JP2990858B2 - Exhaust gas treatment device and its cleaning method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold trap which can be cleaned and regenerated without removing it from an exhaust system of a vacuum processing apparatus, and a method for cleaning the same.

2. Description of the Related Art Since it is necessary to process a large amount of information at a high speed, information processing apparatuses have been downsized and increased in capacity, and components used for this purpose, especially semiconductor parts, have been increased in capacity by downsizing unit elements. LSI and VLSI have been put to practical use.

Here, miniaturization is achieved by thin film formation technology and photolithography technology (photolithography or electron beam lithography).
Has been realized. Initially, physical methods such as vacuum deposition technology and sputtering technology, and chemical methods such as plating were used as thin film formation technologies, and mainly metal thin films were formed. Chemi
cal Vapor Deposition (CVD for short) produces thin films of not only metals but also insulators and semiconductors.

[0004] The use of a reduced pressure CVD method or a plasma CVD method, which is an improved CVD method, improves the film quality and allows the film to be formed at a relatively low temperature. Therefore, these methods are used for forming a semiconductor layer or an interlayer insulating layer of a semiconductor device. Method was used.

Here, CVD is a method in which a compound gas having a high vapor pressure is guided together with a carrier gas onto a substrate to be decomposed, or a plurality of compound gases are reacted on the substrate to form a thin film. In order to properly supply the compound gas to the substrate to be processed, it is necessary to forcibly exhaust the carrier gas.

On the other hand, in the low pressure CVD method or the plasma CVD method, it is necessary to reduce the pressure of a reaction tube in which a substrate to be processed is positioned to a required degree of vacuum, and an exhaust system is provided in a part of the CVD apparatus. Is essential.

In the photolithography technique, a thin film to be patterned is formed on a substrate to be processed by using a thin film forming technique, and then a thin resist is coated by a spin coating method or the like.
When using a negative resist, the exposed part of ionizing radiation such as ultraviolet rays becomes insoluble in the solvent, while in the case of a positive resist, a resist pattern is made using the fact that the exposed part becomes soluble, and this is used as a mask. This is a method of forming a thin film pattern by performing wet etching or dry etching. At present, dry etching is frequently used in terms of pattern accuracy.

Here, the dry etching method includes a parallel plate type plasma etching and a reactive ion etching (Re
active ion etching (abbreviation RIE), etc., and etching is performed in a reduced-pressure atmosphere using reactive chlorine ions (Cl ⁻ ) and fluorine ions (F ⁻ ) as etchants.
This requires the use of an exhaust system.

The present invention relates to a cold trap used to prevent such a reactive gas component from being sucked into a vacuum pump.

[0010]

2. Description of the Related Art Since CVD and dry etching are performed using a highly reactive gas, it is essential to provide a cold trap in the exhaust system. However, the total amount of unreacted gas and by-product gas coming out of the reaction tube is required. It is difficult to capture all of them with a cold trap.

For example, silicon nitride (Si ₃ N ₄ ) is often used as an insulating layer for integrated circuits such as LSI and VLSI.
In order to form a film on a substrate to be processed such as silicon (Si) by the method D, for example, trichlorsilane (SiHCl ₃ ), ammonia (NH ₃ ) and nitric oxide (N ₂ O) are used as sources (supply sources).
These gases react on the heated substrate to form a Si ₃ N ₄ film, but the reaction product is only a part of the supply gas component Therefore, most of the supply gas is sucked and removed from the reaction tube by the exhaust system, and is captured and liquefied in a cold trap provided between the reaction tube and the vacuum pump.

[0012] However, not all gas components are captured, and a part is sucked by a vacuum pump such as a mechanical booster pump _{, a} dry pump _{, or a} turbo pump that constitutes an exhaust system.

As an example of dry etching, a case where a substrate to be processed provided with an insulating layer made of phosphosilicate glass (PSG) is subjected to plasma etching to form a pattern will be described. Carbon tetrafluoride (CF) is used as a reactive gas. ₄ ) Using a gas mixture of oxygen (O ₂ ) and oxygen,
13.56 between the electrodes while maintaining a vacuum of about 0.1 torr
Plasma is generated by applying a high frequency voltage of MHz to generate F radicals, which are used as etchants to etch PSG.

However, not all of the CF ₄ is radicalized, and the radical easily returns to the original ground state, and many side reaction products such as CF ₃ and CF ₂ are generated. These gases are exhausted from the chamber, and considerable components are captured in the cold trap. However, some components are sucked by the vacuum pump of the exhaust system.

As described above, the reaction gas components are liquefied and accumulated in the cold trap, but the reactant formed on the substrate to be processed or the tube wall in the reaction tube or chamber is separated and becomes fine dust. While being sucked into the exhaust system, it is captured and deposited by the trap.

FIG. 3 is a cross-sectional view of a conventional cold trap 1 having an intake port 2 and an exhaust port 3 penetrating through a pipe wall, and a central portion of a lid 4 for a refrigerant such as liquid nitrogen (N ₂ ). There is an insertion tube, and a larger number of shielding plates 5 are provided in the horizontal direction. Exhaust gas enters through the intake port 2 and is exhausted from the exhaust port 3, and reaches a low temperature (-195.8 ° C. in the case of N ₂ ). It is liquefied or solidified by touching the held shield plate 5.

Here, when the deposition amount of the reaction gas component in the cold trap increases, the ultimate vacuum of the reaction tube and the chamber decreases, and evaporation from the cold trap occurs to cause a failure.

For this reason, the cleaning process has been carried out by periodically removing from the exhaust system. However, this removal and attachment requires manpower, and a poor attachment method causes vacuum leaks.

[0019]

It is inevitable to use a cold trap in an exhaust system of a CVD apparatus or a dry etching apparatus. In a mass production process, a cold trap is periodically removed to perform a cleaning process.

However, this removal and attachment requires human labor and is likely to cause a vacuum leak. for that reason,
The challenge is to put a cold trap that can be cleaned without removing it from the exhaust system into practical use.

[0021]

SUMMARY OF THE INVENTION The above object is achieved by a vacuum treatment.
Gas treatment attached to the exhaust system of the equipment and discharged from the equipment
In the exhaust gas treatment device that performs
Equipped with a shower plate or shower pipe
Or further comprising the inner wall and the outer wall
A gap for accommodating cooling and heating liquids
The outer wall has the above-mentioned void portion.
The problem can be solved by providing a heater for heating. Soshi
A shower plate with a vent hole provided inside
Ejects the chemical from the shower tube and deposits
The substance is dissolved and removed. At that time, depending on the chemical
To remove precipitates, use at least acid cleaning or alkali cleaning.
Include.

[0022]

According to the present invention, as a method for cleaning without removing the cold trap, a cold chemical trap supply port and a cleaning chemical spraying means are newly provided in the cold trap, and the cold trap has a double structure and functions as a cold trap. put coolant such as liquid N ₂ during this time if, also when the washing put a heating liquid such as water, is to heatable configuration the heater provided outside.

The washing is performed by supplying an acid, alkali, water, a low boiling point solvent, and the like by switching the cock from the supply port of the cleaning chemical solution. FIG. 1 is a cross-sectional view of a cold trap according to the present invention, and FIG. 2 is an explanatory view of a cleaning operation of the cold trap according to the present invention.

That is, the cold trap 7 according to the present invention has a gap 10 between the inner wall 8 and the outer wall 9 for filling the refrigerant and the liquid for heating, and this replacement is performed by the cocks 11 and 12.

A cleaning liquid supply pipe 13 is provided at the center, and a shower plate 14 having a spiral shape and a shower plate 14 are provided therefrom. Each of the shower pipes 15 has a cleaning liquid blowing hole 16. Further, a plurality of shielding plates 17 are provided as in the related art.

The cold trap 7 has an intake port 2 and an exhaust port 3 as in the prior art, and a bottom portion is provided with a three-way cock 18 for discharging a trap liquid and a cleaning liquid. Is provided with a heater 19 outside.

Next, as a method for cleaning the cold trap 7, the cock 22 between the reactor 21 and the cold trap 7 shown in FIG.
The coolant in 10 is replaced with a heating liquid such as water using cocks 11 and 12, and electricity is supplied to heater 19 to a predetermined temperature (for example, 90 ° C).
(° C).

In this state, the cock 23 shown in FIG. 2 is opened, and in conjunction with the three-way cock 18, the acid, alkali, water, and a low-boiling solvent (eg, methyl alcohol) are sequentially switched to carry out acid washing, water washing, alkali washing, and solvent washing. Perform cleaning.

FIG. 3 shows a case where acid washing, water washing, alkali washing and solvent washing are performed separately for an acid / alkali exhaust pipe 24 and a solvent exhaust pipe 25. After the cleaning of the cold trap 7 is completed in this manner, the exhaust system 26 is driven to sufficiently discharge gas, and then the cleaning liquid is replaced with a coolant to replace the heating liquid in the gap of the cold trap, thereby completing the cleaning process. .

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Reduced pressure CV for forming an insulating layer of Si ₃ N ₄ on a Si substrate using a ternary gas of SiHCl ₃ , NH ₃ , N ₂₀ as a reaction gas
The trap according to the present invention was used as a cold trap for the D furnace.

First, the cock 22 shown in FIG.
After shutting off the exhaust system 21, the three-way cock 18 of the cold trap 7 shown in FIG. 1 was opened to remove the liquefied gas accumulated in the cold trap 7.

Next, take out the liquid N ₂ to open the cock 11 and 12, to replace the water, keeping the water temperature 90 ° C. by energizing the heater 19, was circulated with a circulating function thermostatic bath. In this state, use the cock 23 and the valves provided for each of the acid, alkali, water, and solvent containers. First, a 50% solution of hydrofluoric acid (HF) as an acid is supplied through the shower plate 14 and the outlet 16 of the shower pipe 15. After being ejected and kept for 20 minutes, the three-way cock 18 was switched to the acid / alkali piping side to drain the liquid, and then water was supplied to sufficiently wash.

Next, a 50% solution of ammonia (NH ₃ ) is supplied in the same manner, and the solution is kept for 20 minutes.
The liquid was drained after switching to the alkaline piping side. Next, after supplying ethyl alcohol as a solvent to wash the inside of the cold trap and remove it from the solvent pipe, close the three-way cock 18,
After the inside of the cold trap was sufficiently dried by operating the exhaust system, the water in the voids was replaced with liquid N ₂ to complete the cleaning process.

[0034]

According to the present invention, the cold trap constituting the exhaust system of the CVD apparatus or the dry etching apparatus can be cleaned as it is, thereby eliminating the man-hour for removing and installing the cold trap. be able to.

[Brief description of the drawings]

FIG. 1 is a sectional view of a cold trap according to the present invention.

FIG. 2 is a sectional view illustrating an exhaust system.

FIG. 3 is a sectional view of a conventional cold trap.

[Description of Signs] 1,7 Cold trap 2 Inlet 3 Exhaust 8 Inner wall 9 Outer wall 10 Void 11,12,22,23 Cock 14 Shower plate 15 Shower tube 16 Blow-out hole 17 Shield plate 18 Three-way cock 19 Heater

Claims (5)

(57) [Claims] 1. An apparatus attached to an exhaust system of a vacuum processing apparatus,
Exhaust gas treatment equipment that processes gas exhausted from
And the inside wall has a blowout hole for blowing out the cleaning liquid.
It is characterized that it is equipped with a work plate or a shower tube.
Exhaust gas treatment equipment. 2. A cooling and heating system between the inner wall and the outer wall.
It has a double structure with a cavity for containing heat liquid.
The outer wall has a heater for heating the gap.
2. The apparatus according to claim 1, wherein the apparatus comprises:
Exhaust gas treatment equipment. 3. Processing of gas discharged from the vacuum processing apparatus is performed.
In the cleaning method of the exhaust gas treatment device to be performed, Shower plate or sieve with internal vent holes
A chemical solution is spouted from the shower pipe to remove attached deposits.
Purification of exhaust gas treatment equipment characterized by dissolving and removing
Method. 4. Removal of deposits by the chemical solution is small.
And acid cleaning or alkali cleaning.
The method for purifying an exhaust gas treatment apparatus according to claim 3. 5. The exhaust gas treatment device according to claim 1, wherein the inner wall and the outer wall are
Two gaps containing liquids for cooling and heating
The space is filled with a refrigerant.
After cooling the inner wall, it is discharged from the vacuum processing unit.
Liquefaction or solidification of condensable components to be performed, After replacing the refrigerant in the gap with a heating liquid, the liquid is
In the heated state, a chemical solution from the shower plate or shower tube
To remove the precipitate, and then heating
To dry the inside of the inner wall, and then heat the heating liquid in the void.
4. The method according to claim 3, wherein
A method for cleaning an exhaust gas treatment device.