JP2658838B2 - Vacuum exhaust valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum exhaust valve,
In particular, the present invention relates to a valve used for evacuating gas in a vacuum chamber.

[0002]

2. Description of the Related Art In general, for example, when a semiconductor product is manufactured, various vacuum chambers, for example, a processing chamber for performing a film forming process or the like, or a stage preceding these processing chambers in each processing process in the manufacturing process. There is a load lock chamber and the like arranged in the. By the way, in semiconductor manufacturing, how to improve the yield is a major problem. One of the countermeasures is to minimize the presence of particles that cause defective products in various processing processes. Has been made. For example, taking the above-mentioned load lock chamber as an example, in a conventional vacuum exhaust structure of this vacuum chamber, the vacuum chamber 101 is evacuated by a vacuum exhaust pump 103 via a main exhaust pipe 104 as shown in FIG. However, the throttle valve 106 and the bypass exhaust valve 10 which reduce the pipe diameter in parallel with the main exhaust pipe 104 and reduce the effective area or actively reduce the effective area are provided.
7 is provided. Also, in Japanese Patent Application Laid-Open No. 4-358531, as shown in FIG.
At the initial stage of evacuation of the vacuum chamber 101 by the evacuation pump 103, the speed control means 108 is used to lower the evacuation speed of the evacuation pump 103 and gradually increase the speed. In both technologies, the vacuum chamber is not evacuated at the maximum evacuation speed from the beginning with a vacuum evacuation pump, but a slow evacuation mechanism is used by using the shunt path resistance and the pumping ability. This is when evacuating the vacuum chamber,
If the exhaust speed of the gas is excessively high, a rapid turbulence is generated in the vacuum chamber, and the particles adhering to the inner wall of the vacuum chamber are wound up. The rolled-up particles will eventually re-attach to the wall surface of the vacuum chamber or the like, but if they adhere to the semiconductor wafer, defective products will be generated as described above.

[0003]

In this conventional evacuation mechanism of the bypass type, as shown in FIG.
When the inside of the vacuum chamber 101 is evacuated from the atmospheric pressure, the evacuation speed is reduced by using the bypass exhaust pipe 107 having a narrowed effective cross-sectional area. The vacuum exhaust was performed by switching from the pipe 107 to the main exhaust pipe 104 having a large effective area. However, the bypass exhaust pipe 1
The effective area of 07 is adjusted to the maximum gas flow velocity at the moment when the vacuum chamber 101 is first evacuated from the atmospheric pressure. That is,
The flow velocity is set so as not to wind up the particles. Here, the optimum effective area is determined by the pressure in the vacuum chamber 101 and the exhaust capacity of the vacuum exhaust pump 103. Generally, if the exhaust capacity of the vacuum exhaust pump 103 is constant, the vacuum chamber 101
Is proportional to the pressure of When the vacuum chamber 101 is evacuated from the atmospheric pressure, the optimum effective area changes at the first moment and thereafter, and every moment, and the optimum effective area at the first moment becomes the smallest. . Therefore, when the vacuum chamber 101 is evacuated by the bypass exhaust pipe 107, the slow exhaust is not always performed at any time, but it takes a longer time than the logically optimum value. This causes a decrease in productivity and a decrease in throughput. In addition, the bypass exhaust pipe 107 is assembled separately from the main exhaust pipe 104, and there is a drawback that complexity in mechanical design and complexity in electric software such as adjustment of opening / closing timing of the bypass exhaust valve 105 are added.

In order to cope with the problem described in Japanese Patent Application Laid-Open No. 4-358531 by varying the evacuation capacity of the evacuation pump, frequency modulation of a rotary motor of the evacuation pump can be considered. An expensive modulator has to be installed, and it is not practically used due to a problem of abnormal vibration due to a natural frequency of a mechanical rotation system of a vacuum pump.

[0005]

A vacuum exhaust valve according to the present invention has a flange connected to a vacuum exhaust pipe on a vacuum chamber side and a vacuum exhaust pump side, and has one end on the vacuum exhaust pump side fixed inside the other. The spring that holds the shield plate and the spring shrinks
The gap between the valve internal cavity and the shielding plate
Has an inner wall that makes

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a vacuum exhaust valve according to one embodiment of the present invention. A vacuum pipe flange 2 for mounting a vacuum exhaust pipe for connecting the vacuum chamber and the vacuum exhaust pump is provided at both ends. A shield plate 4 is provided in the vacuum exhaust valve housing 1, and the shield plate 4 includes a spring 3. , Is fixed in the vacuum exhaust valve housing 1. FIG. 2A shows the shielding plate 4 of this embodiment.
FIG. 3 is a plan view of FIG.

FIG. 4 is a block diagram of an embodiment in which the vacuum exhaust valve 4 of the present invention is actually applied to a vacuum exhaust mechanism of a vacuum chamber 101. The vacuum pump 103 connects the vacuum chamber 101 with a main exhaust pipe 104 via the vacuum exhaust valve 1 and the main exhaust valve 102.

Next, a sequence in which the vacuum chamber 101 is at atmospheric pressure and the vacuum chamber 101 is evacuated will be described. The evacuation pump 103 is a main evacuation valve 10 during evacuation.
2 is closed. In this state, as shown in FIG. 1, the spring 3 is in a natural state because there is no gas flow in the vacuum exhaust valve 1 as shown in FIG. The vacuum exhaust valve 1 is provided with a vacuum chamber 101 on the upper side shown in FIG.
The evacuation pump 103 is disposed below. Next, the main exhaust valve 102 is opened. The gas filling the vacuum chamber 101 enters the main exhaust pipe 104 at the maximum instantaneous speed. Eventually, the entered gas reaches the vacuum exhaust valve 1. By colliding perpendicularly with the shielding plate 4 in the evacuation valve 1, a vertical stress acts. The spring 3 holding the shielding plate 4 contracts due to elastic deformation, and comes into contact with the lower part in the vacuum exhaust valve housing 1. The gap between the outer peripheral portion of the shielding plate 4 and the inner surface of the vacuum exhaust valve housing 1 is It is minimized (see FIG. 3).
In this state, gas passing through the vacuum exhaust valve 1 is restricted by the shielding plate 4 and slightly passes through only the slow exhaust through hole 5. When the amount of gas, that is, the pressure in the vacuum chamber 101 decreases, the amount of gas passing through the main exhaust pipe 104 and further through the vacuum exhaust valve 1 naturally decreases, collides with the shielding plate 4, and the generated stress also decreases. Will go. Eventually, the stress pressing the shielding plate 4 becomes smaller than the restoring force of the spring 3, and the spring 3 starts restoring. Since the inner diameter of the internal cavity decreases as approaching the exhaust pump side, the gap between the outer peripheral portion of the shielding plate 4 and the inner wall surface of the vacuum exhaust valve housing 1 increases, and the gas being evacuated is:
It can pass through this gap. That is, the effective sectional area for evacuation gradually increases.

FIGS. 5A to 5C are graphs showing changes in the height of the shield plate and the like with respect to time of the above-described vacuum exhaust valve of the present invention.

As shown in FIG. 2B, the shielding plate 4 is provided with a large number of slow exhaust holes 5,
As shown in (c), a slow exhaust adjusting plate 6 can be used to adjust the area of the slow exhaust hole.

[0011]

As described above, the present invention has a mechanism for automatically adjusting the effective sectional area using the elastic force of the spring in accordance with the flow rate (speed) of the gas passing through the vacuum exhaust valve. So, when evacuating the vacuum chamber from under atmospheric pressure,
Slow exhaust can be performed without winding up particles, and the slow exhaust can be exhausted while maintaining the vacuum exhaust diameter of the optimum effective area. As a result, an optimal slow exhaust mechanism can be realized at low cost and easily as compared with the bypass method and the variable exhaust capacity method of the vacuum exhaust pump. In addition, the slow exhaust speed can be easily and simply adjusted according to the state of particles accumulated in the vacuum chamber by attaching a slow exhaust hole, that is, a function of adjusting the minimum effective area to the shield plate of the vacuum exhaust valve of the present invention. it can.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an evacuation valve according to an embodiment of the present invention.

FIG. 2 is a plan view of the shielding plate shown in FIG.

FIG. 3 is a longitudinal sectional view of the vacuum exhaust valve shown in FIG. 1 during operation.

FIG. 4 is a block diagram of a vacuum chamber exhaust system according to the present invention.

FIG. 5 is an operation graph of one embodiment of the present invention.

FIG. 6 is a block diagram of a vacuum chamber exhaust system according to the related art.

FIG. 7 is a block diagram of a vacuum chamber exhaust system according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum exhaust valve (housing) 2 Vacuum piping flange 3 Spring 4 Shield plate 5 Slow exhaust through hole 6 Slow exhaust adjustment plate 101 Vacuum chamber 102 Main exhaust valve 103 Vacuum pump 104 Main exhaust pipe 105 Bypass exhaust valve 106 Throttle valve 107 bypass exhaust pipe 108 speed control means

Claims (1)

(57) [Claims] 1. A vacuum exhaust valve attached to a vacuum exhaust pipe connecting a vacuum chamber and a vacuum exhaust pump, wherein a gas flow flowing through the vacuum exhaust pipe inside the valve.
Means for gradually varying the pipeline resistance according to the amount,
The variable means is a movable shielding plate having a through hole and the shielding.
A spring for holding the plate, wherein the internal cavity of the valve comprises:
As the spring holding the shield contracts, the internal cavity
Has an inner wall that gradually reduces the gap between the
A vacuum exhaust valve.