JPH0221296B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention utilizes plasma active species, ions, and synchrotron radiation generated by gas discharge as processing materials to produce a predetermined powder, or to perform etching and etching on the surface of a substrate to be processed. This invention relates to a discharge reactor that performs surface treatments such as deposition, modification, and cleaning. (Prior Art and its Problems) Conventionally, the most commonly used discharge reaction apparatus of the above type is a parallel plate type surface treatment apparatus, a schematic cross section of which is shown in FIG. In this device, direct current is supplied from a power source 35 between parallel plate electrodes 32 and 33 (33 is connected to the grounded vacuum vessel 31), which are placed opposite each other in a vacuum vessel 31 having a gas introduction system 30 and an exhaust system 39. A voltage such as an alternating current or high frequency voltage is applied to generate a discharge, and the discharge plasma 38 is used to perform surface treatment on the substrate 37 to be processed on the electrode 33 heated by the heater 36. 34 is an insulator. Similar devices include various devices in which parallel plate electrodes are modified or replaced with coaxial cylindrical electrodes, or the number of electrodes is increased or decreased. However, these devices have a common drawback that the discharge plasma 38 has a low density and cannot perform high-speed processing. Further, since the substrate 37 to be processed is in direct contact with the discharge plasma 38, there is a problem that the substrate is damaged by being irradiated with charged particles. In order to avoid radiation damage to the substrate, various devices have been proposed that generate discharge plasma at a location away from the substrate and transport only the active species or ions in the plasma to the surface of the substrate to be processed. This device also has drawbacks, such as requiring a large amount of power to obtain a processing speed suitable for practical use because the density of the discharge plasma is quite low. Note that each of the above-mentioned apparatuses is not suitable for producing powder due to the low density of plasma and the low pressure range used. A discharge reactor that can obtain high-density discharge plasma, has a high processing speed, and can also be used for powder production is the one whose cross section is schematically shown in Figure 4.
There is a discharge reactor that utilizes electron cyclotron resonance (abbreviated as ECR). To explain this device, when a microwave 43 of, for example, 2.45 GHz is injected into a plasma chamber 41 connected to a plasma generation gas introduction system 42 and provided in a magnetic field B generated by a magnet coil 40, ECR is generated. Plasma of the introduced gas is generated by the discharge. This plasma becomes a plasma flow 44 by the diverging magnetic field created at the lower end of the magnetic field B, and is expanded and accelerated into the processing chamber 45 and ejected (if necessary, the ring-shaped pipe 46 for gas introduction is opened). A reaction gas is introduced into the processing chamber 45 via the reaction chamber 45, and in cooperation with the reaction gas, a predetermined process is performed on the substrate 47 to be processed on the sample stage 50. The processing chamber 45 includes an exhaust system 49 and a plasma chamber 41.
A cooling system 48 is connected to. However, although this device uses high-density plasma, the plasma density is around 10 ¹¹ cm ^-3 , and the ionization efficiency is still low at only a few percent. Therefore, it requires a high-power microwave oscillator, making the device very large. In addition to being expensive, the shape of the discharge chamber is limited to a special shape suitable for ECR. (Objective of the Invention) The present invention solves the above problems, generates high-efficiency and high-density plasma without requiring large electric power, uses the plasma to economically produce powder, or The purpose of the present invention is to provide a small and inexpensive discharge reaction device that can perform high-quality surface treatment with little damage at high speed. (Structure of the Invention) The present invention provides: (1)a means for introducing a predetermined gas into the interior of a hollow cylindrical body made of an insulating material; b a magnetic field directed in the axial direction of the internal space of the cylindrical body; c) applying a high-frequency alternating magnetic field in a direction intersecting the axis over a predetermined length in the axial direction to the internal space of the cylindrical body, using a standing plasma wave in the magnetic field; means for generating plasma in the space; d. active species, ions of the plasma in the space;
A means for introducing synchrotron radiation as a processing material, in part or in its entirety, from the cylindrical body into the processing chamber; A predetermined powder is generated in the processing chamber by taking into account the gas produced, or, more recently, by an electric discharge reaction device that performs a predetermined treatment on the surface of the object to be treated, which is installed in the processing chambers. , the above objective has been achieved. (Example) Hereinafter, an example of the discharge reaction device of the present invention will be described based on the drawings. FIG. 1 is a schematic cross-sectional view of a surface treatment apparatus according to an embodiment of the present invention, and the apparatus is roughly divided into a plasma generation section 1, a treatment material introduction section 2, and a treatment section 3.
It consists of three parts. In the plasma generation section 1, a cylinder 10 (not shown) made of a high melting point insulating material such as glass, quartz, quartz glass, various ceramics, etc. (a cooling system may be attached as necessary) is provided. A discharge gas 12 is introduced from a gas supply device through a valve 11, and a coil 13 (131, 1
A DC current is passed from a DC power supply (not shown) through the cylinder 10 (separated into 32 sections), and a magnetic field B (magnetic flux density is also assumed to be B) is generated in the axial direction of the cylinder 10, as shown by the arrow.
is formed. As means for creating the magnetic field B, not only the electromagnetic coil described above may be used, but a permanent magnet may be used, or a permanent magnet and an electromagnetic coil may be used in combination. Further, this cylinder 10 (diameter D) is provided with an antenna 14 bent into a special shape as shown in the figure over a predetermined length (l) in the axial direction along its surface, and receives a matching signal from a high frequency power source 15. A high frequency voltage (frequency, power W) is applied via the circuit 16, and a high frequency alternating magnetic field is applied inside the cylinder 10 in a direction orthogonal to the magnetic field B described above. As is well known, (References. PHYSICS
LETTERS Vol.33A, No.7.P457−P458,
“PLASMA PRODUCTION USING A
STANDING HELICON WAVE (Plasma generation using standing helicon waves)” 14 December 1970 and the same Vol.91A, No.4.P163-P166, “SOME
FEATURES OF RFEXCITED
FULLYIONIZED LOW PRESSURE ARGON
PLASMA (Characteristics of low-pressure fully ionized argon plasma excited by RF)” 6 September 1982),
The discharge gas 12 is introduced through the valve 11 and exhausted from a gas exhaust valve 25 (described later) to maintain the gas pressure inside the cylinder 10 at a predetermined value, and the antenna 14 is
When applying high frequency power to
nf) ^0.5 , it is possible to generate a standing helicon wave mode as a low frequency resonance, which is one of the standing plasma waves, in the plasma in the discharge tube 10. However, a is the diameter of the plasma, n is the electron density of the plasma, and l, B, and f are as described above. (ICRF is a standing plasma wave that can efficiently generate high-density plasma inside a discharge tube by exciting the standing plasma wave inside the discharge tube and resonantly heating the ions in the plasma.)
(Ion Cyclotron Range Frequency), LH
{Lower Hybrid waves}, Alfven waves, etc. are also possible, but here we will use standing Helicon waves as a representative. ) Under these conditions, electromagnetic waves propagate effectively in the plasma, so by appropriate design specifications of the equipment, relatively small-capacity High-density plasma with a plasma density of about 10 ¹² cm ^-3 or more can be generated extremely efficiently in the cylinder 10 using a high-frequency power source. Furthermore, depending on the conditions, it is possible to ionize almost 100% of the discharge gas, which is more than 10 times higher than that of an ECR plasma device. Since plasma is highly dense, the amount of active species and ions produced is extremely large, and the emitted light is also powerful. There is a risk that the high temperature of the high-density plasma may destroy the cylinder 10, and in that case, the input high-frequency power should be reduced, or in the future, the high-frequency power should be applied intermittently in a pulsed manner to protect it. Further, the same protective effect can be obtained even if the current applied to the coil 13 is pulsed or alternated. The processing material introducing section 2, which introduces some or all of the processing materials such as active species of high-density plasma, ions, and synchrotron radiation into the processing section 3, may be left as it is in the simplest case. As shown in Figure 1,
By providing a single layer or multiple layers such as a wire mesh 17, conductive grid, orifice, and assigning a floating potential, a ground potential, and potentials of high and low positive and negative polarity to each layer, the material to be treated can be selected. , and introduce it into the processing chamber 20 by adjusting the amount of passage and adjusting the acceleration. Note that this wire mesh or the like may be deeply penetrated into the processing chamber 20 and placed at a position quite close to the substrate 24 on the substrate holder 23. Furthermore, if only synchrotron radiation is used, an optical window may be installed. The above-mentioned ECR plasma apparatus has the advantage that the width of the ion flow can be expanded and uniquely adjusted acceleration can be performed by utilizing the diverging magnetic field created by the magnetic field B in the processing material introduction part 2 or its lower part 19. It was hot, but
In the device of the present invention, since the kinetic energy of electrons is sufficiently large, a similar effect can be expected from a similar divergent magnetic field. In addition, the wire mesh, grid, etc. that have penetrated deeply into the processing chamber 20 described above,
This may be installed below the ion flow expanded by the above-mentioned divergent magnetic field, thereby increasing the degree of freedom in adjusting ion acceleration. Such an apparatus is particularly useful when processing the substrate 24 in a sputter ion etching process in which ion acceleration needs to be controlled. The exhaust system connected to the processing chamber 20 includes an exhaust pump (not shown), an exhaust valve 25, etc.
Similar to the conventional case shown in the figure, a method suitable for the type of processing is used. Substrate 2 which is the object to be processed
The same applies to the temperature control system 22 for heating or cooling the air conditioner 4. Similarly to the conventional method, consideration is given to rotating or moving the substrate holder 23 so that the processing is uniform on the substrate 24. Now, if the processing of the substrate is simple etching, the creation of a SiO ₂ film on the surface of a Si substrate, or the removal of organic substances from the surface of a substrate, it is possible to use the apparatus shown in Fig. 1 by simply using Ar or O ₂ as the discharge gas 12. However, when a more complex process is required, a discharge reactor, such as the embodiment shown in FIG. 2 (shown in a schematic cross-sectional view), which incorporates a process gas 28, is advantageous. The processing gas 28 supplied from a gas supply device (not shown) enters the gas introduction ring-shaped pipe 26 via the valve 27, and enters the ring-shaped pipe 26 from a large number of gas ejection holes 260 bored inside the ring of the ring-shaped pipe 26. The active species, ions, and synchrotron radiation emitted from the cylinder 10 into the processing chamber 20 are ejected onto the surface of the substrate 24 toward the surface of the substrate 24, and are irradiated with some or all of the above-mentioned active species, ions, and synchrotron radiation, and undergo a reaction due to their energy. Then, a predetermined process such as thin film deposition is performed on the surface of the substrate 24. Table 1 lists examples of the types of thin films that can be deposited and the combinations of discharge gas and processing gas used at that time. When appropriately selecting the configurations of the processing material introducing section 2 and the processing section 3, these various types of thin films can be deposited on the substrate 24 while making the film quality and thickness distribution uniform and avoiding damage caused by the irradiation impact of charged particles. can be deposited at high speed. Note that when obtaining high-density plasma through electron resonance, as in ECR, for example, the mean free path of the electrons must be sufficiently large compared to the Larmor radius, and the gas pressure cannot be increased beyond a certain level. However, when plasma is generated by a standing plasma wave, such as a standing helicon wave, it is possible to increase the gas pressure and allow the reaction to proceed in a high density state. It is also easy to create powder. In this case, it is effective to increase the pressure.

【table】

[Table] (Effects of the invention) The present invention makes it possible to economically produce powder or perform high-quality surface treatment with little damage at high speed using high-density plasma generated with high efficiency. This has the effect of providing a small and inexpensive discharge reactor.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a discharge reactor according to an embodiment of the present invention. FIG. 2 is a similar diagram of another embodiment.
FIG. 3 is a schematic cross-sectional view of a conventional parallel plate type surface treatment apparatus. FIG. 4 is a schematic cross-sectional view of a conventional ECR plasma device. DESCRIPTION OF SYMBOLS 1...Plasma generation part, 2...Processing material introduction part, 3...Processing part, 10...Cylinder made of an insulator, 11...Valve for introducing discharge gas 12, 1
3... Electromagnetic coil, 14... Antenna, 15...
High frequency power supply, 16... matching circuit, 17... wire mesh,
20...Processing chamber, 22...Temperature control system, 23...
Substrate holder, 24...Substrate, 25...Exhaust valve, 26...Ring-shaped pipe for introducing gas, 27...Valve for introducing processing gas 28.

Claims (1)

[Scope of Claims] 1 a. Means for introducing a predetermined gas into the interior of a hollow cylindrical body made of an insulating material; b. Means for forming a magnetic field in the internal space of the cylindrical body in the axial direction thereof; c. By applying a high-frequency alternating magnetic field in a direction intersecting the axis over a predetermined length in the axial direction to the internal space of the cylindrical body, a standing plasma wave in the magnetic field is used to generate energy within the space. means for generating plasma; d. using active species, ions, and synchrotron radiation of the plasma in the space as processing materials, part or all of which;
means for introducing the processing material from the cylindrical body into the processing chamber, and using the introduced processing material, or by adding a gas separately introduced into the processing chamber, Generate a given powder or
A discharge reaction device is characterized in that it performs a predetermined treatment on the surface of an object to be treated installed in the treatment chambers. 2. The discharge reaction device according to claim 1, wherein the standing plasma wave is a standing helicon wave.