JPH01277687A - Cryopump - Google Patents

Abstract

PURPOSE:To shorten a span of exhaust time for restarting or the like by installing such as orifice that has a required opening between a first stage cryopanel at the outermost part and a second stage cryopanel holding a medium at yet lower temperature than the former. CONSTITUTION:A first stage heat transfer part 6 and a second stage heat transfer part 7 are concentrically set up in a heat transfer part of a refrigerator 5, and the first heat transfer part 6 is connected to a shield 3, cooling a first stage cryopanel 4, and a bladelike second stage cryopanel 8, holding a medium at yet lower temperature than the first stage one 4, is connected to a tip of the second stage heat transfer part 7 internally set up in the shield 3. An orifice 10 is set up on a horizontal cross section of the shield 3 between the first cryopanel 4 and the second stage cryopanel 8 in the shield 3.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application This invention relates to an improvement of a cryopump connected to a sputtering device, etc. By incorporating a fixed orifice, the exhaust system is improved compared to a conventional pump having a variable restriction in the exhaust system. Regarding a cryopump that significantly shortens the time.

BACKGROUND ART Vacuum apparatuses are used in various fields such as semiconductor manufacturing and thin film deposition technology.

For example, in order to avoid contamination with impurities, sputtering equipment usually raises the vacuum level in the chamber to about 1 x 10 Torr, and then
It is used to reduce the temperature to a slightly lower level, such as 'Torr, or to create a required inert gas atmosphere.

The vacuum equipment attached to sputtering equipment, etc. uses a roughing pump for low-level exhaust and a pump for high vacuum, such as a cryopump or turbo molecular pump, for one vacuum chamber. There is.

Therefore, in order to ensure that the controllability of the flow control valve does not go out of the required range, the pump for high vacuum in conventional vacuum equipment has to be designed to ensure controllability suitable for the process used. I is limited.

Taking a semiconductor sputtering apparatus as an example, it is necessary to periodically, for example, once every few days, stop the apparatus and open the vacuum chamber to the atmosphere in order to replace the target.

Therefore, by exposing the inside of the vacuum chamber to the atmosphere,
The system will be restarted with a high gas load such as moisture and air.

In the conventional vacuum apparatus, it took a long time to evacuate from atmospheric pressure to the required high degree of vacuum at L5 upon such restart.

As shown in Figure 2, general sputtering equipment includes
A gate valve (21) cuts off communication with the sputtering chamber (20).
) is attached to the exhaust system piping (22) equipped with a cryopump (2).
3), when connecting the upper part of the pump (23) and the
A variable throttle valve (24) is installed between the stage cryopanel and the gate valve (21), and a large-diameter cryopump is connected to it. Alternatively, a fixed throttle valve is connected to the exhaust system. There are some that use a small-diameter lyopump connection.

In the former case, the reproducibility of performance is poor due to the use of a variable aperture, resulting in unstable operation during sputtering, and due to its structure, the conductance is small and the exhaust resistance is large, resulting in a long start-up exhaust time. There were other problems.

On the other hand, in the latter case, although the stability during sputtering is good, the start-up evacuation time is still long, which poses a problem that becomes a serious obstacle to improving productivity.

OBJECTS OF THE INVENTION The present invention aims to improve the performance of a cryopump connected to a sputtering device or the like, and to provide a cryopump that significantly shortens the evacuation time such as restarting.

Structure of the Invention This invention has a first-stage refrigerator that cools the first-stage cryopanel located at the outermost part, and a second-stage refrigerator that cools the second-stage cryopanel that is maintained at a lower temperature than the first stage cryopanel. In a storage type cryopump that selectively condenses or physically adsorbs gas on a surface, an orifice having a required opening in a cross section in the shield of the pump is provided between the first and second stage cryopanels. This cryopump is characterized by being equipped with.

The cryopump according to the present invention does not use a throttle valve in the exhaust system connecting to the required vacuum chamber, but by providing a fixed orifice between the first-stage cryopanel and the second-stage cryopanel, the cryopump can reach the required degree of vacuum. This has the advantage of significantly shortening the completion time.

