JP2002373885A - Dry etching system and its maintaining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of a process for cleaning and removing deposits in an aluminum dry etching system and an exhaust pipe with pure water that cyan (CN) gas is generated and the problem that the exhaust pipe is clogged with deposits to block continuous operation. SOLUTION: Cyan gas is not generated when deposits are cleaned and removed using an aqueous solution of ammonia or monoethanolamine or triethanolamine having a concentration of 2.5% or above. A deposit trap can be provided when a tape-like heater is provided on exhaust gas piping and an oxygen based gas supply is provided in the exhaust gas piping thus ensuring continuous operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a maintenance method for a dry etching apparatus used for a semiconductor device or the like.

2. Description of the Related Art In a manufacturing process of a semiconductor integrated circuit or the like,
A dry etching device is an indispensable device. In the case of an aluminum-based metal dry etching apparatus, a chlorine-based gas is usually used as an etching gas.
In the present invention, the term “aluminum” means an aluminum alloy containing aluminum as a main component in addition to aluminum. It is known that when aluminum is dry-etched using a chlorine-based gas, a deposit adheres to the inside of a dry etching apparatus or the inside of an exhaust pipe or the like of a dry pump. When such deposits adhere to the inside of the dry etching apparatus, they adhere to the wafer and contaminate the wafer, defective semiconductor devices, decrease the yield, shorten the maintenance cycle due to corrosion of the reaction chamber walls of the dry etching apparatus, and reduce the equipment. Problems such as a decrease in the operation rate occur. Similar deposits also adhere to the inside of a dry pump for exhausting dry etching and an exhaust path such as a pipe. The deposits in these pipes increase with the use time of the dry etching apparatus, causing corrosion of the pipes and clogging of the pipes. However, clogging of the pipes is not preferable because the degree of vacuum in the reaction vessel decreases. For this reason, these precipitates require a maintenance operation of periodically cleaning and removing them. Conventionally, the operation of removing the precipitate has been performed by wiping the precipitate with pure water. For example, deposits attached to a cover called a removable liner installed in a reaction chamber of a dry etching apparatus,
After removing the large particles by hand by the operator, the remaining parts were wiped off with pure water, or a liner was attached to a washing tank filled with pure water in advance to wash the precipitates. .

In the etching of a substance different from aluminum, such as a silicon oxide film, when a deposit such as a polymer film is formed on the inner wall of the reaction chamber, the substance is not washed with a solution or the like. These are usually removed by a plasma treatment such as ashing with oxygen plasma. This is because plasma dry etching equipment requires a high vacuum inside the reaction chamber,
This is because if the foreign matter is removed using a solution, pure water, or the like, the degree of vacuum is reduced, and therefore, after maintenance, baking for removing moisture in the reaction chamber is required. This is because baking takes a long time, and there is a demand that such a step should be practically avoided.
On the other hand, when precipitates are generated inside the aluminum dry etching apparatus, etc., when removing the precipitates,
Use pure water. As described above, although moisture is not preferable in a high vacuum apparatus, pure water is dared to be used in the work of removing aluminum deposits. (1) Since the precipitates are water-soluble, removal is easy. (2) Pure water can be easily used in factories and clean rooms where normal semiconductor manufacturing processes are performed. (3) There is no concern about contamination and the like if pure water is used. it is conceivable that. (4) The reason is that the removal operation is difficult with ethanol / acetone. However, when maintenance work is performed by a conventional method, a large amount of hydrogen chloride gas or chlorine gas harmful to the human body is generated when the precipitate reacts with pure water. For this reason, the worker has performed this removal work on a work bench equipped with a gas mask or with a local exhaust mechanism such as a clean bench or the like. The present inventors analyzed and evaluated the deposits in the pipe of the dry pump of the aluminum dry etching apparatus by EDX (scanning electron microscope) and X-ray diffraction. Further, a method of bubbling white smoke generated when this precipitate was washed with pure water in pure water and performing ion chromatographic analysis, and NH ₄ OH
(0.5N), and each was analyzed and evaluated. Table 1 shows the results.

[Table 1] It was found that the precipitate contained anhydrous aluminum chloride (AlCl ₃ ) as a main component, and the white smoke contained chlorine as a main component and further contained highly toxic cyanide (CN).
It is considered that the nitrogen component contained in cyan was contained in the etching gas and the resist material used for the etching mask. Therefore, according to the conventional method using a gas mask or local exhaust, a worker may inadvertently inhale generated gas due to a limit of use of the mask, a limit of exhaust capability of the exhaust device, a failure of the exhaust device, and the like. Expected and extremely problematic in terms of safety. Conventionally, it was not clear that the gas contained cyan, and it is considered that the countermeasure was not sufficiently taken. It is a first object of the present invention to carry out washing and removal of deposits deposited in a reaction chamber of an aluminum dry etching apparatus and an exhaust pipe thereof while preventing generation of toxic gas. It is a second object of the present invention to suppress the occurrence of the above.

According to a first method of the present invention, a precipitate mainly composed of aluminum chloride is washed and removed not with pure water but with a weak alkaline solution. Thereby, generation of chlorine gas, hydrogen chloride gas, and cyan gas can also be suppressed. It is desirable to use an ammonium hydroxide (NH ₄ OH) solution as the weak alkaline solution. As a result, the precipitate becomes aluminum hydroxide and precipitates in this solution. Aluminum is an amphoteric compound and can be treated by dissolving it in a strong acid or strong alkaline solution in a neutralization tank after taking out the pipe. A second method according to the present invention is to heat a pipe using a tape heater and to introduce the pipe into an abatement apparatus. Precipitation on the pipe is observed at a place where the temperature suddenly drops, so that the generation of the precipitate is prevented. That is, the maintenance method of the dry etching apparatus according to the present invention is a dry etching apparatus for removing a precipitate containing aluminum chloride as a main component, which adheres in the plasma dry etching apparatus or the exhaust dry pump pipe of the plasma dry etching apparatus. The maintenance method, wherein the removal of the precipitate is performed by washing and removing the precipitate with a weakly alkaline aqueous solution. The weak alkaline aqueous solution is preferably an aqueous ammonia solution having a concentration of 2.5% or more. Preferably, the weak alkaline aqueous solution is monoethanolamine or triethanolamine. The plasma dry etching apparatus according to the present invention is a dry etching apparatus of an aluminum-based material having a reaction chamber, a plasma generator, an introduction section for introducing a chlorine-based gas, and an exhaust gas pipe, wherein the exhaust gas pipe has a tape shape. It is characterized by being wound with a heater. Further, the plasma dry etching apparatus according to the present invention is a dry etching apparatus for an aluminum-based material having a reaction chamber, a plasma generator, an introduction section for introducing a chlorine-based gas, and an exhaust gas pipe, wherein the exhaust gas pipe is An oxygen supply source for supplying an oxygen-based gas to the apparatus is provided.

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment)
First Implementation of Maintenance Method for Etching Equipment
The configuration will be described with reference to FIG. Figure 1 shows a high density plasma
It is a dry etching device. Aluminum using this device
Aluminum with silicon as the main component and silicon and copper
Dry using a photoresist as a mask.
Was performed. Specifically, the etching chamber
1) Resist on the wiring formation area on the aluminum alloy thin film
The substrate 4 on which the pattern is formed is set. Inside the chamber
The part is provided with a removable liner 2.
This liner 2 allows deposits to adhere to the inside of the chamber.
Enclose the object to be etched to minimize
It is a type of plastic
Polyetherimides that are resistant to weak alkaline
It is composed of lumite, ceramic, etc. Next, d
Chlorine (Cl_Two) And bromine chloride (BC
l_Three) And nitrogen (N _Two) Are introduced at a flow ratio of 5: 4: 1 and the pressure is
A predetermined pressure (0.8 Pa) is maintained by the force control device 11.
The cathode electrode capacitively coupled by the high frequency power supply 3
13.56MHz, 1000W power
You. Under such conditions, the accumulated use time is about 30 hours.
Then, the inner wall of the liner of the etching chamber
Luminium (AlCl_Three) As the main component, with precipitate
To wear. This was added to 28% by weight ammonia (N
H_Three) And pure water (H_TwoO) ammonia mixed 1:10
Washed with aqueous solution. When the liner is submerged in the cleaning tank,
By reaction, aluminum hydroxide (Al (OH)_Three)
Precipitates and no chlorine gas is generated as in the past.
Was. This precipitate is formed from a strong acid such as hydrochloric acid (HCl) or sodium hydroxide.
Treat with a strong alkaline aqueous solution such as thorium (NaOH)
Can be In this embodiment, the cleaning of the liner is performed.
However, the same applies to exhaust pipe adhering matter, etc.
You. In addition to cleaning in the cleaning tank,
The deposit inside the tube was made to contain the above-mentioned aqueous ammonia solution.
You may wipe it off with a cloth or the like. Also in this case, generation of chlorine gas
Can be prevented. In addition, weak alkaline aqueous solution
Aqueous ammonia solution was used as the liquid.
Ethanol-based amines such as
Using sodium carbonate, potassium carbonate, etc.
The same effects can be obtained. However, use sodium carbonate, etc.
Carbon dioxide is generated, but the carbon dioxide is chlorine
Less toxic than gas generation, but suffers from suffocation
Consider actual use such as needing sufficient exhaust
And a weak alkali made from the above-mentioned ammonia-based gas
An aqueous solution or an ethanolamine-based solution is preferred.
According to the first embodiment, maintenance work becomes easy.
Maintenance work can be performed at high frequency.
Durability of components and piping has been improved, resulting in significant cost reduction
Becomes possible. (Second Embodiment) Among the above exhaust pipes, in particular,
Pipes are bent at locations where a large amount of exudates occur
Location, where the temperature drops rapidly, or where the pressure suddenly rises to normal pressure
While heating with the tape heater 5
If introduced into the abatement system, the generation of precipitates should be minimized
And the maintenance cycle can be lengthened. here
Fig. Shows the vapor pressure curve of aluminum chloride (AlCl3).
It is shown in FIG. According to the figure, aluminum chloride is
It does not solidify under pressure, i.e., does not precipitate,
It turns out that it solidifies (precipitates) under temperature and normal pressure
You. The main components of the solid are AlCl3, B2O3, TiO2
If we focus on B2O3 and TiO2, O2
B2O3 and TiO2 will not be generated if
You. Conversely, actively introduce O2-based gas in the middle of the pipe.
As a result, a precipitate can be trapped. In addition, piping
The large amount of precipitation at the bent part is due to the gas flow rate
Is thought to be due to a sharp decrease. Precipitate trap 7
Is relatively easy to remove, large diameter, large capacity
Amounts are preferred. In the precipitate trap 7, O2 gas
The introduction of a source of gas will cause a sudden pressure drop to normal pressure.
As a result, AlCl3, B2O3, and TiO2-based precipitates are trapped.
Caught. According to these embodiments, the tape heater 5
The exhaust piping in the area heated in
Continuous operation with maintenance of only part 7
It becomes possible.

According to the maintenance method of the dry etching apparatus according to the present invention, the maintenance work can be performed safely by preventing generation of toxic gases such as chlorine gas and cyan gas.

[Brief description of the drawings]

FIG. 1 is a diagram showing a high-density plasma dry etching apparatus used in first and second embodiments;

FIG. 2 is a diagram showing a vapor pressure curve of aluminum chloride (AlCl3).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Etching chamber 2 Liner 3 High frequency power supply 4 Substrate 5 Tape heater 6 Dry pump 7 Deposit trap

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K057 DA01 DB05 DD01 DE01 DE20 DM03 DM37 DM38 DM39 DN01 WA01 WB05 WE23 WE30 WM03 WN10 5F004 AA15 BA04 BB13 BB18 BC03 DA04 DA11 DA25 DA26 EB02

Claims (5)

[Claims] 1. A maintenance method for a dry etching apparatus for removing a deposit containing aluminum chloride as a main component, which adheres in a plasma dry etching apparatus or an exhaust pipe of the plasma dry etching apparatus, the method comprising: The removal is performed by washing and removing the precipitate with a weak alkaline aqueous solution. 2. The maintenance method for a dry etching apparatus according to claim 1, wherein the weak alkaline aqueous solution is an aqueous ammonia solution having a concentration of 2.5% or more. 3. The maintenance method according to claim 1, wherein the weak alkaline aqueous solution is monoethanolamine or triethanolamine. 4. A dry etching apparatus for an aluminum-based material having a reaction chamber, a plasma generator, an inlet for introducing a chlorine-based gas, and an exhaust gas pipe, wherein a tape-like heater is wound around the exhaust gas pipe. A plasma dry etching apparatus. 5. A dry etching apparatus for an aluminum-based material having a reaction chamber, a plasma generator, an inlet for introducing a chlorine-based gas, and an exhaust gas pipe, wherein an oxygen-based gas is supplied into the exhaust gas pipe. A plasma dry etching apparatus having an oxygen supply source.