JPH0332632B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a dry etching apparatus, and particularly to an exhaust treatment method.

[Prior art]

Conventionally, when using a reactive gas containing fluorine as a main component in the exhaust treatment method for dry etching equipment, reactions such as clogging of the exhaust piping or early deterioration of the pump occur without special attention. Problems with objects were not a problem.

However, in recent years, it has become common to etch Al and the like using a reactive gas containing chlorine as a main component as an etching gas. In this case, a so-called cold trap is installed in the front part of the rotary pump in the exhaust system as a reaction product collection system that cools with liquid nitrogen, mainly from the viewpoint of protecting the pump. It is common practice to collect surplus etching gas that has not been consumed.

However, if such a method is used to collect reaction products and residual etching gas, the system becomes complicated and the number of parts that can cause vacuum leaks increases. Furthermore, the trap itself is filled with liquefied etching gas, which is extremely dangerous. In addition, slight fluctuations in the temperature of the cold trap can cause the collected liquefied gas components to flow back into the reaction chamber, disrupting the etching conditions and resulting in the product being etched to be defective. . This will be explained below using the drawings.

FIG. 1 is a block diagram of a conventional dry etching apparatus. The reactive etching gas introduced from the etching gas inlet 1 is consumed as etching gas under glow discharge in the etching chamber 2, and at the same time, the remaining etching gas containing reaction products generated by the reaction passes through the valve 3. After passing through the mechanical booster pump 4 and valve 5, the temperature in the cold trap 9 is around the temperature of liquid nitrogen (~80℃).
〓) is condensed and collected. Liquid nitrogen is inlet 1
Injected from 1. Due to the uncollected gas components and the lack of suitable sensors, the overflow gas passes through the valve 10 and into the oil of the rotary pump 14, due to the fact that it cannot be detected even when the cold trap 9 is full. , some of it is collected and discharged outside. That is, in the practical stage, in most cases, the cold trap 9 loses its function to protect the rotary pump. In addition, when expelling the liquefied gas components that have filled the cold trap 9 (hereinafter referred to as trap 9), close the valves 5 and 10, then open the valve 8, raise the temperature of the trap 9, and release the vaporized gas components through the valve 8. discharge. Next, the valve 6 is opened and an inert gas is introduced from the purge gas inlet 7 to purge the inside of the trap 9. Subsequently, the trap 9 is disassembled and the element is cleaned outside the device.
Although the procedure described above is complicated, the valve 8 is also easily clogged by etching reaction products, etc. In this case, when the temperature of the trap 9 is raised, the trapped liquefied gas is vaporized rapidly. Moreover, due to the large increase in pressure, dangerous gases may be blown out from the seals of the trap 9 or the seals of the valves 5, 6, 8, 10, etc., which is very dangerous. Furthermore, if the above-mentioned balloon does not occur, assuming the worst case scenario, there may even be a danger that the trap 9 will explode. As described above, the conventional apparatus has serious drawbacks both in terms of stable etching of products and in terms of safety.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a dry etching apparatus capable of eliminating the above-mentioned drawbacks and performing stable and safe dry etching.

[Structure of the invention]

The present invention is a dry etching apparatus that uses chlorine or a reactive gas containing chlorine and fluorine as main components as an etching gas, and is characterized in that a dry strainer is installed upstream of the exhaust system. be.

[Explanation of Examples]

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

In the exhaust part of the dry etching equipment,
It is undesirable to have a part of the system with a lower temperature than other parts, a so-called cold spot, and it is important for the equipment to discharge the exhausted gas components to the outside of the vacuum while keeping them as vaporized as possible. This is important from the standpoint of stability.

Therefore, in the present invention, as shown in FIG. 2, a dry strainer 16 is installed in the exhaust system of the dry etching apparatus. As a result, the only valve for introducing gas into the exhaust system from outside the vacuum is the inert gas purge valve 6. Exhaust from the etching reaction chamber 2 passes through a valve 3 and reaches a dry strainer 16 via a mechanical booster pump 4. The dry strainer 16 mainly removes solid components in the reaction product before the rotary pump 14. Therefore, the possibility of solid matter forming after the valve 10 is in the casing of the pump 14, after the part that is exposed to the atmosphere. To prevent this, an inert gas is blown into the casing of the rotary pump 14 from the gas inlet 13 through the valve 12 to prevent solid reaction products from appearing in the pump 14. Therefore, the period for overhaul and maintenance of both the oil filter system 15 and the rotary pump 14 becomes longer, and the oil filter system 15 and the rotary pump 14 operate stably. Furthermore, the danger caused by the aforementioned cold spots as in the conventional method can also be avoided. If maintenance of the strainer 16 is required after long-term use, first close the valve 5 and evacuate the inside of the strainer 16 using the rotary pump 14, then open the valve 6 and introduce inert gas from the gas inlet 7. Purge the inside of the strainer 16.
Thereafter, the valve 10 is closed and the strainer 16 is disassembled.

FIG. 3 is a sectional view of the strainer 16 of FIG. 2. In FIG. 3, a gas inlet 17a is provided on the side of the casing 17, an exhaust port 17b is provided on the upper part of the gas inlet 17a, a cylindrical stainless steel mesh 18 is installed inside the casing 17, and a perforated plate is provided inside the casing 17. A cylinder 19 is installed. Gas enters the casing 17 from the gas inlet 17a, passes through the stainless steel mesh 18, passes through the cylinder 19 having pores, and is discharged from the exhaust port 17b toward the rotary pump. The casing 17, mesh 18, and cylinder 19 are all made of highly corrosion-resistant stainless steel. If maintenance is required, the mesh 18 and cylinder 19 can be easily removed from the casing 17 by removing the lower screws 20 and removing the bottom plate 21 as shown in FIG. 22
is a sealing material.

In the above embodiment, a mechanical booster pump and a rotary pump have been described, but it goes without saying that a turbo molecular pump can be used in place of the mechanical booster pump.

〔Effect of the invention〕

As explained above in detail, according to the present invention, there is no generation of cold spots in the exhaust system of the device, and the exhausted gas is discharged in a vaporized state, thereby reducing the danger of cold spots. This has the effect of greatly improving the stability, maintainability, etc. of the device.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional dry etching apparatus having a cold trap, FIG. 2 is a block diagram of a dry etching apparatus according to an embodiment of the present invention, and FIG. 3 is a structural sectional view of a dry strainer. 1... Etching gas inlet, 2... Etching chamber, 3, 5, 6, 12... Valve, 4... Mechanical booster pump, 7, 13... Inert gas inlet, 9... Cold trap, 11...Liquid nitrogen inlet, 14...Rotary pump, 15...
...Oil filter system, 16...Dry strainer, 17...Strainer casing, 18
...Metsushiyu, 19...Cylinder.

Claims (1)

[Claims] 1. A dry etching apparatus using chlorine or a reactive gas containing chlorine and fluorine as main components as an etching gas, characterized in that a dry strainer is installed in the front stage of the exhaust system.