DISCLOSURE OF THE INVENTION BASED ON DRAWINGS FIG. 1 is a schematic explanatory diagram showing the configuration of a cryopump according to the present invention.

The cryopump consists of a bottomed cylindrical pump case (1) with a mounting flange (2) at the top, and a refrigerator (5) with a heat transfer part fitted inside the case at the bottom of the pump case (1). It is arranged.

Inside the pump case (1), a cylindrical shield (3) with a bottom and a diameter smaller than that of the case, on which a louver-shaped first stage cryopanel (4) is arranged, is coaxially arranged.

The heat transfer part of the refrigerator (5) inserted into the pump case (1) has a first stage heat transfer part (6) and a second stage heat transfer part (7) arranged coaxially. The hot part (6) is connected to the shield (3).
) to cool the first stage cryopanel (4), and a wing-shaped second stage cryopanel (8) is connected to the tip of the second stage heat transfer part (7) inserted into the shield (3). ing.

The orifice (io), which is a feature of this invention, is arranged in the horizontal cross section of the shield (3) between the first stage cryopanel (4) and the second stage cryopanel (8) in the shield (3). Installation-.

Such a cryopump is connected, for example, by fastening the flange of the exhaust system piping from the vacuum chamber of the vacuum device to the mounting flange (2) of the pump case (1), and the exhaust system is not provided with any throttle valve. .

The operatively connected vacuum device first operates the roughing pump to evacuate the room to create a low vacuum in the room, and then operates the cryopump to bring the room to the desired high degree of vacuum.

At this time, the first stage cryopanel (4) mainly condenses and exhausts water vapor and carbon dioxide, and the second stage cryopanel (8) mainly condenses and exhausts water vapor and carbon dioxide gas.
) to condense and exhaust oxygen, nitrogen, argon, etc.
Hydrogen, helium, and neon that do not condense even when
9) Adsorb.

Effect ■ Since gas molecules (mainly water vapor) captured by the first stage cryopanel (4) are difficult to pass through the fixed orifice, stable argon flow rate control is possible.

■Since a variable throttle is not used in the exhaust system, the equipment control system is simplified and stable process control with high reproducibility is possible.

■Compared to conventional cryopumps that have an exhaust system equipped with a throttle valve, the pump has the advantage of faster pumping speed in the low vacuum range and faster start-up after target replacement.

■Since the refrigerator has a large freezing capacity, it cools down quickly and has a large exhaust capacity.

- By incorporating a fixed orifice in the cryopump according to the present invention, it is possible to significantly shorten the startup time after opening to the atmosphere, and it is expected to greatly improve productivity in mass production equipment such as semiconductors.

In the example sputtering apparatus, when the vacuum chamber capacity is 1001, by installing the cryopump according to the present invention having an exhaust capacity equivalent to JIS SB, the rise time of a conventional cryopump without this is reduced to 10. ~1
We were able to shorten the time from 5 hours to 4.5 hours.

Furthermore, when the relationship between the ultimate vacuum level and the pumping speed was investigated, it was found that the pumping capacity in the low vacuum range was significantly improved compared to the conventional pump, as shown in FIG.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing the configuration of a vacuum apparatus according to the present invention. FIG. 2 is a graph showing the relationship between the degree of vacuum and the pumping speed. FIG. 3 is an explanatory diagram showing the configuration of a conventional sputtering apparatus. 1...Pump case, 2...Mounting flange, 3...
・Shield, 4...1st stage cryopanel, 5...
Refrigerator, 6... First stage heat transfer section, 7... Second stage heat transfer section, 8... Second stage cryopanel, 9... Activated carbon, 1
0... Orifice, 20... Sputtering chamber, 21...
- Gate valve, 22... Exhaust system piping, 23... Cryopump, 24... Variable throttle valve.

Claims (1)

[Claims] 1. A first-stage refrigerator that cools the outermost first-stage cryopanel, and a second-stage refrigerator that cools the second-stage cryopanel that is maintained at a lower temperature, In a storage type cryopump that selectively condenses or physically adsorbs gas on a surface, an orifice having a required opening in a cross section in the shield of the pump is provided between the first and second stage cryopanels. A cryopump characterized by being equipped with.