JPS627269B2 - - Google Patents

Description

DETAILED DESCRIPTION OF _THE INVENTION The present invention relates to an exhaust system for an apparatus that performs dry etching such as plasma etching and reactive ion etching. The present invention relates to an exhaust system in a dry etching apparatus that prevents deterioration of exhaust system components due to etching gas containing a halogen element such as carbon (CCl ₄ ).

In recent years, dry etching equipment such as plasma etching equipment and reactive ion etching equipment has been used to finely process solid surfaces in the manufacturing process of solid-state electronic devices. These dissociated molecules generated from an etching gas containing halogen elements such as tetrafluoromethane (CF ₄ ) and carbon tetrachloride (CCl ₄ ) introduced into the etching chamber containing the sample during processing are connected to the etching chamber. There are problems such as deterioration of the hydraulic oil in the exhaust system, that is, the oil sparge pump or oil rotary pump, or excessive wear of the sliding surface of the oil rotary pump, making pump operation difficult. For this reason, this type of exhaust system had to be treated as a kind of consumable part.

SUMMARY OF THE INVENTION An object of the present invention is to provide an exhaust system for a dry etching apparatus that can avoid the adverse effects of dissociated molecules of etching gas containing a halogen element on hydraulic oil and sliding surfaces.

According to the present invention, an etching gas containing a halogen element is introduced into the etching chamber and the etching chamber is evacuated by an exhaust device so that the etching chamber which has absorbed the object to be etched is maintained at a predetermined pressure. By doing so, in the exhaust device of the dry etching apparatus for etching the object, the intake port of the Roots pump is connected to the etching chamber, and the oil rotary pump is connected to the exhaust port of the Roots pump via a cooling trap. An exhaust system for a dry etching apparatus is obtained, which is characterized in that the air inlets are connected to each other.

Furthermore, the cooling trap has a heating heater and a valve for disconnecting from the Roots pump and the oil rotary pump, and release valves at the top and bottom of the cooling trap that can communicate with the atmosphere. There is obtained an exhaust device for a dry etching apparatus characterized in that it is provided with a.

Next, embodiments of the present invention will be described with reference to the drawings. Referring to FIG. 1, CF ₄ or CCl ₄ is added to the etching chamber 1 in order to maintain the pressure within the etching chamber 1 containing the object to be etched at a predetermined pressure.
While introducing an etching gas containing a halogen element such as
By exhausting the inside with exhaust device A,
A dry etching apparatus is shown for etching the object. An exhaust device A according to an embodiment of the present invention has an intake port of a Roots pump 3 connected to the etching chamber 1 via a valve 2, and an exhaust port of the Roots pump 3 having an intake side and an exhaust side, respectively. Cooling trap 6 with valves 4, 5
The inlet port of the oil rotary pump 7 is connected to the oil rotary pump 7 via the inlet port. The cooling trap 6 uses liquid nitrogen as a coolant.

In the figure, B is an exhaust system used before the dry etching operation, and includes two exhaust systems B1 and B2. The exhaust system B1 includes an oil rotary pump 8 for rough evacuation of the inside of the etching chamber 1 before the dry etching operation. Exhaust device B
2 is used after rough evacuation by the oil rotary pump 8, and is used to create a cleaner vacuum atmosphere in the etching chamber 1. Exhaust device B2
is the cooling trap 10 required for the oil diffusion pump 12.
and water-cooled batsuful 11, and oil diffusion pump 12
and an oil rotary pump 13.

Before the dry etching work, the inside of the etching chamber 1, which has absorbed the object to be etched, is roughly evacuated by the oil rotary pump 8 of the exhaust device B1. If it is necessary to create a cleaner atmosphere in the etching chamber 1 depending on the type of object to be etched, evacuation is performed using the evacuation device B2 following the rough evacuation using the evacuation device B1 described above.

When a dry etching operation is subsequently performed in the etching chamber 1, the above-described etching is carried out by the gas introduction system 14 into the etching chamber 1 so that the pressure in the etching chamber 1 is maintained at a pressure suitable for the object to be etched. The object to be etched is etched by evacuating the inside of the etching chamber 1 by the exhaust device A while introducing gas. The Roots pump 3 is a pump in which a pair of rotors rotate with a slight distance between them, and in order to operate it, it is necessary to connect an auxiliary pump to the exhaust port. The oil rotary pump 7 serves as this auxiliary pump, and the roots pump 3 can evacuate the inside of the etching chamber 1 to about 5×10 ^-3 Torr. The dissociated molecules of the etching gas generated in the etching chamber 1 are exhausted to the cooling trap 6 side. Since the Roots pump 3 does not have hydraulic oil like an oil diffusion pump or an oil rotary pump or a sliding friction surface like an oil rotary pump, the dissociated molecules do not have an adverse effect on the Roots pump 3. The dissociated molecules exhausted to the cooling trap 6 have a vapor pressure lower than that of residual gas molecules in a normal vacuum, and all of the dissociated molecules are captured on the cooling surface of the cooling trap 6. Therefore, the above-mentioned dissociated molecules that degrade the hydraulic oil or excessively wear the sliding friction surface are prevented from flowing into the oil rotary pump 7, and as a result, the life of the oil rotary pump 7 can be avoided from being shortened.

The degree of vacuum in the etching chamber 1 is determined by the exhaust speed of the exhaust device A and the flow rate of the etching gas introduced by the gas introduction system 14, and is approximately 5×10 ^-3 depending on the adjustment of the gas introduction system 14. Torr~
It is possible to obtain a vacuum degree of 1 Torr.

Generally, in an exhaust system that connects a cooling trap and an oil rotary pump, temperature changes in the cooling trap directly affect the exhaust effect, but by connecting a Roots pump before the cooling trap, the exhaust effect due to temperature changes can be affected. can be lowered. That is, the pressure on the intake port side can be maintained at 1/10 or less of the pressure on the exhaust port side of the Roots pump, which also contributes to stabilizing the operating pressure of the exhaust system using the cooling trap.

The dissociated molecules of the etching gas trapped in the cooling trap 6 are released when cooling of the cooling trap 6 is stopped (ie, at the end of the working day). Therefore, exhausting the released dissociated molecules with the oil rotary pump 7 would render this invention meaningless, so the cooling trap 6 is provided with a release valve that communicates with the atmosphere. It is preferable to release the released dissociated molecules to the outside through the process, or to form a structure as shown in FIG.

That is, the cooling trap 6 in FIG. 2 is equipped with a heater 15 for heating it, and
Open valves 16 and 17 that can communicate with the atmosphere are provided on the upper and lower side walls, respectively. In this cooling trap 6, when cooling is stopped, valves 4 and 5 are
The etching gas trapped during the etching process is dissociated in a short period of time by closing the trap and forcibly heating the entire trap with the heater 15, and by blowing pressurized air into the cooling trap from one of the open valves 17. Molecules can be released from the other open valve 16.

As explained above, according to the present invention, the operating pressure range during dry etching such as plasma etching and reactive ion etching is increased by 5×.
In addition to ensuring a wide range of 10 ^-3 to 1 Torr,
It is possible to avoid deterioration due to dissociated molecules of the etching gas containing a halogen element, which has the effect of avoiding shortening of the life of the exhaust device.

In addition, if the inlet of the oil rotary pump 7 of the exhaust device B is connected to the valve 9 instead of connecting the inlet of the oil rotary pump 8 to the valve 9 in the exhaust device B1 in FIG. The oil rotary pump 7 can be used instead of the oil rotary pump 8 for pulling, and the oil rotary pump 8 becomes unnecessary.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a dry etching apparatus including an exhaust system A according to an embodiment of the invention, and FIG. 2 is a system diagram of a cooling trap 6 used in another embodiment of the invention. 1... Etching chamber, 2, 4, 5, 9... Valve, 3... Roots pump, 6, 10... Cooling trap, 7, 8, 13... Oil rotary pump, 11...
Water-cooled Batsuful, 12...Oil diffusion pump, 14...
Etching gas introduction system, 15...Heater, 1
6, 17... Opening valve, A... Exhaust device according to an embodiment of the present invention, B... Exhaust device used before dry etching work.

Claims (1)

[Claims] 1. By introducing an etching gas containing a halogen element into the etching chamber and evacuating the etching chamber using an exhaust device so as to maintain a predetermined pressure in the etching chamber containing the object to be etched, In the exhaust system of the dry etching apparatus for etching the object, an intake port of a Roots pump is connected to the etching chamber, and an intake port of an oil rotary pump is connected to the exhaust port of the Roots pump via a cooling trap. An exhaust device for a dry etching device characterized by: