JP2014086129A - Plasma processing apparatus and plasma monitoring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus in which measurement can be carried out without affecting plasma and without being affected by sediment, and the plasma state can be estimated during processing.SOLUTION: A plasma processing apparatus processes an object (103) to be processed placed in a processing chamber (101), by generating plasma (108) between electrodes (102-107) in the processing chamber (101). A plurality of antennas (113a, 113b) are provided around an axis (Z) connecting the electrodes (102-107) outside the processing chamber (101), and the state of plasma is estimated by calculating a correlation of antenna outputs by an operation unit (114).

Description

  The present invention relates to a plasma processing apparatus provided with a plasma monitoring device for measuring a plasma state in a processing chamber.

  In a plasma processing apparatus such as a sputtering apparatus or a dry etching apparatus, the stability or uniformity of the plasma is affected by changes in the state of the processing chamber, for example, turbulence of the introduced processing gas or deposition of a target material in the chamber. Lowers the product yield and lowers the product yield and processing quality.

  In particular, in the case where continuous film formation is performed while a long strip-shaped object having a length of several hundred meters is running, one film formation time is long. Deposits grown during this continuous film formation cause a ground short circuit, causing non-uniform film thickness due to plasma movement and the like, resulting in significant waste of the object to be processed and the target material.

Therefore, in order to detect a decrease in the stability and uniformity of the plasma, a monitoring technique that can grasp the state of the plasma in the processing chamber becomes indispensable.
As a conventional monitoring technique in the processing chamber, there is a method of measuring an electron temperature and an electron density in addition to a method of measuring a plasma electron quantity by installing a probe as typified by a Langmuir probe method.

FIG. 17 shows a plasma processing apparatus described in Patent Document 1.
In this plasma processing apparatus, high-frequency power is applied between an upper electrode 142 and a lower electrode 143 provided in the processing chamber 141 to generate plasma 144. An object 146 to be deposited is placed on the lower electrode 143.

  The plasma monitoring apparatus installs a probe 145 at a position where the plasma 144 is generated, detects an electromagnetic wave of the plasma 144, and monitors the spatial distribution of the electron density in the plasma from this frequency.

JP 2004-103264 A

  However, in the conventional configuration, the density of the plasma 144 and the amount of electrons can be directly measured. However, since the probe 145 is installed in the plasma 144, the fluid distribution of the processing gas introduced into the processing chamber 141 is disturbed. The problem is that the shape of the plasma 144 that is originally obtained between the electrodes is distorted due to the generation or influence on the impedance between the electrodes to which power is applied.

In addition, there is a problem that deposits generated in the plasma processing apparatus adhere to the probe and hinder accurate measurement.
The present invention can detect the plasma state without causing instability of the plasma state in the processing chamber, and is not affected by deposits generated in the plasma processing apparatus, and can stabilize the plasma in the processing chamber. Another object of the present invention is to provide a plasma processing apparatus and a plasma monitoring method capable of monitoring the uniformity.

  In the plasma processing apparatus of the present invention, plasma is generated between electrodes inside a processing chamber to process an object to be processed disposed inside the processing chamber, and the like around an axis connecting the electrodes. A plurality of main antennas provided outside the processing chamber at every angle, and an arithmetic unit for calculating the correlation of outputs of the plurality of main antennas to estimate the plasma state are provided. .

  Further, the plasma monitoring method of the present invention generates plasma between the electrodes inside the processing chamber to process an object disposed inside the processing chamber at an equal angle around an axis connecting the electrodes. In addition, a plurality of main antennas are arranged outside the processing chamber, and a correlation between outputs of the plurality of main antennas is calculated by a calculation unit to estimate the plasma state.

  According to this configuration, the electromagnetic wave generated from the plasma inside the processing chamber is detected by a plurality of main antennas provided outside the processing chamber, and the correlation between the outputs of the plurality of main antennas is calculated by the calculation unit, and the plasma state Therefore, it is possible to detect plasma fluctuations in-line during production without affecting the plasma and without being affected by deposits generated in the processing chamber. In addition, since the plasma state in the processing chamber of a plasma processing apparatus such as a sputtering apparatus or a dry etching apparatus can be measured in real time, it is possible to prevent a reduction in product processing quality and yield.

The plasma processing apparatus in Embodiment 1 of this invention is shown, (a) is a plane sectional view along the AA line, (b) is an elevational sectional view along the BB line. The figure which shows an example of the antenna structure for plasma monitoring by the monopole antenna in the same embodiment The figure which shows an example of another antenna structure for the plasma monitoring by the patch antenna in the embodiment The plasma movement of the X-axis direction in the embodiment is shown, (a) is a plan sectional view along the AA line, (b) is a sectional elevation along the BB line The expansion state of the plasma of the X-axis direction in the embodiment is shown, (a) is a plan sectional view along the AA line, (b) is a sectional elevation along the BB line The reduced state of the plasma of the X-axis direction in the same embodiment is shown, (a) is a plan sectional view along the AA line, (b) is an elevational sectional view along the BB line The structure of the plasma processing apparatus in Embodiment 2 of this invention is shown, (a) is a plane sectional view along the AA line, (b) is an elevational sectional view along the BB line. The plasma movement of the X-axis-Y-axis direction in Embodiment 2 is shown, (a) is a plane sectional view along the AA line, (b) is an elevational sectional view along the BB line. The expanded state and contracted state of the plasma of the X-axis-Y-axis direction in the same embodiment are shown, (a) is a plane sectional view along the AA line, (b) is a vertical section along the BB line. Figure The structure of the plasma processing apparatus in Embodiment 3 of this invention is shown, (a) is a plane sectional view along the AA line, (b) is an elevational sectional view along the BB line. The plasma movement of the X-axis-Y-axis direction in the same embodiment is shown, (a) is a plane sectional view along the AA line, (b) is an elevational sectional view along the BB line. The plasma expansion state in the X-axis-Y-axis direction in the same embodiment is shown, (a) is a plan cross-sectional view along the AA line, (b) is a vertical cross-sectional view along the BB line Configuration diagram of plasma processing apparatus in Embodiment 4 of the present invention The flowchart of the calculating part which detects the X-axis direction movement of the plasma in Embodiment 1 of this invention. The flowchart of the calculating part which detects the X-axis direction expansion of plasma in Embodiment 1 of this invention. The flowchart of the calculating part which detects the X-axis direction reduction | restoration of the plasma in Embodiment 1 of this invention. The figure which shows the structure of the conventional plasma processing apparatus and plasma monitoring apparatus which were described in patent document 1

Hereinafter, a plasma processing apparatus and a plasma monitoring method of the present invention will be described based on each embodiment.
(Embodiment 1)
1 to 6 and FIGS. 14 to 16 show the first embodiment.

FIG. 1 shows a plasma processing apparatus according to Embodiment 1 of the present invention.
This plasma processing apparatus continuously forms a film while a long strip-like object 103 is running. In the case of such continuous film formation, it is important to monitor plasma fluctuations that induce film thickness non-uniformity.

  In this specification, the X-axis direction, the Y-axis direction, the Z-axis direction, the AA cross section, and the BB cross section used for explanation are defined as shown in the figure. FIG. 1A is a plan sectional view (AA section), and FIG. 1B is an elevation sectional view (BB section).

  In FIG. 1, a processing chamber 101 is grounded so that electromagnetic waves do not leak when plasma is generated. The main roller 102 as the upper electrode travels the sheet-like workpiece 103 in the Y-axis direction. The main roller 102 is grounded. A target material 109 which is a material for film deposition is placed on the cathode electrode 107 as the lower electrode. The cathode electrode 107 is connected to the high voltage power source 104 via the application unit 106 and the coaxial cable 105. As the high voltage power source 104, a DC power source or a 13.56 MHz high frequency power source is mainly used. As a result, plasma 108 is generated between the main roller 102 and the cathode electrode 107.

  The application unit 106 has a structure that becomes the center of the cathode electrode 107 and the center of the processing chamber 101, and the plasma 108 is also formed around this. The applied current, voltage, and frequency are controlled by a control unit (not shown) so that the film can be formed at a constant rate. When the film is out of a desired value, error processing such as film formation stop or alarm display is performed. Done.

  When the plasma processing apparatus is a sputtering apparatus, an inert gas such as argon is introduced from the gas inlet 110. The automatic pressure control valve 111 automatically adjusts the valve opening in order to maintain the inside of the vacuum processing chamber at a desired constant pressure after the gas is introduced. The main valve 112 is connected to an exhausting means such as a cryopump or a turbo molecular pump having a sufficiently large exhaust amount, that is, an exhaust capacity equivalent to the chamber volume (not shown). Therefore, gas stays in the processing chamber 101. However, it is possible to exhaust unnecessary intermediate products generated by the reaction between the plasma 108 and the target material 109 without causing an increase in pressure.

  A plurality of antennas 113 a and 113 b as main antennas are provided outside the processing chamber 101 around the Z axis connecting the main roller 102, the cathode electrode 107, and the application unit 106. Corresponding to the antennas 113a and 113b, the processing chamber 101 is provided with two viewing ports (vacuum viewing windows) 115a and 115b as coupling ports through which electromagnetic waves pass while maintaining the hermeticity of the processing chamber 101. It has been.

  Specifically, the processing chamber 101 wall surface parallel to the Y-axis direction in which the workpiece 103 moves is opposed to an X-axis-Y-axis plane passing through the approximate center of the stable plasma with the plasma 108 interposed therebetween. Thus, two viewing ports (vacuum viewing windows) 115a and 115b are provided. The viewing ports 115a and 115b are fitted with quartz glass at the center as a window material.

  A plurality of antennas 113 a and 113 b are provided outside the processing chamber 101 around the Z axis connecting the electrodes. Antennas 113a and 113b are fixed to the outer surfaces of the viewing ports 115a and 115b. The antennas 113a and 113b of this embodiment are arranged at equal intervals of 180 ° around the Z-axis connecting the electrodes.

  The antennas 113a and 113b capture electromagnetic waves from the plasma 108 and convert them into currents or voltages corresponding to the intensity. The electric signal output from the antennas 113a and 113b is arithmetically processed by the arithmetic unit 114 via the electric signal cable 116.

  With the above configuration, while performing the sputter film formation while moving the sheet-like workpiece 103 at a constant speed, the plasma state is monitored by the antennas 113a and 113b, and the measured value in the stable state is obtained in advance. Are stored in the calculation unit 114. The calculation unit 114 determines that the plasma state is incomplete when the measured value deviates from the measured value in the plasma in the stable state. Based on the determination information, the facility is stopped, the processing chamber is cleaned by an operator, and the determination information is added to the product management information.

FIG. 2 shows the antennas 113a and 113b and their mounting structure, and is an example of the antenna 113b side in FIG.
Although FIG. 2 shows an example using a monopole antenna, the antennas 113a and 113b can be similarly configured by a patch antenna as shown in FIG.

  The general processing chamber 101 is made of stainless steel, and even if the antennas 113a and 113b are simply arranged outside the processing chamber 101, electromagnetic waves from the plasma 108 generated inside cannot be detected. Therefore, viewing ports 115a and 115b are provided in the portions where the antennas 113a and 113b are installed, and the antennas 113a and 113b are attached to the outside of the window material of the viewing ports 115a and 115b. The viewing port for the antenna may be used for visual observation as long as it can be used in position and size.

The frequency of the high-voltage power supply for plasma generation used in plasma processing apparatuses such as sputtering apparatuses and dry etching apparatuses is about several tens KHz to several tens MHz. In a 13.56 MHz power supply that is widely used in general, the wavelength λ of the generated electromagnetic wave is 22 m. In general, the length of the antenna is ½ of the wavelength. However, in the case of the present invention, the antennas 113a and 113b are several millimeters or more in order to catch electromagnetic waves from a very large energy for generating plasma relatively close to the antenna. Even a size of about several tens of millimeters can be received sufficiently. In a general plasma processing apparatus, when the distance between the plasma 108 and the antennas 113a and 113b is r,
r <λ / 2π
In this range, of the electromagnetic field represented by Maxwell's electromagnetic equation, the near field becomes dominant and the far field can be ignored. For this reason, the electric field intensity captured by the antenna is inversely proportional to r ³ , and therefore, the plasma electric field intensity at the shortest distance from the antenna has a dominant effect on the output of the antenna.

  In the case where continuous film formation is performed while the long strip-shaped workpiece 103 is traveling in the Y-axis direction, the film pressure distribution in the X-axis direction may be nonuniform even if the energy control of the power to be supplied is good. This factor includes plasma movement in the X-axis direction, expansion and contraction, and the like.

  In these events, the antennas 113a and 113b are arranged at positions facing each other across the plasma 108, the difference between the output of the antenna 113a and the output of the antenna 113b is observed, and the contents stored in the stable state of the plasma 108 It can be detected by comparing. It is possible to distinguish between plasma movement, expansion, and contraction that cannot be determined with an antenna on only one side, and the response after detection can be made appropriate.

A specific configuration of the calculation unit 114 will be described based on specific examples of FIGS.
FIG. 4 shows the movement of the plasma in the X-axis direction on the X-axis-Y-axis plane. (A) is a plane sectional view along an AA line, (b) is an elevational sectional view along a BB line.

FIG. 5 shows the expansion state of the plasma in the X-axis direction on the X-axis-Y-axis plane. (A) is a plane sectional view along an AA line, (b) is an elevational sectional view along a BB line.
FIG. 6 shows a reduced state of the plasma in the X-axis direction on the X-axis-Y-axis plane. (A) is a plane sectional view along an AA line, (b) is an elevational sectional view along a BB line.

4 to 6, a plasma 108A indicated by a solid line indicates a plasma in a stable state, and a plasma 108B indicated by a broken line indicates a plasma after fluctuation.
Symbols used for explanation are defined as follows.

Va1: Voltage value of antenna 113a in plasma 108A in stable state Vb1: Voltage value of antenna 113b in plasma 108A in stable state Va2: Voltage value of antenna 113a in plasma 108B after fluctuation Vb2: Voltage value of antenna 113b in plasma 108B after fluctuation Voltage Value In the example, the case where the output from the antennas 113a and 113b is measured as a voltage is described as a voltage value. However, a current value may be measured and a current value may be used.

The plasma movement in the X-axis direction is detected by the calculation unit 114 as follows.
Here, Va1 and Vb1 are reference values, and Va2 and Vb2 are occasional sample values.
− Detection of plasma movement −
The calculation unit 114 reads the output of the antennas 113a and 113b from time to time. In the case of the state of the plasma 108B shown in FIG. 4, the calculation unit 114 performs “Va2 <Va1” and “Vb2> Vb1”.
It is estimated that “the plasma is not in a stable state and the plasma 108B has moved closer to the antenna 113b than the antenna 113a”.

FIG. 4A shows the detection when the plasma 108B moves in the direction approaching the antenna 113b, but the same applies when the position of the plasma 108B moves in the direction approaching the antenna 113a. “Va2> Va1” and “Vb2 <Vb1”
It is estimated that “the position of the plasma 108B is moving in a direction approaching the antenna 113a”.

  Steps S <b> 1 to S <b> 5 in FIG. 14 are a flow of the X-axis direction movement estimation of the calculation unit 114. By detecting the state of “Va2 = Va1” and “Vb2 = Vb1” in step S3, it is estimated that “the plasma 108 is in a stable state”.

− Detection of plasma expansion −
The calculation unit 114 reads the output of the antennas 113a and 113b from time to time. In the case of the state of the plasma 108B shown in FIG. 5, the calculation unit 114 performs “Va2> Va1” and “Vb2> Vb1”.
It is estimated that “the plasma is not in a stable state. The plasma 108B is in an expanded state closer to the antennas 113a and 113b than in the stable state”.

  Steps S11 to S14 in FIG. 15 are a flow of the X-axis direction expansion estimation of the calculation unit 114. By detecting the state of “Va2 = Va1” and “Vb2 = Vb1” in step S13, it is estimated that “the plasma 108 is in a stable state”.

− Detection of plasma shrinkage −
The calculation unit 114 reads the output of the antennas 113a and 113b from time to time. In the case of the state of the plasma 108B shown in FIG. 6, the calculation unit 114 performs “Va2 <Va1” and “Vb2 <Vb1”.
It is estimated that “the plasma is not in a stable state. And, the plasma 108B is in a contracted state in which it is further away from the antennas 113a and 113b than in the stable state”.

  Steps S <b> 21 to S <b> 24 in FIG. 16 are a flow of the reduction estimation in the X-axis direction of the calculation unit 114. By detecting the state of “Va2 = Va1” and “Vb2 = Vb1” in step S23, it is estimated that “the plasma 108 is in a stable state”.

  Further, the calculation unit 114 detects that the stable state is determined in both step S3 and step S13, the stable state is determined in both step S3 and step S23, or that at least one of these is satisfied. , “Plasma 108 is in a stable state”.

(Embodiment 2)
7 to 9 show the second embodiment.
FIG. 7 shows a plasma processing apparatus according to Embodiment 2 of the present invention.

  This plasma processing apparatus shows a configuration in the case of monitoring plasma fluctuations that induce film thickness non-uniformity when a sheet-like workpiece is placed in a processing chamber to form a film.

  The X-axis direction, Y-axis direction, Z-axis direction, AA cross-sectional view, and BB cross-sectional view used in the following description are defined as shown in the figure. 7A shows a plan sectional view (AA section), and FIG. 7B shows an elevation sectional view (BB section).

  In FIG. 7, the processing chamber 101 is grounded so that electromagnetic waves do not leak when plasma is generated. The processing chamber 101 has an anode electrode 117 at the lower portion and a cathode electrode 107 at the upper portion, the workpiece 103 is placed on the anode electrode 117, and a target material that is a material for forming a film on the cathode electrode 107. 109 is placed. The cathode electrode 107 is connected to the high voltage power source 104 via the application unit 106 and the coaxial cable 105. The high-voltage power source 104 is mainly a DC power source or a 13.56 MHz RF power source, and generates a plasma 108 between the electrodes. The application unit 106 has a structure that is the center of the cathode electrode 107 and the center of the processing chamber 101, and the plasma 108 is also formed around this. The applied current, voltage, and frequency are controlled by a control unit (not shown) so that a film can be formed at a constant rate. If the film is out of a desired value, error processing such as film formation stop or alarm display is performed. Is called.

  In the case of a sputtering apparatus, an inert gas such as argon is introduced from the gas inlet 110. The automatic pressure control valve 111 automatically adjusts the valve opening in order to maintain the inside of the processing chamber 101 at a desired constant pressure after the gas is introduced.

  The main valve 112 is connected to an exhausting means such as a cryopump or a turbo molecular pump having a sufficiently large exhaust amount, that is, an exhaust capacity equivalent to the chamber volume (not shown). Therefore, gas stays in the processing chamber 101. However, it is possible to exhaust unnecessary intermediate products generated by the reaction between the plasma 108 and the target material 109 without causing an increase in pressure.

  A plurality of antennas 113 a, 113 b, 113 c, and 113 d as main antennas are provided around the Z axis connecting the application unit 106 and the cathode electrode 107 and the anode electrode 117 outside the processing chamber 101. Corresponding to the antennas 113a to 113d, the processing chamber 101 is provided with four viewing ports (vacuum viewing windows) 115a to 115d as coupling ports through which electromagnetic waves pass while maintaining the airtightness of the processing chamber 101. ing.

  Specifically, on the X-axis / Y-axis plane passing through the approximate center of the stable plasma on the wall surface of the processing chamber 101, the viewing port 115a is spaced at an equal angle of 90 ° so as to face each other with the plasma 108 interposed therebetween. To 115d are provided. The viewing ports 115a to 115d are fitted with quartz glass at the center as a window material.

  Antennas 113a to 113d are provided on the outer surfaces of the viewing ports 115a to 115d around the Z-axis connecting the electrodes. Antennas 113a to 113d are fixed.

  The antennas 113a to 113d capture electromagnetic waves from plasma and convert them into currents or voltages corresponding to the intensity. The electric signal output from each of the antennas 113 a to 113 d is subjected to arithmetic processing by the arithmetic unit 114 via the electric signal cable 116. While performing sputter deposition with the above configuration, the plasma state is constantly monitored by the antennas 113a to 113d, and when the monitoring result deviates from the measured plasma value in the stable state stored in advance, the plasma state Judge as incomplete. Based on the determination information, the facility is stopped, the processing chamber is cleaned by an operator, and the determination information is added to the product management information.

  In the case where a film-like object to be processed is placed in the processing chamber to form a film as shown in Embodiment Mode 2, even if the power control of the power supply to be input is good, the film pressure distribution may be uneven. . As this factor, there are plasma movement, expansion, and reduction in the X-axis direction and Y-axis direction.

  These events can be detected by arranging the antennas 113a to 113d at positions facing each other across the plasma 108 and observing the difference from the antenna output stored in the stable state of the plasma. It is also possible to distinguish plasma movement, expansion, and contraction that cannot be determined by monitoring only one side in the X-axis direction or the Y-axis direction, and the response after detection can be made appropriate.

A specific configuration of the calculation unit 114 will be described based on the specific examples of FIGS. 8 and 9.
The same components as those in FIGS. 1, 2, and 3 are denoted by the same reference numerals, and description thereof is omitted. In addition, the cross section, the X-axis direction, the Y-axis direction, and the Z-axis direction are the same as those shown in FIG. The antenna used is that shown in FIG. 2 or FIG. 3 described in the first embodiment.

FIG. 8 shows the plasma movement in the X-axis-Y direction. (A) is a plane sectional view along an AA line, (b) is an elevational sectional view along a BB line.
FIG. 9 shows an expanded state of plasma in the X-axis direction and a reduced state of plasma in the Y-axis direction. (A) is a plane sectional view along an AA line, (b) is an elevational sectional view along a BB line.

8 and 9, the plasma 108A indicated by a solid line indicates a plasma in a stable state, and the plasma 108B indicated by a broken line indicates a plasma after fluctuation.
Symbols used for explanation are defined as follows.

In the example, the output from the antenna antennas 113a to 113d is described as a voltage value when measured with a voltage. However, a current value may be measured and a current value may be used.
Symbols used in the following description are defined as follows.

Va1: Voltage value of antenna 113a in plasma 108A in stable state Vb1: Voltage value of antenna 113b in plasma 108A in stable state Vc1: Voltage value of antenna 113c in plasma 108A in stable state Vd1: Voltage value of antenna 113d in plasma 108A in stable state Voltage value Va2: Voltage value of antenna 113a in plasma 108B after fluctuation Vb2: Voltage value of antenna 113b in plasma 108B after fluctuation Vc2: Voltage value of antenna 113c in plasma 108B after fluctuation Vd2: Antenna in plasma 108B after movement Voltage value of 113d Plasma movement in the X-axis-Y-axis direction is detected by the calculation unit 114 as follows. Here, Va1, Vb1, Vc1, and Vd1 are reference values, and Va2, Vb2, Vc2, and Vd2 are occasional sample values.

− Detection of plasma movement −
FIG. 8A shows a state in which the plasma 108B has moved to the upper right zone N1 when the intersection point of the X axis, the Y axis, and the Z axis is the origin O. FIG. This state can be detected by the calculation unit 114 monitoring the outputs of the antennas 113a to 113d.

The outputs of the antennas 113a and 113b arranged in the X-axis direction are “Va2 <Va1” and “Vb2> Vb1”.
Further, the outputs of the antennas 113c and 113d arranged in the Y-axis direction are “Vc2 <Vc1” and “Vd2> Vd1”.
Is detected by the calculation unit 114, and it is estimated that “the plasma 108B has moved to the zone N1”. Similarly,
“Va2> Va1” and “Vb2 <Vb1”
Further, the outputs of the antennas 113c and 113d arranged in the Y-axis direction are “Vc2 <Vc1” and “Vd2> Vd1”.
Is detected by the calculation unit 114, it is estimated that “the plasma 108B has moved to the zone N2.” Also,
“Va2> Va1” and “Vb2 <Vb1”
Further, the outputs of the antennas 113c and 113d arranged in the Y-axis direction are “Vc2> Vc1” and “Vd2 <Vd1”.
Is detected by the calculation unit 114, it is estimated that “the plasma 108B has moved to the zone N3”. Also,
“Va2 <Va1” and “Vb2> Vb1”
Further, the outputs of the antennas 113c and 113d arranged in the Y-axis direction are “Vc2> Vc1” and “Vd2 <Vd1”.
Is detected by the calculation unit 114, it is estimated that “the plasma 108B has moved to the zone N4”.

− Detection of plasma expansion, detection of plasma shrinkage −
FIG. 9A shows a state where the plasma expands in the X-axis direction and contracts in the Y-axis direction. This state can be detected by the calculation unit 114 monitoring the outputs of the antennas 113a to 113d.

The outputs of the antennas 113a and 113b arranged in the X-axis direction are
“Va2> Va1” and “Vb2> Vb1” (1)
And the outputs of the antennas 113c and 113d arranged in the Y-axis direction are “Vc2 <Vc1” and “Vd2 <Vd1” (2)
The calculation unit 114 detects that “the plasma 108B has expanded in the X-axis direction and has contracted in the Y-axis direction”. When the plasma is reduced in the X-axis direction, the outputs of the antennas 113a and 113b arranged with a gap in the X-axis direction are “Va2 <Va1” and “Vb2 <Vb1” (3)
Is detected by the calculation unit 114, and it is estimated that “the plasma 108B has shrunk in the X-axis direction”.

When the plasma expands in the Y-axis direction, the outputs of the antennas 113c and 113d arranged in the Y-axis direction are “Vc2> Vc1” and “Vd2> Vd1” (4).
Is detected by the calculation unit 114, and it is estimated that “plasma 108B has expanded in the Y-axis direction”.

  Further, the calculation unit 114 detects that the relationship of the combination of the expression (1) or (3) in the X-axis direction and the expression (2) or (4) in the Y-axis direction is detected, and the X-axis− Plasma expansion and contraction in the Y-axis direction can be estimated.

(Embodiment 3)
10 to 12 show the third embodiment.
FIG. 10 shows a plasma processing apparatus according to Embodiment 3 of the present invention.

  This plasma processing apparatus is used for monitoring plasma fluctuations that induce non-uniform film thickness when a circular plate-shaped workpiece such as a wafer is placed in a cylindrical processing chamber. The configuration is shown.

  The X-axis direction, Y-axis direction, Z-axis direction, AA cross-sectional view, and BB cross-sectional view used in the following description are defined as shown in the figure. FIG. 10A is a plan sectional view (AA section), and FIG. 10B is an elevation sectional view (BB section).

  In FIG. 10, the processing chamber 101 is grounded so that electromagnetic waves do not leak when plasma is generated. The processing chamber 101 has an anode electrode 117 at the lower portion and a cathode electrode 107 at the upper portion, the workpiece 103 is placed on the anode electrode 117, and a target material that is a material for forming a film on the cathode electrode 107. 109 is placed. The cathode electrode 107 is connected to the high voltage power source 104 via the application unit 106 and the coaxial cable 105. The high-voltage power source 104 is mainly a DC power source or a 13.56 MHz RF power source, and generates a plasma 108 between the electrodes. The application unit 106 has a structure that is the center of the cathode electrode 107 and the center of the processing chamber 101, and the plasma 108 is also formed around this. The applied current, voltage, and frequency are controlled by a control unit (not shown) so that a film can be formed at a constant rate. If the film is out of a desired value, error processing such as film formation stop or alarm display is performed. Is called.

  In the case of a sputtering apparatus, an inert gas such as argon is introduced from the gas inlet 110. The automatic pressure control valve 111 automatically adjusts the valve opening in order to maintain the inside of the processing chamber 101 at a desired constant pressure after the gas is introduced.

  The main valve 112 is connected to an exhaust unit such as a cryopump or a turbo molecular pump (not shown) having a sufficiently large exhaust amount, that is, an exhaust capacity equivalent to the chamber volume. Therefore, the gas stays in the processing chamber 101. In addition to causing no increase in pressure, unnecessary intermediate products generated by the reaction between the plasma 108 and the target material 109 can be exhausted.

  A plurality of antennas 113 a, 113 b, and 113 c as main antennas are provided outside the processing chamber 101 around the Z axis connecting the application unit 106 and the cathode electrode 107 and the anode electrode 117. Specifically, the processing chamber 101 is kept airtight at an equal angle of 120 ° so as to face each other across the plasma 108 on the X-axis-Y-axis plane passing through the approximate center of the stable plasma. Viewing ports (vacuum viewing windows) 115a, 115b, 115c, and 115d are provided as coupling ports through which electromagnetic waves pass. The viewing ports 115a and 115b are fitted with quartz glass at the center as a window material.

  Antennas 113 a to 113 c are provided outside the processing chamber 101 around the Z axis connecting the electrodes. Specifically, the antennas 113a to 113c are fixed to the window members of the viewing ports 115a to 115c.

  The antennas 113a to 113c capture electromagnetic waves from the plasma and convert them into currents or voltages according to their strengths. The electric signal output from each of the antennas 113a to 113c is arithmetically processed by the arithmetic unit 114 via the electric signal cable 116.

  With the above configuration, during the sputtering film formation, the plasma state is monitored by the antennas 113a to 113c. When the monitoring result deviates from the measured plasma value in the stable state stored in advance, the plasma state Judge as incomplete. Based on the determination information, the facility is stopped, the processing chamber is cleaned by an operator, and the determination information is added to the product management information.

  In the case where a film-like object to be processed is placed in a processing chamber to form a film as shown in Embodiment Mode 3, unevenness in film pressure distribution may occur even if the energy control of the power to be supplied is good. . As this factor, plasma movement in the X-axis direction and Y-axis direction, expansion, reduction, and the like can be mentioned.

  These events can be detected by arranging the antennas 113a to 113c at positions facing each other across the plasma 108 and observing the difference from the antenna output stored in the stable state of the plasma. It is also possible to distinguish plasma movement, expansion, and contraction that cannot be determined by monitoring only one side in the X-axis direction or the Y-axis direction, and the response after detection can be made appropriate.

A specific configuration of the calculation unit 114 will be described based on the specific examples of FIGS. 11 and 12.
The same components as those in FIGS. 1, 2, and 3 are denoted by the same reference numerals, and description thereof is omitted. In addition, the cross section, the X-axis direction, the Y-axis direction, and the Z-axis direction are the same as those shown in FIG. The antenna used is that shown in FIG. 2 or FIG. 3 described in the first embodiment.

FIG. 11 shows the plasma movement in the X-axis-Y direction. (A) is a plane sectional view along an AA line, (b) is an elevational sectional view along a BB line.
A plasma 108A indicated by a solid line in FIGS. 11 and 12 indicates a plasma in a stable state, and a plasma 108B indicated by a broken line indicates a plasma after fluctuation. The antennas 113a to 113c to be used are those shown in FIG. 2 or FIG. 3 explained in the first embodiment.

Symbols used in the following description are defined as follows. In the example, the case where the output from the antenna is measured as a voltage is described as a voltage value. However, the current value may be used by measuring a current.
Va1: Voltage value of antenna 113a in plasma 108A in stable state Vb1: Voltage value of antenna 113b in plasma 108A in stable state Vc1: Voltage value of antenna 113c in plasma 108A in stable state Va2: Voltage value of antenna 113a in plasma 108B after fluctuation Voltage value Vb2: Voltage value of antenna 113b in plasma 108B after fluctuation Vc2: Voltage value of antenna 113c in plasma 108B after fluctuation Plasma movement in the X-axis direction is detected by computing unit 114 as follows. Here, Va1, Vb1, and Vc1 are reference values, and Va2, Vb2, and Vc2 are occasional sample values.

− Detection of plasma movement −
FIG. 11A shows a state in which the plasma 108B has moved to the right zones N1 and N4 when the intersection point of the X axis, the Y axis, and the Z axis is the origin O. FIG. This state can be detected by the calculation unit 114 monitoring the outputs of the antennas 113a to 113c.

The outputs of the antennas 113a to 113c are “Va2 <Va1” and “Vb2> Vb1” and “Vc2 <Vc1”.
Is detected by the calculation unit 114, and it is estimated that “the plasma 118B has moved away from the antennas 113a and 113c and approached the antenna 113b”.

  Similarly, the plasma 118B moves to the left zones N2 and N3 so as to move closer to the antennas 113a and 113c and move away from the antenna 113b, and the plasma 118B moves away from the antenna 113a and approaches the antennas 113b and 113c. A state in which the plasma 118B moves away from the antennas 113a and 113b and approaches the antenna 113c, a state in which the plasma 118B moves closer to the antenna 113a and moves away from the antennas 113b and 113c, and a plasma 118B However, even when the antennas 113a and 113b are moved closer and away from the antenna 113c, the reference values Va1, Vb1, and Vc1 and the sample values Va2, Vb2, and Vc2 are input to the calculation unit 114. By treatment, it can be estimated as well.

− Detection of plasma expansion −
FIG. 12 shows a state where the plasma has expanded in the X-axis direction. The arithmetic unit 114 can detect and detect the outputs of the antennas 113a to 113c.

The outputs of the antennas 113a to 113c are “Va2> Va1”, “Vb2> Vb1”, and “Vc2> Vc1”.
Is detected by the calculation unit 114, and it is estimated that “plasma has expanded”.

− Detection of plasma shrinkage −
The outputs of the antennas 113a to 113c are “Va2 <Va1”, “Vb2 <Vb1”, and “Vc2 <Vc1”.
Is detected by the calculation unit 114, and it is estimated that “plasma has contracted”.

Further, in the calculation unit 114, the outputs of the antennas 113a to 113c are “Va2 = Va1”, “Vb2 = Vb1”, and “Vc2 = Vc1”.
Is detected by the calculation unit 114, and is estimated to be “the state of the plasma 108A”.

(Embodiment 4)
FIG. 13 shows a main part of the plasma processing apparatus according to the fourth embodiment of the present invention.
The pair of antennas 113a and 113b in the first embodiment shown in FIG. 1 are provided at the same height in the Z-axis direction, and an antenna different from the antennas 113a and 113b is not provided at a different height. However, in the fourth embodiment, antennas 113e and 113f as auxiliary antennas are added. Other configurations are the same as those of the first embodiment.

  In the first embodiment, when the antennas 113a and 113b as the main antennas are arranged at the height of the origin O where the X axis, the Y axis, and the Z axis intersect, in the fourth embodiment, outside the processing chamber 101, An antenna 113e as an auxiliary antenna is arranged above the height of the origin O. In addition, an antenna 113 f as an auxiliary antenna is disposed outside the processing chamber 101 and below the height of the origin O. The angles around the Z-axis of the antennas 113e and 113f are the same.

  The processing chamber 101 is provided with viewing ports (vacuum viewing windows) 115e and 115f as coupling ports through which electromagnetic waves pass while maintaining the airtightness of the processing chamber 101 corresponding to the positions of the antennas 113e and 113f. Yes. The viewing ports 115e and 115f are fitted with quartz glass at the center as a window material. The antennas 113e and 113f are fixed to the outside of the window material of the viewing ports 115e and 115f.

Plasma 108A indicated by a solid line indicates plasma in a stable state, and plasma 108B indicated by a broken line indicates plasma after fluctuation.
Symbols used in the following description are defined as follows. In the example, the case where the output from the antenna is measured as a voltage is described as a voltage value. However, the current value may be used by measuring a current.

Ve1: Voltage value of antenna 113e in plasma 108A in stable state Vf1: Voltage value of antenna 113f in plasma 108A in stable state Ve2: Voltage value of antenna 113e in plasma 108B after fluctuation Vf2: Voltage value of antenna 113f in plasma 108B after fluctuation Voltage value Plasma movement in the Z-axis direction is detected by the calculation unit 114 as follows. Here, Ve1 and Vf1 are reference values, and Ve2 and Vf2 are occasional sample values.

  When the plasma 108B moves upward, the calculation unit 114 that monitors the outputs of the antennas 113a, 113b, 113e, and 113f can also estimate the movement of the plasma height from the outputs Ve2 and Vf2 of the antennas 113e and 113f.

The outputs of the antennas 113e and 113f arranged in the Z-axis direction are “Ve2> Ve1” and “Vf2 <Vf1”.
It is estimated that “plasma 108B has moved upward”.

The outputs of the antennas 113e and 113f arranged in the Z-axis direction are “Ve2 <Ve1” and “Vf2> Vf1”.
It is estimated that “the plasma 108B has moved downward”.

In addition, the calculation unit 114
“Ve2 = Ve1” and “Vf2 = Vf1”
It is estimated that “the plasma is stable in the Z-axis direction”.

  Note that although the viewing port 115e is provided corresponding to the antenna 113e and the viewing port 115f is provided corresponding to the antenna 113f, the viewing ports are not divided into two, and the antennas 113e and 113f are provided in one viewing port. May be provided.

  In the fourth embodiment, the case of the first embodiment has been described as an example. However, in the second and third embodiments, similarly to the fourth embodiment, antennas 113e and 113f are provided, and the calculation unit 114 performs the same. By monitoring, the movement of the plasma in the height direction can be detected.

  The present invention can be applied in the field of manufacturing semiconductors, display devices, and component devices, and can improve the quality of an object to be processed.

DESCRIPTION OF SYMBOLS 101 Processing chamber 102 Main roller 103 To-be-processed object 104 High voltage power supply 105 Coaxial cable 106 Application part 107 Cathode electrode 108 Plasma 108A Stable plasma 108B Fluctuated plasma 109 Target material 110 Gas inlet 111 Automatic pressure regulating valve 112 Main valve 113 , 113a to 113f Antenna 114 Operation unit 115, 115a to 115f Viewing port 116 Electric signal cable 117 Anode electrode

Claims (7)

In a plasma processing apparatus for generating a plasma between electrodes inside a processing chamber to process an object to be processed disposed inside the processing chamber,
A plurality of main antennas provided outside the processing chamber at equal angles around an axis connecting the electrodes;
A plasma processing apparatus, comprising: an arithmetic unit that calculates a correlation between outputs of the plurality of main antennas to estimate the state of the plasma. The plasma processing apparatus according to claim 1, wherein a coupling port is formed on a wall surface of the processing chamber corresponding to each position of the plurality of main antennas so as to maintain airtightness of the processing chamber and allow electromagnetic waves to pass through. 2. The plasma processing apparatus according to claim 1, wherein the plurality of main antennas have a pair of opposing positions across the plasma, and a pair of the main antennas are disposed. A plurality of auxiliary antennas with different mounting heights in the direction of the axis connecting the electrodes are provided outside the processing chamber,
The plasma processing apparatus according to claim 1, wherein detection states of all the main antennas and the auxiliary antennas are monitored by the arithmetic unit to estimate the plasma state. When processing an object to be processed disposed inside the processing chamber by generating a plasma between the electrodes inside the processing chamber,
A plurality of main antennas are arranged outside the processing chamber at equal angles around an axis connecting the electrodes,
A plasma monitoring method for estimating a state of the plasma by calculating a correlation between outputs of the plurality of main antennas by an arithmetic unit. The plasma monitoring method according to claim 5, wherein the plurality of main antennas have a pair of positions opposed to each other with the plasma interposed therebetween, and a pair or more are disposed. A plurality of auxiliary antennas having different mounting heights in the direction of the axis connecting the electrodes are arranged outside the processing chamber,
The plasma monitoring method according to claim 5, wherein detection states of all the main antennas and the auxiliary antennas are monitored by the arithmetic unit to estimate the plasma state.

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