JP2006019716A - Plasma processing apparatus and impedance control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma processing apparatus capable of controlling impedance on a plasma source side and capable of eliminating impedance errors among devices or cleaning cycles. <P>SOLUTION: The plasma processing apparatus, that performs plasma processing on a wafer W by generating the plasma of a processing gas disposed between an upper electrode 34 and a lower electrode 16 divided into an internal electrode 38 and an external electrode 36, is provided, and the device has a resonant circuit 101, formed so as to allow a high-frequency current to flow into the electrode 38, a variable capacitor 78 provided on a supply line to the electrode 38, a sensor 89 for sensing bias V<SB>PP</SB>of the electrode 16, while making the capacitance of the variable capacitor 78 changed, and a control section 102 for detecting the signal from the sensor 89 to retrieve the resonance point of the circuit 101 and controlling the capacitance of the variable capacitor 78 at the resonance point to a value that serves as a reference. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a plasma processing apparatus that performs plasma processing on a substrate such as a semiconductor substrate and an impedance adjustment method in the plasma processing apparatus.

  For example, in a semiconductor device manufacturing process, plasma processing such as etching, sputtering, and CVD (chemical vapor deposition) is frequently used for a semiconductor wafer that is a substrate to be processed.

  Various plasma processing apparatuses for performing such plasma processing are used, and among them, a capacitively coupled parallel plate plasma processing apparatus is the mainstream.

  In a capacitively coupled parallel plate plasma processing apparatus, a pair of parallel plate electrodes (upper and lower electrodes) are arranged in a chamber, a processing gas is introduced into the chamber, and a high frequency is applied to one of the electrodes to provide a gap between the electrodes. A high frequency electric field is formed, plasma of a processing gas is formed by the high frequency electric field, and the semiconductor wafer is subjected to plasma processing.

  Specifically, a plasma processing apparatus is known that forms a plasma by applying a high frequency for plasma formation to the upper electrode and applying a high frequency for attracting ions to the lower electrode. When such a plasma processing apparatus is applied to etching, an etching process with high selectivity and high reproducibility is possible (for example, Patent Document 1).

By the way, in this type of plasma processing apparatus, there is a slight difference in impedance on the plasma source side between apparatuses or every cleaning cycle due to dimensional tolerance of parts, mounting error, and the like. However, the conventional plasma processing apparatus does not have means for eliminating such an impedance difference, which causes variations in process characteristics between apparatuses or cleaning cycles.
JP 2000-173993 A

  The present invention has been made in view of such circumstances, and it is intended to provide a plasma processing apparatus capable of adjusting the impedance of the plasma source side and eliminating impedance errors between apparatuses or between cleaning cycles. Objective. It is another object of the present invention to provide an impedance adjustment method in a plasma processing apparatus that can easily realize such impedance adjustment.

  In order to solve the above problems, according to a first aspect of the present invention, a processing container in which a substrate to be processed is accommodated and capable of being evacuated, a first electrode and a second electrode disposed to face each other in the processing container, A high-frequency power supply means for supplying high-frequency power for plasma formation to the first electrode; and a processing gas supply means for supplying a processing gas into the processing container; and the first electrode and the second electrode A plasma processing apparatus for generating a plasma of a processing gas to perform plasma processing on a substrate to be processed, further comprising impedance adjusting means for adjusting impedance on a plasma source side, wherein the impedance adjusting means includes the first A resonance circuit formed so that a high-frequency current flows into one electrode, a variable impedance portion provided in a power supply line of the first electrode, and a resonance point of the resonance circuit are grasped. A detector for detecting a device state for detecting the device state signal of the detector while changing a value of the variable impedance unit in a state where the plasma is formed, and a resonance point of the resonance circuit And a control unit that adjusts the value of the variable impedance unit at the resonance point to a reference value.

  In a second aspect of the present invention, a processing container in which a substrate to be processed is accommodated and evacuated, a first electrode and a second electrode disposed opposite to each other in the processing container, and plasma formation on the first electrode A high-frequency power supply means for supplying high-frequency power for use, and a processing gas supply means for supplying a processing gas into the processing container, and plasma of the processing gas is provided between the first electrode and the second electrode. A plasma processing apparatus that generates and performs plasma processing on a substrate to be processed, wherein the first electrode is divided into an inner electrode and an outer electrode, and the plasma processing apparatus further includes an impedance for adjusting an impedance on a plasma source side Adjusting means, wherein the impedance adjusting means includes a resonance circuit formed so that a high-frequency current flows into the inner electrode of the first electrode, and an inner power of the first electrode. The variable impedance section provided in the power supply line to the outer electrode or the power supply line to the outer electrode, the detector for detecting the device state for grasping the resonance point of the resonance circuit, and the variable in the state where the plasma is formed Control that detects the device state signal from the detector while changing the value of the impedance unit, finds the resonance point of the resonance circuit, and adjusts the value of the variable impedance unit at the resonance point to a reference value And a plasma processing apparatus.

  In a third aspect of the present invention, a processing container in which a substrate to be processed is accommodated and evacuated, a first electrode and a second electrode disposed opposite to each other in the processing container, and plasma formation on the first electrode A high-frequency power supply means for supplying high-frequency power for use, and a processing gas supply means for supplying a processing gas into the processing container, and plasma of the processing gas is provided between the first electrode and the second electrode. A plasma processing apparatus that generates and performs plasma processing on a substrate to be processed, wherein the first electrode is divided into an inner electrode and an outer electrode, and the plasma processing apparatus further includes an impedance for adjusting an impedance on a plasma source side Adjusting means, wherein the impedance adjusting means includes a resonance circuit formed so that a high-frequency current flows into the inner electrode of the first electrode, and an inner power of the first electrode. While changing the capacitance of the variable capacitor in the state where the variable capacitor provided in the power supply line to, the detector for detecting the device state for grasping the resonance point of the resonance circuit, and the plasma is formed, And a control unit for detecting a device state signal from the detector, searching for a resonance point of the resonance circuit, and adjusting a capacitance of a variable capacitor at the resonance point to a reference value. A processing device is provided.

  According to a fourth aspect of the present invention, a processing container in which a substrate to be processed is accommodated and evacuated, a first electrode and a second electrode disposed opposite to each other in the processing container, and the first electrode A high-frequency power supply means for supplying a high-frequency power for plasma formation; and a processing gas supply means for supplying a processing gas into the processing container. A processing gas is provided between the first electrode and the second electrode. An impedance adjustment method in a plasma processing apparatus for generating plasma and performing plasma processing on a substrate to be processed, wherein a variable impedance portion is provided in a power supply line of the first electrode so that a high-frequency current flows into the first electrode A detector for detecting a device state for grasping a resonance point of the resonance circuit is provided, and while changing the value of the variable impedance unit while the plasma is formed, A device state signal is detected by an output device to find a resonance point of the resonance circuit, and a value of a variable impedance portion at the resonance point is adjusted to a reference value to adjust a plasma source side impedance. An impedance adjustment method is provided.

  According to a fifth aspect of the present invention, a processing container in which a substrate to be processed is accommodated and evacuated, a first electrode and a second electrode disposed facing each other in the processing container, and the first electrode A high-frequency power supply means for supplying high-frequency power for plasma formation; and a processing gas supply means for supplying a processing gas into the processing container, wherein the first electrode is divided into an inner electrode and an outer electrode, An impedance adjustment method in a plasma processing apparatus for generating a plasma of a processing gas between a first electrode and a second electrode to perform plasma processing on a substrate to be processed, the power supply line to an inner electrode of the first electrode Alternatively, a variable impedance section is provided in the power supply line to the outer electrode, and the device state for grasping the resonance point of the resonance circuit formed so that the high-frequency current flows into the inner electrode of the first electrode is detected. In the state where the plasma is formed, while changing the value of the variable impedance unit, the detector detects a device state signal to find the resonance point of the resonance circuit, and the resonance point The impedance adjustment method is characterized in that the impedance on the plasma source side is adjusted by adjusting the value of the variable impedance part in the reference value to a reference value.

  In a sixth aspect of the present invention, a processing container in which a substrate to be processed is accommodated and evacuated, a first electrode and a second electrode disposed opposite to each other in the processing container, and plasma formation on the first electrode A high-frequency power supply means for supplying high-frequency power for use and a processing gas supply means for supplying a processing gas into the processing container, wherein the first electrode is divided into an inner electrode and an outer electrode, An impedance adjustment method in a plasma processing apparatus for generating a plasma of a processing gas between an electrode and the second electrode and performing plasma processing on a substrate to be processed, wherein the method is variable in a power supply line to the inner electrode of the first electrode A capacitor is provided, a detector for detecting a device state for grasping a resonance point of a resonance circuit formed so that a high-frequency current flows into the inner electrode of the first electrode, and a plasma is formed. In this state, while detecting the device state signal by changing the capacitance of the variable capacitor, the resonance point of the resonance circuit is found, and the value of the capacitance of the variable capacitor at the resonance point is used as a reference. Provided is an impedance adjustment method characterized in that the impedance on the plasma source side is adjusted by adjusting the value.

  According to the present invention, there is provided a resonance circuit, a variable impedance unit provided in a power supply line of the first electrode, and a detector for detecting a device state for grasping a resonance point of the resonance circuit, and the plasma In this state, while changing the value of the variable impedance unit, the device state signal of the detector is detected to find the resonance point of the resonance circuit, and the value of the variable impedance unit at the resonance point is used as a reference. Since the impedance on the plasma source side is adjusted by adjusting to such a value, the difference in the impedance on the plasma source side between apparatuses and every cleaning cycle caused by the dimensional tolerance of parts and mounting errors can be minimized. Further, since adjustment can be performed in a state where plasma is generated, impedance adjustment accuracy is high. Furthermore, since no special measuring equipment or measuring jig is used, it is advantageous in terms of cost. Furthermore, since the adjustment can be automatically performed, there is no human error.

  Further, the first electrode is divided into an inner electrode and an outer electrode, a variable impedance portion is provided in the inner electrode feeding line or the outer electrode feeding line, and an electric field is generated between the inner portion and the outer portion on the plasma contact surface of the first electrode. In a plasma processing apparatus that obtains the effect of improving the uniformity of the spatial distribution of plasma by controlling the impedance, the impedance is obtained by using a variable impedance section provided in this apparatus and a resonance circuit formed so that a high-frequency current flows into the inner electrode. Adjustments can be made. In particular, impedance can be adjusted more effectively by providing a variable capacitor in the power supply line of the inner electrode.

Embodiments of the present invention will be specifically described below with reference to the accompanying drawings.
FIG. 1 is a schematic cross-sectional view showing a plasma etching apparatus according to an embodiment of the present invention.

  This plasma etching apparatus is configured as a capacitively coupled parallel plate plasma etching apparatus, and has a substantially cylindrical chamber (processing vessel) 10 made of aluminum whose surface is anodized, for example. The chamber 10 is grounded for safety.

  A cylindrical susceptor support 14 is disposed at the bottom of the chamber 10 via an insulating plate 12 made of ceramics or the like, and a susceptor 16 made of, for example, aluminum is provided on the susceptor support 14. The susceptor 16 constitutes a lower electrode, on which a semiconductor wafer W as a substrate to be processed is placed.

  On the upper surface of the susceptor 16, an electrostatic chuck 18 that holds the semiconductor wafer W by electrostatic force is provided. The electrostatic chuck 18 has a structure in which an electrode 20 made of a conductive film is sandwiched between a pair of insulating layers or insulating sheets, and a DC power source 22 is electrically connected to the electrode 20. The semiconductor wafer W is attracted and held on the electrostatic chuck 18 by an electrostatic force such as a Coulomb force generated by a DC voltage from the DC power supply 22.

  A focus ring 24 made of, for example, silicon is disposed on the upper surface of the susceptor 16 around the electrostatic chuck 18 to improve etching uniformity. A cylindrical inner wall member 26 made of, for example, quartz is provided on the side surfaces of the susceptor 16 and the susceptor support 14.

  Inside the susceptor support 14, for example, a coolant chamber 28 is provided on the circumference. A coolant having a predetermined temperature, for example, cooling water, is circulated and supplied to the coolant chamber from a chiller unit (not shown) provided outside through the pipes 30a and 30b, and the processing temperature of the semiconductor wafer W on the susceptor is controlled by the coolant temperature. Can be controlled.

  Further, a heat transfer gas, for example, He gas, from a heat transfer gas supply mechanism (not shown) is supplied between the upper surface of the electrostatic chuck 18 and the back surface of the semiconductor wafer W via the gas supply line 32.

  Above the susceptor 16 that is the lower electrode, an upper electrode 34 is provided in parallel so as to face the susceptor 16. A space between the upper and lower electrodes 34 and 16 becomes a plasma generation space. The upper electrode 34 faces the semiconductor wafer W on the susceptor 16 that is the lower electrode, and forms a surface that is in contact with the plasma generation space, that is, a facing surface.

  The upper electrode 34 is disposed in a state of being insulated radially inward of the outer-shaped portion electrode 36 and a ring-shaped or donut-shaped outer upper electrode 36 disposed to face the susceptor 16 at a predetermined interval. And a disk-shaped inner upper electrode 38. In these, the outer upper electrode 36 is mainly used for plasma generation, and the inner upper electrode 38 has an auxiliary relationship.

As shown in the enlarged view of the main part of the plasma etching apparatus in FIG. 2, an annular gap (gap) of, for example, 0.25 to 2.0 mm is formed between the outer upper electrode 36 and the inner upper electrode 38. In this gap, a dielectric 40 made of quartz, for example, is provided. A ceramic member 96 is further provided in the gap. The ceramic member 96 can be omitted. A capacitor is formed between the electrodes 36 and 38 across the dielectric 40. The capacitance C _{40 of} this capacitor is selected or adjusted to a desired value depending on the size of the gap and the dielectric constant of the dielectric 40. A ring-shaped insulating shielding member 42 made of alumina (Al ₂ O ₃ ), for example, is airtightly attached between the outer upper electrode 36 and the side wall of the chamber 10.

  The outer upper electrode 36 is preferably composed of a low resistance conductor or semiconductor with low Joule heat, such as silicon. A first high frequency power source 52 is electrically connected to the outer upper electrode 36 via a matching unit 44, an upper power feed rod 46, a connector 48, and a power feed tube 50. The first high frequency power supply 52 outputs a high frequency power of 13.56 MHz or higher, for example, 60 MHz. The matching unit 44 matches the load impedance with the internal (or output) impedance of the first high-frequency power source 52, and the output impedance and load impedance of the first high-frequency power source 52 when plasma is generated in the chamber 10. Functions to match. The output terminal of the matching unit 44 is connected to the upper end of the upper feed rod 46.

  The power supply tube 50 is made of a conductive plate having a cylindrical shape, a conical shape, or a shape close thereto, such as an aluminum plate or a copper plate. The lower end of 46 is electrically connected. Outside the power supply tube 50, the side wall of the chamber 10 extends upward from the height position of the upper electrode 34 to constitute a cylindrical ground conductor 10a. The upper end portion of the cylindrical ground conductor 10 a is electrically insulated from the upper power supply rod 46 by a cylindrical insulating member 54. In such a configuration, in the load circuit viewed from the connector 48, a coaxial line using the power supply tube 50 and the outer upper electrode 36 as a waveguide is formed by the power supply tube 50, the outer upper electrode 36, and the cylindrical ground conductor 10a.

  As shown in FIG. 1, the inner upper electrode 38 has an electrode plate 56 made of a semiconductor material such as silicon or silicon carbide, and has a plurality of gas discharge holes 56a for gas, and detachably supports the electrode plate 56. An electrode support 58 made of a conductive material, for example, aluminum whose surface is anodized. Inside the electrode support 58, a central gas introduction chamber 62 and a peripheral gas introduction chamber 64 divided by an annular partition member 60 made of, for example, an O-ring are provided. A central shower head is constituted by the central gas introduction chamber 62 and a large number of gas discharge holes 56a provided on the lower surface thereof, and the peripheral gas introduction chamber 64 and a large number of gas discharge holes 56a provided on the lower surface thereof constitute a peripheral area. Shower head is configured.

The two gas introduction chambers 62 and 64 are supplied with a processing gas from a common processing gas supply source 66 at a desired flow rate ratio. That is, the gas supply pipe 68 from the processing gas supply source 66 is branched into two in the middle and connected to the gas introduction chambers 62 and 64, and flow control valves 70a and 70b are provided in the branch pipes 68a and 68b, respectively. Since the conductances of the flow paths from the processing gas supply source 66 to the gas introduction chambers 62 and 64 are equal, the flow rate of the processing gas supplied to the central gas introduction chamber 62 and the peripheral gas introduction chamber 64 by the flow rate control valves 70a and 70b. The ratio can be adjusted arbitrarily. The gas supply pipe 68 is provided with a mass flow controller (MFC) 72 and an opening / closing valve 74. Discharged from this manner, by adjusting the flow rate ratio of the process gas to be introduced into the central gas introduction chamber 62 and the peripheral gas introduction chamber 64, the flow rate F _C and peripheral showerhead gas discharged from the central showerhead The ratio (F _C / F _E ) with the gas flow rate F _E can be arbitrarily adjusted. It is also possible to vary the flow rate per unit area of the processing gas discharged from the central shower head and the peripheral shower head. Furthermore, it is also possible to select the gas type or gas mixture ratio of the processing gas discharged from the central shower head and the peripheral shower head independently or separately.

  The first high-frequency power source is electrically connected to the electrode support 58 of the inner upper electrode 38 via the matching unit 44, the upper power feed rod 46, the connector 48, and the lower power feed cylinder 76. A variable capacitor 78 capable of variably adjusting the capacitance is provided in the middle of the lower feeding cylinder 76. As will be described later, the variable capacitor 78 has a function of adjusting the balance between the outer electric field strength and the inner electric field strength, and also functions as a part of an impedance adjusting mechanism for adjusting the impedance on the plasma source side of the apparatus.

  Although illustration is omitted, the outer upper electrode and the inner upper electrode 38 may be provided with appropriate refrigerant chambers or cooling jackets, and the temperature of these electrodes may be controlled via the refrigerant from the external chiller unit.

  An exhaust port 80 is provided at the bottom of the chamber 10, and an exhaust device 84 is connected to the exhaust port 80 via an exhaust pipe 82. The exhaust device 84 includes a vacuum pump such as a turbo molecular pump, and can reduce the pressure in the chamber 10 to a desired degree of vacuum. Further, a loading / unloading port 85 for the semiconductor wafer W is provided on the side wall of the chamber 10, and the loading / unloading port 85 can be opened and closed by a gate valve 86.

A second high frequency power supply 90 is electrically connected to the susceptor 16, which is the lower electrode, via a matching unit 88. By supplying high frequency power from the second high frequency power supply 90 to the lower electrode susceptor 16, ions are drawn into the semiconductor wafer W side. The second high frequency power supply 90 outputs a frequency within a range of 2 to 27 MHz, for example, a high frequency power of 2 MHz. The matching unit 88 is for matching the load impedance with the internal (or output) impedance of the high-frequency power source 90, and when the plasma is generated in the chamber 10, the internal impedance of the high-frequency power source 90 and the load impedance seem to coincide with each other. To function. The matching unit 88 incorporates a V _PP monitor (voltage detector) 89 that forms part of an impedance adjustment mechanism described later. Hereinafter, V _PP refers to a potential difference between peaks of a high-frequency voltage waveform.

  The inner upper electrode 38 is electrically provided with a low pass filter (LPF) 92 for passing high frequency (2 MHz) from the second high frequency power supply 90 to the ground without passing high frequency (60 MHz) from the first high frequency power supply 52. It is connected to the. The low-pass filter (LPF) 92 is preferably composed of an LR filter or an LC filter, but provides a sufficiently large reactance for the high frequency (60 MHz) from the first high-frequency power source 52 even with only one conductor. You can do that. On the other hand, the susceptor 16 as the lower electrode is electrically connected to a high pass filter (HPF) 94 for passing a high frequency (60 MHz) from the first high frequency power supply 52 to the ground.

The plasma etching apparatus according to the present embodiment has an impedance adjustment mechanism 100 as shown in FIG. The impedance adjustment mechanism 100 generates plasma in the apparatus, the variable capacitor 78 constituting the variable impedance unit, the resonance circuit 101 formed by the current flowing into the inner upper electrode 38, the _VPP monitor 89, and the apparatus. At this time, while changing the capacitance of the variable capacitor 78, the resonance point of the resonance circuit 101 is found based on the value of the bias V _PP of the lower electrode (susceptor 16) detected by the V _PP monitor 89. And a controller 102 for adjusting the capacitance value of the variable capacitor to a reference value. As a result, the impedance on the plasma source side can be adjusted. _The bias _{V PP} of lower electrode detected by the _{V PP} monitor 80 _may be referred to as _{V PP} for high-frequency power from the second RF power supply 90 detected by the _{V PP} monitor 80.

When performing the etching process in the plasma etching apparatus configured as described above, first, the gate valve 86 is opened, and the semiconductor wafer W to be etched is loaded into the chamber 10 via the loading / unloading port 85, and the susceptor is loaded. 16 is mounted. Then, a processing gas for etching is introduced from the processing gas supply source 66 into the central gas introduction chamber 62 and the peripheral gas introduction chamber 64 at a predetermined flow rate and flow rate ratio, and the inside of the chamber 10 is exhausted by the exhaust device 84. Is set to a set value within a range of 0.1 to 150 Pa, for example. Here, various conventionally used gases can be employed as the processing gas, and for example, a gas containing a halogen element such as a fluorocarbon gas (C _x F _y ) can be suitably used. Furthermore, other gases such as Ar gas and O ₂ gas may be contained.

  In this manner, with the etching gas introduced into the chamber 10, a high frequency power (60 MHz) for plasma generation is applied from the first high frequency power source 52 to the upper electrode 34 with a predetermined power, and the second high frequency power source 90. Further, a high frequency (2 MHz) for ion attraction is applied to the susceptor 16 as the lower electrode with a predetermined power. Further, a DC voltage is applied from the DC power source 22 to the electrode 20 of the electrostatic chuck 18 to fix the semiconductor wafer W to the susceptor 16.

  The etching gas discharged from the gas discharge hole 56a of the inner upper electrode 38 is turned into plasma in a glow discharge between the upper electrode 34 and the lower electrode susceptor 16 generated by the high frequency power, and radicals and ions generated by this plasma. As a result, the surface to be processed of the semiconductor wafer W is etched.

  In this plasma etching apparatus, high frequency power in a high frequency region (5 to 10 MHz or more at which ions cannot move) is supplied to the upper electrode 34, so that the plasma can be densified in a preferable dissociated state, and the lower pressure can be reduced. High density plasma can be formed even under conditions.

  Further, in the upper electrode 34, the inner upper electrode 38 that directly faces the semiconductor wafer W is used as a shower head type, and the ratio of gas discharge flow rate can be arbitrarily adjusted between the central shower head and the peripheral shower head. The spatial distribution of the density of gas molecules or radicals can be controlled in the radial direction, and the spatial distribution characteristics of etching characteristics mainly caused by radicals can be arbitrarily controlled.

  On the other hand, in the upper electrode 34, as will be described later, as the high-frequency electrode for plasma generation, the outer upper electrode 36 is the main and the inner upper electrode 38 is the auxiliary, and the electrodes 36, 38 give the electrons directly below them. Since the electric field strength ratio can be adjusted, the spatial distribution of plasma density can be controlled in the radial direction, and the spatial characteristics of reactive ion etching can be controlled arbitrarily and finely.

  Here, the control of the plasma density space distribution performed by changing the ratio of the electric field strength or the input power between the outer upper electrode 36 and the inner upper electrode 38 is performed between the central shower head and the peripheral shower head. It does not substantially affect the control of the radical density spatial distribution performed by changing the flow rate of the processing gas, the gas density, or the ratio of the gas mixture ratio. That is, since the dissociation of the processing gas ejected from the central shower head and the peripheral shower head is performed in an area immediately below the inner upper electrode 38, the balance of the electric field strength is changed between the inner upper electrode 38 and the outer upper electrode 36. However, since the central shower head and the peripheral shower head are in the inner upper electrode 38 and are in the same area, the radical generation amount or density balance between them is not significantly affected. Therefore, the spatial distribution of plasma density and the spatial distribution of radical density can be controlled substantially independently.

  Further, the plasma etching apparatus of the present embodiment is mainly the outer upper electrode 36, and most or most of the plasma is generated immediately below it and diffused immediately below the inner upper electrode 38. For this reason, since the inner upper electrode 38 that also serves as a shower head receives less attack from plasma ions, the sputtering progress of the gas discharge holes 56a of the electrode plate 56, which is a replacement part, is effectively suppressed, and the electrode plate 56 The service life can be greatly extended. On the other hand, the outer upper electrode 36 that generates most or most of the plasma does not have a gas discharge port in which an electric field concentrates, and therefore, there is little ion attack and the life is not shortened.

  Next, with reference to FIGS. 2 and 4, the control of the plasma density spatial distribution performed by varying the electric field strength or input power between the outer upper electrode 36 and the inner upper electrode 38 will be described in more detail. . 2 shows the configuration of the main part of the plasma etching apparatus according to the present embodiment, in particular, the main part of the plasma generation unit as described above, and FIG. 4 shows the equivalent circuit of the main part of the plasma generation unit. . In FIG. 2, the structure of the shower head portion is omitted, and the resistance of each portion is omitted in FIG.

As described above, in the load circuit viewed from the connector 48, the outer upper electrode 36 and the power feeding tube 50 and the cylindrical ground conductor 10a form a coaxial line having the outer upper electrode 36 and the power feeding tube 50 as the waveguide Jo. . Here, if the radius (outer diameter) of the feeding tube 50 is ao and the radius of the cylindrical ground conductor 10a is b, the characteristic impedance or inductance Lo of this coaxial line can be approximated by the following equation (1).
Lo = K · ln (b / ao) (1)
However, K is a constant determined by the carrier mobility and dielectric constant of the waveguide.

On the other hand, in the load circuit viewed from the connector 48, a coaxial line having the lower power feed rod 76 as the waveguide Ji is formed between the lower power feed rod 76 and the cylindrical ground conductor 10a. Although the inner upper electrode 38 is also on the extension of the lower power feed rod 76, the impedance of the lower power feed rod 76 becomes dominant because the diameters are extremely different. Here, if the radius (outer diameter) of the lower feed rod 76 is ai, the characteristic impedance or inductance Li of this coaxial line can be approximated by the following equation (2).
Li = K · ln (b / ai) (2)

  As understood from the above formulas (1) and (2), the inner waveguide Ji for transmitting a high frequency to the inner upper electrode 38 provides the same inductance Li as that of the conventional general high frequency system, whereas the outer upper portion Ji. The outer waveguide Jo that transmits a high frequency to the electrode 36 can provide a remarkably small inductance Lo as the diameter increases. Thereby, in the load circuit ahead of the connector 48 when viewed from the matching unit 44, high frequency is easily propagated through the low-impedance outer waveguide Jo (voltage drop is small), and a relatively large high-frequency power Po is applied to the outer upper electrode 36. By supplying, a strong electric field strength Eo can be obtained on the lower surface (plasma contact surface) of the outer upper electrode 36. On the other hand, the high-impedance inner waveguide Ji hardly propagates high frequency (a large voltage drop), and the inner upper electrode 38 is supplied with high-frequency power Pi smaller than the high-frequency power Po supplied to the outer upper electrode 36. The electric field strength Ei obtained on the lower surface (plasma contact surface) of the electrode 38 can be made smaller than the electric field strength Eo on the outer upper electrode 36 side.

  Thus, in the upper electrode 34, electrons are accelerated by a relatively strong electric field Eo immediately below the outer upper electrode 36, and at the same time, electrons are accelerated by a relatively weak electric field Ei immediately below the inner upper electrode 38. As a result, most or most of the plasma P is generated immediately below the outer upper electrode 36, and a part of the plasma P is auxiliaryly generated immediately below the inner upper electrode 38. Then, the high-density plasma generated immediately below the outer upper electrode 36 diffuses inward and outward in the radial direction, so that the plasma density in the plasma processing space between the upper electrode 34 and the susceptor 16 is uniform in the radial direction. Is done.

The maximum transmission power P _max in the coaxial line formed by the outer upper electrode 36 and the feed cylinder 50 and the cylindrical ground conductor 10a depends on the radius ao of the feed cylinder 50 and the radius b of the cylindrical ground conductor 10a. (3).
P _max / Eo _max ² = ao ² [ln (b / ao)] ² / 2Zo (3)
However, Zo is the input impedance of the coaxial line viewed from the matching unit 44 side, and Eo _max is the maximum electric field strength of the RF transmission system.

In the above equation (3), the maximum transmission power P _max is a maximum value at b / ao≈1.65. Therefore, in order to improve the power transmission efficiency of the outer waveguide Jo, the ratio (b / ao) of the diameter size of the cylindrical grounding conductor 10a to the diameter size of the feeding tube 50 is set to about 1.65. Most preferably, it is configured to fall within the range of at least 1.2 to 2.0. Furthermore, it is the range of 1.5-1.7.

In order to arbitrarily and finely control the spatial distribution of the plasma density, the outer electric field intensity Eo directly below the outer upper electrode 36 (or the input electric power Po to the outer upper electrode 36 side) and the inner electric field intensity Ei immediately below the inner upper electrode 38. It is preferable to adjust the ratio, that is, the balance with (or the input electric power Pi to the inner upper electrode 38 side), and a variable capacitor 78 is inserted in the middle of the lower power feed rod 76 as the means. Relationship between the ratio of the input power Pi into the inner upper electrode 38 side with respect to the total input power and the capacitance C ₇₈ of the variable capacitor 78 is as shown in FIG. As is apparent from this figure, by changing the capacitance C ₇₈ of the variable capacitor 78, the impedance or reactance of the inner waveguide Ji is increased or decreased, and the relative voltage drop between the outer waveguide Jo and the inner waveguide Ji is decreased. The ratio can be changed, and as a result, the ratio between the outer field strength Eo (outer input power Po) and the inner field strength Ei (inner input power Pi) can be adjusted.

It should be noted that the impedance of the ion sheath that gives a plasma potential drop is generally capacitive. In the equivalent circuit of FIG. 4, the sheath impedance capacitance immediately below the outer upper electrode 36 is assumed to be C _Po , and the sheath impedance capacitance immediately below the inner upper electrode 38 is assumed to be C _Pi . Further, the capacitance C ₄₀ of the capacitor formed between the outer upper electrode 36 and the inner upper electrode 38 is combined with the capacitance C ₇₈ of the variable capacitor ₇₈ to combine the outer electric field strength Eo (outer input power Po) as described above. And the inner electric field strength Ei (inner input electric power Pi) are determined or adjusted to values that can optimize the electric field intensity (input electric power) balance adjustment function by the variable capacitor 78. It is preferable.

  By the way, in this kind of plasma processing apparatus, there is a slight difference in impedance on the plasma source side between apparatuses and every cleaning cycle due to dimensional tolerance of parts, mounting error, and the like, and thereby process characteristics vary.

For this reason, in this embodiment, the variable capacitor 78 for adjusting the ratio of the outside electric field strength Eo (outside input power Po) and the inside electric field strength Ei (inside input power Pi) as described above is used as the variable impedance unit. Impedance adjustment is performed in advance in a state where plasma is generated by the impedance adjustment mechanism 100 including the plasma. The impedance adjustment mechanism 100 uses the impedance variable function by the variable capacitor 78 and the resonance circuit 101 formed by the current flowing into the inner upper electrode 38 of the upper electrode 34, and the resonance of the resonance circuit is performed by the V _PP monitor 89. A point is found, and the value of the variable impedance portion at the resonance point, that is, the capacitance value of the variable capacitor 78 is adjusted to a reference value.

Specifically, when plasma is generated in the apparatus, the value of the bias V _PP of the lower electrode is detected by the V _PP monitor 89 while changing the capacitance of the variable capacitor 78, and the controller 102 detects this lower value. Based on the value of the electrode bias V _PP , the resonance point of the resonance circuit 101 formed by the current flowing into the inner upper electrode 38 is found, and the capacitance value of the variable capacitor 78 at the resonance point is adjusted to a reference value. As a result, the impedance on the plasma source side can be adjusted. Here, the impedance on the plasma source side in the present embodiment is an impedance of a circuit within a range indicated by PI in FIG.

  The resonance circuit 101 will be described in more detail as shown in FIG. That is, the resonance circuit 101 includes a line indicated by a solid line in FIG. 6A that flows from the power supply rod 46 to the connector 48, the power supply cylinder 50 that supplies power to the outer upper electrode 36, and the inner upper electrode 38 through the outer upper electrode 36. The line shown by the broken line in FIG. 6 (b) flows from the power supply rod 46 to the connector 48, the power supply cylinder 50 that supplies power to the outer upper electrode, the outer upper electrode 36, the power supply cylinder 50, and the variable capacitor 78 to the inner upper electrode 38. Formed with. In the resonance circuit configured as described above, the high-frequency current flowing through the inner upper electrode 38 is the largest at the resonance point. As shown in FIG. 6, the high frequency current flows on the surface of the conductor.

  As shown in FIG. 5 described above, by changing the capacitance of the variable capacitor 78, the ratio of the inner electric field intensity Ei from the inner upper electrode 38 can be changed, so that the capacitance of the variable capacitor 78 is changed. The resonance point of the resonance circuit 101 can be searched.

The high-frequency current flowing through the inner upper electrode 38 at this time is reflected in the device state, for example, the bias V _PP of the susceptor 16 that is the lower electrode, and the value of V _{PP at} the resonance point where the largest high-frequency current flows through the inner upper electrode is Indicates the minimum value. That is, as shown in FIG. 7, when the step (CPI value) of the variable capacitor 78 is increased or decreased while the plasma is generated and the capacitance is changed, the value of the bias V _PP of the lower electrode detected by the V _PP monitor 89 is detected. Changes, and the value of V _PP shows a minimum value at a certain CPI value. In this way, when the value of V _PP shows a minimum value, the resonance circuit shows a resonance point. The CPI value is a value obtained by dividing the change width of the capacitance of the variable capacitor 78 into a predetermined number of steps, and corresponds to the actual capacitance value.

  In the present embodiment, utilizing this, the controller 102 of the impedance adjustment mechanism 100 performs impedance adjustment in the following procedure. The procedure at this time will be described in detail with reference to the flowchart of FIG.

First, a dummy wafer is carried into the plasma etching apparatus, and plasma is generated by supplying power to the first high-frequency power source 52, and the bias V _PP of the lower electrode (susceptor 16) at the initial step (CPI value) of the variable capacitor 78 is set. A value is acquired (STEP 1). The V _PP in this case, a plurality, for example, an average value of 20 data. At this time, it is determined whether V _PP does not indicate an abnormal value by plasma instability and abnormal discharge or the like (STEP2). Specifically, if the amplitude of the plurality of _VPP data is, for example, 50 V or more, a retry is determined as the possibility of plasma instability or abnormal discharge.

This _STEP2, by monitoring the variation of _{V PP,} for example performed as follows.
Of the plurality of _VPP data, the first three points are compared as follows.
−50 <V _PP (i + 1) −V _PP (i) <50 (i = 0, 1, 2)
The rest from the fourth point is compared with the moving average as follows.
−50 <V _PP (i) − {(V _PP (i−1) + V _PP (i−2) + V _PP (i−3)) / 3} <50 (3 <i <19)

If each V _PP value is normal, it is determined whether or not the average V _PP value is a minimum value (STEP 3). This determination is performed by the controller 102 as follows. That is, the relationship between the step value (CPI value) of the variable capacitor 78 and the (average) V _PP value is expressed as shown in FIG. 7, and V _PP (j + 1) −V _PP (j) is calculated ( Where j: CPI value, V _PP (j): average V _PP value at CPI value j).
V _PP (j + 1) −V _PP (j) <0
, It is determined that V _PP (j) is not a local minimum,
V _PP (j + 1) −V _PP (j)> 0
If it is, it is determined that V _PP (j) is a minimum value.

  When the method of determining whether or not the average VPP value is a minimum value is adopted, the CPI value (initial CPI value) when executing the above STEP 1 to 3 is the CPI value near the resonance point. It is necessary to set a smaller CPI value.

If the obtained average V _PP value is not the minimum value, the CPI value is increased by 1 (STEP 4), and the above STEPs 1 to 3 are performed again. If there is no resonance point even if the CPI value is increased by 10 or more by repeating this, the CPI value may exceed the resonance point. In this case, the CPI value is decreased by 1 and V _PP Find the point where the value is a local minimum.

On the other hand, when the obtained V _PP value is a minimum value, this CPI value is used as a resonance point, and the difference between the CPI value at this resonance point and the reference CPI value is calculated as an offset amount (STEP 5). That is, offset amount = (reference CPI value) − (current resonance point CPI value) is calculated. Here, the reference CPI value is the CPI value at the resonance point of the resonance circuit 101 before cleaning or the CPI value at the resonance point of the resonance circuit 101 of another device of the same structure whose impedance is adjusted. The resonance point is set as a parameter in the controller 102. The offset amount, as shown in FIG. 9, which reference waveform V _PP (CPI at the resonance point when the reference value) corresponding to the deviation with respect to grasp a deviation of CPI value at the resonance point thus Thus, it is possible to grasp the deviation of the impedance value from the reference value.

  This offset amount is displayed on the apparatus screen, for example, and the user can check the calculated offset value on this screen (STEP 6). Then, an offset command is executed by the user's operation (STEP 7), whereby a command is transmitted from the controller 102 to a control box (not shown) of the variable capacitor 78, the control box of the variable capacitor 78 is initialized, The CPI value at the resonance point of the variable capacitor 78 is offset by a value corresponding to the offset value calculated as described above (STEP 8). Thereafter, it is determined whether or not the initialization command has been normally executed (STEP 9). When it is determined that the initialization command has been normally executed, the above STEP 1 to 3 are executed to determine whether or not the resonance point has been corrected. (STEP 10), the impedance adjustment is terminated if it has been corrected, and the impedance adjustment is performed again if it has not been corrected.

  In this manner, the capacitance value of the variable capacitor 78 can be adjusted to a reference value by using the resonance point of the resonance circuit 101, and therefore, between apparatuses or each cleaning cycle caused by part dimensional tolerance or mounting error. The difference in impedance on the plasma source side can be minimized. Further, since adjustment can be performed in a state where plasma is generated, impedance adjustment accuracy is high. Furthermore, since no special measuring equipment or measuring jig is used, it is advantageous in terms of cost. Furthermore, since the adjustment can be performed almost automatically, there is almost no human error. In the above description, the procedure for performing impedance adjustment by loading a dummy wafer into the plasma etching apparatus has been described. However, impedance adjustment can be performed by the same method without loading the dummy wafer.

  FIG. 10 shows an example of actual impedance adjustment as described above. In this example, the CPI value at the reference resonance point is 63, and the CPI value at the resonance point before adjustment is 64. For this reason, the CPI value at the resonance point was adjusted to 63 according to the above procedure.

In the above example, the resonance point of the resonance circuit 101 is grasped by using the bias V _PP at the lower electrode, but it is also grasped by using the capacitances of the two capacitors C1 and C2 of the matching device 44 of the upper electrode shown in FIG. Can do. FIG. 12 shows the result of grasping the resonance point by this and actually adjusting the impedance. C1 indicates a minimum value at the resonance point, C2 indicates a maximum value at the resonance point, and in this example, the reference CPI value is 65, and the CPI value before adjustment is 66. Even in this case, the impedance can be adjusted by adjusting the minimum value of C1 and the maximum value of C2 to 65 according to the above-described procedure.

  In addition, when a VI probe (detector capable of detecting current, voltage, phase, harmonics at a certain frequency, etc.) is installed on the upper electrode side, or when a VI probe is installed on the lower electrode side, the voltage value or current The resonance point of the resonance circuit 101 can be grasped even if the value is used.

The present invention can be variously modified without being limited to the above embodiment. For example, in the above embodiment, a variable capacitor is used as the variable impedance unit. However, the present invention is not limited to this, and other circuits such as a variable coil and a variable resistor can also be used. Moreover, in the said embodiment, although the variable impedance part was provided in the electric power feeding line to an inner side upper electrode, you may provide in the electric power feeding line of an outer side upper electrode. Furthermore, although a plasma processing apparatus that applies high-frequency power for plasma generation to the upper electrode has been shown, it may be a plasma processing apparatus that applies to the lower electrode. Furthermore, although the example in which the electrode to which the high-frequency power for plasma generation is applied is a divided electrode, it is not necessarily divided. Furthermore, as an example of the device status monitor, the lower electrode bias V _PP , the capacitance of the capacitor included in the upper electrode matcher, and the voltage value and current value detected by the VI probe are exemplified, but not limited to this, the resonance There is no particular limitation as long as the resonance point of the circuit can be grasped. Furthermore, although the plasma etching apparatus has been described as an example in the above embodiment, the present invention can be applied to other plasma processing apparatuses such as a CVD film forming apparatus and a sputtering apparatus.

1 is a schematic sectional view showing a plasma etching apparatus according to an embodiment of the present invention. The partial expanded sectional view which shows the structure of the principal part of the plasma etching apparatus of FIG. The schematic block diagram for demonstrating the impedance adjustment mechanism of the plasma etching apparatus which concerns on one Embodiment of this invention. The circuit diagram which shows the equivalent circuit of the principal part of the plasma production | generation means in the plasma etching apparatus of FIG. The figure which shows the relationship between the capacitance of a variable capacitor and the electric field strength ratio in the plasma etching apparatus of FIG. The figure for demonstrating in detail the resonance circuit of the impedance adjustment mechanism in the plasma etching apparatus of FIG. The figure which shows the relationship between the CPI value of the variable capacitor of the impedance adjustment mechanism in the plasma etching apparatus of FIG. 1, and the bias V _{PP of the} lower electrode. The flowchart for demonstrating the impedance adjustment procedure of the impedance adjustment mechanism in the plasma etching apparatus of FIG. The figure which shows the reference | standard waveform and measurement waveform of the relationship between the CPI value of the variable capacitor of the impedance adjustment mechanism in the plasma etching apparatus of FIG. 1, and the bias V _{PP of the} lower electrode. The figure which shows the relationship between the CPI value of a variable capacitor and bias V _PP of a lower electrode when impedance adjustment is actually performed. The figure which shows schematic structure of the matching device connected to the 1st high frequency power supply in the plasma etching apparatus of FIG. The figure which shows the relationship between the CPI value of a variable capacitor, and the value of the capacitor | condenser of a matching device at the time of using the capacitor | condenser of the matching device connected to the 1st high frequency power supply as an apparatus state.

Explanation of symbols

10 ... Chamber (processing container)
16 ... susceptor (lower electrode)
34 ... Upper electrode 36 ... Outer upper electrode 38 ... Inner upper electrode 44, 88 ... Matching device 46 ... Feeding rod 50 ... Feeding cylinder 52 ... First high frequency power supply 66 ... Processing gas supply source 78 ... Variable capacitor (variable impedance unit)
84 ... Exhaust device 89 ... Bias V _PP monitor 90 ... Second high frequency power supply 100 ... Impedance adjustment mechanism 101 ... Resonant circuit 102 ... Controller W ... Semiconductor wafer (substrate to be processed)

Claims (23)

A processing container in which a substrate to be processed is accommodated and evacuated;
A first electrode and a second electrode disposed opposite to each other in the processing container;
High-frequency power supply means for supplying high-frequency power for plasma formation to the first electrode;
A processing gas supply means for supplying a processing gas into the processing container, and generating plasma of the processing gas between the first electrode and the second electrode to perform plasma processing on the substrate to be processed A device,
Furthermore, it comprises impedance adjusting means for adjusting the impedance on the plasma source side,
The impedance adjusting means includes
A resonant circuit formed such that a high-frequency current flows into the first electrode;
A variable impedance unit provided in the power supply line of the first electrode;
A detector for detecting a device state for grasping a resonance point of the resonance circuit;
While changing the value of the variable impedance unit in the state where the plasma is formed, the signal of the device state of the detector is detected to find the resonance point of the resonance circuit, and the value of the variable impedance unit at the resonance point And a controller for adjusting the value to a reference value.   The plasma processing apparatus according to claim 1, wherein the variable impedance unit is a variable capacitor. A processing container in which a substrate to be processed is accommodated and evacuated;
A first electrode and a second electrode disposed opposite to each other in the processing container;
High-frequency power supply means for supplying high-frequency power for plasma formation to the first electrode;
A processing gas supply means for supplying a processing gas into the processing container, and generating plasma of the processing gas between the first electrode and the second electrode to perform plasma processing on the substrate to be processed A device,
The first electrode is divided into an inner electrode and an outer electrode,
The plasma processing apparatus further includes impedance adjusting means for adjusting impedance on the plasma source side,
The impedance adjusting means includes
A resonant circuit formed such that a high-frequency current flows into the inner electrode of the first electrode;
A variable impedance unit provided in a power supply line to the inner electrode of the first electrode or a power supply line to the outer electrode;
A detector for detecting a device state for grasping a resonance point of the resonance circuit;
While the plasma is formed, the value of the variable impedance unit is changed, the device state signal from the detector is detected, the resonance point of the resonance circuit is found, and the variable impedance unit at the resonance point is detected. And a control unit that adjusts the value to a reference value.   The value of the reference variable impedance unit is the value of the variable impedance unit at the resonance point of the resonance circuit before cleaning, or the variable impedance unit at the resonance point of the resonance circuit of another device of the same structure in which the impedance is adjusted. The plasma processing apparatus according to any one of claims 1 to 3, wherein the plasma processing apparatus has a value of. A processing container in which a substrate to be processed is stored and evacuated;
A first electrode and a second electrode disposed opposite to each other in the processing container;
High-frequency power supply means for supplying high-frequency power for plasma formation to the first electrode;
A processing gas supply means for supplying a processing gas into the processing container, and generating plasma of the processing gas between the first electrode and the second electrode to perform plasma processing on the substrate to be processed A device,
The first electrode is divided into an inner electrode and an outer electrode,
The plasma processing apparatus further includes impedance adjusting means for adjusting impedance on the plasma source side,
The impedance adjusting means includes
A resonant circuit formed such that a high-frequency current flows into the inner electrode of the first electrode;
A variable capacitor provided in a power supply line to the inner electrode of the first electrode;
A detector for detecting a device state for grasping a resonance point of the resonance circuit;
While changing the capacitance of the variable capacitor while the plasma is formed, the signal of the device state from the detector is detected to find the resonance point of the resonance circuit, and the capacitance of the variable capacitor at the resonance point is determined. A plasma processing apparatus comprising: a control unit that adjusts to a reference value.   The capacitance of the reference variable capacitor is the capacitance of the variable capacitor at the resonance point of the resonance circuit before cleaning, or the capacitance of the variable capacitor at the resonance point of the resonance circuit of another device of the same structure whose impedance is adjusted. 6. The plasma processing apparatus according to claim 5, wherein the plasma processing apparatus is provided.   The resonance circuit sequentially includes a line through which a high-frequency current flows from a power supply line to the outer electrode to the inner electrode, a power supply line to the outer electrode, the outer electrode, a power supply line to the outer electrode, and the variable impedance unit. 6. The plasma processing apparatus according to claim 3, wherein the plasma processing apparatus is formed by a line through which a high-frequency current flows to the inner electrode.   The plasma processing apparatus according to claim 1, wherein the detector that detects the apparatus state is a voltage detector provided on the second electrode side.   The high-frequency power supply means includes a high-frequency power source and a matching unit that matches a load impedance to an internal impedance or output impedance of the high-frequency power source, and the detector that detects the device state is a capacitance of a capacitor of the matching unit The plasma processing apparatus according to any one of claims 1 to 7, wherein:   8. The detector for detecting the apparatus state is a VI probe that is provided on the first electrode side or the second electrode side and detects a current or voltage of plasma. The plasma processing apparatus of any one of Claims.   The said 2nd electrode is a support electrode which supports a to-be-processed substrate, It further has a high frequency electric power supply means for drawing in ion to the said 2nd electrode, The any one of Claims 1-10 characterized by the above-mentioned. The plasma processing apparatus according to 1.   12. The plasma processing apparatus according to claim 11, wherein the high-frequency power supply means for drawing ions includes a high-frequency power source and a matching unit that matches a load impedance to an internal impedance or an output impedance of the high-frequency power source. .   The plasma processing apparatus according to claim 12, wherein the detector that detects the apparatus state is a voltage detector provided in the matching unit on the second electrode side. A processing container in which a substrate to be processed is accommodated and evacuated;
A first electrode and a second electrode disposed opposite to each other in the processing container;
High-frequency power supply means for supplying high-frequency power for plasma formation to the first electrode;
A processing gas supply means for supplying a processing gas into the processing container, and generating plasma of the processing gas between the first electrode and the second electrode to perform plasma processing on the substrate to be processed An impedance adjustment method in an apparatus,
A variable impedance unit is provided in the power supply line of the first electrode, and a detector for detecting a device state for grasping a resonance point of a resonance circuit formed so that a high-frequency current flows into the first electrode is provided; In this state, while changing the value of the variable impedance unit, the detector detects the signal of the device state, finds the resonance point of the resonance circuit, and uses the value of the variable impedance unit at the resonance point as a reference The impedance adjustment method is characterized by adjusting the impedance on the plasma source side by adjusting to a value to be   The impedance adjustment method according to claim 14, wherein the variable impedance unit is a variable capacitor. A processing container in which a substrate to be processed is accommodated and evacuated;
A first electrode and a second electrode disposed opposite to each other in the processing container;
High-frequency power supply means for supplying high-frequency power for plasma formation to the first electrode;
A processing gas supply means for supplying a processing gas into the processing container, wherein the first electrode is divided into an inner electrode and an outer electrode, and a processing gas is supplied between the first electrode and the second electrode. An impedance adjustment method in a plasma processing apparatus for generating plasma and performing plasma processing on a substrate to be processed,
A variable impedance portion is provided in a power supply line to the inner electrode of the first electrode or a power supply line to the outer electrode, and a resonance point of a resonance circuit formed so that a high-frequency current flows into the inner electrode of the first electrode is grasped. A detector for detecting a device state for detecting a device state signal by the detector while changing a value of the variable impedance unit in a state where the plasma is formed, and a resonance point of the resonance circuit And adjusting the impedance on the plasma source side by adjusting the value of the variable impedance portion at the resonance point to a reference value.   The value of the reference variable impedance unit is the value of the variable impedance unit at the resonance point of the resonance circuit before cleaning, or the variable impedance unit at the resonance point of the resonance circuit of another device of the same structure in which the impedance is adjusted. The impedance adjustment method according to any one of claims 14 to 16, wherein the impedance adjustment method is a value of. A processing container in which a substrate to be processed is stored and evacuated;
A first electrode and a second electrode disposed opposite to each other in the processing container;
High-frequency power supply means for supplying high-frequency power for plasma formation to the first electrode;
A processing gas supply means for supplying a processing gas into the processing container, wherein the first electrode is divided into an inner electrode and an outer electrode, and a processing gas is supplied between the first electrode and the second electrode. An impedance adjustment method in a plasma processing apparatus for generating plasma and performing plasma processing on a substrate to be processed,
Detection for detecting a device state for grasping a resonance point of a resonance circuit formed so that a high-frequency current flows into the inner electrode of the first electrode by providing a variable capacitor in a power supply line to the inner electrode of the first electrode While the plasma is formed, the detector detects a device state signal while changing the capacitance of the variable capacitor, finds the resonance point of the resonance circuit, and the variable capacitor at the resonance point An impedance adjustment method, wherein the impedance on the plasma source side is adjusted by adjusting the value of capacitance to a reference value.   The capacitance of the reference variable capacitor is the capacitance of the variable capacitor at the resonance point of the resonance circuit before cleaning, or the capacitance of the variable capacitor at the resonance point of the resonance circuit of another device of the same structure whose impedance is adjusted. The impedance adjustment method according to claim 18, wherein the impedance adjustment method is provided.   The resonance circuit sequentially includes a line through which a high-frequency current flows from a power supply line to the outer electrode to the inner electrode, a power supply line to the outer electrode, the outer electrode, a power supply line to the outer electrode, and the variable impedance unit. The impedance adjustment method according to claim 16 or 18, wherein the impedance adjustment method is formed by a line through which a high-frequency current flows to the inner electrode.   21. The impedance adjustment method according to claim 14, wherein the detector that detects the device state is a voltage detector provided on the second electrode side.   The high-frequency power supply means includes a high-frequency power source and a matching unit that matches a load impedance to an internal impedance or output impedance of the high-frequency power source, and the detector that detects the device state is a capacitance of a capacitor of the matching unit 21. The impedance adjustment method according to claim 14, wherein the impedance is detected.   The detector for detecting the apparatus state is a VI probe that is provided on the first electrode side or the second electrode side and detects a current or a voltage of plasma. The impedance adjustment method according to any one of the above items.

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