JPH03164581A - Evacuation apparatus - Google Patents

Abstract

PURPOSE:To securely prevent a turbulent flow from occurring in an early stage of evacuation by providing a main evacuating line and a bypass line to be used when a pressure on a vacuum chamber is larger than a specific value and providing the bypass line with a pressure-sensitive flow control valve. CONSTITUTION:When a vacuum chamber 1 is to be evacuated, a main solenoid valve 4 is first closed, a sub-electromagnetic valve 8 is opened, and a rotary vacuum pump 6 is driven to evacuate the chamber 1 through a bypass line 7 of a small capacity at a relatively slow evacuating speed. When a pressure detector 7 detects a specific evacuating pressure reached, the main solenoid valve 4 is opened, the sub-electromagnetic valve 8 is closed and further a turbine vacuum pump 5 is driven to rapidly evacuate the chamber 1 through a main evacuation line 2 of a large capacity. In such an evacuation apparatus, a pressure-sensitive flow control valve 10 whose opening degree increases as a negative pressure of evacuation increases is provided on an upstream side of the sub-electromagnetic valve 8 of the bypass line 7 so as to securely prevent a turbulent flow from occurring at an early stage of evacuation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vacuum evacuation device for equipment that requires a vacuum and highly clean atmosphere, such as semiconductor manufacturing equipment and analyzers.

[Conventional Technique 11f] In equipment that performs various processes in a vacuum and highly clean atmosphere, such as semiconductor manufacturing equipment and analyzers, the length of evacuation time affects productivity,
This is a major factor in improving operating rates. Furthermore, the presence or absence of R dust inside the vacuum chamber greatly affects product quality and processing accuracy.

However, shortening the exhaust time leads to rapid exhaust,
Active current is generated during the exhaust process. This turbulent flow caused substances adhering to the walls of the vacuum chamber to be peeled off, resulting in the generation of fine dust.

Therefore, the conventional method has been to reduce the exhaust flow rate at the beginning of exhaustion, and increase the exhaust flow rate when the pressure drops below the required level.

Referring to FIG. 2, a conventional vacuum evacuation device will be explained.

1 in the figure is a vacuum chamber, and a main exhaust line 2 is connected to the vacuum chamber 1, and from the upstream side of the main exhaust line 2, a pressure detector 3, a main solenoid valve 4, a turbine vacuum pump 5, a rotary vacuum pump 6 are provided in sequence. Furthermore, a bypass line 7 with a smaller diameter and smaller capacity than the main exhaust line 2 is connected between the pressure detector 3 and the main solenoid valve 4 and downstream of the turbine vacuum pump 5.
A sub-electromagnetic valve 8 is provided in the bypass line 7.

Further, 9 is a controller which controls the main solenoid valve 4, the sub solenoid valve 8 and the re-vacuum pump 5 based on the signal from the pressure detector 3.
．． It is designed to operate 6.

When the vacuum chamber 1 is evacuated using such a vacuum evacuation device, first the main solenoid valve 4 is closed, the sub solenoid valve 8 is opened, and the rotary vacuum pump 6 is used to evacuate the vacuum chamber 1 through the bypass line 7. The line 7 has a smaller capacity than the main exhaust line 2, and the only vacuum pump is the rotary vacuum pump 6, so the pumping speed is slow, and the pressure detected by the pressure detector 3 is 3.
000 Pa, the main solenoid valve 4 is opened, the sub solenoid valve 8 is closed, and the turbine vacuum pump 5 is further driven.

The main exhaust line 2 has a large diameter and a large capacity, and the exhaust is rapidly carried out by the two-stage pumping of the turbine vacuum pump 5 and the rotary vacuum pump 6.

The manner in which the pressure decreases due to such evacuation is shown by curve 3 in FIG.

[Problem to be solved by the invention] In the conventional vacuum evacuation equipment described above, initial evacuation is performed using a bypass line in consideration of dust generation due to turbulence. The pressure drop is extremely large, and the present inventor has confirmed that turbulence occurs in the area shown in Figure 3. For this reason, if the diameter of the bus pass line is further reduced to limit the exhaust speed in the bypass line in order to prevent turbulence at the initial stage of exhaust, the result will be as shown in curve (■) in Figure 3, making it possible to achieve a practical exhaust time. Can not.

The present invention has been developed in view of the above circumstances, and aims to completely prevent turbulence from occurring in the initial stage of exhaust, and further shorten the exhaust time.

