JPH04247878A - Vhf/uhf reacting device - Google Patents

Abstract

PURPOSE: To provide a plasma enhanced reaction apparatus which uses high-frequency AC energy by constituting an electrode as part of an integrated coaxial transmission line structural body which directly connects AC energy to a chamber and forms plasma therein.

CONSTITUTION: The plasma processing reaction apparatus 10 is formed of the chamber 33 and the electrode 32C. The electrode 32C is constituted as part of the integrated coaxial transmission line structural body 32 which directly connects the AC energy of the selected frequency to the chamber 32 and forms the plasma therein. The integrated coaxial transmission line structural body 32 is opened by a central conductor 32C, insulator 32I and outer conductor 320 which are wafer supporting electrodes. As a result, the vapor deposition and energy velocity commercially executable for various kinds of the conductors, insulators and semiconductor blanks may be provided.

COPYRIGHT: (C)1992,JPO

Description

[Detailed description of the invention]

0001

TECHNICAL FIELD This invention relates to RF (radio frequency) plasma processing reactors, and specifically to an inventive plasma reactor that uses UHF/VHF to generate plasma.

0002

BACKGROUND OF THE INVENTION As a result of increasingly dense integrated geometries, components and devices are capable of sensing electrically when applied with voltages as low as about 200-300 volts.
This resulted in small geometric arrays of the same standard that are sensitive to breakage. Unfortunately, such voltages are lower than the voltages that circuit components experience during standard integrated circuit assembly processes. First, consider prior art semiconductor processing equipment, such as CVD (chemical vapor deposition) and RIE (reactive ion etching) reactors. These devices have approximately 10 to 500
From low frequency of KHz to approximately 13.56-40.68MHz
It uses radio frequency energy up to high frequencies. Below about 1 MHz, ions and electrons are accelerated by the oscillating electric field and any steady state electric field generated within the prolasma. At these relatively low frequencies, the sheath voltage of the electrodes formed on the wafer reaches peaks of 1 kilovolt or more. This peak voltage is much higher than the failure threshold of 200-300 volts. Number M
Above Hz, electrons can still follow the changing electric field. Heavier ions cannot follow the changing electric field, but are accelerated by the steady-state electric field. In this frequency band (and at practical gas pressure and power levels), steady state sheath voltages range from a few hundred volts to over 1000 volts.

A suitable method of reducing this bias voltage is to apply a magnetic field to the plasma. This bias field confines electrons to regions near the surface of the wafer, increasing ion flux density and ion current, thereby reducing voltage and ion energy requirements. By comparison,
Etch silicon dioxide. Exemplary non-magnetic RIE
The method uses RF energy supplied at 13.56 MHz, a volume of 10 to 15 liters, a pressure of 50 ml, and a ratio of anode area/wafer supporting cathode area of (8
~10)~1 asymmetric devices have been used to generate a wafer (cathode) sheath voltage of about 800 volts. When applying a magnetic field of 60 Gauss, the bias voltage is approximately 2
5-30%, about 500-60 from 800 volts
The etch rate decreases to 0 volts and the etch rate increases by about 50 percent.

However, applying a magnetic field of stationary flux density B parallel to the wafer creates EXB ion/electron shear and an associated plasma density gradient oriented diametrically in the plane of the wafer. This plasma gradient causes non-uniform etching, deposition, and other film characteristics across the wafer. This non-uniformity can be reduced by rotating the magnetic field around the wafer, but typically by mechanical movement of the permanent magnets or by a 90 degree phase shift.
By using several pairs of magnetic coils driven in quadrature, or by momentarily controlling the current in several pairs of coils to advance or reduce the magnetic field at a controlled speed. However, although rotation of the magnetic field reduces the non-uniform gradient, some non-uniformity usually remains.

[0005]Furthermore, magnetic fields include windows, slit valves,
There are other drawbacks to the hardware and susceptibility to variations due to the presence of discontinuities. Therefore, when using magnetic fields, careful attention must be paid to vacuum chamber design, taking into account the effects of geometry and components within the magnetic field. Finally, it is difficult to accommodate the coils less than completely, and in particular to accommodate more than one pair of coils around a chamber to achieve a compact device. This is particularly difficult when using multi-chamber devices such as Helmholtz coil structures or separate magnetically enhanced reaction chambers around a common loading lock.

