WO2008004318A1

WO2008004318A1 - Method of microwave plasma treatment and apparatus therefor

Info

Publication number: WO2008004318A1
Application number: PCT/JP2006/317994
Authority: WO
Inventors: Takayuki Fukasawa; Raju Ramasamy; Tohru Yasuda; Shuitsu Fujii; Hiroshi Kajiyama; Tsutae Shinoda
Original assignee: Adtec Plasma Technology Co., Ltd.
Priority date: 2006-07-06
Filing date: 2006-09-11
Publication date: 2008-01-10
Also published as: JPWO2008004318A1

Abstract

It is intended to generate a plasma of high electron density at low temperature and carry out plasma treatment therewith. There is provided a method comprising performing a microwave excitation of plasma generation gas to thereby generate plasma and exposing a treatment object thereto so as to attain plasma treatment of the treatment object, wherein either a mixed gas consisting of Xe gas and Ne gas or Xe gas alone is used as the plasma generation gas.

Description

Specification

Microwave plasma processing method and apparatus

Technical field

[0001] The present invention relates to a method and an apparatus for generating a plasma by microwave excitation of a plasma generating gas, and irradiating the object to be processed with the plasma to plasma the object to be processed.

Background art

[0002] In the prior art, it has been practiced to irradiate an object to be processed with plasma and perform plasma processing such as etching, CVD, ashing and surface modification on the object to be processed. For example, there is known an apparatus that generates plasma by exciting a plasma generation gas by glow discharge or corona discharge, irradiates the generated plasma to a plastic film, and plasma-treats the surface of the plastic film. However, since the plasma is usually at a high temperature of 200 to 500 ° C, there is a problem that the plastic film is thermally damaged by the plasma irradiation. For this reason, the plastic film must be cooled during the plasma treatment. It was very powerful (see Patent Documents 1 to 3).

[0003] This problem has also occurred in objects to be processed other than plastic films. Even if measures are taken to cool the workpiece, if the thermal conductivity of the workpiece itself is poor, the cooling action by the cooling means is weakened, and eventually the surface of the workpiece is destroyed. There was a problem of being covered. In addition, plasma generated by glow discharge or corona discharge has a relatively low electron density and has a very high plasma processing efficiency.

[0004] Patent Document 1: Japanese Patent Laid-Open No. 10-60140

Patent Document 2: Japanese Patent Laid-Open No. 2001-49470

Patent Document 3: Japanese Patent Laid-Open No. 2005-123159

Disclosure of the invention

Problems to be solved by the invention

[0005] Accordingly, an object of the present invention is to generate a plasma having a high electron density at a low temperature and to perform plasma processing using the plasma. Means for solving the problem

[0006] In order to solve the above-described problem, the first invention is a method of generating plasma by microwave excitation of a plasma generating gas, and irradiating the workpiece with the plasma to plasma-treat the workpiece. The microwave plasma processing method is characterized in that a mixed gas of Xe gas and Ne gas is used as the plasma generating gas.

[0007] In order to solve the above problems, the second invention generates plasma by microwave excitation of a plasma generating gas, and irradiates the processing object with the plasma to perform plasma processing on the processing object. A microwave plasma processing method is characterized in that Xe gas is used as the plasma generating gas.

[0008] In the configurations of the first and second inventions, the plasma treatment is preferably plasma etching, plasma CVD, plasma ashing, or plasma surface modification.

[0009] In order to solve the above problems, the third invention provides a plasma processing chamber into which an object to be processed is introduced, a plasma generation unit that supplies plasma to the plasma processing chamber, and a plasma generation gas in the plasma generation unit A microwave plasma processing apparatus comprising: a gas supply source that supplies a microwave; and a microwave generation source that supplies a microwave for exciting a plasma generation gas to the plasma generation unit, wherein the gas supply source This is a microwave plasma processing device that is characterized by a mixed gas supply source of Xe gas and Ne gas.

[0010] In order to solve the above-mentioned problems, the fourth invention is a plasma processing chamber into which an object to be processed is introduced, a plasma generation unit for supplying plasma to the plasma processing chamber, and plasma in the plasma generation unit A microwave plasma processing apparatus comprising: a gas supply source for supplying a generation gas; and a microwave generation source for supplying a microwave for exciting a plasma generation gas to the plasma generation unit, The gas supply source constitutes a microwave plasma processing apparatus characterized by being an Xe gas supply source.

[0011] In the configurations of the third and fourth inventions, the plasma treatment is preferably plasma etching, plasma CVD, plasma etching, or plasma surface modification. The invention's effect

[0012] According to the present invention, a mixed gas of Xe gas and Ne gas, or Xe gas is used as a plasma generating gas, and it is microwave-excited to generate a plasma having a high electron density and a low temperature. Can be generated. Since the object to be processed can be irradiated with plasma having a high electron density at this low temperature, it is not necessary to cool the object to be processed at the time of plasma processing. It can be done efficiently.

Brief Description of Drawings

FIG. 1 is a longitudinal sectional view showing a schematic configuration of a plasma torch used in an experiment for confirming the effect of a microwave plasma processing method according to the present invention.

FIG. 2 is a graph showing the relationship between the distance in the z-axis direction with the origin at the tip of the discharge tube and the plasma temperature when different types of plasma generating gases are supplied to the plasma torch of FIG.

[Fig. 3] A graph showing the relationship between the distance in the z-axis with the discharge tube opening at the origin and the electron density of the plasma when different types of plasma generating gas are supplied to the plasma torch in Fig. 1. is there.

FIG. 4 is a perspective view showing a schematic configuration of a microwave plasma processing apparatus according to one embodiment of the present invention.

FIG. 5 is a cross-sectional view taken along line XX in FIG.

6 is a cross-sectional view taken along the line II ′ of FIG.

FIG. 7 is a cross-sectional view taken along the line Π—Π ′ in FIG.

Explanation of symbols

[0014] 1 discharge tube

2 Ground electrode

3 Gas inlet pipe

4 Antenna

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described. According to the microwave plasma processing method of the present invention, a mixed gas of Xe gas and Ne gas, or Xe gas is used as a plasma generating gas, and the plasma generating gas is microwave-excited to generate plasma. The plasma is applied to the workpiece by irradiating the workpiece with the plasma. In this case, when using a mixed gas of Xe gas and Ne gas, it is preferable to contain 0.05% or more of Xe gas in the mixed gas.

[0016] Thus, according to the method of the present invention, it is possible to generate a plasma having a low temperature and a high electron density, and irradiating the workpiece with the generated plasma, thereby cooling the workpiece. Without any special means for rejecting, plasma processing can be performed without causing thermal damage to the object to be processed.

[0017] An experiment was conducted to confirm the effect of the method according to the present invention. In the experiment, a plasma torch as shown in Fig. 1 was used, plasma was generated under the same conditions by supplying different types of plasma generating gas, and the temperature and electron density of the generated plasma were measured. It was done by the method of doing.

As shown in FIG. 1, the plasma torch includes a discharge tube 1 (inner diameter 10 mm) made of quartz glass and a stainless steel ground electrode 2 covering the outside of the discharge tube 1. Inside, a stainless steel antenna 4 is disposed along the central axis for supplying microwaves. Furthermore, a gas introduction tube 3 made of quartz glass is connected to the upper part of the discharge tube 1.

[0019] Then, this plasma torch is attached to the chamber, and as a gas for generating plasma, He gas, a mixed gas of He gas and Xe gas (two kinds of Xe gas ratio force and 10%), Ne gas, Ne Gas and Xe gas mixture gas (2 kinds of Xe gas ratio power and 10%), Ar gas is supplied, plasma is generated under the conditions of 3 OTorr, 20 W, 1.5 SLM, and the plasma torch discharge tube 1 The z-axis was set in the axial direction of the discharge tube 1 with the tip opening as the origin (see Fig. 1), and the plasma temperature and electron density were measured while changing the distance in the z-axis direction.

[0020] The measurement results of the plasma temperature are shown in the graph of FIG. 2, and the measurement results of the electron density of the plasma are shown in the graph of FIG. As can be seen from the graphs in Fig. 2 and Fig. 3, the plasma generated by the excitation of the mixed gas of Ne gas and Xe gas is different from that of other gases. It can be seen that the temperature is low and the electron density is remarkably high. In the graph of Fig. 2, the force at which the temperature of the plasma generated by the excitation of the He gas is much lower, as shown in the graph of Fig. 3, has an extremely low electron density.

[0021] Further, using a mixed gas of Xe gas and Ne gas, the range of the pressure at which the plasma ignites in this plasma torch was examined. Under the pressure in the range of atmospheric pressure to several Ton: It was confirmed that the plasma was surely ignited.

Sarakuko has confirmed that the desired effect can be obtained when mixed gas containing 0.05% or more of Xe gas is used. Also, in this experiment, the same result as in the case of a mixed gas of Xe gas and Ne gas can be obtained even in the case of only the force Xe gas that did not supply only the Xe gas to the plasma torch.

FIG. 4 is a perspective view showing a schematic configuration of a microwave plasma processing apparatus according to one embodiment of the present invention. Referring to FIG. 4, according to the present invention, a plasma processing chamber 10 into which an object to be processed is introduced, and a plasma generation unit 11 that supplies plasma to the plasma processing chamber 10 are provided. In addition, a gas supply source 12a for supplying a plasma generation gas to the plasma generation unit 11, a gas supply source 12b for supplying a reaction gas to the plasma generation unit 11, and a plasma generation unit for exciting the plasma generation gas A microwave source 13 for supplying microwaves is provided. The gas supply source 12a supplies a mixed gas of Xe gas and Ne gas or only Xe gas as a plasma generating gas.

In this apparatus, a plasma generating gas and a reactive gas are supplied to the plasma generating unit 11, and both gases are excited into a plasma state substantially simultaneously.

[0023] FIG. 5 is a cross-sectional view taken along line XX in FIG. 4, FIG. 6 is a cross-sectional view taken along line XX in FIG. 5, and FIG. It is sectional drawing along a line. In FIGS. 6 and 7, since the longitudinal length y of the waveguide 16 is longer than the thickness b, the left portion is partially omitted.

Referring to FIG. 5, a longitudinally long opening extending in the microwave propagation direction is formed in waveguide 16, and discharge tube 14 is attached to this opening. The discharge tube 14 is made of a dielectric material such as quartz glass or ceramic, and both end portions are closed, and an intermediate portion has an inverted U-shaped cross section. The discharge tube 14 has a part 14 ”of its peripheral wall that invades the internal space of the waveguide 16. The vertically long opening that faces the part 14 ″ of the peripheral wall is disposed downward. The vertically long opening forms a plasma emission port 15.

The waveguide 16 is supported by the support block B, and the discharge tube 14 is held by the support block B. On both sides of the support block B, gas introduction paths Gl and G2 for supplying gas to the discharge tube 14 are provided. As shown in FIG. 6, a plurality of gas introduction paths Gl and G2 are arranged at equal intervals along the longitudinal direction of the support block B against the peripheral wall of the discharge tube 14 by force.

[0026] Regarding the mounting of the plasma generating unit 11 to the plasma processing chamber 10, when the apparatus is operated near atmospheric pressure, the mounting portion of the waveguide 16 and the discharge tube 14, the support block B and the discharge tube However, when operating in a low pressure state of about several Torr, plasma operating in a conventional reduced pressure state is unnecessary. An airtight seal like a processing device is required.

[0027] Referring again to FIG. 4, G1 is a plasma generation gas introduction path, which is connected to a gas supply source 12a via a gas supply pipe 20, and G2 is a reaction gas introduction path, which supplies gas. The pipe 21 is connected to the gas supply source 12b. W is a coolant reflux path for cooling the heat generated in the discharge tube 14 by plasma. The coolant return path W is used to prevent the waveguide 16 and the support block B from becoming hot due to the plasma heat in the discharge tube. If necessary, the waveguide 16 and the plasma generation gas can be introduced. It can also be provided between the path G1 and at the side of the discharge tube 14.

[0028] As shown in Fig. 7, a slit-like gas introduction opening 14 "is provided along the longitudinal direction at the side of the discharge tube 14. This slit-like gas introduction opening. 14 "has a burrow-like opening array to maintain the mechanical strength of the discharge tube. In addition, the plasma generating gas introduction path G1 includes an extension G1 ′ in the vicinity of the gas introduction part to the discharge tube 14, and is connected to the gas introduction opening 14 ″ in the extension G1 ′. The gas introduced from the gas generating channel G1 for plasma generation is diffused in the length direction of the discharge tube 14 in the extended portion G1 ′ and introduced into the discharge tube 14. Although not shown, the reaction gas is introduced. The connection between the route G2 and the discharge tube 14 has the same configuration.

Sl and S2 are baffle plates arranged in the expansion part G1 ′ of the gas introduction paths Gl and G2, that is, A gas diffusion plate having a large number of holes spreads the gas flow introduced from the gas introduction paths Gl and G2 in the longitudinal direction of the discharge tube 14 and guides it uniformly into the discharge tube 14.

In this embodiment, in order to generate a uniform plasma in the longitudinal direction of the waveguide 16, it is important to make the gas flow as uniform as possible. Therefore, in this example, the gas was diffused in the longitudinal direction through the kaffle plates Sl and S2 so that both the plasma generating gas and the reaction gas were uniformly introduced along the longitudinal direction of the side force of the discharge tube. In this state, it is introduced uniformly into the discharge tube 14. As a result, radicals generated by the plasma reaction can be made uniform, and a uniform plasma stable in the longitudinal direction can be obtained.

[0030] In the above embodiment, the gas generating gas is introduced into G1 and the reaction gas is introduced into G2, and both gases may be introduced simultaneously from both gas introduction paths Gl and G2. In this case, gas mixing in the discharge tube 14 is improved, which contributes to plasma stability. In addition, gas inlets may be provided in three or four layers, and different types of reaction gases may be introduced individually into each pipe line.

If no reaction gas is used in the plasma treatment, either supply the gas for generating plasma to both gas introduction paths G1 and G2, or block the reaction gas introduction pipe G2.

[0031] Thus, according to the microwave plasma processing apparatus of the present invention, it is generated by microwave excitation of a mixed gas of Xe gas and Ne gas, or a simple substance of Xe gas, at a low temperature and with a high electron density! By irradiating the workpiece with plasma, there is no special means for cooling the workpiece, and etching, CVD, ashing, and surface modification that do not cause thermal damage to the workpiece Etc. can be performed.

Claims

The scope of the claims

[1] A method of generating plasma by microwave excitation of a plasma generating gas, irradiating the processing object with the plasma, and plasma processing the processing object,

A microwave plasma processing method, wherein a mixed gas of Xe gas and Ne gas is used as the plasma generating gas.

[2] A method of generating plasma by microwave excitation of a plasma generating gas, irradiating the processing object with the plasma, and plasma processing the processing object,

A microwave plasma processing method, wherein Xe gas is used as the plasma generating gas.

[3] The microwave plasma processing method according to claim 1 or 2, wherein the plasma processing is plasma etching, plasma CVD, plasma ashing, or plasma surface modification.

[4] A plasma processing chamber into which an object to be processed is introduced, a plasma generation unit that supplies plasma to the plasma processing chamber, a gas supply source that supplies a plasma generation gas to the plasma generation unit, and the plasma generation A microwave plasma processing apparatus including a microwave generation source for supplying a microwave for exciting a plasma generating gas to a section,

The microwave plasma processing apparatus, wherein the gas supply source also has a mixed gas supply source power of Xe gas and Ne gas.

[5] A plasma processing chamber into which an object to be processed is introduced, a plasma generation unit that supplies plasma to the plasma processing chamber, a gas supply source that supplies a plasma generation gas to the plasma generation unit, and the plasma generation A microwave plasma processing apparatus including a microwave generation source for supplying a microwave for exciting a plasma generating gas to a section,

The microwave plasma processing apparatus, wherein the gas supply source is an Xe gas supply source.

6. The microwave plasma processing apparatus according to claim 4, wherein the plasma processing is plasma etching, plasma CVD, plasma etching, or plasma surface modification.