JPH088152A - Evacuation device - Google Patents

Abstract

PURPOSE:To provide an evacuation device without turbulence in gas flow near a wafer at initial evacuation by minimizing evacuation conductance through a throttle mechanism at the initial evacuation and increasing the evacuation conductance gradually by evacuating an opened area of the throttle. CONSTITUTION:In a vacuum chamber 1, air in a lower space under an evacuating plate 4 is spurted into a driving chamber 16 at the initial evacuation. A blade member 17 is turned counterclockwise by the air flow, and a movable plate 11 is turned through the rotary axle 8 at the same time. When time goes on, the pressure of the vacuum chamber 1 is reduced and the flow rate for turning the blade member 17 is lowered. Gradually, the blade member 17 is pulled back with springs 14a and 14b to the original position so that each opening part 7 of an evacuating plate 6 and each opening part of the movable plate 11 are aligned to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evacuation device for evacuating a vacuum chamber containing a wafer to a vacuum.

[0002]

2. Description of the Related Art Two or more kinds of exhaust valves having different conductances are conventionally used in order to prevent dust from flying and adhering onto a wafer due to turbulence of air flow when a vacuum chamber containing a wafer is evacuated to a vacuum. Was used. That is,
First, the exhaust valve with low conductance is opened to exhaust the vacuum chamber for a certain period of time or until the pressure in the vacuum chamber reaches the set pressure, and then the exhaust valve with large conductance is opened to perform exhaust. It was

[0003]

However, in the above-described structure, it is necessary to attach two or more exhaust valves to the vacuum chamber, which not only complicates the piping and the exhaust sequence, but also especially in the wafer in the vacuum chamber. There was a problem that the vicinity did not become a laminar flow and that it could not be said that the turbulence of the air flow was actually suppressed.

The present invention has been made in view of the above-mentioned problems of the prior art, and provides an exhaust device capable of preventing the turbulence of the air flow in the vicinity of the wafer during the initial exhaust without complicating the piping and the exhaust sequence. The purpose is to provide.

[0005]

According to the present invention, there is provided an exhaust device for evacuating the inside of a chamber in which a wafer supported by a support is housed, to an exhaust pipe for the chamber. An exhaust pump means connected via a first partition member for partitioning the wafer side and the exhaust pump means side and having a plurality of first openings for making an air flow a laminar flow; A second partition member having a second opening and partitioning one partition member side from the exhaust pump means side, and a diaphragm mechanism capable of changing the area of the second opening, the diaphragm mechanism According to the present invention, the exhaust device is provided with a control means for minimizing the exhaust conductance during the initial exhaust and changing the area of the second opening so that the exhaust conductance gradually increases. It is.

[0006]

In the exhaust system of the present invention, the area of the second opening is changed according to the pressure difference or the exhaust flow velocity to minimize the exhaust conductance during the initial exhaust and to gradually increase the exhaust conductance. By changing the area of, the turbulence of the airflow during initial exhaust can be suppressed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An exhaust system 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 schematic structure of a main part of a wafer processing apparatus having an exhaust device according to a first embodiment of the present invention, and FIG. 2 is a view taken along line II-II in FIG. FIG. As shown in FIG. 1, a lid 2 sealed with an O-ring for loading and unloading the wafer A is provided above the cylindrical vacuum chamber 1. In the vacuum chamber 1, a disk-shaped support base 3 for supporting the wafer A is provided. An exhaust plate 4 serving as a donut-shaped first partition member is provided between the peripheral portion of the support base 3 and the inner wall surface 1 a of the vacuum chamber 1. This exhaust plate 4
The inside of the vacuum chamber 1 is partitioned by the support table 3 and the support table 3. The exhaust plate 4 is provided with a number of first openings 5.

The support 3 in the vacuum chamber 1 shown in FIG.
And a second opening 7 formed in the lower part of the exhaust plate 4 and having a plurality of second openings 7 formed in the periphery under the exhaust plate 4 as shown in FIG.
A disc-shaped exhaust plate 6 is provided as a partition member. A rotary shaft 8 is rotatably supported by bearings 9 and 10 between the center of the exhaust plate 6 and the bottom of the vacuum chamber 1. On the upper side of the rotary shaft 8, a movable plate 11 arranged in close contact with the lower side of the exhaust plate 6 in FIG. 1 is supported so that it can rotate together with the rotary shaft 8.
By rotating the movable plate 11, the movable plate 11 can have a position aligned with each second opening 7 arranged in the exhaust plate 6 and a position not aligned (broken line in FIG. 2). Second
A plurality of third openings 12 corresponding to the openings 7 are opened. In addition, as shown in FIG.
The ends of the pair of tension coil springs 14a and 14b are engaged with each other via. The other ends of the springs 14a, 14b are engaged with the inner wall surface 1a of the vacuum chamber 1, and the rotation axis is directed toward the position where each third opening 12 of the movable plate 11 is aligned with each second opening 7 of the exhaust plate 6. We are pushing 8. Although the tension coil spring is used as the spring 14 in this embodiment, it is needless to say that a torsion coil spring, an air spring, a leaf spring, or the like may be appropriately used.

On the other hand, a drive chamber 16 is defined below the lower bearing 10 in FIG. 1, and a rotary shaft 8 penetrates the bearing 10 and projects into the drive chamber 16. At the lowermost end of the rotary shaft 8, a wing member 17 received in the drive chamber 16 is provided. The drive chamber 16 communicates with the vacuum chamber 1 on the upper side, and is connected to the exhaust pump 20 via the vacuum valve 18 and the exhaust pipe 19 on the lower side. Then, when the exhaust pump 19 is operated to increase the exhaust flow velocity in the drive chamber 16, the wing member 17 rotates against the urging force of the springs 14a and 14b, that is, the second opening 7 and the third opening 12 respectively. The movable plate 11 is adapted to rotate toward a position where is not aligned.
That is, in this embodiment, the rotary shaft 8, the movable plate 11 having the third opening 12, the springs 14a and 14b, the drive chamber 16, and the wing member 17 can variably control the area of the second opening 7 by the exhaust flow. It is like this.

Next, an operation procedure of the exhaust device having the above-mentioned structure will be described.

In the figure, before exhausting the inside of the vacuum chamber 1, the exhaust plate 6 is urged by the urging force of the springs 14a and 14b.
The movable plate 11 is located at a position where the respective third openings 12 of the movable plate 11 corresponding to the respective second openings 7 are aligned. Then, the vacuum valve 18 is opened and the exhaust pump 20 is operated to evacuate the vacuum chamber 1. At the time of initial evacuation, air in the lower space of the vacuum chamber 1, that is, the air below the evacuation plate 4 suddenly flows into the driving chamber 16, and the wing member 17 rotates counterclockwise in FIG. The movable plate 11 also rotates together with the shaft 8. Thereby, as shown by the broken line in FIG.
And the third openings 12 of the movable plate 11 are no longer aligned,
That is, the exhaust gas is exhausted only through the gap between the exhaust plate 6 and the movable plate 11, and the exhaust conductance is reduced. Then, the air above the exhaust plate 4 of the vacuum chamber 1 in FIG. 1 becomes a laminar flow in combination with being exhausted through a large number of small first openings 5, and there is no turbulence of the air flow in the initial stage. Exhaust is performed. Here, each second opening 7 of the exhaust plate 6 is actually
And the amount of deviation between each third opening 12 of the movable plate 11 and the spring 14
The magnitude of the exhaust conductance at the time of initial exhaust can be made variable by adjusting by changing the settings of the urging forces of a and 14b and the shape or size of the wing member.

When the pressure in the vacuum chamber 1 decreases as the evacuation time elapses, the flow velocity for rotating the vane member 17 in the drive chamber 16 weakens, and the springs 14a and 14b gradually pull it back to its original position. Returning, the second openings 7 of the exhaust plate 6 and the third openings 12 of the movable plate 11 are aligned with each other. That is,
The exhaust conductance gradually increases, and the exhaust speed can be increased to allow early exhaust. The graph of FIG. 3 shows the relationship between the exhaust conductance and the time from the initial exhaust to the exhaust completion.

As shown in FIG. 3, the conductance for exhausting the interior of the vacuum chamber 1 is changed according to the elapse of the exhaust time, so that the turbulence of the air flow during the initial exhaust is suppressed and the generation of dust is prevented while preventing the generation of dust. Exhaust can be performed.

FIG. 4 is a sectional view similar to FIG. 1, showing a schematic structure of a main part of a wafer processing apparatus having an exhaust device according to a second embodiment of the present invention, which is similar to the first embodiment. The same reference numerals are given to the parts, and detailed description thereof will be omitted.

In this embodiment, as shown in FIG. 4, the exhaust pipe 19 is directly opened at the center of the bottom of the vacuum chamber 1 to form a second opening 22. A shaft member 24 is provided between the support base 3 and the support member 23 provided in the middle portion of the exhaust pipe 19 in FIG. 4, and the trapezoidal columnar valve body 2 is provided on the shaft member 24.
5 is supported so as to be vertically movable between a position where the second opening 22 is closed and a position where the second opening 22 is opened. Second opening 22
A valve seat 26 for the valve body 25 is provided around the. A large number of spiral grooves 25a are provided on the peripheral surface of the valve body 25, and an exhaust bypass passage for ensuring a predetermined exhaust amount at the time of exhaust, which will be described later, is provided even when the valve body 25 closes the second opening 22. I am doing it. In addition, the support member 23 and the valve body 2
A compression coil spring 27 is provided between the valve 5 and the valve 5, and biases the valve element 25 in the direction in which the second opening 22 opens. That is, in this embodiment, the valve body 25 and the valve seat 26 having a large number of grooves 25a are provided.
The compression coil spring 27 can variably control the area of the second opening 22 by the pressure difference between the inside of the chamber and the exhaust pipe. The other configuration is the same as that of the first embodiment.

Next, an operation procedure of the exhaust device having the above-mentioned structure will be described.

First, before exhausting, the valve body 25 is on the upper side in FIG. 4 so that the second opening 22 is opened by the urging force of the spring 27. Then, the vacuum valve 18 is opened and the exhaust pump 20 is operated to perform vacuum exhaust. During the initial exhaust, the valve body 25 closes the second opening 22 due to the pressure difference between the inside of the vacuum chamber 1 and the exhaust pipe 19, that is, the exhaust is conducted only through the groove 25a, so that the exhaust conductance becomes small. Then, the air above the exhaust plate 4 of the vacuum chamber 1 in FIG. 4 becomes a laminar flow in combination with being exhausted through a large number of small first openings 5, and there is no turbulence of the air flow in the initial stage. Exhaust is performed. Here, similarly to the first embodiment, the magnitude of the exhaust conductance at the time of initial exhaust can be made variable by changing the setting of the biasing force of the spring 27, the shape or the size of the groove 25a, etc. .

When the evacuation time elapses and the pressure in the vacuum chamber 1 decreases, the spring 27 gradually presses the valve body 25 back to its original position, and the opening area of the second opening 22 becomes large. Is coming. That is, the exhaust conductance is gradually increased, and the exhaust speed is increased to allow early exhaust.

[0020]

As is apparent from the above description, according to the exhaust device of the present invention, the inside of the chamber is divided into the wafer side and the exhaust pump means side by the first partition member having the first opening. A second flow having a second opening on the side of the first partition member and on the side of the exhaust pump means.
The area of this second opening is changed by the pressure difference between the inside of the chamber and the exhaust pipe or the exhaust, so that the exhaust conductance is minimized during the initial exhaust and the exhaust conductance is gradually increased. By changing the area of the second opening so as to increase, the turbulence of the air flow in the vicinity of the wafer during the initial exhaust can be prevented without complicating the piping and the exhaust sequence.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a main part of a wafer processing apparatus including an exhaust device according to a first embodiment of the present invention.

FIG. 2 is a view seen from a line II-II in FIG.

FIG. 3 is a graph showing the relationship between exhaust time and exhaust conductance in the first embodiment.

FIG. 4 is a sectional view showing a schematic configuration of a main part of a wafer processing apparatus having an exhaust device according to a second embodiment of the present invention.

[Explanation of symbols]

 1 vacuum chamber 1a inner wall surface 2 lid 3 support 4 exhaust plate 5 first opening 6 exhaust plate 7 second opening 8 rotary shaft 9, 10 bearing 11 movable plate 12 third opening 13 arm 14a, 14b tension coil spring 16 Drive Chamber 17 Blade Member 18 Vacuum Valve 19 Exhaust Pipe 20 Exhaust Pump 22 Second Opening 23 Support Member 24 Shaft Member 25 Valve Body 25a Groove 26 Valve Seat 27 Compression Coil Spring

Claims (3)

[Claims] 1. An exhaust device for evacuating the inside of a chamber, in which a wafer supported by a support table is housed, to an vacuum, wherein exhaust pump means connected to the chamber via an exhaust pipe, and the wafer side. A first partition member having a plurality of first openings for partitioning an air flow into a laminar flow, and partitioning the first partition member side and the exhaust pump means side. And a second partition member having a second opening, and a throttle mechanism capable of changing the area of the second opening. The throttle mechanism minimizes the exhaust conductance during initial exhaust, and gradually exhausts the exhaust gas. And a control unit that changes the area of the second opening so that the conductance increases. 2. The diaphragm mechanism has a third opening that can be aligned with the second opening, and is substantially in close contact with the second partition member, and the third opening is aligned with the second opening. A movable plate that is slidable between the second opening and the position that substantially closes the second opening, and the movable plate is directed to a position where the third opening is aligned with the second opening. Urging means for urging the movable plate against the urging force of the urging means by the exhaust flow between the chamber and the exhaust pipe at the time of initial evacuation. 2. The exhaust system according to claim 1, comprising means for driving in a direction to close the opening. 3. A valve body in which the throttle mechanism and control means are movable in the axial direction between a valve seat provided in the second opening and a position for closing the second opening and a position for opening the second opening. An exhaust bypass passage provided between the valve seat and the valve body to secure a predetermined amount of exhaust when the valve body is in a position to close the second opening; Means for urging the valve element toward the position where the opening is opened, and the valve element against the urging force of the urging means due to the pressure difference between the inside of the chamber and the exhaust pipe during initial exhaust. The second
2. The exhaust gas according to claim 1, wherein the opening of the second opening is closed, and the second opening is gradually opened by the urging force of the urging means as the pressure difference becomes smaller. apparatus.