JP2787006B2 - Processing method and processing apparatus and plasma light source - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing method and a processing apparatus.
And relates to a plasma light source, in particular, the microwave power and the excitation source, e.g., a semiconductor material of the etching or deposition, surface treatment or surface modification, as a light emitting or ion source in the elemental analysis, a higher brightness for photoreaction A processing method, a processing apparatus , and a processing method that can be used as a short wavelength light source or the like.
Related to plasma light source .

[0002]

2. Description of the Related Art Conventional plasma generating means using microwave (1 GHz or more) power is described in (1) Review Scientific Instruments (Rev. Sci.
Instrum), 36, 3 (1965), 294-298
Page, (2) IEE Transaction of Plasma Science (IEEE Trans. Of Elect.
Plasma Sci.), PS-3, 2 (1975), 55-5
Page 9, (3) Review Scientific Instruments (Rev. Sci. Instrum.), 39, 11 (196)
8), pp. 295-297, and the like.

On the other hand, plasma generation means using high-frequency power of several hundred MHz or less are described in, for example, (4) Philips Tech.
v.), 23, 2 (1973), pp. 50-59.

A plasma generator for generating plasma with high frequency power of several MHz to several tens of GHz is disclosed in US Pat. Nos. 3,663,858 and 3,980,855.

[0005]

The above-mentioned reference (1),
The conventional techniques (2) and (3) using microwave power have a complicated structure and are limited in size and the like, so that the microwave power utilization rate is increased, the plasma diameter is increased, and the density is increased. No consideration has been given to optimizing the radial distribution and further increasing the excitation microwave power. The physical quantity (density, etc.) of the plasma, its generation efficiency, and the properties of the film material obtained when used for deposition, etc. There have been problems in sensitivity, cost, and the like in analytical instruments when used for throughput, elemental analysis, and the like.

On the other hand, the prior art using high-frequency power disclosed in the above-mentioned reference (4) has a complicated structure of an oscillator and the like, and has problems in high-frequency power utilization, measures against radio interference, cost, and the like. Note that the microwave-excited plasma generator is
And the inner conductor form a cylindrical coaxial waveguide, and a non-conductive discharge tube
Is placed inside the inner conductor, and
Apply microwave power. In addition, generation of plasma and its closing
Magnetic field generating means outside the outer conductor to improve confinement
May be provided. Discharge to the discharge tube of the plasma generator
Gas that reacts chemically or physically with the generated plasma
And samples introduced into the reaction chamber system and placed in the reaction chamber system
To plasma processing. Alternatively, the discharge tube
At least one of ions and neutral particles from the generated plasma
Is selectively taken out and introduced into the reaction chamber system.
Perform surface treatment and surface modification of materials. Or to the discharge tube
At least ions from the generated plasma are transferred to the mass spectrometer
Introduce and analyze, or direct luminescence to a spectrometer to analyze elemental
Analyze. Alternatively, radiate from the plasma generated in the discharge tube
The photochemical reaction is performed using the short wavelength light.

An object of the present invention is to solve the problems of the prior art described above, high-density, large diameter, a processing method with less plasma impurities uniform capable of generating a stable high efficiency and processing apparatus, and It is to provide a plasma light source .

[0008]

An object of the present invention is to form a cylindrical coaxial waveguide with a cylindrical outer conductor and a helical coil-shaped inner conductor, and to place at least a part of a non-conductive discharge tube inside the inner conductor. This is achieved by arranging and applying a microwave power between the outer conductor and the inner conductor.

[0009] That is, the processing method of the present invention, the material to be processed placed in a reaction chamber, Mai from microwave generating source
One end is connected to a coaxial waveguide converter from a three-dimensional circuit.
And the other end is connected to the outer conductor of the coaxial waveguide.
Microwave to the coaxial waveguide having an il-shaped inner conductor.
With a coaxial waveguide converter to match the impedance
Discharge tube supplied after conversion and arranged inside the inner conductor
A gas for plasma generation is introduced into the
Microwave power is applied between the outer conductor and the inner conductor.
To generate plasma, and the reaction is performed using the plasma.
Processing the material with the reaction gas introduced into the chamber
It is characterized by. In addition, the processing device of the present invention should process
Reaction chamber for placing materials, microwave source, and outer conductor
And a coaxial waveguide having a helical coil-shaped inner conductor,
Microwave from the microwave source to the coaxial waveguide
And a three-dimensional circuit for supplying the coaxial waveguide from the three-dimensional circuit.
In order to transmit microwaves to the tube, the microwave impulse
Transform the impedance to match the
A coaxial waveguide converter, and disposed inside the inner conductor.
A discharge tube and a gas introduction system for introducing a reaction gas into the reaction chamber
And a gas introduction unit for supplying gas to the discharge tube.
One end of the helical coil-shaped inner conductor is connected to the coaxial conductor.
Connected to the wave tube converter, the other end is connected to the outer conductor,
A gap between the outer conductor and the inner conductor of the coaxial waveguide
A plasma is generated by applying
Processing the material with the reactive gas using a mask
It is characterized by. The processing method of the present invention should be processed
A first step of placing the material in the reaction chamber, and a helical coil
Coaxial waveguide having at least a part of
Plasma generation consisting of a discharge tube placed inside the inner conductor
A gas for plasma generation is introduced into the discharge tube of the generator.
Microwaves introduced from the three-dimensional circuit
The coaxial waveguide converter supplies the magnet to feed the axial waveguide.
The impedance is set so that the
The outer conductor of the coaxial waveguide and the
Apply the microwave power between the inner conductor and release the gas.
A second step of generating a plasma by
Third step of extracting ions or neutral particles from zuma
Irradiates the target with selected ions or neutral particles.
A fourth step of firing and a target from the target
Irradiating a substance to the material to process the material.
And features. Further, the plasma light source of the present invention
A microwave source, and a microwave from the microwave source.
Three-dimensional circuit for transmitting waves, outer conductor and helical coil
A coaxial waveguide having an inner conductor made of
Transmitting microwaves from the three-dimensional circuit to the coaxial waveguide
To match the microwave impedance
A coaxial waveguide converter for converting the impedance to
A discharge tube at least partially disposed inside the inner conductor
And means for introducing a gas into the discharge tube.
And the gas is turned into plasma to emit ultraviolet light,
It is characterized by the following.

[0010]

[0011]

[0012]

[0013]

[0014]

[Function] A microwave is used as an excitation power source, the inner conductor of the cylindrical coaxial waveguide is a helical coil inner conductor, and a discharge tube is provided inside the inner conductor to generate plasma. Operate as the primary coil of the transformer, while the plasma equivalently operates as the secondary coil of the transformer (1 turn).

Thus, the dimensions and shapes of the inner and outer conductors can be freely set, so that a plasma having a diameter suitable for the purpose of use can be obtained with a simple configuration. The outer conductor also functions as a shield case.

Further, the discharge current I ₂ flowing in the plasma
Is proportional to the product of the excitation current I ₁ flowing through the primary side coil and the excitation frequency f (I ₂ ∝f · I ₁ ). Therefore, in order to increase the discharge current I ₂ , the excitation frequency f is increased. It is effective. Therefore, the high frequency (100 MHz
The use of microwaves (1 GHz or more) can increase the discharge current I ₂ by 10 times or more even when the constant I ₁ is used as compared with the use of (i.e. It can also be used as a high brightness light source.

Further, since the skin depth (skin depth) δ becomes δ∝1 / √ (f) in inverse proportion to the square root of the excitation frequency f, δ becomes smaller when a microwave having a larger f is used. will flow a large discharge current in the peripheral portion of the plasma, the electric field strength of the outward toward the periphery of the plasma E ₀
And acts to efficiently generate a toroidal or toroidal plasma particularly in a high pressure region. On the other hand, in the low pressure region, the above E ₀ compensates for the diffusion loss, so that it acts to form a large-diameter and uniform plasma.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a cross-sectional view and a top view of a microwave-excited plasma generation system which is the basis of the present invention. The plasma generation system of the present embodiment includes a cylindrical outer conductor 30 and a helical coil-shaped inner conductor (a wire or pipe of copper or the like having about 2 to 10 turns, for example, a pitch of 0.5 cm, an inner diameter of 1 to 10 cm).
20), a discharge tube 10 made of quartz glass or the like, and a coaxial waveguide converter 40 are arranged as shown in the figure. In order to efficiently transmit the microwave power to the inner conductor 20 in the form of a helical coil, the dimension of the E-plane of the coaxial waveguide converter 40 is made smaller than the standard size to reduce the characteristic impedance, and the input side is connected to the input side. A quarter-wave transformer 50 is provided to match the characteristic impedance of the coaxial portion, and a plunger 6 is provided on the opposite side.
It is good to set 0 and take matching. Further, the coaxial portion of the coaxial waveguide converter 40 may be a doorknob type or the like. Furthermore, especially at low pressure operation, in order to improve the generation and confinement of plasma, a magnetic field generator (consisting of an air-core coil or a permanent magnet, etc.) is used. The direction of the lines of magnetic force that forms a divergent beach magnetic field or the like is not limited) 90 may be provided. Further, although the tip 21 of the helical coil-shaped inner conductor 20 is shown to be connected to the outer conductor 30, this need not be connected.

Next, the basic operation will be described. Microwave power (for example, 2.45 GHz, 1.5 kW, stationary or pulse modulation, etc.) from a microwave generator such as a magnetron is transmitted from the coaxial waveguide converter 40 to the helical coil-shaped inner conductor 20, Generates a magnetic field in the axial direction. At this time, an electric field is induced by the magnetic field induction in a direction opposite to the direction of the current flowing through the inner conductor 20 in the helical coil shape, and the gas or the like introduced into the discharge tube 10 from the gas / sample introducer 70 is ionized, and the plasma 80 Generate and heat.
In the plasma 80, a current proportional to the product of the current flowing in the helical coil and the microwave frequency flows intensively in the peripheral portion due to the skin effect. For this reason, at high pressure, the temperature and density distribution of the plasma has a so-called donut shape or a toroidal shape having a peak at the peripheral portion. Therefore, when a sample to be analyzed is introduced into the inside of the donut, the sample is heated by heat conduction or radiation, and can be efficiently ionized (plasma). The operation is performed in a steady or unsteady state (pulse).

In the above embodiment, since the microwave transmission circuits are all composed of three-dimensional circuits, large power can be supplied, and large-capacity high-temperature and high-density (cut-off density or more) can be easily obtained. . Note that forced air cooling or water cooling may be performed as necessary.

FIG. 2 shows a cross section of a low power embodiment. This embodiment is characterized in that an output from a microwave generator such as a magnetron is transmitted to a microwave-excited plasma generation system via a coaxial cable and a matching circuit (may be omitted). In FIG. 2, reference numeral 41 denotes a microwave input coaxial connector, and other reference numerals denote the same parts as those in the embodiment of FIG. Although the tip 21 of the helical coil-shaped inner conductor 20 is not connected to the outer conductor 30 in the figure, it may be connected.

According to this embodiment, since the diameter of the inner and outer conductors can be set arbitrarily, there is an advantage that the diameter of the discharge tube 10 can be arbitrarily set correspondingly. Therefore, the plasma 80
Can also be set arbitrarily, which is particularly useful when large-diameter plasma is required. In this embodiment, an external magnetic field generator (9 in FIG.
0) may be provided.

The discharge tube 1 in the embodiment shown in FIGS. 1 and 2
The shape of 0 and the inlet for gas or the like are not limited to the illustrated example. The operating gas is H ₂ , H depending on the purpose.
e, O ₂ , Ar, Xe, Hg, CH ₄ , NH _3, etc. are selected, and the pressure in the tube is set in the range of 10 ^{−6 to} 760 Torr.

Next, referring to FIGS. 3 to 6, the microwave-excited plasma generation system is replaced with a plasma processing apparatus for creating a new material such as a deposition, a surface modification of the material, and the like.
An example in which the present invention is applied to trace element analysis and a light source such as ultraviolet light will be described.

FIG. 3 is a block diagram of an embodiment of the present invention in which the microwave-excited plasma generating system is applied to a plasma processing apparatus such as etching and deposition. In FIG. 3, reference numeral 100 denotes a microwave generation system, which includes a high-voltage power supply (DC or pulse), a microwave oscillator (such as a magnetron and a gyratron), an isolator, a power meter, an EH tuner, and the like. Reference numeral 200 denotes a microwave plasma generation system, which comprises the components shown in FIG. 1 or FIG. Reference numeral 300 denotes a gas / sample introduction system, and gas (H ₂ , He, Ne, O ₂ , Ar,
Xe, Hg alone or a mixed gas thereof) or reactive fine particles (for example, BaCO ₃ + Y ₂ O ₃ + CuO or LaB ₆ )
And a device for introducing Reference numeral 400 denotes a reaction chamber system, which comprises a high vacuum vessel, a substrate mounting table, a substrate heating or cooling device, a bias applying device, and the like. Reference numeral 500 denotes a substrate temperature / bias system, which comprises a substrate temperature and bias control circuit and the like. Reference numeral 600 denotes a reaction gas / sample introduction system.
It comprises a reaction gas introducer for introducing a reaction gas such as H ₄ , CF ₄ , SiF _{4 and the} like, and an electron beam or laser vapor deposition apparatus for producing and introducing the ultrafine particles. Reference numeral 700 denotes an observation system such as a substrate surface state, which is constituted by a spectroscope, a mass analyzer, and the like. 800 shows an exhaust system, the reaction chamber system 4
A turbo pump for evacuating the reaction chamber in the fuel cell 00, the discharge tube in the microwave plasma generation system 200, and the like.
Reference numeral 1000 denotes a control system composed of a microcomputer or the like, which includes a microwave generation system 100, a substrate temperature / bias control system 500, a gas / sample introduction system 300, a reaction gas / sample introduction system 600, and a substrate surface state observation system 700. It has a function to control and optimize the entire apparatus (optimization of the obtained material etc.) and to sort and store various data. The feature of the apparatus shown in FIG. 3 is that a gas or a sample that chemically or physically reacts with the plasma generated by the discharge tube of the microwave-excited plasma generation system is introduced into the reaction chamber system and placed in the reaction chamber system. To perform plasma processing on the material.

FIG. 4 shows a state in which ions and neutral particles (radicals, etc.) from the generated high-density plasma are selectively taken out.
FIG. 3 is a block diagram of an embodiment in the case where surface processing, surface modification, and the like of a material are performed. In FIG. 4, reference numeral 900 denotes a particle sorting system, which comprises an electromagnetic field applying device for selectively extracting ions, radicals, and the like from the microwave plasma generation system 200. Other symbols are the same as those in FIG. In addition, in this microwave-excited plasma generator, the ions and radicals are directly reacted with the substrate to modify the surface of the material, and the ions are used to bombard the target once and released from the target. It can also be used as an apparatus for depositing a target material on a substrate. The feature of the apparatus shown in FIG. 4 is that at least one of ions and neutral particles is selectively extracted from the plasma generated by the discharge tube of the microwave-excited plasma generation system and introduced into the reaction chamber system. Surface treatment and surface modification of the above materials.

FIG. 5 is a block diagram showing an embodiment in which trace elements are analyzed by using light emission and ions from the generated high-density and high-temperature plasma. In FIG. 5, reference numeral 310 denotes a sample / gas introduction system, which comprises a sample to be analyzed, a carrier gas (He, N ₂ , Ar, etc.), and a nebulizer for atomizing these. Reference numeral 1100 denotes an ion extraction system, which is composed of an electrostatic lens system such as a skimmer and an Einzel lens. Reference numeral 1200 denotes a mass spectrometry system, which includes a mass filter or the like. Reference numeral 1300 denotes an emission analysis system, which comprises a spectroscope or the like. In the elemental analysis according to the present embodiment, operating conditions can be set so as to generate toroidal plasma (for example, generation of a small-diameter plasma having a diameter of about 2 cm or less at atmospheric pressure), and high sensitivity and high efficiency can be achieved. There are significant advantages that can be realized. The feature of the apparatus shown in FIG. 5 is that elemental analysis means for introducing at least ions from a plasma generated in a discharge tube of the above-mentioned microwave-excited plasma generating system into a mass spectrometer for analysis, or guiding luminescence to a spectroscope for analysis. It is located with.

FIG. 6 is a block diagram showing an embodiment in which a material is subjected to surface treatment or the like using ultraviolet rays or the like radiated from plasma. In FIG. 6, reference numeral 1400 denotes an ultraviolet extraction system, which is a plate or a metal mesh (bias potential) such as quartz or calcium fluoride so as to prevent plasma from diffusing into the reaction chamber system 400 and improve the transmission of ultraviolet light. Application). In addition, as plasma,
The operating conditions are set (for example, set to a low pressure) using Ar-Hg, Xe, or the like so that a large-diameter uniform plasma is obtained so that ultraviolet rays are generated efficiently. In this embodiment, a thin film is formed by photochemical reaction (eg, activation of Cl ₂ ) or a thin film formed by epitaxially growing Si by decomposing SiH ₄ (ie, photochemical vapor deposition). First, it can be used in fields such as resist ashing (ashing) performed by irradiating O ₂ with light. The advantage of this embodiment is that light of an arbitrary wavelength can be obtained with high brightness and a large area by selecting a gas. In the case of this embodiment, the discharge tube (10 in FIGS. 1 and 2) installed in the microwave plasma generation system 200 may be composed of a plurality of discharge tubes. A feature of the apparatus shown in FIG. 6 is that a photochemical reaction is performed using short-wavelength light radiated from plasma generated in a discharge tube of the microwave-excited plasma generating system.

[0030]

As described above, according to the present invention,
The inner conductor of the cylindrical coaxial waveguide is formed into a helical coil shape, a discharge tube is provided inside it, and microwave power is used, so that the size and shape are not limited by the microwave excitation frequency. Large current that is proportional to the product of the frequency and the microwave excitation frequency can flow in the plasma. In addition, a plasma having an arbitrary diameter can be generated efficiently and easily with a diameter distribution according to the purpose.

[0031] Thus, the plasma generated more to the onset Ming, including the plasma processing such as etching or deposition process, such as a semiconductor material, new material of creation and surface processing and surface modification, light emission in the elemental analysis and ion As a light source, there is an advantage that it can be widely used as a high-luminance short-wavelength light source for photoreaction.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view and a top view of one embodiment of a microwave-excited plasma generation system of the present invention.

FIG. 2 is a sectional view of another embodiment of the microwave-excited plasma generation system of the present invention.

FIG. 3 is a block diagram of an embodiment of an apparatus using plasma generated by the plasma generation system shown in FIG. 1 or 2 and used for plasma processing of a material.

FIG. 4 is a block diagram of an embodiment of an apparatus using plasma generated by the plasma generation system of FIG. 1 or 2 and used for surface treatment of a material or the like.

FIG. 5 is a block diagram of an embodiment of an apparatus using plasma generated by the plasma generation system of FIG. 1 or 2 and used for elemental analysis.

FIG. 6 is a block diagram of an embodiment of an apparatus using a plasma generated by the plasma generation system of FIG. 1 or 2 and used for a photochemical reaction.

[Description of Signs] 10 ... discharge tube, 20 ... helical coil-shaped inner conductor, 30 ...
Cylindrical outer conductor, 40: coaxial waveguide converter, 41: coaxial connector, 50: quarter-wave transformer, 60: plunger, 70: gas / sample introducer, 80: plasma, 90 ...
Magnetic field generator, 100: microwave generation system, 200: microwave plasma generation system, 400: reaction chamber system, 900: particle sorting system, 1000: control system.

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI H05H 1/46 H01L 21/302 B (56) References JP-A-63-279599 (JP, A) JP-A-63-80449 ( JP, A) JP-A-53-7199 (JP, A) JP-A-62-290054 (JP, A) JP-A-63-7376 (JP, A) JP-A-62-228482 (JP, A) (58) ) Surveyed fields (Int.Cl. ⁶ , DB name) H01J 37/32 C23F 4/00 H01J 27/00-27/26 H01J 37/08 H01L 21/3065 H05H 1/46

Claims (9)

(57) [Claims] 1. A material to be processed is placed in a reaction chamber, and microwaves from a microwave generation source are sent from a three-dimensional circuit to one.
One end is connected to the coaxial waveguide converter and the other end is outside the coaxial waveguide.
A helical coil-shaped inner conductor connected to the conductor.
Match the microwave impedance to the coaxial waveguide
The coaxial waveguide converter converts and supplies the converted plasma to a discharge tube arranged inside the inner conductor for plasma generation.
Gas between the outer conductor and the inner conductor of the coaxial waveguide.
A plasma gas is generated by applying a microwave power, and a reaction gas introduced into the reaction chamber using the plasma.
A processing method, wherein the material is processed by the following method. 2. The temperature of the material for processing the material.
The processing method according to claim 1, wherein the control is performed. 3. A coaxial waveguide having a reaction chamber in which a material to be processed is arranged, a microwave source, an outer conductor and a helical coil-shaped inner conductor.
Tube and microwave from said microwave source to said coaxial waveguide
And transmitting microwaves from the three-dimensional circuit to the coaxial waveguide.
In order to match the impedance of the microwave
And a discharge tube arranged inside the inner conductor, a gas introduction system for introducing a reaction gas into the reaction chamber, and a gas for supplying a gas to the discharge tube. One end of the helical coil-shaped inner conductor is provided with the coaxial waveguide.
The other end of the coaxial waveguide is connected between the outer conductor and the inner conductor of the coaxial waveguide.
A microwave power is applied to generate plasma, and the material is applied by the reaction gas using the plasma.
A processing device characterized by processing. 4. A temperature control means for heating or cooling said material.
The processing apparatus according to claim 3, further comprising a step.
Place. 5. The method according to claim 1, wherein said reaction gas is etched or deposited.
4. The processing according to claim 3, wherein the processing gas is an application gas.
apparatus. 6. The pressure in the discharge tube is 10 ^{-6 to} 760 To.
The processing apparatus according to claim 3, wherein rr is rr. 7. A first method for placing a material to be processed in a reaction chamber.
Process and a coaxial waveguide with a helical coil-shaped inner conductor
And a part from the discharge tube arranged inside the inner conductor.
Plasma is generated inside the discharge tube of the plasma generator.
Introduce raw gas and use the three-dimensional circuit
Coaxial waveguide conversion to supply
To match the impedance of the microwave
Transform the impedance so that it is in front of the coaxial waveguide
Microwave power is applied between the outer conductor and the inner conductor.
To generate plasma by discharging the gas
A degree, third taking out the ions or neutral particles from the plasma
And irradiating the target with selected ions or neutral particles
Irradiating a fourth step that the target material from the target to the material
And a fifth step of processing.
Law. 8. The method according to claim 1, wherein a reaction gas is introduced into the reaction chamber.
The processing method according to claim 7, which is characterized in that: 9. A microwave generation source, and for transmitting microwaves from said microwave generation source.
Three-dimensional circuit and an outer conductor and an inner conductor made of a helical coil wire.
It is transmitted and coaxial waveguide, the microwave to the coaxial waveguide from the microwave circuit to
In order to match the impedance of the microwave
And a discharge tube at least partially disposed inside the inner conductor.
And means for introducing a gas into the discharge tube, wherein the gas becomes plasma and emits ultraviolet light to serve as a light source.
A plasma light source characterized in that: