JPH06283484A - Cleaning method of plasma device - Google Patents

Abstract

PURPOSE:To remove a reaction product adhering in a reaction vessel efficiently in a short time by introducing a halogen gas into the reaction vessel and generating plasma in a specific pressure region. CONSTITUTION:A plasma forming chamber 11 and the inside of a reaction chamber 13 are set at the fixed degree of vacuum, an RF power supply 28 is applied to an electrode plate 26 in a sample base 17, currents are made to flow through a double magnetic coil 17a, a coolant is passed into a coolant pipe 16, and cooling water is also passed into a cooling chamber 15. The inside of the plasma forming chamber 11 is supplied with a halogen gas as a reactive gas. Pressure at the time of plasma formation is set at 0.3-10Torr, currents are made to flow through an exciting coil 14, microwaves are introduced into the plasma forming chamber 11 while forming a magnetic field, and the gas is made to resonate and excited while employing the plasma forming chamber 11 as a cavity resonator and plasma is formed. A reaction product adhering on the reaction chamber 13 is removed by ions and radicals changed into plasma.

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 a plasma device, and more particularly to a method for cleaning a plasma device used for manufacturing semiconductor devices.

[0002]

2. Description of the Related Art In the manufacture of large-scale integrated circuits, it is necessary to form a fine pattern on a semiconductor wafer. For this reason, plasma CVD is widely used to form a thin film on the wafer.

In the formation of the thin film by the plasma CVD method, a microwave is introduced into the reaction vessel while generating a magnetic field to generate plasma to form the thin film on the wafer. However, at that time, when the reaction product adheres to the reaction container and the adhered reaction product peels off, it causes particles, and when the particles adhere to the wafer, there is a problem such as wiring short circuit. Therefore, it is necessary to prevent the particles from being generated by cleaning the reaction product attached in the reaction device.

A conventional plasma device cleaning method will be described with reference to the drawings. Figure 2 shows a typical ECR-CV
FIG. 3 is a cross-sectional view schematically showing the D apparatus, in which 10 denotes a reaction container, and the reaction container 10 forms a plasma generation chamber 11 and a reaction chamber 13. The peripheral wall of the plasma generation chamber 11 has a double structure, and the inside thereof is a cooling chamber 15 for allowing cooling water to flow therethrough, and a microwave introduction hole 11a is formed substantially in the center of the upper wall of the plasma generation chamber 11. The quartz plate 11b is provided above the microwave introduction hole 11a.
And the waveguide 12 is connected above the quartz plate 11b. A plasma extraction window 11d is formed in the lower part of the plasma generation chamber 11, and a reaction chamber 13 is arranged so as to face the plasma extraction window 11d. An anti-adhesion cylinder 29 is provided inside the reaction chamber 13, and an anti-adhesion plate 30 having a substantially L-shaped cross section is provided near the plasma extraction window 11d. A turbo molecular pump 23, a rotary pump 24, and an oil cleaner 2 for setting a predetermined pressure inside the reaction chamber 13 are provided below the reaction chamber 13.
5 is connected. Further, the exciting coil 1 is concentrically formed around the plasma generating chamber 11 and one end of the waveguide 12 connected to the plasma generating chamber 11 so as to surround them.
4 are provided.

On the other hand, a sample stage 17 is arranged in the reaction chamber 13 at a position facing the plasma extraction window 11d, and a sample 18 such as a wafer is placed on the sample stage 17. An electrode plate 26 is embedded inside the sample table 17, and the electrode plate 26 is connected to an RF power source 28 via a matching box 27 by a connecting wire 26 a. Sample stand 17
The cooling liquid pipe 16 is arranged so as to surround the inner connection line 26a, and the double magnetic coil 17a is arranged so as to further surround the cooling liquid pipe 16.

Reference numeral 11c in the figure denotes a reaction gas supply pipe communicating with the plasma generation chamber 11, and 13b denotes a reaction chamber 1.
3 shows a reaction gas supply pipe communicating with No. 3, 15a, 1
Reference numeral 5b indicates a supply pipe and a discharge pipe of cooling water, and 16a,
Reference numeral 16b indicates a supply pipe and a discharge pipe for the cooling liquid.

Further, a sample loading chamber 19 is arranged on one side of the reaction chamber 13, and the sample loading chamber 19 is provided.
A cassette 19a on which the sample 18 is placed is arranged inside. A sample cassette chamber 20 is disposed on one side of the sample loading chamber 19, and a cassette 20a on which the sample 18 is placed is disposed in the sample cassette chamber 20. A turbo molecular pump 21 and a rotary pump 22 are connected to the sample cassette chamber 20 in order to maintain the same pressure in the reaction chamber 13 as in the reaction chamber 13.

In the ECR-CVD apparatus configured as described above, cleaning is performed when 100 or more particles are generated on a silicon wafer having a diameter of 6 inches during the CVD process. When about 25 wafers are processed, cleaning is performed regularly. As the cleaning method, the EC
The R-CVD apparatus is disassembled, parts such as the adhesion-preventing cylinder 29 and the adhesion-preventing plate 30 to which the reaction product is attached are removed, and the removed parts are subjected to wet cleaning using hydrofluoric acid or the like and glass bead blasting or the like. The method of removing the reaction product is used.

However, in such a method of removing and cleaning the parts, the cleaned parts are replaced to shorten the maintenance time, but it still takes about 8 hours to disassemble and assemble the device, and the parts are replaced. It is necessary to reserve spare parts to do so. Further, the ECR-CVD apparatus is disassembled, the parts are replaced, and the parts are reassembled, which is troublesome. Furthermore, since the inside of the reaction chamber 13 is opened to the atmosphere for 2 to 3 hours at the time of decomposition, moisture in the atmosphere adheres to the wall surface inside the reaction chamber 13 and the reproducibility of the vacuum system cannot be guaranteed. There's a problem. In addition, after replacing the parts, it is necessary to perform degassing by vacuuming for about 12 hours or more in order to return the inside of the reaction chamber 13 to a vacuum state, and it takes a lot of time before it becomes operable.

In order to solve these problems, cleaning is performed by dry etching by introducing a fluorine-based reaction gas to generate plasma.

In the cleaning by dry etching, first, the inside of the plasma generation chamber 11 and the reaction chamber 13 is set to a required degree of vacuum, and then nitrogen trifluoride (NF) as a reaction gas is supplied into the plasma generation chamber 11 through the gas supply pipe 11c. ₃ ) Or supply gas such as chlorine trifluoride (ClF ₃ ). Then, a direct current is passed through the exciting coil 14 and at the same time microwaves are guided to the plasma generation chamber 11. The plasma generation chamber 11 is generated by the flow of current to the exciting coil 14.
A magnetic field is generated in the reaction chamber, and the divergent magnetic field guides the plasma into the reaction chamber 13, where the reaction products attached to the reaction chamber 13 are removed by etching.

[0012]

By the way, with the remarkable development of the semiconductor industry in recent years, there is an increasing demand for further shortening the maintenance time in the plasma device under the usage condition of full operation for 24 hours. .

In the above-mentioned cleaning method by dry etching, since there is no need to disassemble the ECR-CVD apparatus, the spare parts for replacement are unnecessary, and it is easy to return to the original vacuum state. Further, the labor can be reduced. However, there are problems that the etching rate is slow, the cleaning takes a long time, and the efficiency is extremely low.

The present invention has been made in view of the above-mentioned problems, and it is possible to efficiently remove a reaction product attached in a reaction vessel,
It is an object of the present invention to provide a cleaning method for a plasma device that can be removed in a short time.

[0015]

In order to achieve the above-mentioned object, a method of cleaning a plasma apparatus according to the present invention is designed so that a halogen-based gas is introduced into a reaction vessel to obtain 0.3 To.
It is characterized in that plasma is generated in a pressure region of rr or more and 10 Torr or less to remove the reaction product attached in the reaction vessel.

[0016]

According to the above-described method for cleaning a plasma apparatus, halogen ions and radicals are generated by introducing a halogen-based gas into the reaction vessel to generate plasma in the pressure region, and the reaction vessel The reaction product adhering to the inside is decomposed and discharged as a halide to the outside of the apparatus. For example, Si using SF ₆ gas
The cleaning of the O ₂ film is particularly effective, in which case Si and F are easily combined in plasma to form a fluoride. This makes it possible to efficiently remove the reaction product.

As the halogen-based gas, it is possible to use fluorine-based gas, chlorine-based gas, bromine-based gas and iodine-based gas, and among them, it is desirable to use fluorine-based gas and chlorine-based gas.

Further, as a result of examining the etching rate of the reaction product when plasma is generated under various pressure changes around the deposition preventive plate and the sample stage of the ECR-CVD apparatus (FIG. 1), Is less than 0.1 Torr,
The deposition rate is about 0.1 μm / min.
And about 0.001 μm / min around the sample table.
Further, when the pressure is 0.1 Torr or more, the pressure is gradually increased in both places of the adhesion preventing plate and the periphery of the sample table, and when the pressure is 0.3 Torr or more, the adhesion preventing plate is about 0.3 μm / min. And about 0.1 μm / min around the sample table. Furthermore, 1.0 Tor
When it is set to about r, it is about 1.0 μm / min for the deposition prevention plate
Around 0.15 μm / m around the sample table
It turned out to be faster. Therefore, the conventional dry etching cleaning method is several mT
It was found that it took a long time because the reaction product was etched under the pressure of orr.

However, when the pressure exceeds 10 Torr, the plasma becomes unstable and stable cleaning cannot be performed. Therefore, the pressure should be 0.3 Torr or more and 10 Torr.
It must be within the range of r or less.

Therefore, 0.3 Torr or more and 10 To
By generating the plasma in the pressure region of rr or less, the reaction product attached to the reaction container is etched very quickly, and cleaning can be performed in a short time.

[0021]

EXAMPLES AND COMPARATIVE EXAMPLES Examples and comparative examples of the plasma device cleaning method according to the present invention will be described below with reference to the drawings. In this embodiment, S is placed on the silicon wafer.
A cleaning method after forming the iO ₂ film will be described. Further, in this embodiment, a general ECR-CVD apparatus similar to the conventional one is used as the plasma apparatus, and the description of the configuration of the ECR-CVD apparatus is omitted here.

First, O ₂ gas (54 sc
cm) and SiH ₄ gas (45 sccm) are used to deposit SiO ₂ on the silicon wafer having a diameter of 6 inches to form a SiO ₂ film having a thickness of 1.0 μm.
00 repeat.

After that, SiO ₂ deposited in the reaction chamber 13
In order to remove the reaction product of (1) by cleaning, first, the turbo molecular pump 23 and the rotary pump 24 are operated to set the inside of the plasma generation chamber 11 and the reaction chamber 13 to a predetermined vacuum degree, and then the electrodes in the sample table 17 are removed. RF power source 2 on plate 26
8 is applied, a current is passed through the double magnetic coil 17a, a cooling liquid is passed through the cooling liquid pipe 16, and cooling water is also passed through the cooling chamber 15. Then, a halogen-based gas as a reaction gas is supplied into the plasma generation chamber 11 through the reaction gas supply pipe 11c. The pressure at the time of plasma generation is set to about 1.0 Torr, a microwave is introduced into the plasma generation chamber 11 while forming a magnetic field by passing a current through the exciting coil 14, and the gas is used as a cavity resonator in the plasma generation chamber 11. Resonance excitation is performed to generate plasma. The generated plasma is the excitation coil 1
4 is formed in the reaction chamber 13 by a divergent magnetic field whose magnetic flux density decreases toward the reaction chamber 13 side, and the reaction chamber 1 is projected by the ions and radicals that are turned into plasma and are converted into plasma.
The reaction product attached inside 3 is removed.

The cusp surface of the plasma in the reaction chamber 13 can be moved by changing the current passed through the double magnetic coil 17a.

Table 1 shows the deposition prevention in the case where the cleaning was carried out for 1 hour under the pressure of about 1.0 Torr according to the example and the case where the cleaning was carried out for 1 hour under the pressure of about 0.01 Torr according to the comparative example. Adhesion points A to J of the reaction product 31 on the plate 30 and around the sample table 17b
FIG. 3 is a comparison of the etching amount and etching rate in FIG.

The etching conditions at this time are NF ₃ (300 sccm) and O ₂ (100
The power of the microwave is set to 2500 W, the RF power is set to 1000 W, the current of the exciting coil 14 is set to 20 A, and the current of the double magnetic coil 17a is set to 15 A.

[0027]

[Table 1]

As is clear from Table 1, in the case of the cleaning method according to the comparative example under the pressure of about 0.01 Torr, the reaction product 31 was scarcely removed at all places, and the etching rate was very high. It is slow, and particularly, the portions H and J around the sample table 17b are not etched at all, but in the case of the cleaning method under the pressure of 1.0 Torr according to the embodiment, the etching amount in the deposition preventive plate 30 is significantly increased. However, it is completely removed particularly at the points A and B. In addition, in the periphery 17b of the sample table, 3 μm to
It is etched away by 8 μm. In addition, the etching rate is as high as about 20 times particularly in the area of E, and is greatly improved in all areas. Therefore, it was confirmed that the reaction product 31 around the deposition preventive plate 30 and the sample table periphery 17b can be removed very efficiently by setting the pressure to about 0.1 Torr or more.

As described above, in the plasma apparatus cleaning method according to the embodiment, since halogen-based gas is introduced as an etching gas to generate plasma under the pressure range, halogen ions and radicals are not generated. The reaction product 31 generated and attached to the reaction chamber 13 can be decomposed, and the reaction product 31 attached to the reaction chamber 13 can be efficiently removed.

Further, since the plasma is generated in the pressure region of 0.3 Torr or more and 10 Torr or less, the reaction chamber 1
The reaction product 31 attached inside 3 can be etched very quickly, and can be cleaned in a short time.

Although the effect of the cleaning method according to the embodiment in the reaction chamber 13 has been described in the above embodiment, the same effect can be obtained in the plasma generation chamber 11.

Further, in the above embodiment, the cleaning method in the case where the SiO ₂ film is formed by the CVD method has been described, but other metal films such as TiN and W are CVD-formed.
The present invention can be similarly applied to the case of forming by.

[0033]

As described above in detail, in the plasma apparatus cleaning method according to the present invention, a halogen-based gas is introduced as an etching gas into the reaction vessel to obtain 0.3T.
Since the plasma is generated in the pressure range of not less than orr and not more than 10 Torr, halogen ions and radicals can be generated to decompose the reaction product attached in the reaction vessel, and the reaction attached in the reaction vessel. The product can be removed efficiently.

Further, since the plasma is generated in the pressure range of 0.3 Torr or more and 10 Torr or less, the reaction product adhering to the inside of the reaction vessel can be etched at a very high speed, and it is stable in a short time. The plasma device can be cleaned.

Therefore, the maintenance time of the plasma device can be greatly shortened.

[Brief description of drawings]

FIG. 1 is a graph showing the results of investigating the etching rates of reaction products around the deposition preventive plate and the sample table when the pressure during plasma generation was variously changed in a general ECR-CVD apparatus. is there.

FIG. 2 is a schematic cross-sectional view showing a general ECR-CVD apparatus used in an embodiment of a plasma apparatus cleaning method according to the present invention.

FIG. 3 is a schematic cross-sectional view showing adhesion points A to J of the reaction product 31 around the deposition preventive plate and the sample table according to the embodiment.

[Explanation of sign]

 10 reaction vessel 31 reaction product

Claims (1)

[Claims] 1. A plasma characterized by introducing a halogen-based gas into a reaction vessel to generate plasma in a pressure region of 0.3 Torr or more and 10 Torr or less, and removing a reaction product attached to the reaction vessel. How to clean the device.