JPH0432231A - High-frequency voltage-detection device of film-forming device - Google Patents

Abstract

PURPOSE:To enable a high-frequency voltage to be grounded accurately and adjustment of plasma strength between each electrode and a substrate to be made highly accurately by achieving a length integer multiples of a half wavelength of the high frequency to be measured and by providing a first and second coaxial line paths which connect the high-frequency voltage introduction part to the first and second electrodes and first and second measuring equipment. CONSTITUTION:Coaxial line paths 36 and 37 are connected between RF detection parts 38 and 39 and electrodes as circuits to be subjected to geodesic and the length of the coaxial line paths is multiples of a half length (lambda/2) of a high frequency to be measured. In this high-frequency voltage detection device, an input impedance of the RF detection parts 38 and 39 is equal to an impedance Z4 including the coaxial line paths 36 and 37 and a differential constituent which is a measuring signal is equivalent when directly connecting the RF detection parts 38 and 39 to high-frequency introduction parts N and M points. Since one part of the coaxial line paths 36 and 37 is formed in coil shape, in-phase constituents can be reduced by the coil-shaped parts, thus enabling highly accurate voltage detection to be made.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a detection device for a high frequency voltage applied to a high frequency electrode in a film forming apparatus such as a high frequency excitation type plasma CVD apparatus.

[Prior Art] Sputtering apparatuses, plasma CVD apparatuses, and the like have conventionally been used as apparatuses for forming thin films on substrates.

In conventional plasma CVD equipment, a high-frequency electrode is placed in the center of the chamber, ground electrodes are provided on both sides of the high-frequency electrode, and a substrate is attached to each ground electrode to form films on two substrates at the same time in vertical double-sided deposition. Equipment is provided.

FIG. 4 shows such a conventional vertical double-sided film forming apparatus. In this film forming apparatus, first and second high frequency electrodes 2 and 3 are arranged within a chamber 1 with a predetermined interval. Each high frequency electrode 2, 3 is electrically insulated via an insulating member or the like. A substrate 4.degree. 5 can be placed so as to face each of the high-frequency electrodes 2 and 3, respectively. In addition, each high frequency electrode 2. ! Earth shield 6 around 3
．． 7 is provided. Variable capacitors 8 and 9 are connected to each high frequency electrode 2 and 3, respectively. These variable capacitors 8 and 9 are connected to a high frequency power source 10 via a matching circuit 11.

In such a device, by appropriately changing the capacitance of the variable capacitors 8 and 9, the intensity of the plasma generated between each high-frequency electrode 2 and 3 and the substrate 4.5 can be independently controlled. .

In the apparatus shown in FIG. 4, the high frequency power output from the high frequency power source 10 is transmitted to two high frequency electrodes 2.
3, the capacitance of the variable capacitor 8.9 is adjusted so that the high frequency voltages at the introduction points N and M of the high frequency electrodes 2 and 3 are equal.

[Problem to be solved by the invention]

As mentioned above, in order to adjust the plasma intensity of the two electrodes 2, 3 and each electrode 4, 5, it is necessary to measure the high frequency voltage at the introduction points N and M. Therefore, a high frequency voltage detector may be connected to each of the N and M points. ζIn general,
When performing voltage detection, the input impedance Z1 of the voltage detection section 12 is compared with the input impedance Z2 of the circuit under test 13, as shown in FIG. 5, in order to avoid affecting the circuit under test during measurement. It needs to be large enough.

However, the introduction section N of the device as shown in FIG.

Point M is a high frequency introduction section and a gas introduction section at the same time, and there is no sufficient space for installing a high frequency voltage detector. Therefore, the single conductor wire 14.15 is placed at the N and M points.
and the detector must be connected via these conductor single wires 14,15.

However, when the circuit under test and the voltage detection section are connected through the conductivity 41i14, 15, as shown in FIG. , the input impedance z3 of the voltage detection section including the single conductor wires 14 and 15 changes greatly. Therefore, in some cases, the impedances Z3 and 22 have almost the same value, causing a large error when measuring the high frequency voltage in the voltage detection section.

An object of the present invention is to provide a high-frequency voltage detection device for a film forming apparatus that can accurately detect the high-frequency voltage applied to the electrodes and can supply power to two electrodes in a well-balanced manner.

[Means to solve the problem]

The high-frequency voltage detection device of the film-forming apparatus in the present invention applies a high-frequency voltage from a high-frequency power supply to the first and second electrodes, and generates plasma discharge between each electrode and the substrate facing each other to form a film. This is used in film forming equipment that performs this process.

It also includes first and second measuring instruments and first and second coaxial lines.

The first and second measuring devices measure high frequency voltages applied to the first and second electrodes, and
The coaxial line has a length that is an integral multiple of a half wavelength of the high frequency to be measured, and connects the high frequency voltage introduction part to the first and second electrodes and the first and second measuring instruments. be.

[Effect]

In the present invention, as shown in FIG. 3, by connecting the voltage detection section and the high frequency voltage introduction section to the electrode with a coaxial line having a length that is an integral multiple of the half wavelength of the high frequency to be measured, the coaxial Human power impedance z of voltage detection section including line
4 is equal to the input impedance Z1 of only the voltage detection section. In other words, this is equivalent to the case where the high frequency voltage detection section is directly connected to the point to be measured.

As a result, even if there is no space to install a voltage detection unit, such as in a vertical double-sided film deposition system,
Measurement results with very little error can be obtained, and the intensities of the two plasma discharges can be adjusted in a well-balanced manner.

〔Example〕

FIG. 1 shows a vertical double-sided film forming apparatus and a high frequency voltage detection apparatus according to an embodiment of the present invention.

In FIG. 1, high-frequency electrodes 21 and 22 made of stainless steel, for example, are arranged in a vertical position in a film forming chamber 20, and the electrodes 21 and 22 are maintained at a predetermined distance by an insulating member. An earth shield 23.24 is arranged around each high frequency electrode 21.22. Film forming chamber 2
Heaters 25 and 26 are arranged on both left and right side walls of 0. Further, variable capacitors 27 and 2B are connected to each of the high frequency electrodes 21 and 22, and both variable capacitors 27 and 28 are connected to a high frequency power source 31 via a matching circuit 29 and a coaxial line 30.

Note that the variable capacitors 27 and 28 are provided within the intermediate box 32.

Further, a substrate cart 33 can be carried into the film forming apparatus 20 in a direction perpendicular to the plane of the paper in FIG.

The substrate cart 33 functions as a ground electrode, and substrates 34 and 35 are mounted in a vertical position so as to face each of the high frequency electrodes 21 and 22, respectively.

Coaxial lines 36 and 37 are connected to points N and M of the high frequency voltage introducing portions to each high frequency electrode 21 and 22, respectively. Further, a coil-shaped portion is formed in a part of the coaxial line 36, 37. RF detectors 38, 39 are connected to the other ends of each of the coaxial lines 36, 37 for measuring the high frequency voltage applied to each electrode 21, 22. Note that a gas pipe 40 for introducing gas is also connected to the high-frequency voltage injection part of the film-forming bag W20.

FIG. 2 shows a block diagram of the high frequency voltage detection device.

As shown in this figure, a coaxial line 36.37 is connected between the RF detection section 38.39 and the introduction part of the electrode 21.22 as the circuit under test.
As shown in FIG. 3, the length is an integral multiple of the half wavelength (λ/2) of the high frequency to be measured.

In the high frequency voltage detection device configured as described above, the RF
The input impedance Z1 of the detection section 38.39 and the impedance Z4 including the coaxial line 36.37 are equal, and regarding the differential component (see Fig. 2) which is the measurement signal,
This is equivalent to the case where the RF detection sections 38 and 39 are directly connected to the high frequency introduction sections N and M points. In addition, coaxial line 36.37
Although a part of the coaxial line 36.
Since the number of turns of the center conductor and the outer conductor of No. 37 are the same, there is no influence on the differential component.

Here, it will be explained in detail that when the length of the coaxial line is an integral multiple of the half wavelength of the high frequency to be measured, the impedance including the coaxial line is equal to the impedance not including the coaxial line.

Here, the reflection coefficient F at the line A section shown in FIG. 3, and B
The relationship between the reflection coefficient F at
...Represented by (1). Here, since K=2π/λ...(2), the phase constant becomes λ/2=π/K...(3), and /! = n-λ/2-n-x/K - (4), then, substituting (4) into (1), r, = r,, e-
``Mouth Z/becomes 1'', = r, -e bow aJ7L = r.

becomes.

In this way, the reflection coefficients F and r become equal. That is, the input impedance Z4 of the A section and the input impedance Z1 of the B section are equal.

In addition, the in-phase component as shown in FIG. 2 causes an error during measurement, but by making a part of the coaxial line 36, 37 into a coil shape, this in-phase component can be reduced by the coiled part. More accurate voltage detection can be performed.

〔Effect of the invention〕

As described above, in the present invention, as long as there is space to connect a coaxial line around the measurement point, the high frequency voltage introduced to the electrode can be measured accurately and easily with very little error, and the connection between each electrode and the substrate can be easily measured. It becomes possible to reliably adjust the plasma intensity between the two positions with high precision.

[Brief explanation of drawings]

FIG. 1 is a schematic longitudinal cross-sectional view of a vertical double-sided film forming apparatus employing a high-frequency voltage detection device according to an embodiment of the present invention, FIG. 2 is a schematic block diagram of the high-frequency voltage detection section, and FIG. A diagram for explaining the input impedance of the high-frequency voltage detection section, FIG. 4 is a schematic vertical cross-sectional view of a film forming apparatus employing a conventional high-frequency voltage detection device, and FIG. 5 is a block diagram of the high-frequency voltage detection section. , FIG. 6 is a diagram for explaining the conventional problems. 21.22... High frequency electrode, 31... High frequency power supply,
34.35... Board, 36.37... Coaxial line, 3
8゜39...High frequency voltage detection section. Patent applicant Shimadzu Corporation Representative Patent attorney Yukio Ono and Mitsuo

Claims (1)

[Claims] (1) A high-frequency voltage detection device for a film-forming apparatus that applies a high-frequency voltage from a high-frequency power supply to the first and second electrodes to generate a plasma discharge between each electrode and a substrate facing each other to form a film. The first and second measuring devices measure the high-frequency voltage applied to the first and second electrodes, and the first and second measuring devices have a length that is an integral multiple of a half wavelength of the high-frequency wave to be measured. A high frequency voltage introduction part to the second electrode and the first and second electrodes.
A high-frequency voltage detection device for a film forming apparatus, comprising: first and second coaxial lines connecting a measuring device;