanism 14, and a large number of semiconductors, for example, about 150 semiconductors are provided on the lid 13. Wafer boats 15 that hold the wafers W in a horizontal state in multiple stages at intervals in the vertical direction are mounted via a heat insulating cylinder 16. It should be noted that the lid 13 is provided with a rotation mechanism 17 that rotationally drives the heat retaining cylinder 16.

On the other hand, the exhaust system 18 is composed of a stainless steel pipe 19 having a predetermined pipe diameter, for example, about 80 mm, and a variable opening degree valve device 20 and a pressure reducing pump 21 are provided in this pipe 19 in order. . Further, a pressure sensor 22 is provided on the upstream side of the variable opening valve device 20 of the pipe 19, and the controller 23 controls the variable opening valve device 20 by feeding back a value detected by the pressure sensor 22. Is configured. The pressure sensor 22 in the illustrated example is composed of two sensors having different detection ranges, for example, for 0-10 Torr and for 0-1000 Torr, but only one if it can accurately detect a wide range of pressure. Good.

As shown in FIG. 1, the variable opening valve device 20 is provided with a so-called angle valve-shaped valve chamber (casing) 26 having an inlet 24 at its lower end and an outlet 25 at its side. A flat valve seat 27 is formed in the inside of the inlet 24, which is expanded radially outward at the inner part of the inlet 24, and the valve body 2 is seated on the valve seat 27 and can be adjusted to move away from and away from the valve seat 2.
8 are provided. The valve chamber 26 and the valve body 28 are both made of a material having heat resistance and corrosion resistance, for example, stainless steel, and a portion of the valve body 28 that is seated on the valve seat 27 is an O-ring 29 made of, for example, fluorocarbon rubber as a sealing means.
Is provided.

A valve rod 30 is provided vertically at the center of the upper end of the valve body 28, and the valve body 28 is valved at the top of the valve chamber 26 through the valve rod 30 penetrating the upper end of the valve chamber 26. The seat 27 is provided with a valve body drive unit 31 including a pulse motor and a screw feed mechanism as drive means for adjusting the seating and separating movement. Further, as means for covering the periphery of the valve rod 30 between the upper end portion of the valve body 28 and the upper end portion in the valve chamber 26 to allow the movement of the valve body 28 and seal the penetrating portion of the valve rod 30. A bellows 32 made of stainless steel is provided by welding.

The valve body 28 is formed in a circular shape and has a diameter gradually reduced downward, and the inlet 24 side of the valve seat 27 is also gradually reduced corresponding to the shape of the valve body 28. It is formed with a diameter. The lower surface of the upper end maximum diameter portion 33 of the valve body 28 is formed so as to face the upper surface portion of the valve seat 27, and the O-ring 29 is provided at that portion. The reduced diameter portion of the valve body 28 is formed in a plurality of stages below the uppermost maximum diameter portion 33, in the embodiment, three stages of an upper stage 34, an interruption 35 and a lower stage 36.

A peripheral wall portion 28 that faces the reduced diameter portion of the valve body 28 and the valve seat 27 in a direction orthogonal to the moving direction of the valve body 28.
a, 27a are formed, and the peripheral wall portions 28a, 27 of these pairs are formed.
a is formed by gradually increasing the diameter in the valve opening movement direction (upward direction) of the valve body 28. In addition, the peripheral wall portion 28a,
A fine adjustment gap 37 is provided between the valve body 2 and each of the stages 34, 35, 36 of the fine adjustment gap 37.
When the dimension in the moving direction of 8, that is, the height of each step 34, 35, 36 is h1, h2, h3, the upper step 34 which is the large diameter side
Is formed such that h1>h2> h3 is larger than the size of the lower stage 36 on the smaller diameter side. When the sizes of the fine adjustment gaps 37 in the respective steps 34, 35, 36 are s1, s2, s3, s1> s2 so that the size of the upper step 34 is larger than that of the lower step 36.
> S3.

The conductance of the vacuum pressure in the fine adjustment gap 37 is proportional to the cross-sectional area of the gap 37.
It is in inverse proportion to the distance dimension of 7. Further, when the valve body 28 is gradually opened from the closed position, the pressure is first dominated by the gap 37 of the lower stage 36 having the smallest cross-sectional area, and then the gap 37 of the interruption 35 and the gap 37 of the upper stage 34.
Move in that order.

Therefore, since the fine adjustment gap 37 is formed as described above, the weak depressurization control can be performed in a relatively wide range, for example, in the range of about 200 to 760 Torr. In this embodiment, the size of the gap 37 is s in order to further widen the control range of the weak depressurization control.
Although formed as 1>s2> s3, the cross-sectional area of the gap 37 increases in proportion to the diameter, so the size of the gap 37 may be constant, that is, s1 = s2 = s3. In addition, the maximum opening position (2 / from the lower side in the valve chamber 26) from the position of the valve body 28 in which the cross-sectional area between the valve body 28 and the valve seat 27 exceeds the cross-sectional area of the fine adjustment gap 37 of the upper stage 34. Pressure control from medium pressure reduction to strong pressure reduction is performed in a movement range up to a position of about 3), and it is possible to reduce the pressure to about 3 × 10 ⁻³ Torr at the maximum opening, although it depends on the capacity of the pressure reduction pump 21. Become.

Next, the operation of the above embodiment will be described. First, nitrogen gas is introduced from the inlet port 8 and the outlet port 9
The inside of the reaction tube 4 of the reduced pressure heat treatment furnace 1 by replacing the inside of the reaction tube 4 with nitrogen gas by exhausting the gas through the exhaust system 18.
And the wafer boat 15 supporting the semiconductor wafer W is loaded into the reaction tube 4 together with the heat insulation cylinder 16.

Next, with the valve of the processing gas supply system of the inlet port 8 closed, the inside of the reaction tube 4 is evacuated and decompressed through the exhaust system 18 to perform vacuum replacement. At this time, in order to prevent the particles from being wound up, first, the opening degree variable valve device 2
0 valve body 28 is slightly opened from the valve closed position, and the fine adjustment gap 3
After performing slow vacuum through 7 to, for example, about 10 Torr, the valve body 28 is then fully opened and the inside of the reaction tube 4 is evacuated to about 0.5 Torr.

When the vacuum replacement is completed, the valve body 28 is once closed, and in this state the valve of the processing gas supply system is gradually opened to introduce the processing gas into the reaction tube 4, whereby the inside of the reaction tube 4 is introduced. When the pressure reaches a processing pressure, for example, about 400 Torr, the valve body 28 is opened and the inside of the reaction tube 4 is maintained at the processing pressure by weak pressure reduction control through the minute adjustment gap 37.
Then, when the processing of the semiconductor wafer W is completed, the inside of the reaction tube 4 is vacuum-replaced and replaced with nitrogen gas in the reverse order, and then the reaction tube 4 is opened while the lid 13 is opened downward.
The wafer boat 15 may be carried out from the inside.

According to the opening degree variable valve device 20 constructed as described above, the valve body 28 is seated on the valve seat 27 (when the valve is closed) and the valve body 28 is separated from the valve seat 27 (opened). (During valve operation), a state in which the valve element 28 moves within the stroke of the fine adjustment gap 37 (during slow vacuum and weak decompression control), and a state in which the valve element 28 moves outside the stroke of the fine adjustment gap (intermediate decompression or Since each state of (strong decompression control) is obtained, not only the opening / closing of the exhaust system 18 but also a wide range of pressure control such as strong decompression control, slow vacuum and weak decompression control can be performed with one valve. . Therefore, the exhaust system 18
The main on-off valve that was conventionally required on the pipe 19 of
Since it suffices to provide only one opening degree variable valve device 20 in place of the main pressure control valve, the bypass pipe, the auxiliary opening / closing valve and the auxiliary pressure control valve, the equipment cost and the equipment space can be reduced and the control can be simplified.

Further, since the length of the pipe 19 can be shortened, the operating efficiency can be remarkably improved. Further, the peripheral wall portions 28a, 27a formed on the valve body 28 and the valve seat 27 are formed by gradually increasing the diameter in the valve opening movement direction of the valve body 28, and the fine diameter of the upper stage 34 on the large diameter side thereof. Adjustment gap 3
7 is formed such that the dimension of the valve body 28 in the moving direction is larger than that of the lower stage 36 having the smaller diameter side, the control range in the weak depressurization control is increased, and the precise pressure control suitable for the processing is performed. It will be possible.

3 to 6 show different modifications in which the structure of the fine adjustment gap 37 in the valve device for a reduced pressure heat treatment furnace is changed. First, the valve device 20 of FIG.
An inner peripheral edge portion of the valve body 28 is vertically raised, and an annular groove 39 is formed in a lower portion of the valve body 28 so as to accommodate the raised annular raised portion 38. The groove 3 of the valve body 28
An O-ring 29 is provided on the lower peripheral portion of the outer side of
One peripheral wall portion 39a of the groove 39 and the inner peripheral wall portion 3 of the raised portion 38
8a and the other peripheral wall portion 39b of the groove 39 and the raised portion 3
The fine adjustment gaps 37 are provided between the outer peripheral wall portions 38b and the outer peripheral wall portions 38b.

In the valve device 20 shown in FIG. 4, the raised portion 38 is formed thick and the upper surface thereof serves as the valve seat 27, and the O-ring 29 is provided on the lower surface of the valve body 28 facing the valve seat 27. Has been. An annular portion 40 surrounding the outer peripheral wall portion 38b of the raised portion 38 is formed on the lower peripheral edge portion of the valve body 28, and fine adjustment is performed between the inner peripheral wall portion 40a of the annular portion 40 and the outer peripheral wall portion 38b of the raised portion 38. A clearance 37 is provided.

In the valve device 20 of FIG. 5, a circular recess 41 concentric with the central inlet 24 is formed in the bottom surface of the valve chamber 26 as a valve seat 27, and the valve body 28 is accommodated in the recess 41. And is seated on the valve seat 27. And
Inner peripheral wall portion 41a of the recess 41 and outer peripheral wall portion 2 of the valve body 28
A fine adjustment gap is provided between the groove 8a and 8a.

In the valve device 20 shown in FIG. 6, the upper surface of the raised portion 38 serves as the valve seat 27 as in the embodiment shown in FIG. 4, and the valve body 28 has a circular convex portion that enters the inside of the raised portion 38. 42
Are formed. Then, the convex portion 42 of the valve body 28
A fine adjustment gap 37 is provided between the outer peripheral wall portion 42a of the above and the inner peripheral wall portion 38a of the raised portion 38. According to the opening degree variable valve device 20 of the embodiment of FIGS. 3 to 6, the weak decompression control is narrower than that of the embodiment having the multistage fine adjustment gaps 37, except that the control range is weak. Almost the same effects as those of the embodiment can be obtained.

Regarding the peripheral wall portions, for example, 42a and 38a, which face each other in the direction orthogonal to the moving direction of the valve body 28, at least one of the peripheral wall portions traverses the fine adjustment gap 27 in accordance with the valve opening movement of the valve body 28. It may be formed so as to be inclined so that the area gradually increases. For example, in the opening degree variable valve device 20 of FIG. 6, the outer peripheral wall portion 42 of the convex portion 42.
The a may be formed so as to be inclined as shown by an imaginary line. As a result, the cross-sectional area of the fine adjustment gap 37 is gradually increased as the valve body 28 is moved, so that in the weak pressure reduction control, a small movement of the valve body 28 enables a wide range of pressure control, and the device is small in size. Can be realized.

The present invention is not limited to the above embodiment, but various modifications can be made within the scope of the gist of the present invention. For example, the low-pressure heat treatment furnace 1 may not have the inner tube 5, and may be a furnace that can perform processes such as oxidation, diffusion, and annealing in addition to the low-pressure CVD.

[0036]

In summary, according to the present invention, the following excellent effects can be obtained.

(1) According to the invention of claim 1, the valve body is seated on the valve seat (when the valve is closed), the valve body is separated from the valve seat (when the valve is open), and the valve body is finely adjusted. The state of moving within the stroke of the working gap (during slow vacuum and weak decompression control),
Also, since each state is obtained in which the valve body moves outside the stroke of the fine adjustment gap (during strong pressure reduction control), opening and closing of the exhaust system, strong pressure reduction control, slow vacuum and weak pressure reduction control are performed with one valve. It is possible to reduce the facility cost and facility space and simplify the control.

(2) According to the second aspect of the invention, since the cross-sectional area of the fine adjustment gap gradually increases as the valve body moves to open the valve body, a small range of movement of the valve body in a wide range is achieved in the weak pressure reduction control. The pressure can be controlled and the device can be downsized.

(3) According to the invention of claim 3, the peripheral wall portion is formed such that its diameter increases stepwise in the valve opening movement direction of the valve body, and the fine adjustment gap on the large diameter side has a small diameter. Since the valve body is formed such that the dimension in the moving direction of the valve body is larger than that on the side, the control range in the weak depressurization control is further increased, and precise pressure control suitable for processing can be performed.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an essential part showing an embodiment of a variable opening valve device for a reduced pressure heat treatment furnace according to the present invention.

FIG. 2 is a cross-sectional view showing an example of a reduced pressure heat treatment furnace.

FIG. 3 is a partial cross-sectional view showing a modified example of the variable opening valve device for a reduced pressure heat treatment furnace.

FIG. 4 is a partial cross-sectional view showing a modified example of a variable opening valve device for a reduced pressure heat treatment furnace.

FIG. 5 is a partial cross-sectional view showing a modified example of a variable opening valve device for a reduced pressure heat treatment furnace.

FIG. 6 is a partial cross-sectional view showing a modified example of the variable opening valve device for the reduced pressure heat treatment furnace.

FIG. 7 is a diagram showing an example of a valve device used in a conventional reduced pressure heat treatment furnace.

FIG. 8 is a sectional view of an essential part showing an example of a conventional on-off valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Decompression heat treatment furnace 18 Exhaust system 20 Variable opening valve device 26 Valve chamber 27 Valve seat 28 Valve body 27a, 28a Circular wall part 37 Fine adjustment gap

Claims (3)

[Claims] 1. A variable opening valve device provided in an exhaust system of a decompression heat treatment furnace, comprising a valve seat formed in a valve chamber, and a valve provided so that seating and separating movement of the valve seat can be adjusted. A body, a peripheral wall portion formed so as to face the valve body and the valve seat in a direction orthogonal to the moving direction of the valve body, and a fine adjustment gap provided between the peripheral wall portions. A variable opening valve device for a reduced pressure heat treatment furnace. 2. The at least one peripheral wall portion is formed so as to be inclined so that the cross-sectional area of the fine adjustment gap gradually increases in accordance with the valve opening movement of the valve body. A variable valve opening device for the reduced pressure heat treatment furnace described. 3. The peripheral wall portion is formed such that the diameter is increased stepwise in the valve opening movement direction of the valve body, and the fine adjustment gap on the large diameter side of the valve body is larger than that on the small diameter side. The variable valve opening device for a reduced pressure heat treatment furnace according to claim 1, wherein the variable valve device is formed so as to have a large dimension in the moving direction.