Measuring apparatus and method for impedance characteristic measurements of a capacitively coupled plasma processor

Abstract

An impedance characteristic measuring device for a capacitively coupled plasma processor, characterized in that the impedance characteristic measuring device comprises: an upper contact plate and a lower contact plate, wherein the upper contact plate is used to contact the lower surface of a gas shower head of the capacitively coupled plasma processor, and the lower contact plate is used to contact the upper surface of an electrostatic chuck in the capacitively coupled plasma processor; at least one elastic conductive part is located between the upper contact plate and the lower contact plate, and the elastic conductive part provides elastic force, so that the upper and lower contact plates are in close contact with the gas shower head and the electrostatic chuck respectively after the distance between the upper and lower contact plates is compressed when the impedance characteristic measuring device measures the impedance characteristic curve of the capacitively coupled plasma processor. The impedance characteristic curve of the plasma processor is accurately measured without plasma ignition.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor, and in particular to a measuring device and a measuring method applied to impedance characteristic measurement of a capacitively coupled plasma processor. BACKGROUND

[0002] Plasma processors are widely used in the manufacturing process of integrated circuits, such as deposition, etching, etc. Among them, the capacitive coupled plasma (CCP) device is one of the mainstream technologies in plasma processors.

[0003] During the design, manufacture and debugging process of the capacitive coupled plasma processor, the frequency characteristics of the processor need to be mastered, such as the impedance characteristics at different frequencies, the radio frequency power flow path at different frequencies, i.e. the distribution of radio frequency power inside the reaction chamber. However, it is difficult to obtain the above frequency characteristics. During the plasma processing process, the plasma between the upper and lower electrodes is conductive, and its impedance characteristics are affected by the gas concentration in the plasma, the gas pressure, the input radio frequency power size, etc. A large number of tests are required to obtain sufficient data to construct the radio frequency impedance model of the plasma processor. Moreover, each time the internal hardware of the plasma processor changes will affect the impedance, so it is necessary to perform a large number of tests again, so this method of a large number of tests to ensure accuracy is not suitable for the development process of the plasma processor which needs to be frequently improved. Moreover, these tests need to be performed after the reaction chamber is completely assembled, and the test results cannot be predicted during the design and development process. If it is found that the relevant parameters need to be adjusted after the assembly is completed, it will lead to the extension of the development cycle and a substantial increase in cost. Another method is to not ignite the plasma, and directly input the radio frequency power into the reaction chamber to scan the impedance characteristics of the reaction chamber at each frequency. However, under the condition of not igniting the plasma, the impedance of the reaction chamber is very different from the impedance of the reaction chamber during actual plasma processing.

[0004] Therefore, it is necessary to develop a new method or device to realize accurate measurement of the full-band impedance of the plasma processor without a large number of experimental tests. SUMMARY

[0005] The present invention provides an impedance characteristic measurement device for a capacitively coupled plasma processor, characterized in that the impedance characteristic measurement device includes: a contact plate and a lower contact plate, wherein the upper contact plate is used to contact the lower surface of a gas showerhead of the capacitively coupled plasma processor, and the lower contact plate is used to contact the upper surface of an electrostatic chuck in the capacitively coupled plasma processor; at least one elastic conductive portion is located between the upper and lower contact plates, and the elastic conductive portion provides an elastic force and a low-impedance conductive path, so that when the impedance characteristic measurement device measures the impedance characteristic curve of the capacitively coupled plasma processor, the upper and lower contact plates are compressed and closely contact the gas showerhead and the electrostatic chuck, respectively.

[0006] The upper and lower contact plates are made of insulating material with a thickness of 0.1-1 mm, or made of semiconductor material with a thickness of 0.6-3 mm. By selecting such materials and thicknesses, the impedance of the sheath layer appearing during the plasma processing process can be simulated, so that the impedance characteristic curve of the processor detected in the non-plasma state is more accurate.

[0007] The elastic conductive part includes an elastic support member that provides elastic force and a conductive contact device that provides a conductive path. The combination of the two achieves the design goal of providing vertical elastic force and a conductive path, and the inductance is small, which does not affect the impedance measurement of high-frequency signals.

[0008] Furthermore, the conductive contact device includes a contact head mounted on the upper or lower contact plate and a conductive clamp located on the opposite contact plate. When the upper and lower contact plates are compressed, the contact head is inserted into the conductive clamp to form a stable electrical connection.

[0009] The upper and lower contact plates are disc-shaped and include multiple elastic conductive portions. These portions are spaced apart at different azimuth angles on the upper and lower contact plates to uniformly distribute the RF current between the portions. Furthermore, current detection devices can be provided on the multiple elastic conductive portions to measure impedance distribution at different azimuth angles, and the reaction chamber structure or plasma treatment process parameters can be optimized based on the impedance distribution data.

[0010] The lower contact plate covers more than 1 / 2 of the upper surface of the electrostatic chuck, and the larger coverage area can be closer to the impedance spatial distribution of the actual plasma.

[0011] The impedance characteristic measuring device further comprises a contact ring surrounding the periphery of the lower contact plate, the contact ring corresponds to the position of the focus ring in the capacitively coupled plasma processor, and the contact ring is connected to the upper contact plate via an elastic conductive portion.

[0012] The application also provides a capacitively coupled plasma processor, which comprises at least two components exposed to the plasma, and an impedance characteristic measuring device arranged in the gap between the two components, wherein the impedance characteristic measuring device comprises first and second contact plates and at least one elastic conductive part between the first and second contact plates, so that the two contact plates are respectively attached to the surfaces of the two components and provide a conductive path.

[0013] Further, the application also provides a method for detecting the impedance characteristic of a capacitively coupled plasma processor, which comprises the following steps: opening the top cover of the capacitively coupled plasma processor; placing the impedance characteristic measuring device as described in claim 1; closing the top cover of the plasma processor, so that the upper contact plate of the impedance characteristic measuring device is attached to the gas shower head and the lower contact plate is attached to the upper surface of the electrostatic chuck; pumping out the air in the plasma processor; inputting a plurality of radio frequency signals with different frequencies into the pedestal or the gas shower head in the plasma processor, detecting the feedback radio frequency signals at the detection end of the plasma processor, and obtaining the impedance characteristic of the plasma processor at the plurality of frequencies according to the feedback radio frequency signals. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 Fig. 1 is a structural schematic diagram of a plasma processor;

[0015] Figure 2 Fig. 5 is a schematic diagram of the frequency characteristic curve detected when the plasma is not ignited and the characteristic curve accurately measured;

[0016] Figure 3a 、 Figure 3b Fig. 6 is the initial shape of the impedance characteristic measuring device of the application and the compressed shape structure in the test process;

[0017] Figure 4 Fig. 7 is a structural schematic diagram of the plasma processor comprising the impedance characteristic measuring device of the application;

[0018] Figure 5 Fig. 8 is a structural schematic diagram of the impedance characteristic measuring device of another improved embodiment of the application. DETAILED DESCRIPTION

[0019] Figure 1A schematic view of a capacitively coupled plasma (CCP) processing chamber is shown. The CCP etching apparatus is an apparatus that generates plasma in a reaction chamber by means of a radio frequency power source applied to an electrode plate through capacitive coupling and is used for etching. It includes a vacuum reaction chamber 100, which includes a generally cylindrical reaction chamber sidewall 101 made of a metal material, and an opening 102 provided in the reaction chamber sidewall for accommodating the substrate in and out. The top of the reaction chamber includes a top cover 124, and a gas shower head 120 and a susceptor 110 are provided below the top cover 124. The gas shower head 120 is connected to a gas supply device 125 for delivering a reaction gas to the vacuum reaction chamber and simultaneously serving as an upper electrode of the vacuum reaction chamber. The susceptor simultaneously serves as a lower electrode, and an electrostatic chuck 112 is provided above the susceptor. A reaction region is formed between the upper electrode and the lower electrode. At least one radio frequency power source 150 is applied to one of the upper electrode or the lower electrode through a matching network 152 to generate a radio frequency electric field between the upper electrode and the lower electrode for dissociating the reaction gas into plasma 10 containing a large number of active particles such as electrons, ions, excited state atoms, molecules and radicals. The active particles can have various physical and chemical reactions with the surface of the substrate to be processed, so that the topography of the substrate surface is changed, i.e. the etching process is completed. An exhaust pump 140 is further provided below the vacuum reaction chamber 100 for exhausting the reaction byproducts from the reaction chamber to maintain the vacuum environment of the reaction chamber.

[0020] An electrostatic electrode 113 is provided inside the electrostatic chuck 112 for generating an electrostatic attraction force to support and fix the substrate W to be processed during the process. A heating device 114 is provided below the electrostatic chuck for controlling the temperature of the substrate during the process. A focus ring 132 and an edge ring 134 are provided around the susceptor. The focus ring and the edge ring are used to adjust the electric field or temperature distribution around the substrate to improve the uniformity of the substrate processing. A plasma confinement ring 135 is provided around the edge ring, and an exhaust passage is provided on the plasma confinement ring. By reasonably setting the depth-width ratio of the exhaust passage, the reaction gas is exhausted while the plasma is confined in the reaction region between the upper electrode and the lower electrode, so as to avoid the plasma from leaking to the non-reaction region and causing damage to the components in the non-reaction region. A middle ground ring 136 is provided below the plasma confinement ring 135, and the middle ground ring is used to provide an electric field shielding for the plasma confinement ring. A lower ground ring 137 is provided below the middle ground ring, and the middle ground ring 136 and the lower ground ring 137 are electrically connected to form a radio frequency ground loop in the reaction chamber. A shielding ring 138 is provided between the lower ground ring and the susceptor for shielding the radio frequency signal applied to the susceptor in the susceptor to electrically isolate the susceptor from the lower ground ring.

[0021] The above-mentioned capacitively coupled plasma processor needs to master the frequency characteristics of the processor during the design, manufacture and debugging process, such as the impedance characteristics at different frequencies, the radio frequency power flow path at different frequencies, i.e. the distribution of radio frequency power inside the reaction chamber. However, it is difficult to obtain the above-mentioned frequency characteristics. During the plasma processing, the plasma between the upper and lower electrodes is conductive, and its impedance characteristics are affected by the gas concentration in the plasma, the gas pressure, the input radio frequency power, etc. A large number of tests are required to obtain sufficient data to construct the radio frequency impedance model of the plasma processor. Moreover, each change in the internal hardware of the plasma processor will affect the impedance, so a large number of tests need to be performed again to ensure accuracy. Therefore, this method of a large number of tests to ensure accuracy is not suitable for the development process of the plasma processor which needs to be frequently improved. Moreover, these tests need to be performed after the reaction chamber is assembled, and the test results cannot be predicted during the design and development process. If it is found that the relevant parameters need to be adjusted after the assembly is completed, it will cause the development cycle to be prolonged and the cost to be greatly increased. Another method is to not ignite the plasma and directly input the radio frequency power into the reaction chamber to scan the impedance characteristics of the reaction chamber at each frequency. However, the impedance of the reaction chamber under the condition of not igniting the plasma is very different from the impedance of the reaction chamber during actual plasma processing. As shown in Figure 2 Fig. 20 is the impedance characteristic curve of the plasma processor directly obtained under the condition of not igniting the plasma, and Fig. 21 is the more accurate impedance characteristic curve of the plasma processor obtained after a large number of tests. It can be clearly seen from the two figures that although the waveforms are similar, the impedance peak value directly detected is about 2 MHz different from the accurate impedance peak value. In addition, the direct detection method cannot detect low frequency and direct current signals because there is a centimeter gap between the upper and lower electrodes, and the coupling ability of low frequency is weak and cannot be coupled to the opposite electrode across this distance. Therefore, this direct detection method not only has poor measurement accuracy, but also cannot obtain low frequency and direct current signals.

[0022] The inventors have found that the current methods for measuring the impedance characteristics of the plasma reaction chamber include measuring multiple times under the condition of igniting the plasma and directly inputting the radio frequency power into the reaction chamber to scan the impedance characteristics of the reaction chamber at each frequency without igniting the plasma. As shown in Figure 2 Fig. 20 is the impedance characteristic curve of the plasma processor directly obtained under the condition of not igniting the plasma, and Fig. 21 is the more accurate impedance characteristic curve of the plasma processor obtained after a large number of tests. It can be clearly seen from the two figures that although the waveforms are similar, the impedance peak value directly detected is about 2 MHz different from the accurate impedance peak value. In addition, the direct detection method cannot detect low frequency and direct current signals because there is a centimeter gap between the upper and lower electrodes, and the coupling ability of low frequency is weak and cannot be coupled to the opposite electrode across this distance. Therefore, this direct detection method not only has poor measurement accuracy, but also cannot obtain low frequency and direct current signals.

[0023] According to the problems of the prior art detection method, the inventors propose a new impedance characteristic measurement device, which is placed on the electrostatic chuck in the capacitively coupled plasma processing chamber, realizes the radio frequency connection between the upper electrode and the lower electrode, and can simulate the impedance of the plasma at different frequencies, so as to realize the accurate measurement of the frequency characteristic curve under the condition of no plasma ignition. The specific structure of the impedance characteristic measurement device 200 proposed by the present application is shown in Figure 3a and 3b The device includes a lower contact plate 202 and an upper contact plate 201, and an elastic support 213 is arranged between the two contact plates. The elastic support 213 can typically be a spring or other metal elastic sheet to provide elastic force in the up-down direction. The elastic support 213 is preferably made of a conductor to realize the conductive connection between the two support plates. During the process of igniting the plasma to process, a sheath layer is included between the plasma 10 and the substrate W and between the gas shower head 120. The electrons are repelled in the sheath layer, so the plasma in the actual reaction chamber is composed of two layers of insulating sheath layer and the plasma conductor between the two sheath layers. In order to simulate such an impedance structure, the contact plates 201 and 202 can be made of insulating materials such as Teflon, but the thickness needs to be small, typically less than 0.1mm-1mm, so that the low frequency or direct current signal from the pedestal 110 or the electrostatic electrode 113 can be coupled to the gas shower head 120. Alternatively, the contact plates 201 and 202 can be made of semiconductor materials such as silicon or silicon carbide, but the thickness of the contact plates made of semiconductor materials needs to reach 1-3mm to simulate the impedance of the sheath layer.

[0024] Since the plasma also includes an inductance value, the impedance characteristic measurement device 200 needs a certain amount of inductance value. However, as described in the foregoing embodiment, using multiple springs to simultaneously realize the functions of electric conduction and elastic support requires the spring to have a large cross-sectional area to achieve high conductivity, but the larger the cross-sectional area of the spring, the larger the inductance, and excessive inductance will affect the detection accuracy of the impedance characteristic curve in the high frequency band. It is impossible to meet the three design requirements of electric conduction characteristic, inductance characteristic and elastic support by one conductive spring. Therefore, the inventors propose another variant embodiment, in which the size and material of the elastic support 213 are only designed to provide elastic force and inductance value, and the electric conduction capability is provided by the conductive contact device, wherein the conductive contact device includes a contact head 211 including an outwardly protruding side wall. Opposite to the conductive contact head 211 is a conductive chuck 212, which includes at least two clamping pieces, so that the contact head 211 can achieve good electric conduction performance when being pressed into the two clamping pieces. The conductive chuck 212 and the contact head can be made of high-conductivity materials such as copper or silver to ensure sufficient electric conduction performance.

[0025] AsFigure 3a and 3b Fig. 6a and Fig. 6b respectively show the state of the conductive contact device 210 before being put into the plasma processing chamber and the state of the conductive contact device 210 after being put into the plasma processing chamber and the elastic support member is compressed. During the measurement of the plasma processor, first, the reaction chamber top cover 124 is opened, the impedance characteristic measurement device 200 is put in, then the reaction chamber top cover is put on the top of the reaction chamber to achieve air tightness in the reaction chamber, and then the air in the reaction chamber is pumped out to form a low pressure environment similar to that in the reaction process. Because the application provides good vertical thrust, the upper and lower contact plates 201, 202 can be well attached to the lower surface of the gas shower head 120 above and the upper surface of the electrostatic chuck 112 below, even if the gas shower head and the electrostatic chuck are slightly tilted or have a small gap adjustment, they can achieve close contact and ensure stable electrical connection between the gas shower head 120 and the electrostatic chuck 112. After the installation of the impedance characteristic measurement device is completed, the radio frequency power can be input into the reaction chamber, such as the susceptor 110. In order to test the impedance of the plasma processor, the input radio frequency power needs to be frequency scanned, which continuously changes in a large frequency range, and a network analyzer or other measuring instrument can be used to scan the data. At the same time, the current and amplitude signals flowing through the plasma processor are detected at the ground end or other suitable positions, and finally the impedance characteristic curve of the plasma processing chamber at different frequencies is obtained by comparing and calculating the input signal and the detected signal. For example, Figure 4 Fig. 8 shows the structure of the plasma processor after the impedance characteristic measurement device 200 is installed, in which at least one elastic support member 213 and the conductive contact device 210 together form an elastic conductive part, and multiple elastic conductive parts are arranged between the upper and lower contact plates 201, 202 along the circumference of the contact plate, so that the current flowing through is uniformly distributed among the multiple elastic conductive parts. The size of the contact plate 201, 202 needs to be large enough to cover most of the area of the electrostatic chuck (more than 1 / 2) to simulate the impedance of the plasma, and preferably to cover the entire upper surface of the electrostatic chuck 112 or extend outward to the focusing ring 132. Because there is also plasma above the focusing ring 132 in the actual plasma processing process, it is best to extend the contact ring 202R to cover the upper surface of the focusing ring. Because the height of the focusing ring 132 is different from that of the upper surface of the electrostatic chuck, an independent height contact ring 202R is needed, such as Figure 5The lower contact plate 202 and the contact ring 202R shown are suitable for covering the electrostatic chuck and the focus ring at the same time, and a larger coverage area can obtain a more accurate impedance distribution curve of the plasma processor. A plurality of elastic conductive parts can be provided with independent current detection devices for detecting the current size distribution of the plasma processor at different azimuth angles, and the impedance distribution at different azimuth angles is also detected. The parallelism of the upper and lower electrodes may not be sufficient due to installation accuracy problems, or the opening 102 for transferring the wafer on the side wall of the reaction chamber will cause uneven distribution of radio frequency current on the entire cavity. Through the current detection device provided in each elastic conductive part, the uneven distribution of radio frequency current can be quantified according to the detected current data, and various means can be used to accurately offset the uneven plasma processing effect caused by the uneven distribution of radio frequency impedance in the circumferential direction.

[0026] During the impedance characteristic curve detection process, a dummy wafer can also be provided on the electrostatic chuck 112, which has the same material composition as the wafer to be processed, except that the dummy wafer does not have semiconductor devices formed thereon. Then the impedance characteristic measuring device proposed in the present application is placed on the dummy wafer, and during the subsequent impedance detection process without igniting the plasma, the data detected is closer to the actual impedance of the plasma processor during the plasma process execution process, that is, the data is more accurate. Due to the addition of the dummy wafer, the thickness of the lower contact plate 202 in the present application can be further reduced, for example, the lower contact plate 202 made of a semiconductor material can be reduced to 0.6-2mm in thickness, so that the impedance formed by the combination of the dummy wafer and the lower contact plate is still close to the impedance during the actual process.

[0027] The elastic conductive part in the present application can be an embodiment of a plurality of uniform arrangements in the circumferential direction, or a circular ring structure covering the entire annular area near the edge of the upper / lower contact plate. The circular ring-shaped contact head 211 matches the circular ring-shaped conductive chuck 212 located on the lower contact plate 202. During the impedance characteristic detection process, the contact head and the conductive chuck 212 form a uniformly distributed conductive path in the circumferential direction, so that the radio frequency current can be uniformly distributed in the entire circumferential direction.

[0028] The plasma simulation device 200 in the present application can be applied not only between the susceptor and the gas shower head, but also in other slits with plasma, such as the slit between the electrostatic chuck and the focus ring or the slit on the confinement ring 135. In order to adapt to various shapes of slits, the size and shape of the plasma simulation device in the present application need to be modified accordingly, but the working principle and structure are the same as the embodiments disclosed in the present application, and also belong to the protection scope of the present application.

[0029] The elastic conductive part in the present application can be directly composed of a high-conductive elastic metal as described in one embodiment of the present application, or composed of a spring and a conductive contact device as described in another embodiment of the present application, as long as the device can realize the purpose of simultaneously improving the elastic pressure and the low conductive impedance. The lower impedance can simulate the comprehensive impedance of the sheath layer and the plasma in the actual plasma. Considering the accuracy of the inductance parameter, the elastic support can be composed of other materials with low inductance value, such as organic materials such as rubber, etc., and the inductance and conductive characteristics are provided by the conductive contact device.

[0030] Although the present application has been disclosed with reference to the above embodiments, the present application is not limited to the above. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application, and the protection scope of the present application should be defined by the scope of the claims.

Claims

1. An impedance characteristic measuring device for a capacitively coupled plasma processor, characterized in that: The impedance characteristic measuring device comprises: an upper contact plate and a lower contact plate, wherein the upper contact plate is used to contact the lower surface of the gas shower head of the capacitively coupled plasma processor, and the lower contact plate is used to contact the upper surface of the electrostatic chuck in the capacitively coupled plasma processor; At least one elastic conductive portion is located between the upper contact plate and the lower contact plate. The elastic conductive portion provides elastic force and a low-impedance conductive path, so that when the impedance characteristic measurement device measures the impedance characteristic curve of a capacitively coupled plasma processor, the upper and lower contact plates are compressed and closely contact the gas shower head and the electrostatic chuck, respectively. The upper and lower contact plates are made of an insulating material with a thickness of 0.1-1 mm, or made of a semiconductor material with a thickness of 0.6-3 mm.

2. The impedance characteristics measuring device according to claim 1, wherein: The elastic conductive part includes an elastic support member providing elastic force and a conductive contact device providing a conductive path.

3. The impedance characteristics measuring device according to claim 2, wherein: The conductive contact device includes a contact head mounted on an upper or lower contact plate and a conductive clamp located on the opposite contact plate. When the upper and lower contact plates are compressed, the contact head is inserted into the conductive clamp to form a stable electrical connection.

4. The impedance characteristics measuring device according to claim 2, wherein: The upper and lower contact plates are disc-shaped and include a plurality of elastic conductive parts. The plurality of elastic conductive parts are arranged at intervals at different azimuth angles on the upper and lower contact plates.

5. The impedance characteristics measuring device according to claim 4, wherein: The multiple elastic conductive parts are provided with current detection devices.

6. The impedance characteristics measuring device according to claim 1, wherein: The lower contact plate covers more than 1 / 2 of the upper surface of the electrostatic chuck.

7. The impedance characteristics measuring device according to claim 1, wherein: The impedance characteristic measuring device further comprises a contact ring surrounding the periphery of the lower contact plate, the contact ring corresponds to the position of the focus ring in the capacitively coupled plasma processor, and the contact ring is connected to the upper contact plate via an elastic conductive portion.

8. A capacitively coupled plasma processor, comprising: The cavity includes a base, on which an electrostatic chuck is provided for fixing the substrate to be processed; A top cover is provided below which is a gas shower head; at least one radio frequency power supply is connected to the base or the gas shower head, and a plasma is formed below the gas shower head and above the base for processing the substrate; a focusing ring and an edge ring are also provided around the base, and a plasma confinement ring is also provided around the edge ring; The four components, namely the gas shower head, electrostatic chuck, focusing ring, and plasma confinement ring, are all exposed to the plasma. An impedance characteristic measuring device is arranged in the gap between the base and the gas shower head, or in the gap between the electrostatic chuck and the focusing ring. The impedance characteristic measuring device includes first and second contact plates, and at least one elastic conductive portion is included between the first and second contact plates, so that the two contact plates are respectively attached to the surfaces of the base and the gas shower head or the surfaces of the electrostatic chuck and the focusing ring, and provide a conductive path. The first and second contact plates are made of insulating material with a thickness of 0.1-1 mm, or made of semiconductor material with a thickness of 0.6-3 mm.

9. A method for detecting impedance characteristics of a capacitively coupled plasma processor, characterized in that: The detection steps include: Open the top cover of the capacitive coupled plasma processor; Place the impedance characteristic measuring device described in claim 1; Closing the top cover of the plasma processor so that the upper contact plate in the impedance characteristic measurement device is in close contact with the gas shower head and the lower contact plate is in close contact with the upper surface of the electrostatic chuck; extracting air from the plasma processor; Multiple radio frequency signals with different frequencies are input to the base or gas shower head in the plasma processor, the feedback radio frequency signals are detected at the detection end of the plasma processor, and the impedance characteristics of the plasma processor at the multiple frequencies are obtained according to the feedback radio frequency signals.

10. A method for detecting impedance characteristics of a capacitively coupled plasma processor according to claim 9, characterized in that: The method further includes placing the experimental wafer on the upper surface of the electrostatic chuck before placing the impedance characteristic measuring device, and then placing the impedance characteristic measuring device on the experimental wafer.

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