[Means for Solving the Problems] The present invention has a main exhaust line and a bypass line with a small exhaust capacity for the main exhaust line, and when the pressure on the vacuum chamber side is higher than a predetermined value, the bypass line is operated. exhaust,
When the pressure on the vacuum chamber side becomes lower than a predetermined value, the main exhaust line is used to exhaust the air, and the bypass line is provided with a pressure-sensitive flow rate regulating valve whose opening degree increases as the negative pressure of the exhaust increases. It is characterized by:

[Function] At the beginning of exhaust, exhaust is carried out by the bypass line, and at the very beginning of exhaust, the flow rate adjustment valve is greatly restricted, and the exhaust speed is slow.As the exhaust progresses and the negative pressure of the exhaust increases, the flow rate is adjusted. The valve opening becomes larger and the exhaust speed becomes faster. When the exhaust reaches a predetermined pressure, main exhaust is performed through the main exhaust line.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

Components in FIG. 1 that are the same as those shown in FIG. 2 are given the same reference numerals.

A pressure detector 3, a main solenoid valve 4, a turbine vacuum pump 5,
Rotary vacuum pumps 6 are installed one after another. Also, pressure detector 3
A bypass line 7 having a smaller capacity than the main exhaust line 2 connects between the main solenoid valve 4 and the downstream side of the turbine vacuum pump 5, and a pressure-sensitive flow Jl regulating valve is connected to the bypass line 7 from the upstream side. 10. A sub solenoid valve 8 is provided.

The controller 9 operates the main solenoid valve 4, the sub solenoid valve 8, and the revacuum pumps 5 and 6 based on the signal from the pressure detector 3.

The operation will be explained below.

The main solenoid valve 4 is closed, the sub solenoid valve 8 is opened, and the rotary vacuum pump 6 is driven to perform exhaust through the bypass line 7.

The pressure sensitive flow rate regulating valve 10 is biased in the closing direction by a spring 11, and negative pressure on the upstream side is further applied against the spring 11. Therefore, the flow rate regulating valve 1
When the negative pressure upstream of 0 is small (pressure force is large),
The flow rate is reduced to a minimum.

As the exhaust progresses and the negative pressure increases, the opening degree of the flow rate regulating valve 10 increases, and the exhaust flow rate also increases. Furthermore, if the diameter of the exhaust line itself is made larger than the diameter of the conventional exhaust line described above, the initial stage of exhaustion, that is, the time required for exhaustion to reach 3000 Pa can be shortened.

When the pressure detected by the pressure detector 3 reaches 3000 Pa, the main solenoid valve 4 is opened, the sub solenoid valve 8 is closed, and the turbine vacuum pump 5 is further driven.

Main exhaust is performed by a turbine vacuum pump 5 and a rotary vacuum pump 6 through a main exhaust line 2 with a large opening diameter and a large capacity.

The state of such exhaust is shown by the curve (2) in FIG.

As shown by curve (2), in the very early stages such as exhaustion, the pressure drop with respect to time is extremely slow, and when the range A is sufficiently exceeded, the pressure drop becomes large. Then,
It can be seen that the total exhaust time is shortened compared to the conventional curve (■).

[Effects of the Invention] As described above, according to the present invention, during vacuum evacuation, the evacuation is performed slowly enough so as not to cause turbulence at the initial stage of evacuation, and quickly after the range where turbulence occurs. This has the excellent effect of preventing dust generation and shortening the exhaust time.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram of a conventional example, and FIG. 3 is a diagram showing an exhaust state. 1 is a vacuum chamber, 2 is a main exhaust line, 3 is a pressure detector, 7 is a bypass line, and 10 is a pressure-sensitive flow rate regulating valve. Patent issuer Kokusai Denki Co., Ltd. Patent agent Sho Miyoshi Figure 2 Figure 3

Claims (1)

[Claims] 1) A main exhaust line and a bypass line with a small exhaust capacity are provided for the main exhaust line, and when the pressure on the vacuum chamber side is greater than a predetermined value, the bypass line is used to exhaust the air, and the pressure on the vacuum chamber side is maintained at the predetermined value. When the vacuum becomes smaller than the above value, the main exhaust line is used to exhaust the air, and the bypass line is provided with a pressure-sensitive flow rate regulating valve whose opening degree increases as the negative pressure of the exhaust increases. Device.