JP2008277275A - Plasma processing apparatus, measuring apparatus, measuring method and control apparatus - Google Patents

Abstract

High frequency power in the vicinity of a substrate is measured.
A microwave plasma processing apparatus 10 includes a processing container 100 that performs a desired process on a substrate G by plasma, a susceptor 106 (mounting table) that is provided inside the processing container 100 and places the substrate G thereon, The power supply unit 108 is embedded in the mounting table, and the high frequency power source 112 is connected to the power supply unit 108 and applies high frequency power. The power supply unit 108 is provided between the power supply lines 114 located inside the processing container 100 among the power supply lines 114 that connect the power supply unit 108 and the high-frequency power source 112 or in part or all of the power supply unit 108, and has a sheath capacity. A capacitor 108a having a capacity of 10 times or less is provided. The measuring means 20 measures the voltages V ₁ and V ₂ of both electrodes of the capacitor 108a connected to the probes 142a and 142b with the oscilloscopes 144a and 144b. Thereby, the electric power directly under the substrate can be measured.
[Selection] Figure 1

Description

  The present invention relates to a plasma processing apparatus capable of measuring parameters for controlling plasma, a measuring apparatus and method for measuring parameters for controlling plasma, and a control apparatus for controlling a plasma processing apparatus capable of measuring parameters for controlling plasma. About.

  As shown in FIG. 15, there is generally known a plasma processing apparatus 1000 that converts a gas into a plasma in a processing chamber U and performs plasma processing such as etching and sputtering on the substrate G using the plasma. The plasma processing apparatus 1000 is provided with a susceptor 1010 on which a substrate G is placed inside a processing container 1005 in which plasma processing is performed, and an electrode 1015 is embedded in the susceptor 1010. A high frequency power source 1020 is connected to the electrode 1015, and a predetermined bias voltage is applied to the inside of the processing chamber U by the high frequency power output from the high frequency power source 1020. Thereby, the energy at the time of the charged particle contained in plasma colliding with the board | substrate G can be increased.

A matching unit 1025 is provided between the electrode 1015 and the high-frequency power source 1020. Matching unit 1025 is provided with series variable capacitor C ₁ connected in series to electrode 1015 via power line 1030a, parallel variable capacitor C ₂ connected between power line 1030b and the ground line, and inductor L. ing. The matching unit 1025 functions to apparently match the output impedance of the high-frequency power source 1020 with the load impedance obtained by combining the load of the matching unit 1025 and the load inside the processing container 1005. As a result, the high frequency power supply 1020 can be protected and the utilization efficiency of the high frequency power output from the high frequency power supply 1020 can be increased.

  However, in the microwave plasma processing apparatus 1000, an electrostatic capacitance Cs (parasitic capacitance) is generated between the processing container 1005 and the susceptor 1010 or between the processing container 1005 and the power supply rod 1010a that supports the susceptor 1010. Further, at high frequency, there exists an inductance L that causes a considerable voltage drop in the power supply line 1030a. Due to the impedance on the downstream side of the matching unit 1025 generated in this way (the high frequency power supply 1020 side is the upstream), a considerable amount of high frequency power is consumed when the high frequency power output from the high frequency power supply 1020 is transmitted through the power supply line 1030a. Is done. That is, the larger the impedance on the downstream side of the matching unit 1025, the smaller the high frequency power that can be used for plasma control.

  In addition to this, the state of the capacitive component and the inductive component generated on the downstream side of the matching unit 1025 depends on the size and material of the microwave plasma processing apparatus 1000, and the processing container 1005 and the susceptor 1010. It varies depending on the amount and type of sediment deposited on the wall. In this way, since an unpredictable change occurs in the impedance on the downstream side of the matching unit 1025, an unpredictable loss occurs in the high-frequency power while the high-frequency signal is transmitted on the downstream side of the matching unit 1025.

  Therefore, a measuring instrument 1035 is connected to the power line 1030a between the matching unit 1025 and the electrode 1015, and the measuring instrument 1035 measures, for example, the voltage and power applied to the measuring position P, and is measured by the control circuit 1040. There has been proposed a system SS that compares the measured parameter with a desired target value and feedback-controls the high-frequency power source 1020 based on the result (see, for example, Patent Document 1).

JP-A-2005-116818

  However, as described above, the high-frequency power is generated by the electrostatic capacitance Cs generated around the susceptor 1010 and the power supply rod 1010a and the inductance L generated in the power supply line 1030 while the high-frequency signal is transmitted from the measurement position P to just below the substrate. Is consumed. Therefore, a considerable power difference is generated between the actually measured value of the high-frequency signal transmitted through the measurement position P and the high-frequency power directly under the substrate. Furthermore, as described above, this power difference varies as the capacitive component Cs and the inductive component L vary. In actuality, when the state of deposits or the state of the process adhered to the processing container 1005 varies due to maintenance (cleaning) or the like, the capacitive component Cs and the inductive component L greatly vary with them. Along with this, the high-frequency power lost during transmission of the high-frequency signal from the measurement position P to the electrode 1015 also varies greatly.

  As described above, the loss of high-frequency power in the process of transmitting a high-frequency signal is relatively large and changes with time depending on the state in the processing chamber, and includes an unpredictable part. For these reasons, the measurement method that measures voltage and power at the measurement position P away from the substrate cannot accurately grasp the state of the high-frequency power directly under the substrate. Therefore, with the measurement method, it has been difficult to control the process with high accuracy and to perform the process more stably. As a result, every time maintenance is performed, the process conditions including the high-frequency power output from the high-frequency power source 1020 must be manually reset based on the experience so far, which is complicated.

  On the other hand, such a large loss or fluctuation of the high-frequency power in the process of propagation of the high-frequency signal may change the process speed unexpectedly. For this reason, in order to control the plasma with high accuracy and perform the process more stably, it is desirable to directly measure the high-frequency power directly under the substrate that can be used for plasma control.

  Therefore, in order to solve the above problem, the present invention provides a plasma processing apparatus capable of measuring high-frequency power near the substrate using a capacitor, a measuring apparatus for measuring high-frequency power near the substrate using a capacitor, and A measuring method and a control device for controlling a plasma processing apparatus by measuring high-frequency power near a substrate using a capacitor are provided.

  That is, in order to solve the above-described problem, according to an aspect of the present invention, a processing container that performs a desired process on a target object with plasma therein and a target object to be placed in the processing container. A mounting table, a high-frequency power supply for supplying high-frequency power to the mounting table, a capacitor provided on the mounting table, and a voltage across the capacitor with respect to the high-frequency power applied to the mounting table from the high-frequency power source There is provided a plasma processing apparatus comprising: a measuring means for measuring

In this case, the capacitance C of the capacitor, C _sheath ground side sheath capacitance, when the ratio of the ground side sheath capacitance C ₂ [psi for electrode side sheath capacitance C ₁ of the capacitor, 1 + [psi × C _sheath ^{2 /} {(1 + ^ψ ) × C _sheath × C} may be determined so as to be equal to or higher than a voltage ratio in which an error is within an allowable range among the voltage ratio of the electrodes measured using the capacitor. Further, the capacitance C of the capacitor may be not more than 4.2 times the ground-side sheath capacitance C _sheath .