A novel reaction system with the ability to selectively change magnetic field strength and direction instantaneously and designed for use in a compact multi-chamber reactor is
US Patent No. 4,842,683, June 1989
Published on May 27, 2013, disclosed by the inventor Cheng et al. Other known reactors are 800 MHz
Microwave energy at frequencies above 2.45 GHz is used to excite the plasma. This method generates a high density plasma and low molecular energy to minimize electrically induced device damage. However, for many processes, such as reactive etching of silicon dioxide, a minimum reaction threshold energy must be exceeded. In this type of process, low frequency power must be supplied in addition to the microwave power in order to generate a voltage high enough to create an energy barrier. Therefore, this reactor requires two power supplies and matching networks, resulting in an expensive and complex device.

[0007]

Relatively high frequency VHF/UHF energy of approximately 50 MHz to 800 MHz has the potential to reduce the voltage developed on the wafer during plasma processing; It is understood that, apart from the degree of commercial success, it has never been used in semiconductor processing equipment. In part, this failure is due to the very short transmission lines required in this frequency band and the typically stringent equipment design requirements for efficiently connecting energy to the room.

[0008]

[Means for solving the problem] 1. OBJECTS In view of the above description, it is an object of the present invention to provide a plasma reactor that uses high frequency AC energy to generate a plasma. Another object of the present invention is to provide a plasma reactor that uses VHF/UHF energy to generate plasma.

Another related objective is the severe high frequency VH
It is an object of the present invention to provide a plasma reactor that couples VHF/UHF energy into the vacuum chamber of a plasma generating device in a manner that meets F/UHF design requirements. Yet another object is to provide a plasma reactor in which the reactor itself is configured as a transmission line structure that efficiently connects high frequency energy, such as VHF/UHF energy, to the plasma chamber of the reactor.

Another related object is to provide a processing plasma characterized by a sufficiently low electrode sheath voltage of 200-300 volts to prevent electrically induced damage to semiconductor devices during plasma processing. V to the vacuum chamber that generates
A plasma reactor is provided that efficiently couples HF/UHF energy to provide commercially viable deposition and etch rates for a variety of conductor, insulator, and semiconductor materials. 2. SUMMARY In one aspect, the present invention, which accomplishes the above and other objects, is implemented in a plasma processing reactor where the reactor itself is configured as a transmission line structure that connects AC energy directly to the plasma.

In another aspect, the present invention is implemented in an RF-powered plasma processing reactor comprising a plasma chamber and a wafer support electrode, the wafer support electrode converting AC energy into a vacuum to form a plasma. The coaxial transmission line structure is configured to operate a coaxial transmission line structure coupled to the chamber. Preferably, the transmission line structure has a frequency of about 50 MHz to 80 MHz.
It is used to connect AC energy to the room at a frequency selected from the 0 MHz range.

Preferably, the transmission line structure (1) has a length significantly less than one-fourth the wavelength of the frequency of interest;
with an effective electrical length selected from a multiple of 1/2 the wavelength of the frequency of interest, n=1, 2, etc. In other aspects, the invention includes a housing forming a plasma chamber, a wafer-supporting cylindrical electrode arrangement disposed within the housing, a gas intake manifold disposed within the housing supplying reactant gases to the plasma chamber, and a vacuum A pump system is implemented in a plasma process reactor consisting of an integrated transmission line structure used to deliver AC energy at a selected frequency from an external power source to the plasma chamber. The transmission line structure includes (1) a cylindrical electrode device, (2) an outer conductor surrounding the cylindrical electrode device, and (3) an insulator between the cylindrical electrode device and the outer conductor. With this configuration, the transmission line structure routes AC energy, like a coaxial cable, along the cylindrical electrode arrangement to the plasma chamber, and from the plasma chamber through the housing to the outer conductor. The plasma processing reactor suitably includes an annular exhaust manifold surrounding the outer electrode arrangement. The manifold includes a conductive pump screen around a cylindrical electrode arrangement. The exhaust gas is
It flows from the periphery of the wafer support through the pump screen and into the vacuum pump system. The screen also electrically connects the chamber wall to the outer conductor to form a current path to the outer conductor.

The present invention also includes a matching network that is used to efficiently route external AC energy to the transmission line structure. In a preferred combination arrangement, the cylindrical electrode arrangement consists of columnar electrodes or
The external conductor is connected to the columnar electrode, and the external conductor consists of or is connected to the peripheral electrode, and the matching network includes a variable parallel capacitor and a variable series capacitor between the columnar electrode and the peripheral electrode. It consists of

[0014]

[Example] 1. Referring to FIG. 1, a schematic representation of a reactor 10, generally designated by the reference numeral 10, includes a high frequency V
A HF/UHF reaction chamber apparatus is shown, which embodies the present invention. In one of a few novel aspects described below, the reactor itself is constructed in part as a transmission line structure that conveys high frequency plasma generation energy from a matching network to the plasma chamber 33 (see Number 33 indicates the chamber and the plasma within it). This new combinational transmission line structure is designed primarily for frequencies 50-8
At 0.00 MHz, the requirement of a very short transmission line between the matching network and the load is met. This allows for efficient and controllable delivery of energy to generate a radio frequency plasma to the plasma electrode, resulting in commercially acceptable etching and deposition at low ion energies and low sheath voltages. This voltage is low enough to prevent damage to electrically sensitive semiconductor devices. Moreover, the present VHF/UHF device avoids various drawbacks of prior art techniques such as ECR and magnetic enhancement techniques.

The present device 10 includes a housing 1 of the vacuum chamber.
1, the housing 11 is formed of aluminum or other suitable material and includes a side wall 12 and top and bottom walls 13 and 14. Vacuum seals 34, such as O-rings, are inserted between the many mating surfaces to maintain a vacuum seal. The interior of housing 11 is evacuated by a vacuum system consisting of one or more pumps. For example, device 1
6 consists of a turbomolecular pump assisted by a mechanical pump (not shown) and an optional Roots-type blower (not shown), with a throttle valve to regulate pressure independent of flow rate. It is connected to the chamber 33 via. Of course, other modifications and arrangements can also be used. For example, turbomolecular pumps are omitted by many high pressure only devices.

Reactant gases are generally passed from a pressurized source of gas through a computer-controlled flow controller (not shown) through a gas manifold 27, as indicated by the reference numeral 19. and flows into the internal vacuum processing chamber 33. The manifold, which may be showerhead shaped or of other suitable design, directs etching or deposition gases to chamber 33 to generate an etching or deposition plasma upon application of high frequency RF energy. High frequency AC energy, such as VHF/UHF energy with a frequency of 50 to 800 MHz, is applied to electrode 32C (typically
the cathode of the apparatus), the top surface of the electrode 32 supporting the wafer 15, and a second electrode (the anode of the apparatus) consisting of the side wall 12, top wall 13, and manifold 27 of the reaction chamber. Additionally, other embodiments may also be used. For example, in a few high pressure applications or when an electrode area ratio of approximately 1:1 (anode area:cathode area = 1:1) is desired, it is possible to isolate the sidewall 12 from the plasma, i.e., to use the sidewall as an anode. It is preferable to use two electrodes insulated from the side walls.

Other aspects incorporated into the reaction chamber apparatus 11 include fluid heat transfer to maintain the temperature inside or outside the gas intake manifold 27 above or below a certain value, or within a certain range. Although a medium may be used, the present invention is not limited to this. That is,
The use of a fluid heat transfer medium to heat or cool the cathode 32C, the use of a fluid heat transfer medium to heat or cool the side wall 12 or the top wall, resistive heating of the cathode 32C, or the use of a gas between the wafer 15 and the cathode 32C. These include the use of a heat transfer medium and mechanical or electrostatic devices to clamp the wafer 15 to the cathode 32C. Such aspects are discussed in U.S. Patent No. 4,872,947, 10/1989
Published on May 10th and US Patent No. 4,842,68
3, published June 27, 1989.

The present vacuum chamber design is useful for both high and low pressure operation, and the spacing d between the wafer support cathode 32C and the gas intake manifold electrode is compatible with both high and low pressure operation. are doing. For example, for high pressure operation from 500 mTorr to 50 Torr, it is appropriate to use a spacing d<about 5 cm, and for low pressure operation, from 2 mTorr to 5 cm.
In the range 00 mTorr, a spacing d>5 cm is preferred. As shown, the vacuum chambers may employ a constant spacing d, or a variable spacing design may be used, such as a replaceable or telescoping vacuum chamber top. Reactor 10 performs high and low pressure deposition of materials such as silicon oxide and silicon nitride, low pressure anisotropic reactive ion etching of materials such as silicon dioxide, silicon nitride, silicon, polysilicon and aluminum, and deposition of the above materials. CVD facet thinning (facetin) consisting of simultaneous etchback and etchback operations.
g) It is useful for. These and other processes in which reactor 10 is used are described in commonly assigned U.S. Patent Application Ser. (Docket No. 151-2), name “
VHF/UH used for forming integrated circuits on semiconductor wafers
"F Plasma Treatment", by Collins et al., which Collins et al. patent application is incorporated by reference.

Preferably, the flow of gas from the intake manifold 27 travels downwardly toward the wafer and then is exhausted radially outwardly from the wafer 15. To this end, the annular vacuum manifold 23 has a cathode transmission line between the side wall 12 on one side and the external transmission line conductor 32O on the opposite side, and between the chamber floor wall 14 at the bottom and the conductive pump screen 24 at the top. It is formed around the line structure 32. Manifold screen 24 is inserted between vacuum manifold 23 and plasma chamber 33 to form a conductive electrical circuit between sidewall 12 and external conductor 32O of transmission line structure 32. The manifold 23 forms an annular exhaust groove that uniformly discharges exhaust gas radially from the periphery of the wafer 15. Exhaust manifold 23 communicates with exhaust gas system 16 via one or more apertures 26 in bottom wall 14 . The overall gas flow is typically along passage 19 into intake manifold 27, then along passage 20 from the intake manifold to wafer 15, and radially outward along passage 21 from the peripheral edge of the wafer to the screen. 24 into the gas manifold, and along the flow path 22 from the exhaust manifold 23 into the exhaust system.

Further, with respect to FIGS. 1 and 2, power supply 30
High frequency VH with a frequency of 50 to 800 MHz sent from
F/UHF energy is input to matching network 31;
From there, the chamber components collectively identified by reference numeral 32 connect to chamber 33 and the plasma within the chamber. 2. Transmission Line Requirements As discussed below, the collective component 32 approximates a very low-loss coaxial transmission line, and the matching network 31 does not present an impedance that is very different from the load impedance. As such, it must be a very short coaxial transmission line that minimizes the transformation of the load impedance Z1.

The characteristic impedance Z0 of the coaxial cable transmission line 32 is given by (Equation 1). Z0 = (μ/e)1/2 2π In (γ0/γ
i) Here, μ=μo ・μr Magnetic permeability μr = 1 For non-magnetic material μo = 4π×10-7 Henry/meter ε=εo・
εr Dielectric constant εr = induction constant εo = 8.85×10-22 Farad/meter γ
o = inner radius of the outer conductor γi = radius of the inner conductor Zin is the input impedance to this structure (the impedance seen from the matching circuit) when the transmission line structure terminates in the plasma in the room; It is a function of the characteristic impedance Zo. Zin is given by (Formula 2).

[0022] Zin=Z0・(ZL +jZ0 t
anβl)/ (Z0+jZL tan βl)
(2) where Z1 is the plasma load impedance and l is the physical length of the transmission line. β is the phase constant 2π/λm and λm is the wavelength of the material concerned. Also, λm = λfs/((εr)
1/2 ×mur ), where εr is the relative permittivity (dielectric constant), mur is the relative permeability, λfs is the wavelength/meter in free space, and (300×106 meters/second)/(frequency Hz ).

From (Equation 2), if Z0 = Z1, the impedance is the same regardless of the length of the transmission line. However, if the quality is not satisfied, the transmission line impedance changes from Z1 to some new impedance, λ/2
Convert with a period of . To minimize this conversion, the transmission line must be very short, on the order of 1/10 to 1/20 of the wavelength of the AC energy at the highest frequency of use. For example, in the case of the conventional technology with a frequency of 13.56 MHz,
λfs is equal to 22.1 meters. However, for example,
At the relevant frequency of 300 MHz, λfs is very short, about 1 meter. Therefore, 300M
At high frequencies of Hz, the transmission line structure between the matching network and the plasma load must be smaller than 0.05-0.1 meter so as not to exceed the maximum length requirements. 3. Transmission Line Structure 32 A suitable high frequency coax/transmission line design requires a feed path through a low characteristic impedance, a short transmission line from the matching network to the wafer, and a return path along the transmission line. This design requirement is based on the transmission line structure 3 shown in Figures 1 and 2.
2 is satisfied. This structure 32 includes a cathode 32C, a concentric annular conductor 32O, and a nonporous low-loss insulation 32I that surrounds the cathode 32C, insulating it from the concentric conductor, and excluding process gases that would otherwise destroy it. It is composed of For example, Teflon™ or quartz materials are suitable because of their high dielectric strength, low dielectric constant, and low loss. The input side of this structure is connected to a matching network in the manner described below. Insulated cathode 32C and outer conductor 3
2O forms a separate current path between matching network 31 and plasma 33. One reversible current path 37 is
The matching network extends along the outer periphery of cathode 32C to the plasma envelope on the upper surface of the electrode. Another reversible path 3
8 is from the plasma 33 to the gas manifold 27 and the side wall 1
2, then along the conductive exhaust manifold screen 24 and inside the outer conductor to the matching network. Note that the exhaust manifold screen 24 is part of the uniform radial gas exhaust system and is also the return path for the RF current.

During the application of alternating current energy, the RF current path alternates between the indicated direction and its opposite direction. The coaxial cable type transmission line structure specifically provides a high internal impedance of the cathode 32C (relative to its outer surface) and a high impedance toward the outer surface of the conductor 32O (relative to its inner surface). Due to certain things, R
The F current flows through the outer surface of cathode 32C and the inner surface of outer conductor 32O, like a coaxial transmission line. Approximately 5
At high operating frequencies of VHF/UHF from 0 to 800 MHz, these currents are 2/10 to 3/1 of a millimeter.
Concentrates on the surface thickness at a depth of about 0, that is, the epidermis. However, by using a large wafer, e.g., a 4-8 inch diameter wafer, and a cathode 32C of the same standard diameter as well as a large diameter outer conductor 32O, a large effective cross-section, i.e., a transmission line structure A low impedance current path is formed along the body.

As shown in (Equation 2), the coaxial type transmission line structure 32 has its characteristic impedance Z0
The matching network has a constant impedance Z0, regardless of the length of the transmission line. However, this is not the case with the present invention. The reason is that plasma can be generated over a certain range of pressure, power,
and frequencies, and is composed of various gases,
This is because the plasma causes an intensive change in the load impedance Z1 as it appears at the end of the transmission line 32. Since the load Z1 is not matched to the non-ideal (i.e., non-lossless) transmission line 32, the persistent waves appearing on the transmission line are caused by resistive, dielectric, etc. increase losses. Matching network 3
1 represents all sustained waves and the losses caused by them,
Plasma within the matching network, transmission line 32, and vacuum chamber between the transmission line 32 and the matching network can be used to remove from the input of the matching network flowing back to the amplifier or power supply 30. In addition, it constitutes a resonant system that increases losses due to resistivity, dielectricity, etc. In short,
Although the load impedance Z1 does not match the loss, Z1
It is minimum when =Z0.

To reduce losses due to load mismatch, the coaxial transmission line structure 32 is designed to have a characteristic impedance Z0 that best matches the range of load impedances associated with plasma operation. There is. In general, for the operating variables and related materials described above, the equivalent series RC load impedance Z1 induced by the plasma into the transmission line will have a resistance in the range of 1 ohm to 30 ohms and a range of 50 picofarads to about 400 picofarads. It consists of a capacitance within. As a result, an optimum transmission line characteristic impedance Z0 centered within the range of the load impedance, that is, in the range of about 10 ohms to 15 ohms, was obtained.

As also shown in equation 2, the transmission line 32 needs to be very short to prevent transformation of the plasma impedance experienced by the matching network. Preferably, the transmission line is 1/4 wavelength, λ/4
much smaller than, more preferably about (0.05 to 0.
1) λ. More generally, if it is not possible to place the matching network at a distance to the load that is much less than a quarter wavelength, the advantage is that
By using transmission line lengths equal to , 2, 3, etc., there is a half-wave periodicity associated with the impedance (λ/2, λ, 3λ/2, etc.). More precisely, preferred values are between λ/2 and (λ/2+0.05λ
), λ~(λ+0.05λ), 3λ/2~(3λ/2+
0.05λ), etc. Under these conditions, 1/
The 4-wavelength part (or nλ/4, n is an odd number) is Z1
Convert Zin=Z02/Z1, and Z1
is generally small and generates a very large Zin, so the matching network has a 1/4 wavenumber odd integer (λ/4,
λ/4, 5λ/4). In that case, the matching network cannot match the plasma load and it is very difficult to connect power to the plasma without unacceptable device resonance and power dissipation.

Regarding efficient power connection, the inner diameter (cross-sectional dimension) of the return conductor 32O is
It must not be much larger than the outer diameter (cross-sectional dimension) of 2C. Simply put, a vacuum chamber has a frequency of approximately 50 to 800 MHz.
A transmission line structure is incorporated which connects VHF or UHF power from the matching circuit 31 to the plasma 33. The transmission line structure is (1) very short compared to a quarter wavelength at the frequencies of interest to prevent undesirable transformations of the plasma impedance, and (2) very short compared to a quarter wavelength between the plasma and the matching network. In order to reduce losses due to the presence of persistent waves in the line, the selected characteristic Z0
and (3) using outer conductor path cross-sectional dimensions that are not significantly larger than the center conductor dimensions. 4. The physical length of the matched network transmission line structure is short compared to a quarter wavelength, i.e. suitably smaller than 1/10 or 1/20 of a wavelength, or a multiple of the above mentioned 1/2 wavelength. By keeping it slightly larger, if the load is a typical series RC impedance, there are slightly inductive components connected to the transmission line network. Typically, to match resistive loads, L-networks require an inductance in series with a capacitance. However, since the very short transmission line structure 32 is terminated with a very small resistance or low impedance load, it
Presenting inductive and resistive components to a matching network. Although plasma 33 is an RC load, the presence of inductive components eliminates the need for inductance in the matching network. This allows a simple implementation of a matching network consisting of two variable capacitors.

3 and 4, the preferred matching network 31 includes a shunt capacitor C1 connected from the input of the matching network to ground, and a series capacitor C1 connected from the input of the matching network to the output of the matching network. C2 is connected directly to the input of the transmission line structure 32. The matching network configuration shown in FIGS. 3 and 4 provides a 50 ohm resistive impedance at the typical power supply output and a 1-50 ohm resistive impedance component at the typical plasma 33. It should be noted that more generally, the power supply output resistive component is larger than the load resistive component. If the resistive portion of the plasma load impedance Z1 is larger than the output resistive impedance of the power supply, the input and output connections of the matching network are reversed.

Capacitors C1 and C2 are air capacitors consisting of a fixed plate and a movable plate, and are generally made of copper or silver-plated copper plates. Capacitor C1
The fixed plate 58 is the case or housing 35 of the matching network and is connected to ground. Also, with reference to FIG. 1, the plate 57 is connected to the input 50 from the power supply 30, and based on the real-time Zin or reflected power, the motor M1 is routed by the motor M1 under the control of the device's built-in computer 60. You can move along 62. This input is used to control the separation of the plates and thus the capacitance of the capacitor in a known manner. A sheet 61 of Teflon™ or other suitable low loss, high dielectric strength material is inserted between capacitor plates 57 and 58 for arc prevention. It is noted that, as illustrated in FIG. 1, a computer 60 (or a separate computer) is conveniently used to control the operation of power supply 30 and select the appropriate frequency within the relevant range. and thereby select the desired voltage and power combination for a given process. The ability to control voltage and power by selecting from a wide frequency band of 50-800 MHz opens up a very large processing window.

A similarly configured series capacitor C2
is composed of an insulating, arc-resistant sheet 59 made of a material such as Teflon TM, and its foot portion 56
is connected to the input section 50, like the capacitor C1,
Motor M2 moves along path 63 and changes the capacitance of C2. The fixed foot 55 is connected to an output 52 of the matching network, which comprises a clip 54 that locks a conductive column 53 extending downward, as shown. . The pillar is part of or electrically connected to the cathode 32C.

Generally, the legs of any variable capacitor are connected to the input section 5 by conductive strips made of a material such as copper.
electrically connected to 0. An annular electrode 6 between the bottom of the reaction chamber housing 12 and the top of the matching network case 35
4 connects the matching network 31 and the outer conductor 32O to the same potential, i.e. to equipment ground, and together with the matching network, the output connection 52 connects the matching network to the transmission line structure 32. Forms the necessary coaxial cable type connections or terminations. The structure also capacitively connects the matching network to the transmission line structure to block DC bias when the sheath voltages are not equal.

For typical process variables and coupled plasma RC impedances of 1-30 ohms in series with 50-400 Farads, C1 and C2 are 10-40
It varies in the range of 0 picofarads. Naturally, if the requirements of a very short transmission line are not met, the inductor C2
It is necessary in series with These common techniques in this field are:
It is easily extracted and used in the construction of other or standard matching circuits compatible with the present device. For example, the inductor of choice uses C2 when operating at a low frequency of interest.
can be incorporated in series with Also, the matching network is connected to another D
A C blocking capacitor may also be included.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram of the present UHF/VHF plasma reactor.

FIG. 2 is a perspective view of a transmission line structure incorporated into the reactor of FIG. 1;

FIG. 3 is a circuit diagram of a suitable matching network.

FIG. 4 is a cross-sectional view showing a circuit diagram physically equivalent to the circuit diagram of FIG. 3;

[Reference numbers] 10 Plasma processing reactor 11 Housing 12 Chamber wall 23 Exhaust manifold 24 Conductive screen 27 Gas intake manifold 32 Integrated coaxial transmission line structure 32C Wafer support electrode 32I Insulator 32O Outer conductor 33 Plasma chamber 31 Matching circuit network

Claims (11)

[Claims] 1. A plasma processing reactor (10) comprising a chamber (33) and an electrode, wherein the electrode (32C) connects AC energy of a selected frequency directly to said chamber to generate a plasma therein. A plasma processing reactor characterized in that it is part of an integrated coaxial transmission line structure (32) forming a plasma processing reactor. [Claim 2] An integrated coaxial transmission line structure (3
2) is the central conductor (32C) which is the wafer support electrode.
2. A reactor according to claim 1, characterized in that it consists of an insulator (32I) and an outer conductor (32O). 3. The electrode is a wafer support electrode (32C
), and the reactor further comprises a plasma chamber (33).
a housing (11) having a wall (12) forming a
A gas intake manifold (27) located within the housing for supplying reactive gases to the plasma chamber (33), vacuum pump means and a conductive screen surrounding and surrounding the wafer support electrode (32C). (2
4) and a screen (2) forming a controlled radial flow of exhaust gas around the periphery of the wafer support electrode (32C) and through said screen (24) to the vacuum pumping means.
4) a plasma chamber (
33) and an integrated coaxial transmission line structure (
32) surrounds the wafer support electrode (32C) and the exhaust gas manifold (22C).
The outer conductor (3) forms the inner wall of the plasma chamber (3) and is electrically connected to the wall (12) of the plasma chamber via the screen (24).
2O), the wafer support electrode (32C) and the outer conductor (
This configuration allows the transmission line structure to run along the wafer support electrode (32C) like a coaxial cable to the plasma chamber (32C).
33), from the plasma chamber to the chamber wall (12) and the screen (
24) The reactor according to claim 1, characterized in that it is reversibly connected to 24). 4. AC energy is passed through a matching network (31) consisting of a variable shunt capacitor (C1) and a variable series capacitor (C2) to a transmission line structure (32).
4. The reactor according to claim 1, wherein the reactor is supplied to a reactor according to any one of claims 1 to 3. 5. Furthermore, a wafer support electrode (32C)
4. A reactor according to claim 3, characterized in that it comprises a matching network used to contact the outer conductor (32O) and connect the AC energy to the transmission line structure. 6. The wafer support electrode (32C) is electrically connected to the columnar electrode (53), the outer conductor (32O) is connected to or has a peripheral electrode, and the matching network (31) is 6. The reactor according to claim 5, characterized in that it comprises a variable shunt capacitor (C1) and a variable series capacitor (C2) connected between the utility pole (53) and the peripheral electrode. 7. The reaction apparatus according to claim 4, further comprising an inductor connected in series with a series capacitor (C2). 8. Any one of claims 1 to 7, characterized in that the length of the transmission line structure (32) is significantly smaller than 1/4 electrical wavelength at the selected frequency. A reaction apparatus according to claim 1. [Claim 9] External AC energy is approximately 50 MHz.
and approximately 800 MHz, and the length of the transmission line structure (32) is approximately 800 MHz at the selected frequency.
8. A plasma processing reactor according to any one of claims 1 to 7, characterized in that the wavelength is sufficiently smaller than 4 electrical wavelengths. 10. If n=1, 2, 3, etc. and λ is the wavelength of the external AC energy at the selected frequency, then the physical length of the transmission line structure (32) is λ/ Claims 1 to 7 characterized in that: 2.
A plasma processing reactor according to any one of the claims. [Claim 11] The frequency of the AC energy is approximately 50M.
Hz to about 800 MHz, and where n=1, 2, 3, etc., and λ is the wavelength at the selected frequency, the length of the transmission line structure (32) is nλ/2. The plasma processing reaction apparatus according to any one of claims 1 to 7, characterized in that: