JPH1121683A - Method for cleaning aluminum parts for semiconductor device manufacturing equipment - Google Patents

Abstract

An object of the present invention is to provide a method for cleaning an aluminum part for a semiconductor device manufacturing apparatus without affecting the manufacture of the semiconductor device. SOLUTION: An aluminum cylinder 21 arranged inside a side wall of a plasma generation chamber 11, an aluminum cylinder 22 arranged inside a side wall of a reaction chamber 12, and an aluminum cylinder 23 arranged inside an exhaust pipe 17 are provided. After being removed from the apparatus and subjected to pickling with nitric acid, hydrochloric acid, hydrofluoric acid or a mixed acid thereof, heat treatment is performed. The heat treatment condition after pickling, the temperature is 200 ℃ or more
The temperature is preferably 400 ° C. or lower. When the temperature is lower than 200 ° C., the process performance such as the etching rate and the selectivity is not improved. When the temperature exceeds 400 ° C., the aluminum or the aluminum alloy recovers, recrystallizes, softens and deforms.
Also, between 200 and 400 ° C., the higher the temperature, the faster the process performance recovers. The atmosphere is air, Ar or N ₂
Or in an inert gas such as the above, or in a vacuum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning an aluminum or aluminum alloy part used in an apparatus for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art In recent years, aluminum or aluminum alloy parts (hereinafter referred to as aluminum parts) are frequently used in apparatuses for manufacturing semiconductor devices. this is,
This is because heavy metal contamination that occurs when using stainless steel or a Ni-based alloy does not occur with aluminum. For example, heavy metal contamination of a silicon wafer has a great adverse effect on the characteristics of a semiconductor device.

[0003] An example of the use of aluminum parts is shown in Fig.
As shown in Fig. 1, SiO on the wafer surface_TwoEtch oxide film
Inner in the plasma generation chamber 11 of the plasma processing apparatus
There is a bell jar (aluminum cylinder) 21.
No. 86 and JP-A-7-273091. This
Here, CF is used for etching the oxide film._Four, C_TwoF₆, C _Four 
F₈, CHF_Three, NF_Three, SF₆ Etc. are used,
Plasma is generated from these gases and ions in the plasma are generated.
In the sample S in the reaction chamber 12 by the
Etching of a certain wafer proceeds.

[0004] As the etching proceeds, reaction products such as plasma polymerization products and plasma decomposition products adhere to the side walls of the apparatus such as a plasma generation chamber, a reaction chamber or an exhaust passage. As the adhesion of the reaction product progresses, the reaction product accumulates and easily peels off, leading to generation of particles. Therefore, JP-A-7-
In Japanese Patent No. 273086, by adjusting the temperature of the device side wall to 200 ° C. or more, the adhesion of reaction products to the device side wall is suppressed, and the selectivity to the Si film (the etching rate of the SiO ₂ oxide filmSiOthe etching of the Si film) Speed) is improved. By suppressing the adhesion of the reaction product to the side wall, the generation of particles due to the detachment of the adhered substance is prevented.

[0005] The use of aluminum parts also has the advantage that heat conduction is excellent and heating to a desired temperature of 200 ° C or more can be performed in a short time. Thereby, during the semiconductor device manufacturing process, by adjusting the plasma generation time and the stop time and maintaining a predetermined high temperature state, it is possible to suppress the temperature fluctuation of the apparatus.

[0006]

However, as described above, even if the side wall of the apparatus is controlled at a temperature of 200 ° C. or more, if the production is continued for a long time, the side wall of the reaction product such as a plasma polymerized product or a plasma decomposed product may be formed. Deposition is inevitable, causing particles. Therefore, there is a need for a method of removing the deposited deposits.

The present invention has been made in view of such circumstances, and has as its object to provide a method of cleaning an aluminum part for a semiconductor device manufacturing apparatus without affecting the manufacture of the semiconductor device.

[0008]

SUMMARY OF THE INVENTION The present invention is a method of cleaning an aluminum part used in an apparatus for manufacturing a semiconductor device, comprising an acid selected from the group consisting of nitric acid, hydrochloric acid, and hydrofluoric acid. The above component is cleaned with a cleaning liquid, and the cleaned component is heat-treated at a temperature of 200 ° C to 400 ° C. In the present invention, an aluminum part generally refers to a part made of aluminum or a part made of an aluminum alloy.

[0009] The deposits deposited on the aluminum parts are:
It was found to be removed by acid. However, pickling requires heat treatment after pickling, since OH groups remain on the surface of the component and the performance of the restarted process deteriorates. If the heat treatment temperature is lower than 200 ° C., the processing speed in the apparatus may decrease, or a desired treatment may not be obtained. If the temperature exceeds 400 ° C., the aluminum or aluminum alloy may recover, recrystallize, soften or deform.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments. FIG. 1 is a schematic sectional view showing a plasma processing apparatus used for carrying out the cleaning method according to the present invention. In the figure, reference numeral 10 denotes a reaction vessel made of an aluminum alloy which comprises a substantially columnar plasma generation chamber 11 and a substantially columnar reaction chamber 12 having a larger diameter than the plasma generation chamber 11 and coaxially arranged above and below. A plasma extraction window 15 having a predetermined diameter is formed at the center of the wall separating the plasma generation chamber 11 and the reaction chamber 12.

An opening 13 is formed at the center of the upper wall of the plasma generation chamber 11.
The opening 13 has a waveguide 18 for guiding microwaves oscillated from a microwave oscillator (not shown).
Are connected. A gas introduction pipe 14 is connected to an upper wall near the opening 13. Further, an exciting coil 19 surrounding the plasma generating chamber 11 and one end of the waveguide 18 connected thereto is provided, and the exciting coil 19 is directly connected to a power source (not shown).

At a substantially center of the reaction chamber 12, a quartz sample table 16 is provided so as to face the plasma extraction window 15, and a sample S is mounted thereon. An exhaust pipe 17 is connected to a lower wall of the reaction chamber 12, and the exhaust pipe 17 is connected to an exhaust system (not shown).

A reaction vessel 10 made of an aluminum alloy
For the purpose of preventing heavy metal contamination and heat radiation due to the above, an aluminum cylinder 21 having a predetermined diameter is disposed inside the side wall of the plasma generation chamber 11, and an aluminum cylinder 22 having a predetermined diameter is installed inside the side wall of the reaction chamber 12. Are arranged. Also exhaust pipe
An aluminum cylinder 23 having a predetermined length and a predetermined diameter is disposed inside the 17.

The etching of the sample S in the plasma processing apparatus configured as described above will be described. First, after the pressure inside the reaction vessel 10 is reduced by the exhaust system, a fluorine-based gas at a predetermined flow rate is introduced from the gas introduction pipe 14. Next, the microwave oscillated from the microwave oscillator is applied to the waveguide 18 and the opening 13.
To the plasma generation chamber 11 through the, and supplies a current to the exciting coil 19 to generate a magnetic field. As a result, the high energy electrons collide with the gas to generate plasma.
The generated plasma is accelerated by the diverging magnetic field, passes through the plasma extraction window 15 in the direction of arrow A, is guided to the reaction chamber 12, and reacts with the reactive ions on the surface of the sample S placed on the sample stage 16. Perform etching.

If such a process is performed for a long time,
Deposits accumulate on the side walls of the device. Cleaning using an acid is effective as a method for removing this. As the type of acid,
Nitric acid, hydrochloric acid, hydrofluoric acid, or a mixed acid thereof. The temperature of the acid may be room temperature, but it is desirable to raise the temperature when shortening the washing time. It is necessary to perform a heat treatment after performing the pickling treatment on the aluminum component removed from the apparatus. When the aluminum component after the pickling is mounted on the apparatus without performing the heat treatment and the process is performed, the performance of the apparatus is deteriorated as compared with the apparatus before the pickling. For example, in an oxide film etching process, a desired etching process cannot be achieved because the etching rate is reduced and the productivity is reduced, or the selectivity to the Si film or the photoresist film is reduced.

The heat treatment conditions after pickling are as follows:
It was found that the temperature had to be 400 ° C. or less. The atmosphere may be air, an inert gas such as Ar or N ₂ , or a vacuum. The heat treatment time is desirably 1 hour or more.

When the heat treatment temperature is lower than 200 ° C., the etching rate and the selectivity are not improved. Heat treatment temperature is 4
If the temperature exceeds 00 ° C., the aluminum or aluminum alloy may recover, recrystallize, soften or deform.
Also, between 200 and 400 ° C., the higher the temperature, the faster the process performance recovers.

The heat treatment may be performed before or after the aluminum component is pickled, as long as it is after pickling of the aluminum part. However, in order to perform the heat treatment after the aluminum component is mounted on the device, a vacuum holding structure inside the device is required. (Especially, vacuum sealing material) becomes a problem, and there is a great restriction on the device configuration. In consideration of such a point, it can be said that the heat treatment is desirably performed before attachment to the apparatus.

As a result of performing various analyzes to confirm the suitability of the heat treatment temperature, the following was found. First, ESCA
The condition of the component surface after the heat treatment was analyzed. 200 ℃
At the following heat treatment temperatures, OH groups remained, and at 200 to 400 ° C, the OH groups were completely removed. In addition, when the process was carried out by mounting components heat-treated at 200 ° C or less to the device, the process was performed by mounting components heat-treated at 200-400 ° C to the device because OH groups were present in the plasma. In this case, the absence of OH groups in the plasma was confirmed by plasma emission analysis and plasma mass spectrometry. This is thought to be due to the presence of OH groups on the component surface.

When OH groups are present in the plasma, process characteristics such as etching rate and selectivity are deteriorated. However, when the OH groups are removed by heat treatment at 200 to 400 ° C., such deterioration is prevented. In addition, it has been newly found that the process characteristics can be improved. It is considered that this is because the concentration of ions in the plasma contributing to the etching of the substrate is reduced by the OH groups, and an etching phenomenon different from the intended purpose is caused by O ions or H ions having the OH groups dissociated.

The heat treatment time is preferably at least one hour in order to recover the process performance in a short time. This is to remove OH groups on the surface of the aluminum component. When the aluminum parts are washed with alcohol after the pickling and before the heat treatment, the time until the process performance recovers can be further reduced.

Further, the method of the present invention provides a plasma processing apparatus utilizing electron cyclotron resonance (ECR) excitation, a plasma processing apparatus for applying a voltage between electrodes arranged in parallel, and a dielectric waveguide connected to a microwave waveguide. And can be applied to aluminum parts in various devices such as a plasma processing device utilizing a surface wave propagating through a dielectric line. Further, it goes without saying that the processing content can be applied to aluminum parts of an apparatus for any processing such as CVD, ashing, sputtering, vapor deposition and the like, as well as etching.

[0023]

[Example] Plasma generation chamber 11 (outside diameter 200 mm × inside diameter 190 mm
× 200mm height) Aluminum tube 21 (outside diameter 1
90mm x thickness 3mm x height 200mm), reaction chamber 12 (outer diameter
Equipped with an aluminum cylinder 22 (outside diameter 380 mm × thickness 3 mm × height 300 mm) inside the side wall of 400 mm × inside diameter 380 mm × height 200 mm) and aluminum on the inside wall of the exhaust pipe 17 (outside diameter 50 mm × inside diameter 40 mm × length 500 mm) Tube 23 (outer diameter 40mm x thickness 3mm x length 500
(mm), the SiO ₂ oxide film on the surface of the wafer as the sample S was etched using a plasma processing apparatus equipped with a plasma processing apparatus, and each characteristic value was measured.

Each characteristic value was measured for the amount of particles P on the wafer, the etching rate ER, and the selectivity SR of the SiO ₂ oxide film to the photoresist. The amount of particles was measured by a particle counter. The particle counter irradiates the wafer surface with an S-polarized laser,
This is an apparatus that measures the size and amount of particles by detecting scattered light from foreign matter. Specifically, a predetermined pattern is regarded as a plane on a wafer formed by etching, and foreign matter adhering to this pattern is regarded as a complex set of irregularities. At this time, the fact that the side polarized component of the laser beam eliminated by the minute unevenness is larger than that by the pattern is used.

As each condition of the etching process, the microwave power was 2.8 kW, the frequency was 2.45 GHz, and the magnetic field of the exciting coil 19 was 875 Gauss. After the pressure in the reaction vessel 10 was once reduced to 1 × 10 ⁻⁵ torr, C ₄ F ₈ gas was introduced from the gas introduction pipe 14 at a flow rate of 50 sccm.

The process of etching the SiO ₂ oxide film on 450 wafers is one minute per wafer.
It was performed continuously for 450 minutes. Then, aluminum cylinder 2
Pickling was performed by removing 1, 22, and 23. The acid used for washing is nitric acid of 5% concentration, the temperature is 25 ° C., and the time is 10 minutes. Parts removed from the acid were washed with distilled water and then heat-treated. The heat treatment temperature is 200 ° C. and 400 ° C., and the heat treatment time is 1 hour for each temperature. The heat treatment was carried out in the atmosphere at 200 ° C., in an inert gas of Ar or N ₂ , and in a vacuum.

As comparative examples, a case before pickling, a case with only pickling (no heat treatment), and a case with a heat treatment at 100 ° C. after pickling were carried out. After attaching each component to the apparatus, a process for 25, 75, 125, 250, and 450 minutes was performed, and after this process, the particle amount P, the etching rate ER, and the selectivity SR with respect to the photoresist were obtained. Was. Before pickling, measurements were taken only after the end of the 450 minute process.

As aluminum cylinders 21, 22, and 23,
Table 2 shows the measurement results of each property when the Al-Mg alloy was used. The particle amount P in Table 2 is 0.01 μm on the wafer.
The case where the density of the particles is 0.1 particles / cm ² or more is indicated by x, and the case where the density is lower than 0.1 / cm ² is indicated by ○.

[0029]

[Table 1]

[0030]

[Table 2]

As is clear from Table 2, when not pickling,
After completion of the process for 450 minutes, the density of particles of 0.01 μm or more is 0.1 particles / cm ² or more.
0.1 / cm ² or less. However, when the heat treatment is not performed, the etching rate ER and the selectivity SR are lower than when the pickling is not performed. In contrast, in each of the examples where the heat treatment was performed at 200 ° C. or 400 ° C., the etching rate was
Both ER and selectivity SR recovered to the same level as before pickling in a short time. When the heat treatment was performed at 100 ° C., the etching rate ER and the selectivity SR did not recover to the same level until 450 minutes had elapsed from the start of the process.

Heat treatment was performed at 200 ° C. or 400 ° C. in the air, but only the measured value after the completion of the process for 25 minutes was measured.
It can be said that 00 ° C. was slightly higher. In the atmosphere, Ar
Almost no significant difference was observed between each atmosphere in an inert gas of N ₂ and in a vacuum. Further, the same experiment was performed on pure Al and Al-Mg-Si alloy in Table 1, and similar results were obtained.

[0033]

As described above, the method of cleaning an aluminum part for a semiconductor device manufacturing apparatus according to the present invention can be performed by cleaning with an acid and then performing a heat treatment without deteriorating the performance of the process after restarting. The present invention has excellent effects, for example, it is possible to remove deposits deposited on aluminum parts.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a plasma processing apparatus used for carrying out a method of cleaning an aluminum part for a semiconductor device manufacturing apparatus according to the present invention.

[Explanation of symbols]

 21,22,23 Aluminum tube

Claims (1)

[Claims] 1. A method for cleaning an aluminum part used in an apparatus for manufacturing a semiconductor device, comprising cleaning the part with a cleaning liquid containing an acid selected from the group consisting of nitric acid, hydrochloric acid, and hydrofluoric acid. 200 ° C after cleaning
A method for cleaning an aluminum part for a semiconductor device manufacturing apparatus, comprising: performing a heat treatment at a temperature of 400 ° C. or lower.