According to the actual measurement by the inventor, the measurement error increases when the predetermined electrode voltage amplitude ratio is smaller than 1.2, that is, when the voltage amplitude ratio is smaller than about 1.2, the measurement accuracy is increased. Is known to get worse. When this experiment is applied to “1 + ψ × C _sheath ² / {(1 + ψ) × C _sheath × C} ≧ voltage amplitude ratio” shown in Equation (9), which will be described later, the power feeding unit in the processing container of the plasma processing apparatus. If a capacitor having a capacity equal to or less than 4.2 times the sheath capacity is provided in the vicinity, the measurement error is allowed. That is, it is considered that the measurement error when measuring the voltages V ₁ and V ₂ across the capacitor is within the allowable range.

ｋ＝高調波の次数 Here, the voltages V ₁ and V ₂ are decomposed into frequency components, that is, harmonic components having a power source frequency as a fundamental wave, coefficients are determined by the least square method, and the amplitude M _k and phase difference φ _K at each frequency are determined. (See equations (1) to (3) to be described later), and from the effective values and power _factors (cos (φ _Ik −φ _VIk )) of the amplitudes M _Ik and M _VIk , the power P applied to the capacitor is It is calculated directly by the following formula.

k = harmonic order

In this way, based on the actually measured values of the voltages V ₁ and V ₂ across the capacitor, the power P directly applied to the capacitor, in other words, the power P substantially equal to the power just below the substrate is measured. Can do. Further, the measurement error included in the electric power P calculated by the above equation can be sufficiently reduced by setting the capacitance of the capacitor to 4.2 times or less (preferably 2.1 times or less) of the sheath capacitance. The measurement error will be described later.

  As an example of setting the capacity of the capacitor to 4.2 times or less of the sheath capacity, a method of providing the capacitor in a part or all of the power feeding unit at a position facing the object to be processed placed on the mounting table. Is mentioned.

  Further, as another example in which the capacity of the capacitor is 4.2 times or less of the sheath capacity, the capacitor is placed in a part of the power feeding unit at a position not facing the object to be processed placed on the mounting table. The method of providing is mentioned.

  Moreover, you may provide the said capacitor | condenser in a part of said electric power feeding part in the edge part of the said electric power feeding part.

  Further, the capacitor has a predetermined dielectric constant between the electrodes of the capacitor, or the electrode area and the electrode interval are set to predetermined values. You may make it 2 times or less.

  Furthermore, a resonance circuit connected in series with the capacitor may be provided.

  According to this, the load impedance increased by providing the capacitor can be eliminated by using the resonance circuit provided in series with the capacitor. Thereby, the high frequency power which can be utilized for plasma control can be further increased by reducing the impedance on the power supply line and reducing the loss of the high frequency power.

  The plasma processing apparatus further includes a mounting table for mounting an object to be processed inside the processing container, the power feeding unit is embedded in the mounting table, and the capacitor is mounted on the mounting table. It may be provided in a part or all of the power feeding unit at a position facing the placed object to be processed, and the capacitor may be formed inside the mounting table. According to this, the inside of the processing container can be kept clean by embedding a capacitor that can be a particle generation source in the mounting table.

  In order to solve the above-mentioned problem, according to another aspect of the present invention, a processing container for performing a desired process on a target object with plasma inside, and a target object placed in the processing container A high frequency power supply for supplying high frequency power to the mounting table, and a capacitor provided on the mounting table, with respect to the high frequency power from the high frequency power applied to the mounting table of the plasma processing apparatus. Thus, a measuring device for measuring the voltage across the capacitor is provided.

In this case, the capacitance C of the capacitor, the sheath capacitance C _sheath and ground side sheath capacitance C _2, when the ratio of the ground side sheath capacitance C ₂ with respect to the electrode side sheath capacitance C ₁ of the capacitor and the ψ, 1 + ψ × C _sheath ^{The value of 2} / {(1 + ψ) × C _sheath × C} may be determined so as to be equal to or higher than a voltage ratio in which an error is within an allowable range among the voltage ratio of the electrodes measured using the capacitor. .

  In order to solve the above-mentioned problem, according to another aspect of the present invention, a processing container for performing a desired process on a target object with plasma inside, and a target object placed in the processing container A high frequency power supply for supplying high frequency power to the mounting table, and a capacitor provided on the mounting table, with respect to the high frequency power from the high frequency power applied to the mounting table of the plasma processing apparatus. Thus, a measuring method for measuring the voltage across the capacitor is provided.

  In order to solve the above-described problem, according to another aspect of the present invention, a processing container for performing a desired process on a target object by plasma, and a target object provided on the inside of the processing container. A plasma processing apparatus comprising: a mounting table; a capacitor provided in the mounting table; a power supply unit embedded in the mounting table; and a high-frequency power source connected to the high-frequency power source and applying high-frequency power. Measuring a parameter for controlling the plasma, and controlling the plasma based on the measured parameter, the high frequency power applied to the mounting table from the high frequency power supply for the capacitor The high-frequency power is calculated using a measuring means for measuring the voltage of both electrodes, and the voltage of the two electrodes of the capacitor measured by the measuring means, and based on the calculated high-frequency power. Control device is provided and a control unit for feedback control of the high frequency power source are.

In these cases, the control unit may measure a parameter for controlling the plasma using the capacitor having a capacitance C that is 4.2 times or less of the sheath capacitance C _sheath . In addition, at least one of a voltage value, a current value, and a phase value of both electrodes of the capacitor may be measured as a parameter for controlling the plasma, and the high-frequency power may be calculated from the measured parameter.

  According to these, accurate electric power directly under the substrate can be grasped from at least one of the above parameters.

  A high-frequency power source that is connected to the power supply unit and applies high-frequency power is further provided, and is connected to the high-frequency power source and the power supply unit between the high-frequency power source and the power supply unit. A matching unit that matches the load impedance on the power feeding unit side may be further provided.

  According to this, the matching device is provided between the high-frequency power source and the power feeding unit. As a result, on the upstream side of the matching unit, while optimizing the high-frequency power output from the high-frequency power source by feedback control, the load impedance that constantly changes on the downstream side of the matching unit is changed to the output impedance of the high-frequency power source using the matching unit. Can be matched. Thereby, the loss of the high frequency power output from the high frequency power supply can be minimized, and the high frequency power can be utilized to the maximum to control the plasma.

  As described above, according to the present invention, it is possible to measure high-frequency power near the substrate using a capacitor.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the following description and the accompanying drawings, the same reference numerals are given to the constituent elements having the same configuration and function, and redundant description is omitted. In this specification, at 0 ° C. and 1 atm, 1 sccm is (10 ⁻⁶ / 60) m ³ / sec, and 1 mTorr is (10 ⁻³ × 101325/760) Pa.

  First, the configuration of a measurement system using a microwave plasma processing apparatus according to an embodiment of the present invention will be described with reference to FIG.

(Measurement system)
The measurement system S performs feedback control of the high-frequency power source based on the measurement unit 20 that measures the voltage in the vicinity of the substrate as a parameter for controlling the plasma generated by the microwave plasma processing apparatus 10 and the voltage value measured by the measurement unit 20. A control device 148 is included. Below, the microwave plasma processing apparatus 10, the measurement means 20, and the control apparatus 148 are demonstrated in order. Note that the microwave plasma processing apparatus is an example of a plasma processing apparatus that performs a desired process on an object to be processed using plasma.

(Configuration of microwave plasma processing equipment)
A microwave plasma processing apparatus 10 according to the present embodiment includes a processing container 100 and a lid 102. The processing container 100 has a bottomed cubic shape with an upper portion opened. The processing container 100 and the lid body 102 are sealed by an O-ring 104 disposed on the contact surface between the processing container 100 and the lid body 102, thereby forming a processing chamber U in which plasma processing is performed. The processing container 100 and the lid 102 are made of, for example, a metal such as aluminum and are electrically grounded.

  The processing container 100 is provided with a susceptor 106 for placing a glass substrate (hereinafter referred to as “substrate”) G therein. The susceptor 106 is made of, for example, aluminum nitride, and a power feeding unit 108 is provided therein. The susceptor 106 is supported by a power supply rod 106a. The portion including the susceptor 106 and the power feeding rod 106a is hereinafter referred to as a mounting table.

  A power feeding unit 108 is provided inside the susceptor 106. The power feeding unit 108 is provided as a capacitor 108 a made of two metal plates having the same area as the substrate G at a position facing the substrate G. A low dielectric constant dielectric 108b having the same area as the metal plate is sandwiched between the capacitors 108a. As described above, by sandwiching the dielectric 108b between the capacitors 108a, the capacitance of the capacitor 108a is 4.2 times or less of the sheath capacitance.

  Note that the capacitance of the capacitor 108a is 4.2 times or less of the sheath capacity by increasing the distance between the two metal plates constituting the capacitor 108a instead of sandwiching the dielectric 108b having a low dielectric constant between the capacitors 108a. The capacity may be as follows. The reason why the capacity of the capacitor 108a is set to 4.2 times or less (preferably 2.1 times or less) of the sheath capacity will be described later.

  A high frequency power source 112 is connected to the power feeding unit 108 via a matching unit 110. The matching unit 110 and the high frequency power source 112 are provided outside the processing container 100, and the high frequency power source 112 is grounded.

  The power supply unit 108 applies a predetermined bias voltage to the inside of the processing container 100 by the high frequency power output from the high frequency power source 112. The power feeding unit 108 electrostatically attracts the substrate G with a DC voltage output from a high-voltage DC power source (not shown).

The matching unit 110 is provided with a series variable capacitor C ₁ connected in series to the power supply unit 108 via the power line 114a, and a parallel variable capacitor C ₂ connected between the inductor L and the power line 114b and the ground line. It has been. The matcher 110 apparently matches the output impedance of the high-frequency power source 112 with the load impedance obtained by combining the load of the matcher 110 and the load inside the processing container 100, thereby minimizing the loss of high-frequency power during transmission. It works to suppress. An O-ring 116 is disposed on the bottom wall of the processing container 100 through which the power supply line 114b penetrates, thereby sealing the inside of the processing container. A capacitor 118 is provided on the power supply line 114b and in the vicinity of the high frequency power supply 112 so that the high frequency power supply 112 and the matching unit 110 are connected with the lowest possible impedance.

  A baffle plate 120 for controlling the gas flow in the processing chamber U to a preferable state is provided around the susceptor 106. A vacuum pump (not shown) is provided outside the processing container 100 at the bottom of the processing container 100, and the processing chamber U is discharged by discharging the gas in the processing container 100 through the gas discharge pipe 122. The pressure is reduced to a desired degree of vacuum.

The lid 102 is provided with six waveguides 124, a slot antenna 126, and a dielectric window 128 (consisting of a plurality of dielectric parts 128a). The six waveguides 124 have a rectangular cross-sectional shape and are arranged in parallel inside the lid 102. The inside of each waveguide 124 is filled with a dielectric member 124a such as fluororesin (for example, Teflon (registered trademark)), alumina (Al ₂ O ₃ ), quartz, etc., and λg ₁ = λc by the dielectric member 124a. The in-tube wavelength λg ₁ of each waveguide 124 is controlled according to the equation / (ε ₁ ) ^1/2 . Here, λc is the wavelength of free space, and ε ₁ is the dielectric constant of the dielectric member 124a.

  A slot antenna 126 that functions as an antenna is provided below each waveguide 124. A slot (opening) 126 a is cut in the slot antenna 126 at the lower surface of each waveguide 124. The number of slots 126a formed on the lower surface of each waveguide 124 is arbitrary.

  The dielectric window 128 is composed of a plurality of dielectric parts 128a, and each dielectric part 128a is made of alumina. The dielectric part 128a may be formed of a dielectric material such as quartz glass, AlN, sapphire, SiN, or ceramics. Concavities and convexities are formed on each dielectric part 128a on the surface facing the substrate G.

  A plurality of dielectric parts 128 a are provided on the lower surface of the slot antenna 126. The plurality of dielectric parts 128 a are fixed to the ceiling surface of the processing container 100 by lattice beams 130. The beam 130 is formed of a conductive material that is a nonmagnetic metal body such as aluminum. A plurality of gas introduction pipes 132 pass through the beam 130, and an opening A is provided at the end of the gas introduction pipe 132 so as to introduce the gas toward the substrate G.

  The gas supply source 134 controls the opening and closing of the valve and the opening of the mass flow controller (both not shown) to pass a desired gas through the gas flow path 136 and downward from the openings A of the plurality of gas introduction pipes 132. To supply.

  A cooling water supply source 140 is connected to the cooling water pipe 138, and the cooling water supplied from the cooling water supply source 140 circulates in the cooling water pipe 138 and returns to the cooling water supply source 140. The body 102 is kept at a desired temperature.

  With the configuration described above, the microwave plasma processing apparatus 10 transmits microwaves output from a microwave generator (not shown) to the six waveguides 124, passes through the slots 126a of the slot antenna 126, and transmits a plurality of sheets. The dielectric parts 128a are transmitted and supplied to the inside of the processing vessel 100. Plasma is generated from the gas supplied into the processing chamber 100 by the electric field energy of the microwave supplied in this manner, and a desired plasma processing is performed on the substrate G in the processing chamber U by the generated plasma. .

(Measurement means)
Next, the measuring means 20 for measuring the high frequency power directly under the substrate using the microwave plasma processing apparatus 10 configured as described above will be described.

  The measuring means 20 has two probes 142a and 142b and an oscilloscope 144. The two probes 142a and 142b are connected at one end to the upper metal plate and the lower metal plate of the capacitor 108a. The other end of each probe 142a, 142b penetrates the wall of the processing container 100 and is connected to an oscilloscope 144 connected to the outside of the processing container 100. The oscilloscope 144 is grounded.

The oscilloscope 144 measures the voltages V ₁ and V ₂ across the capacitor 108 a and outputs the measured voltages V ₁ and V ₂ to the control device 148. In this way, the measuring means 20 measures the high frequency power (voltage) applied from the high frequency power supply 112 to the capacitor 108a via the power supply line 114 as a parameter for controlling plasma.

  The parameter for controlling the plasma is not limited to the voltage value of both electrodes of the capacitor 108a, but may be, for example, at least one of a current value and a phase value. Note that O-rings 146a and 146b are disposed on the walls of the processing container 100 through which the probes 142a and 142b penetrate, and thereby the inside of the processing container 100 is sealed.

(Control device)
Next, the control device 148 that controls the high-frequency power using the voltages V ₁ and V ₂ measured by the measuring means 20 will be described with reference to FIG. 2 showing the hardware configuration. The control device 148 includes two waveform shaping circuits 148a and 148b, a voltage / phase comparator 148c, and a control circuit 148d. The waveform shaping circuits 148a and 148b receive the potentials V ₁ and V ₂ measured by the measuring unit 20 and respectively shape the waveforms. Voltage and phase comparator 148c receives the voltage _V 1, _{V 2,} which is waveform-shaped to obtain the phase difference between the voltage _V 1, _{V 2.} The control circuit 148d determines the power P applied to the susceptor 106 based on the amplitude difference and phase difference between the waveform-shaped voltages V ₁ and V ₂ . A method for calculating the power P will be specifically described below.

First, the following expression (1) is derived by decomposing the voltages V ₁ and V ₂ across the capacitor into frequency components (that is, harmonic components having the fundamental frequency of the high-frequency signal output from the high-frequency power source). . Here, k represents the order of harmonics, and I represents the position of the measurement point. At this time, the coefficient is determined by the least square method.

Next, the following equation (2) is obtained from the difference between the voltages V ₁ and V ₂ .

Next, the current amplitude M _k and phase φ _k are calculated at each frequency. Specifically, instead of over the jωC to ΔV obtain a current I flowing through the capacitor, over the kωC the amplitude difference M _DerutaVk of voltages _V 1, _{V 2,} the phase difference phi _DerutaVk voltage _V 1, _{V 2} [pi Add / 2. When the results are M _Ik and φ _Ik , the following equation (3) is established.

From the effective values and power _factors (cos (φ _Ik −φ _VIk )) of the amplitudes M _Ik and M _VIk , the power P applied to the capacitor is obtained as in the following equation (4).

Thus, the power P obtained based on the measured values V ₁ and V ₂ at two points in the vicinity of the substrate is considered to be substantially equal to the high-frequency power directly under the substrate, that is, the power available for plasma control. . Further, the measurement error included in the electric power P calculated by the equation (4) obtained in this way causes the capacitance of the capacitor to be 4.2 times or less (preferably 2.1 times or less) of the sheath capacitance. Can be made sufficiently small. In this way, based on the measured values of the voltages V ₁ and V ₂ of the _two electrodes of the capacitor having a capacity of 4.2 times or less (preferably 2.1 times or less) of the sheath capacity, the susceptor is calculated using the equation (4). By obtaining the high-frequency power P applied to 106, the power available for plasma control can be accurately grasped.

  The control circuit 148d obtains the power of the high-frequency power source 112 to be input in order to perform the desired desired process processing from the calculated power, and outputs a control signal having the obtained power information to the high-frequency power source 112. . As a result, a high-frequency signal having a desired high-frequency power is output from the high-frequency power source 112, and as a result, the power directly under the substrate G can be controlled to a desired value. Thereby, process speeds, such as an etching rate, can be controlled more accurately, and the substrate G can be subjected to plasma processing with high accuracy. The power feedback control executed by the control device 148 based on the measurement result will be further described later.

(Sheath voltage)
The plasma generated in the processing container 100 includes charged particles including electrons and ions. Since electrons are light, they move at high speed. On the other hand, ions are slower and move slower than electrons. Therefore, when plasma is generated, electrons in the plasma first collide with the inner wall surface of the processing vessel 100 and the surface of the substrate G, and are combined with ions existing on the surface of the wall surface. Thereby, the inner wall surface of the processing container 100 and the surface of the substrate G are negatively charged by losing ions. The negatively charged inner wall surface and substrate surface of the processing container reject electrons and attract ions. For this reason, these surfaces are covered with positive charges. This is generally called space charge, or sheath.

  FIG. 3A shows a modeled microwave plasma processing apparatus 10. Above the baffle plate 120, a ground-side sheath Su formed on the surface of the inner wall surface of the processing vessel 100 is formed. Further, an electrode-side sheath S1 is formed on the surface of the substrate G. The electric potential of each sheath Su, S1 serves to attract heavy ions to each surface. In particular, the potential Vdc of the electrode-side sheath S1 mainly determines the energy when ions in the plasma collide with the substrate G. Therefore, if the potential Vdc of the electrode-side sheath S1 can be accurately controlled, the etching rate, film quality, and the like can be controlled with high accuracy.

(Measurement error)
Therefore, in order to accurately control the high-frequency power source 112 as a method for accurately controlling the potential Vdc of the electrode-side sheath Sl, as described above, the capacitance of the capacitor 108a is 4.2 times or less of the sheath capacitance. is required. This is a process of obtaining the power P from the voltages V ₁ and V ₂ across the capacitor 108a, and if the capacity of the capacitor 108a is 4.2 times or less of the sheath capacity, the measurement error included in the calculated power P This is because the inventors have confirmed that the value of is acceptable. This backing method will be described below.

If the ratio of the amplitudes of the voltages V ₁ and V ₂ across the capacitor 108a is α _k (= M _v1K / M _v2k ) and the phase difference between the voltages V ₁ and V ₂ is φ _k , ΔV (= V ₂ −V ₁ = I / jωC) phase θ _k and amplitude M _Δvk are expanded as follows: Here, k is the harmonic order.

  Next, the inventors considered the estimation of the error included in the measured power P based on the equivalent circuit of FIG. 3B for the modeled microwave plasma processing apparatus 10 of FIG. Here, the impedance Zu of the ground-side sheath Su has a capacitive component C2 and an inductive component R2. The impedance Zl of the electrode-side sheath S1 has a capacitive component C1 and an inductive component R1. Between the ground-side sheath Su and the electrode-side sheath Sl, there is a plasma impedance Zp having an inductive component Rp. Further, in the case of the microwave plasma processing apparatus 10 according to the present embodiment, there is an impedance Z associated with the addition of the capacitor 108a in addition to the total sum Z ′ of the impedances (Zu, Zl, Zp) described above.

At this time, the following equation holds.
ν = 1 / α _k = V ₂ / V ₁ = (Z + Z ′) / Z ′ = Z / Z ′ + 1

Next, using this equation, the absolute value of the phase difference (−φ _k ) and the voltage ratio V ₂ / V ₁ (= 1 / α _k (= M _v2K / M _v1k )) is evaluated. The conditions at this time are R _p ≈0, R _1,2 >> 1 / ωC _1,2 (= 1 / ωC).

(Evaluation of phase)
First, to evaluate the phase difference φ between the voltage V ₂ and the voltage V _1. FIG. 4 shows the relationship between Z, Z ′, and angle ε on a complex plane with the horizontal axis representing the real axis and the vertical axis representing the imaginary axis.

As described above, the voltage ratio and the impedance ratio are expressed by the following equations.
_{V 2 / V 1 = Z /} Z '+ 1
Further, the following equation is obtained from FIG.
arg (Z) = − π / 2
arg (Z ′) = − π / 2 + ε
arg (Z / Z ′) = ε

From the above, the following equation is derived.
| Arg (ν) | = | arg (Z / Z ′ + 1) | <| ε |

Since R _p ≈0 and R _1,2 >> 1 / ωC, | ε | is a very small value and can be approximated as arg (ν) ≈0. As a result, the absolute value of the phase difference φ between the voltage V ₂ and the voltages V ₁ is considered to be a small value regardless of the capacitance C of the capacitor 108a.

(Evaluation of absolute value of voltage ratio)
Next, the absolute value of the voltage ratio V ₂ / V ₁ is evaluated. The absolute value of the voltage ratio V ₂ / V ₁ is expressed as follows from the above-described equation.
1 / α = | ν | = | V ₂ / V ₁ | = | Z / Z ′ + 1 |
Z / Z′≈C ₁ C ₂ / (C ₁ + C ₂ ) C
Here, R _1,2 >> 1 / ωC and R _p ≈0.

FIG. 5 shows the relationship between the absolute value of V ₂ / V _{1 with} respect to the electron temperature Te (eV) on the horizontal axis and the electron density Ne (cm ⁻³ ) on the vertical axis between the capacitance C of the capacitor and the capacitance C _sheath of the _sheath. It is the figure which showed what kind of value it takes in. According to this graph, the absolute value of V ₂ / V ₁ varies depending on the plasma state indicated by the electron temperature Te and the electron density Ne. When the capacitance C of the _sheath is substantially equal to the capacitance C of the capacitor, α = | V ₁ / V ₂ | = 0.667 is measured, so the absolute value of V ₂ / V ₁ is asymptotic to “1.5”. To do.

On the other hand, when the capacitance C of the _sheath is substantially equal to 1/10 of the capacitance C of the capacitor, α = | V ₁ / V ₂ | = 0.95 is measured, so the absolute value of V ₂ / V ₁ is “ Asymptotic to 1.05 ".

Ｍ_ΔＶｋ：Ｖ_１とＶ_２の振幅差 φ_ｋ：Ｖ_１とＶ_２の位相差 Ｍ_Ｖ２ｋ：Ｖ_２の振幅
α_ｋ：Ｖ_１とＶ_２の絶対値の比 φ_ｋ：Ｖ_１とＶ_２の位相差 (Estimation of error)
Next, the error .delta..alpha _k measured values _V 1, the amplitude of _{V 2} alpha and the phase phi, .delta..phi _k is applied to a phase difference phi _k of the voltage _V 1, the amplitude difference between _{V 2} M _ΔVk and voltage _V 1, _{V 2} Each partial derivative was calculated to estimate the impact.

_M ΔVk: amplitude difference _{V 1} and _{V 2} phi _{k: V 1} and _{V 2} of the phase difference M _v2k: amplitude of _{V 2} alpha _k: the ratio of the absolute value of _{V 1} and _{V 2} phi _{k: V 1} and _{V 2} Phase difference

Ｍ_Ｖ２ｋ：Ｖ_２の振幅 α_ｋ：Ｖ_１とＶ_２の絶対値の比
θ_ｋ：Ｖ_１とＶ_２の位相 φ_ｋ：Ｖ_１とＶ_２の位相差 From the above-described evaluation of the phase, it is known that the phase difference φ _k is almost close to “0”. Therefore, the behaviors of the equations (5) to (8) in the vicinity of φ _k = 0 are approximately expressed as follows.

M _v2k: amplitude of _{V 2} alpha _k: the ratio of the absolute value of _{V 1} and _{V 2} theta _k: a phase phi _k of _{V 1} and _{V 2:} phase difference between _{V 1} and _{V 2}

Considering the equations (5) to (8) approximated as described above, with respect to the equation (8), the value of the equation (8) diverges under the condition that α _k is asymptotic to “1”. This means that the influence of the phase measurement error of V ₁ and V _{2 on} the phase error of V ₂ −V ₁ (= I / jωC) becomes large.

Also, looking at equation (6), when φ = 0, the value of equation (6) is “0”, but there is (1−α _k ) ^{2 in the} denominator, so α _k becomes “1”. Asymptotically, it takes a large value in the vicinity. The fact that equation (6) takes a large value means that a calculation error of absolute values of V ₁ and V ₂ can cause a phase error.

In any case, α _k (ratio of the absolute values of V ₁ and V ₂ ) asymptotically approaches “1”, that is, it approaches 1E + 10 shown in FIG. ) It is understood that at least one of cases where Ne is low or electron temperature Te is high, an error is likely to occur.

(measurement)
Based on the above estimation of error, the inventors actually performed measurement using the microwave plasma processing apparatus 10 having the capacitor 108a described above. First, as shown in FIG. 6, the inventors have eight plates of the same area on the susceptor 106, a glass substrate G ₄ , a metal electrode MP ₄ , a glass substrate G ₃ , a metal electrode MP ₃ , and a glass substrate G. ₂ , metal electrode MP ₂ , glass substrate G ₁ , and metal electrode MP ₁ were laminated in this order. A weight of an aluminum plate Wg was placed on the top to stabilize the capacitance between the metal electrodes.

The capacity C of the capacitor is set to 4.2 times or less of the sheath capacity. Specifically, the capacity C ₄₃ of the capacitor composed of the metal electrode MP ₄ and the metal electrode MP ₃ is 1.001 × 10 ⁻⁸ (F ), the capacity _{C 32} of the capacitor consists of a metal electrode MP ₃ and the metal electrode MP ₂ ^{is, 1.019 × 10 -8 (F)} , the capacitance of the capacitor constituted by the metal electrodes MP ₂ and the metal electrodes MP ₁ C ₂₁ was set to 1.015 × 10 ⁻⁸ (F).

  At the time of measurement, as an oscilloscope calibration, all probes are attached to the aluminum plate Wg placed at the top, the same signal is measured, and the amplitude and phase between channels are corrected by the waveform. Created a table.

  As process conditions, a microwave of 5500 W or 3000 W was supplied from the upper part of the processing vessel 100. A high frequency power of 100 W was output from the high frequency power source 112 located at the bottom. Further, the pressure in the processing chamber U was controlled to 30 mTorr. Further, as a processing gas, 500 sccm of argon (Ar) gas was introduced.

Using the experimental apparatus set in this way, the inventors measured the voltages V _{1 to} V ₄ using the _four metal electrodes MP _{1 to} MP 4 during the process execution, and the potential difference (V _{2 / V 1, V 3 /} V 2, was determined _V 4 / V _3). The result is shown in FIG.

FIG. 7 shows the measurement results and measurement of each electrode voltage (V _{1 to} V ₄ ) when the microwave power P _μ is set to 3000 W or 5500 W and the high-frequency power P _rf is set to 100 W or 500 W. Voltage ratios V ₂ / V ₁ , V ₃ / V ₂ , and V ₄ / V ₃ calculated from the results are shown. That is, the inventors first measured each electrode voltage (V) and each phase (rad) when the microwave power P _μ is 3000 W and the high-frequency power P _rf is 100 W and 500 W, and from these, The ratio of the amplitude of the voltage is obtained, and then each electrode voltage (V) and each phase (rad) when the microwave power P _μ is 5500 W and the high-frequency power P _rf is 100 W and 500 W are measured. From this, the voltage amplitude ratio was obtained.

Next, the inventors calculated the current waveforms (I ₂₁ , I ₃₂ , I ₄₃ ) of FIG. 8 calculated using the equation (4) based on the measured electrode voltages (V) and the phases (rad). And electric power (P ₂₁ , P ₃₂ , P ₄₃ ) were calculated. According to this, when the power of the microwave is 5500 W, the current waveform and power of FIG. 8 calculated from the electrode potentials (V ₄ , V ₃ , V ₂ , V ₁ ) of each substrate shown in FIG. The values of the values coincided relatively well, but in the case of 3000 W, the accuracy deteriorated.

As shown in FIG. 5, when the plasma density (electron density Ne) is not high or low and the density is appropriate as in the case where the microwave power P _μ is 5500 W, the result is shown in FIG. Since the C _sheath is almost equal to the capacitance C of the capacitor, and the absolute value of V ₂ / V ₁ is asymptotic to “1.5”, no matter what value the capacitance C of the capacitor is, an error hardly occurs. When the plasma density (electron density Ne) is low, such as when the wave power P _μ is 3000 W, the capacitance C of the _sheath is approximately equal to 1/10 of the capacitance C of the capacitor, and V ₂ / V ₁ Since the absolute value is asymptotic to “1.05”, the result agrees with the result of the consideration of the above formulas (5) to (8) that an error is likely to occur.

  Looking at the ratio of the voltage amplitude in FIG. 7, the ratio of the voltage amplitude depends on the power of the microwave and does not depend on the high frequency power. Therefore, when attention is paid to the power of the microwave, when the power of the microwave is 5500 W, each ratio is about 1.26 to 2. On the other hand, when the power of the microwave is 3000 W, each ratio is about 1.11 to 1.28. As a result, the inventors have found that, in the current measurement accuracy, the measurement error increases with a voltage amplitude ratio of about 1.2 as a boundary, that is, the voltage amplitude ratio has a measurement accuracy of about 1.2 as a boundary. It turns out that it gets worse. It was also found that the voltage amplitude ratio should be about 1.4 in order to eliminate measurement errors reliably.

(Optimization of capacitor capacity)
From the above experimental results, the inventors considered the optimum value of the capacitance of the capacitor in which the measurement error is within an allowable range as follows. As described above, according to the evaluation of the phase during estimation of the error attempted by the inventors, it is known that the phase φ _k is almost close to “0”. Therefore, as shown in FIG. 3 (a), by approximating the impedance Z of the capacitor, the impedance Zu of the ground-side sheath, the impedance Zl of the electrode-side sheath, and the plasma impedance Zp by a real number, The relationship between the sheath capacitance C _sheath and the capacitance C of the capacitor can be derived as follows.

C _sheath = C ₂ (ground side sheath capacity in FIG. 3B) = ψC ₁ (electrode side sheath capacity).
As described above, ν = 1 / α _k = V ₂ / V ₁ = (Z + Z ′) / Z ′ = 1 + Z / Z ′ and Z / Z′≈C ₁ C ₂ / (C ₁ + C ₂ ) C Therefore, substituting the above capacity relation into these equations,
ν = 1 + Z / Z ′ = 1 + ψ × C _sheath ² / {(1 + ψ) × C _sheath × C}

With the current measurement accuracy, the measurement error increases with a voltage amplitude ratio of about 1.2 as a boundary. From the result, the following can be said as the relationship between the C _sheath and C.
1 + ψ × C _sheath ² / {(1 + ψ) × C _sheath × C} ≧ 1.2 (9)

Here, when ψ is equal to “1”, that is, when the sheath capacitance C _sheath is equal to the ground-side sheath capacitance C ₂ and the electrode-side sheath capacitance C ₁ , the coefficient 5ψ / (1 + ψ) of the sheath capacitance C _sheath is 2 .5. However, when ψ is equal to “1”, the ground-side sheath capacitance and the electrode-side sheath capacitance are equal. Considering the width of the sheath region when plasma is generated, it is not considered that the ground-side sheath capacity and the electrode-side sheath capacity are equal. In practice, the ground-side sheath capacity is 1. It is considered to be about 5 to 5 times. Therefore, when the above equation (9) is calculated with ψ = 1.5 to 5, when ψ is “1.5”, the capacitance C of the capacitor is not more than three times the sheath capacitance C _sheath , and ψ is “5”. In this case, the capacitance C of the capacitor is 4.2 times or less of the sheath capacitance C _sheath . Therefore, the inventors concluded that the capacitance C of the capacitor in which the measurement error is within an allowable range is 4.2 times or less of the sheath capacitance C _sheath .

Further, in order to reliably eliminate measurement errors, as described above, the voltage amplitude ratio should be about 1.4, and in this case, the following equation holds.
1 + ψ × C _sheath ² / {(1 + ψ) × C _sheath × C} ≧ 1.4 (10)

Here, similarly to the previous calculation, when the above equation (10) is calculated with ψ = 1.5 to 5, when ψ is “1.5”, the capacitance C of the capacitor is 1.5 of the sheath capacitance C _sheath . When ψ is “5”, the capacitance C of the capacitor is 2.1 times or less of the sheath capacitance C _sheath . Therefore, the founders concluded that the capacitance C of the capacitor that can reliably eliminate the measurement error is 2.1 times or less of the sheath capacitance C _sheath .

From the above experiment, according to the measuring means 20 according to the present embodiment, the power of the capacitor 108a can be accurately measured if the capacitance C of the capacitor 108a is 4.2 times or less of the sheath capacitance C _sheath . Further, it has been found that the capacitance C of the capacitor 108a is preferably 2.1 times or less of the sheath capacitance C _sheath in order to reliably eliminate the error. Based on the measurement result using the capacitor 108a with the capacitance C determined in this way, a design for efficiently using high-frequency power by controlling the plasma (that is, the configuration and material of the processing apparatus at the time of design). Can be optimized.

From the above considerations and experiments, it has been found that the measurement error increases when the capacitance C of the capacitor 108a provided for measurement is 5 times or more the sheath capacitance C _sheath . From the above, the inventors have shown that the capacitance C of the capacitor provided for measurement is 4.2 times or less than the sheath capacity and needs to be sufficiently small (preferably 2.1 times or less). I caught it.

Therefore, the inventors have considered a plurality of methods in order to make the capacitance C of the capacitor 108a 4.2 times or less of the sheath capacitance C _sheath . First, as shown in FIG. 1, an electrode having the same area as the substrate G is provided in the susceptor 106 at a position facing the substrate G placed on the susceptor 106, and a dielectric having a low dielectric constant. This is a method of sandwiching the body 108b. Alternatively, the capacitance C of the capacitor 108a may be set to 4.2 times or less of the sheath capacitance C _sheath by increasing the distance between the electrodes instead of sandwiching the dielectric 108b having a low dielectric constant.

According to this, the measurement error included in the measured voltages V ₁ and V ₂ between the electrodes can be greatly reduced by setting the capacitance C of the capacitor 108a to 4.2 times or less of the sheath capacitance C _sheath. it can. However, with this method, it is necessary to sufficiently reduce the capacitance of the capacitor 108a even when the plasma conditions change.

(Feedback control)
The feedback control executed by the control device 148 will be described with reference to the flowchart of feedback control shown in FIG. The storage area (not shown) of the control device 148 stores in advance a table T showing the relationship between the film quality D determined by the amount of ions mixed into the film and the power P for obtaining the film quality. ing. Here, in order to obtain the target film quality Ds, the power Ps is output from the high-frequency power source 112 in the initial state.

The feedback control executed by the control device 148 starts processing from step 1300 in FIG. 13, and measures voltages V ₁ and V ₂ across the capacitor 108 in step 1305. Next, the waveforms of the voltages V ₁ and V ₂ measured in step 1310 are shaped, and the process proceeds to step 1315 where the voltages V ₁ and V ₂ are converted into frequency components, that is, harmonic components having a power source frequency as a fundamental wave. Decompose and determine coefficients by least squares method. Next, in step 1320, the amplitude M _k and the phase difference φ _K at each frequency are calculated based on the equations (1) to (3). In step 1325, the obtained amplitudes M _Ik and M _VIk are effective. The power Pr applied to the capacitor is calculated by substituting the value and the power factor (cos (φ _Ik −φ _VIk )) into the equation (4).

  When the electric power Pr is applied to the capacitor 108a (susceptor 106), the film quality Dr of the formed film is different from the target film quality Ds according to FIG. Therefore, the process proceeds to step 1330, and a power difference Pd (= Pr−Ps) between the power Ps at which the target film quality Ds is obtained and the calculated power Pr is obtained based on the table T. Next, the process proceeds to step 1335, and when the power difference Pd is determined to be “0” or more, the power Pr applied to the capacitor 108a is larger than the ideal power Ps as shown in the table T of FIG. At 1340, the power P output from the high-frequency power source 112 is controlled to be reduced by the power difference Pd, and the process ends at step 1395. On the other hand, if it is determined in step 1335 that the power difference Pd is smaller than the value of “0”, the power Pr applied to the capacitor 108a is smaller than the ideal power Ps, and is output from the high frequency power source 112 in step 1345. The power P is controlled to be increased by the power difference Pd, and the process ends at step 1395.

  As described above, by directly measuring the high-frequency power applied to the susceptor 106 using the control device 148, more accurate feedback control of the power can be realized. As a result, a high-quality film can be continuously formed with very high accuracy regardless of the state of the processing chamber and the type of process.

Further, according to the equation (4), the power P is calculated based on the data of only the voltages V ₁ and V ₂ between the electrodes without requiring other data. Moreover, electric power can be measured on the entire electrode surface. Thereby, very accurate measurement can be realized. In this way, the voltages V ₁ and V ₂ of the _two electrodes of the capacitor 108a having a capacity of 4.2 times or less of the sheath capacity are actually measured, and the high frequency power is obtained from the actually measured value, so that it can be used for plasma control. It is possible to accurately grasp the high-frequency power directly under the substrate.

(Modification 1)
The second method that the inventors have found to reduce the capacitance C of the capacitor 108a to 4.2 times or less of the sheath capacitance C _sheath is that it does not face the substrate G, as shown in FIG. This is a method of forming a small electrode (capacitor 108 a) at the end of the susceptor 106 that does not affect the susceptor 106.

Also by this, as in the first method, the high frequency power P of the susceptor 106 is calculated based on the measured values of the voltages V ₁ and V ₂ across the capacitor, so that it can be used for plasma control. High frequency power can be accurately derived. In addition, according to the method of the first modification, the voltages V ₁ and V ₂ can be measured without affecting the process. Further, the capacitance of the capacitor 108a can be easily reduced. However, since the voltages V ₁ and V ₂ are measured at a portion not facing the substrate, an error may occur between the measurement result and the actual power value when the in-plane distribution inside the electrode is large.

(Modification 2)
The third method found by the inventors to reduce the capacitance C of the capacitor 108a to 4.2 times or less of the sheath capacitance C _sheath is as shown in FIG. In this method, the capacitor 108a is connected to the power supply line 114a inside.

Also by this, by obtaining the high-frequency power P of the susceptor 106 based on the actually measured values of the voltages V ₁ and V ₂ across the capacitor 108a, the high-frequency power directly under the substrate that can be used for plasma control can be accurately derived. . However, when there is power leakage from the lower part of the susceptor 106 to the processing container 100, the power leakage may not be detected.

(Modification 3)
Furthermore, in any of the capacitors 108a shown in FIGS. 1, 9 and 10, for example, as shown in FIG. 11, a resonance circuit (LC = 1 / ω ₀ ² ; ω ₀ resonance frequency) is connected in series with the capacitor 108a. ) May be connected.

  According to this, the impedance of the power supply line 114a can be reduced by erasing the increased load impedance due to the provision of the capacitor 108a by the inductor 150 (series resonance circuit). Thereby, the load of the matching device 110 can be reduced.

  According to the embodiment and the modification described above, it is possible to accurately measure the power directly under the substrate using the capacitor 108a.

  In the embodiment described above, the voltage value of the electric signal of both electrodes of the capacitor 108a is measured as a parameter for controlling the plasma. However, the present invention is not limited to this, and at least one of the voltage value, the current value, and the phase value is measured. Alternatively, a combination of these may be measured.

Further, when the area of the capacitor is smaller than the size of the substrate, the limitation of the sheath capacitance C _sheath (= ground-side sheath capacitance C ₂ ) may be changed.

  Further, the control circuit 148d is an example of a control unit that calculates high-frequency power using the parameter measured by the measuring unit 20, and feedback-controls the high-frequency power source 112 based on the calculated high-frequency power. That is, the control unit may be configured by hardware (circuit) or may be configured by software (program).

  The size of the substrate G to be processed by the processing apparatus is, for example, a G4.5 substrate size of 730 mm × 920 mm (inside chamber dimensions: 1000 mm × 1190 mm) or 1100 mm × 1300 mm (inside chamber dimensions: 1470 mm × 1590 mm). It may be a G5 substrate size. Further, the target object to be processed is not limited to the substrate G having the size described above, and may be, for example, a 200 mm or 300 mm silicon wafer.

  In the above embodiment, the operations of the respective units are related to each other, and can be replaced as a series of operations in consideration of the relationship between each other. And by substituting in this way, embodiment of the measuring device using a plasma processing apparatus can be made into embodiment of the measuring method using a plasma processing apparatus.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, the measurement system S according to the present invention not only measures the voltage of the cathode side electrode (lower electrode, RI mode) of the microwave plasma processing apparatus 10 shown in FIG. 1, but also the microwave shown in FIG. The voltage of the anode side electrode (upper electrode, RI mode) may be measured as a parameter for controlling the plasma generated by the plasma processing apparatus.

  That is, the measurement system according to the present invention is not limited to the case of measuring the voltage of the electrode in the cathode coupling in which the substrate G is placed on the high frequency power supply side, as shown in the microwave plasma processing apparatus of FIG. As shown in the microwave plasma processing apparatus of FIG. 12, the substrate G is placed on the ground electrode side, and the electrode voltage is measured in the anode coupling in which plasma is generated by irradiating microwaves from above. Can be used. In particular, in the anode coupling, since the plasma generated in the upper part of the processing chamber is lost on the inner side wall of the processing vessel while being diffused, it is significant to actually measure the voltage of the electrode.

  Further, the plasma processing apparatus using the dielectric member according to the present invention is not limited to the above-described microwave plasma processing apparatus having a plurality of dielectric window parts, but an RLSA (Radial Line Slot Antenna) type microwave plasma processing. The present invention can be used in an apparatus, an inductively coupled plasma (ICP) plasma processing apparatus, a capacitively coupled plasma processing apparatus, and an electron cyclotron (ECR) plasma processing apparatus. Therefore, the measurement system according to the present invention can be used to measure the voltage of the anode-side or cathode-side electrode of such various plasma processing apparatuses.

  Furthermore, the types of processes executed in the plasma processing apparatus are not limited, such as etching, sputtering, and CVD.

It is a measurement system block diagram containing the microwave plasma processing apparatus concerning one Embodiment of this invention. It is an internal block diagram of a control apparatus. FIG. 3A is a diagram for explaining an electrical state in the processing apparatus, and FIG. 3B is a diagram showing an equivalent circuit. It is the figure which showed the relationship between Z and Z 'in a complex plane. The change in the absolute value of V _{2 /} V ₁ with respect to the state change of the plasma is a diagram showing a graph on the basis of the magnitude relationship between the capacitance C _sheath capacitance C and the sheath of the capacitor. It is the figure which expanded the electrode vicinity of the experimental apparatus. It is the figure which showed the measurement result of the electrode potential of each board | substrate. It is the figure which showed the electric current waveform and electric power which are calculated from the measured electric potential. It is a measurement system block diagram containing the microwave plasma processing apparatus concerning the modification 1. FIG. It is a measurement system block diagram including the microwave plasma processing apparatus concerning the modification 2. It is a measurement system block diagram containing the microwave plasma processing apparatus concerning the modification 3. FIG. It is a measurement system block diagram containing the modification of the microwave plasma processing apparatus of one Embodiment of this invention. It is the flowchart which showed the feedback control of the high frequency electric power. It is the table which showed the relationship between electric power and film quality. It is a system block diagram containing the related plasma processing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Microwave plasma processing apparatus 20 Measuring means 100, 1005 Processing container 106, 1010 Susceptor 106a, 1010a Feeding rod 108 Feeding part 108a Capacitor 108b Dielectric 110, 1025 Matching device 112, 1020 High frequency power supply 114a, 114b, 1030a, 1030b 142a, 142b Probe 144a, 144b Oscilloscope 148 Controller 150 Inductor S Measurement system

Claims (20)

A processing container for performing a desired process on the object to be processed by plasma inside;
A mounting table for mounting an object to be processed in the processing container;
A high frequency power supply for supplying high frequency power to the mounting table;
A capacitor provided on the mounting table, and
A plasma processing apparatus comprising: a measuring unit that measures a voltage of both electrodes of the capacitor with respect to the high frequency power applied to the mounting table from the high frequency power source. The capacitance C of the capacitor is
When the sheath capacitance C _sheath is the ground-side sheath capacitance C ₂ and the ratio of the ground-side sheath capacitance C _{2 to} the electrode-side sheath capacitance C ₁ of the capacitor is ψ, 1 + ψ × C _sheath ² / {(1 + ψ) × C _sheath × 2. The plasma processing apparatus according to claim 1, wherein a value of C} is determined such that an error is equal to or higher than a voltage ratio in which an error is within an allowable range among voltage ratios of electrodes measured using the capacitor. The plasma processing apparatus according to claim 2, wherein a capacitance C of the capacitor is 4.2 times or less of a sheath capacitance C _sheath . It further includes a power feeding unit provided inside the mounting table,
The capacitor is
The plasma processing apparatus as described in any one of Claims 1-3 provided in a part or all of the said electric power feeding part in the position facing the to-be-processed object mounted in the mounting table. It further includes a power feeding unit provided inside the mounting table,
The capacitor is
The plasma processing apparatus described in any one of Claims 1-3 provided in a part of said electric power feeding part in the position which does not oppose the to-be-processed object mounted in the said mounting base. The capacitor is
The plasma processing apparatus according to claim 4, wherein the plasma processing apparatus is provided at a part of the power supply unit at an end of the power supply unit. The capacitance C of the capacitor is
By having a predetermined dielectric constant as a dielectric between the electrodes of the capacitor, or by setting the electrode area and the electrode interval to predetermined values, it is formed to be 4.2 times or less of the sheath capacitance C _sheath. The plasma processing apparatus as described in any one of Claims 2-6.   The plasma processing apparatus according to claim 1, further comprising a resonance circuit connected in series to the capacitor.   The plasma processing apparatus according to claim 1, wherein the capacitor is formed inside the mounting table. 10. The plasma processing apparatus according to claim 2, wherein a capacitance C of the capacitor is 2.1 times or less of a sheath capacitance C _sheath . The high-frequency power source applies high-frequency power through the power feeding unit,
5. A matching device connected to the high-frequency power source and the power supply unit between the high-frequency power source and the power supply unit, further comprising a matching unit that matches an output impedance of the high-frequency power source and a load impedance on the power supply unit side. 10. The plasma processing apparatus described in any one of 10 above.   A processing container that performs a desired process on a target object with plasma inside, a mounting table for mounting the target object in the processing container, a high-frequency power source that supplies high-frequency power to the mounting table, and A measuring device that measures the voltage of both electrodes of the capacitor with respect to the high-frequency power from the high-frequency power source applied to the mounting table of the plasma processing apparatus including the capacitor provided on the mounting table. The capacitance C of the capacitor is
When the sheath capacitance C _sheath is the ground-side sheath capacitance C ₂ and the ratio of the ground-side sheath capacitance C _{2 to} the electrode-side sheath capacitance C ₁ of the capacitor is ψ, 1 + ψ × C _sheath ² / {(1 + ψ) × C _sheath × The measuring device according to claim 12, wherein the value of C} is determined so as to be equal to or higher than a voltage ratio in which an error is within an allowable range among voltage ratios of electrodes measured using the capacitor. 14. The measuring device according to claim 12, wherein the voltage of both electrodes of the capacitor having a capacitance C that is 4.2 times or less of the sheath capacitance C _sheath is measured.   A processing container that performs a desired process on a target object with plasma inside, a mounting table for mounting the target object in the processing container, a high-frequency power source that supplies high-frequency power to the mounting table, and A measurement method for measuring voltages at both electrodes of the capacitor with respect to a high-frequency power from the high-frequency power source applied to a mounting table of a plasma processing apparatus including a capacitor provided on the mounting table. The capacitance C of the capacitor is
When the sheath capacitance C _sheath is the ground-side sheath capacitance C ₂ and the ratio of the ground-side sheath capacitance C _{2 to} the electrode-side sheath capacitance C ₁ of the capacitor is ψ, 1 + ψ × C _sheath ² / {(1 + ψ) × C _sheath × The measurement method according to claim 15, wherein the value of C} is determined so as to be equal to or higher than a voltage ratio in which an error is within an allowable range among the voltage ratios of the electrodes measured using the capacitor. The measurement method according to claim 15 or 16, wherein a voltage of both electrodes of the capacitor having a capacitance C that is 4.2 times or less of a sheath capacitance C _sheath is measured. A processing container for performing a desired process on the object to be processed by plasma inside, a mounting table for mounting the processing object in the processing container, a capacitor provided on the mounting table, and an inside of the mounting table A control device for controlling the plasma using a plasma processing apparatus including a power supply unit embedded in the high frequency power source and a high frequency power source connected to the high frequency power source,
Measuring means for measuring the voltage across the capacitor with respect to the high frequency power applied to the mounting table from the high frequency power source,
A control apparatus comprising: a control unit that calculates the high-frequency power using the voltage across the capacitor measured by the measuring means, and feedback-controls the high-frequency power source based on the calculated high-frequency power. The capacitance C of the capacitor is 1 + ψ × C _sheath ² / {, where the sheath capacitance C _sheath is the ground-side sheath capacitance C ₂ and the ratio of the ground-side sheath capacitance C _{2 to} the electrode-side sheath capacitance C ₁ of the capacitor is ψ. The value of (1 + ψ) × C _sheath × C} is determined so that an error is equal to or higher than a voltage ratio in which an error is within an allowable range among the voltage ratios of the electrodes measured using the capacitor. Control unit. The measuring means includes
20. The control device according to claim 18, which measures a voltage at both electrodes of the capacitor having a capacitance C that is 4.2 times or less of a sheath capacitance C _sheath .

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