JPS6267166A - Deposit taking out device - Google Patents

Abstract

PURPOSE:To improve the efficiency of a taking-out operation by attaching a gate valve to the bottom of a vacuum vessel can be taken out in the vacuum state. CONSTITUTION:This device 12 for taking out the deposits accumulating in the vacuum vessel 8 consists of the gate valve 17 which is attached via an expandable and contractable bellows 16 to the bottom of the vacuum vessel, the collecting box 19 which is removably attached to the lower part of the valve 17 and is evacuated to a vacuum and a funnel 15, etc. The funnel 15 is provided to the inside of the bellows 16 and the bottom end 15a thereof the valve 17 when the bellows 16 is contracted.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for removing deposits accumulated in a vacuum container of, for example, a molecular beam epitaxy device, a vacuum evaporation device, etc. while maintaining the vacuum state of the vacuum container. The present invention relates to a device for removing deposits from which deposits can be removed.

[Background technology]

FIG. 4 is a schematic perspective view showing an example of the liquid nitrogen surroundings in the molecular beam epitaxy apparatus. Molecular beam epitaxy equipment uses ultra-high vacuum (e.g. 10-1° Torr).
The growth chamber (vacuum container, No. 1 cylinder No. 8) is evacuated to the
), the epitaxial layer is grown by depositing molecular beams 5 from one or more molecular beam sources 4 on the substrate 3, and the substrate 3 is usually surrounded by a cylinder as shown in the figure. It is covered with a liquid nitrogen shroud 2, which absorbs and removes stray evaporated substances.

In that case, as the operation continues, the liquid nitrogen shroud 2
For example, deposits 6 such as arsenic and phosphorus are adsorbed and accumulated on the inner wall 2a of the liquid nitrogen shroud 2. If this is left unattended, not only will the adsorption capacity of the liquid nitrogen shroud 2 decrease, causing vacuum deterioration, but also the deposits will A part of 6 may peel off as flakes and adhere to the substrate 3, causing defects in the crystals formed on its surface, or depending on the arrangement, may fall into the molecular beam source 4 and evaporate. It can also cause impurities to be mixed into the material.

Therefore, in order to prevent the above-mentioned problems, the same applicant has proposed eight separate mechanisms for removing the deposits 6 from the inner wall 2a and dropping them to the bottom of the growth chamber while maintaining the vacuum state of the growth chamber. ing.

[Purpose of the invention]

If too much of the deposit 6 is left at the bottom of the growth chamber, it may block the molecular beam source 4 located below.
It is necessary to take it out from the growth chamber from time to time because it may block the back side of the liquid nitrogen shroud 2 and reduce its adsorption capacity, or in some cases it may look up and adhere to the substrate 3 and cause defects in the crystal. However, if the vacuum in the growth chamber is broken every time, it will take a very long time (for example, about a week to raise the vacuum to about 10-IO Torr) to restart the vacuum in the growth chamber after the operation. Therefore, it can be said that the efficiency is not good.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a deposit removal device capable of removing deposits from a growth chamber, that is, a vacuum container, while maintaining the vacuum state therein.

[Means to achieve the purpose]

The deposit removal device of this invention consists of a gate pulp attached to the bottom of a vacuum container via an expandable bellows, and a sealing surface of a gate valve provided at the inside of the bellows, whose lower end is the sealing surface of the gate valve when the bellows is contracted. The present invention is characterized by comprising a funnel that goes lower and a collection box that is removably attached to the bottom of the gate valve and is evacuated.

[Effect]

To take out the deposits accumulated in the vacuum container, first open the gate valve and contract the bellows, and collect the deposits accumulated at the bottom of the vacuum container into the collection box. In this case, since the lower end of the funnel is below the sealing surface of the gate valve, deposits are prevented from adhering to the sealing surface of the gate valve. Next, with the bellows extended and the gate valve closed, the inside of the collection box is brought to atmospheric pressure, and then the collection box is removed from the bottom of the gate pulp. This means that the deposit has been removed from the vacuum container.

In this case, the vacuum state of the vacuum container is maintained by the gate valve. After the collection box is reattached to its original state, the operations described in (g) can be repeated by evacuating the inside of the collection box. As described above, according to this device, the deposit can be taken out from the vacuum container while maintaining the vacuum state therein, so the work efficiency is very high.

〔Example〕

FIG. 1 is a schematic cross-sectional view showing an example of a molecular beam epitaxy apparatus equipped with a deposit removal device according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view taken along the line ■-H in FIG. be. Components equivalent to those in FIG. 4 are given the same reference numerals and their explanations will be omitted.

A liquid nitrogen shroud 2 as described above is provided in a vacuum container, for example, a cylindrical growth chamber 8, and in this example, the liquid nitrogen shroud 2 has an inner wall 2.
A ring-shaped separation plate 10, which is a part of a mechanism for removing deposits 6 from the inner wall 2a, is provided so as to be able to slide along the inner wall 2a, and the ring plate 10 is moved outside the growth chamber 8 by a drive mechanism (not shown). For example, it is driven as shown by arrow A.

Note that 7 is an opening for making it easier for the deposit 6 to fall to the bottom 8a of the growth chamber 8, and 9 is a liquid nitrogen shroud for the molecular beam source 4.

The bottom 8a of the growth chamber 8 in this example is shaped like a gutter, as shown in FIG. , so that they naturally gather at the bottom 8a. A deposit removal device 12 comprising a mechanism described in detail below is provided at the bottom portion 8a.

First, in this example, in order to facilitate the collection of the deposits 6, a hoe-shaped collection rod 14 having a collection plate 14a is provided at the bottom 8a, and the collection rod 14 has an extendable bellows 1.
3, it can be moved from the atmosphere side in the front and rear directions, for example, as shown by arrow B.

In addition, a gate valve 17 is connected to the bottom 8a of the growth chamber 8 via an expandable bellows 16.
JL' state 1, and +1 inside the relevant state II-z 16.
-1-(leak'l)+5 is provided. , F Physically, l'l -1-15 is the 11-16 of the growth chamber 8.
5a is 16 to 4iH: El! Seal surface 17 a of H2N gate valve 17, 1,
It's going to be a lido).

In this example, a collection box 19 is attached to the lower part of the gate valve 17 via a short pipe 18, and the inside of the pipe 18 and the collection box 19 are as follows: n
Place an empty vacuum in the apparatus and place it in an ultra-high vacuum equivalent to that of the growth chamber 8 (for example, I0-101' o r r f'l!tf
lj) Nitl) I'm worried.) / ('C) The Tosho vacuum OF gas equipment, in this example, includes a vacuum valve 21, a roughing pump 22, a gate valve 23, and an ultra-high vacuum pump 24.
and a vacuum gauge 25, etc. Note that 20 is a slow leak valve.

Hypothesis 1 to explain the effect without removing the It product 6 accumulated in the chamber 8.
When redoing 4, first refer to Figure 1 and check the gate valve 17.
Open the funnel 16 and retract the lower end of the funnel 15 +
5a from the sealing surface 17a of the valve 17. This prevents the load 6 and the like from adhering to the sealing surface 17a of the gate valve 17 and interfering with vacuum sealing. In this state, the sediment 6 accumulated on the bottom 8a of the growth chamber 8 is collected using the collecting tray 14.
1-) and drop it into the collection box 19 through 15.

In addition, the lower part 115 and the like are arranged directly below the open lower part of the liquid nitrogen shroud 2.
If the sediment 6 naturally falls into the funnel 15, the collecting rod 14 and the funnel 13 therefor are particularly useful.
It is not necessary to provide

After collecting the deposits 6 in the collection box 19 as described above, as shown in FIG.
Close the gate valve 17 so that

Then, open the slow leak valve 20 to gradually inject, for example, dry nitrogen gas into the collection box I9.
Bring the inside to atmospheric pressure.

Thereafter, the collection box 19 is removed and the deposits 6 inside are collected. It means that the deposit 6 has been removed from the growth chamber 8 due to the dirt. Of course, in this case, the ultra-high vacuum state of the growth chamber 8 is maintained by the gate valve 17.

Next, after reinstalling the collection box 19 to its original state,
- Close the leak valve 20 and evacuate the inside of the collection box 19 to an ultra-high vacuum using the evacuation device described above. As a result, the same operation as described in 1- can be repeated.

In this way, according to the deposit removal device 12, the deposit 6 can be taken out of the growth chamber 8 while maintaining the ultra-high vacuum state of the growth chamber 8, so the work efficiency is very high. Therefore, it also contributes to improving the productivity of molecular beam epitaxy equipment. Of course, by removing the deposit 6, substances that may cause defects in the crystals of the substrate 3F are eliminated, which also leads to improvement in film quality.

Although the present invention has been described above using a molecular beam epitaxy apparatus as an example, the present invention is not limited thereto, and may be applied to, for example, removing deposits from a vacuum container in a vacuum evaporation apparatus or the like. I can do it.

〔Effect of the invention〕

As described above, according to the present invention, the deposits accumulated in the vacuum container can be removed from the vacuum container while maintaining the vacuum state of the vacuum container. Therefore, the efficiency of the extraction work is very high.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a molecular beam epitaxy apparatus equipped with a deposit removal device according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view along line nn of 1M. FIG. 3 is a partial cross-sectional view for explaining one operation of the deposit removal device of FIG. 1. FIG. 4 is a schematic perspective view showing an example of a liquid nitrogen tube in a molecular beam epitaxy apparatus. 2...Liquid nitrogen shroud, 619. Sediment, 8...
・Growth chamber (vacuum container), 10... Separation plate, 12...
Sediment removal device, 15... Funnel, 16... Bellows, 17... Gate pulp, 19... Collection box

Claims (1)

[Claims] (1) A device for removing deposits accumulated in a vacuum container, which includes a gate valve attached to the bottom of the vacuum container via an extensible bellows, and a lower end provided inside the bellows that contracts the bellows. A sediment removal device characterized by comprising a funnel that is below the sealing surface of a gate valve when the gate valve is closed, and a collection box that is detachably attached to the bottom of the gate valve and is evacuated to a vacuum.