JP6510922B2 - PLASMA PROCESSING APPARATUS AND PLASMA PROCESSING METHOD - Google Patents

Description

  The present invention relates to plasma processing technology. The present invention also relates to a technique for controlling high frequency bias power for plasma processing.

  In general, in the process of manufacturing a semiconductor integrated circuit element or the like, processing such as etching using plasma suitable for processing is performed on a target substrate such as a wafer using a plasma processing apparatus. There are various methods for processing of the plasma processing apparatus. As one method, there is a method of applying a high frequency bias voltage for causing plasma to act on an electrode of a holding unit which holds a target substrate in a processing chamber.

  Along with the improvement of the degree of integration of elements, the improvement of the fine processing accuracy is required, and at the same time, the improvement of the uniformity within the wafer surface in the processing such as the plasma etching is required. For example, it is required to improve the in-plane uniformity of the etching rate and the critical dimension of the etching pattern shape.

  The in-plane uniformity is affected by the distribution of plasma density, gas flow, temperature, reaction products, incident ion energy, and the like. For example, when the plasma density distribution is uneven in the radial direction in the plane, the etching rate etc. may be uneven in the plane due to the influence. For example, even if a uniform rate of the film to be etched is obtained, in-plane shape differences may occur between the inner and outer peripheral portions of the surface due to retention and deposition of reaction products. In addition, even if the etching depths in the plane are combined, the hard mask height may be different in the plane because the in-plane selection ratio is different.

  Therefore, the conventional plasma processing apparatus has a distribution adjustment function of adjusting electrical problems around the wafer, in particular, plasma density distribution, ion energy distribution, etc., in order to improve or control in-plane nonuniformity related to the etching rate etc. There is something.

  Patent 5496568 (patent documents 1) is mentioned as a prior art example about realization of in-plane uniformity in processing of a plasma processing apparatus. The plasma processing apparatus described in Patent Document 1 includes a lower electrode and an upper electrode as electrodes, a first power supply for applying power of a first frequency to the electrode, and power of a second frequency for the lower electrode in the processing chamber. , A bias distribution control electrode provided at the periphery of the lower electrode, and a power supply applying a rectangular wave voltage of a third frequency to the bias distribution control electrode.

Patent No. 5496568 gazette

  As in Patent Document 1, as a conventional plasma processing apparatus, in accordance with distribution adjustment, high frequency bias voltage is applied to the electrode of the holding unit of the wafer to realize in-plane uniformity and the like related to plasma processing. There is something.

  However, according to the study of the present inventors, when control of predetermined distribution adjustment is performed by applying a high frequency bias voltage during plasma processing of a wafer using the distribution adjustment function of the conventional plasma processing apparatus. There are the following issues. For example, even when control of desired distribution adjustment is performed so as to have a flat distribution in the radial direction in the plane, desired results such as uniform etching rate may not be obtained unlike the intention. It has been found that when the desired control of distribution adjustment is performed, the effect of the distribution adjustment may change due to the influence of the wafer resistivity during plasma processing.

  An object of the present invention is to provide, with regard to a plasma processing apparatus, a technique capable of achieving desired distribution adjustment such as in-plane uniformity and etching rate related to plasma processing.

  A typical embodiment of the present invention is a plasma processing apparatus, and is characterized by having the following configuration.

  In the plasma processing apparatus according to one embodiment, a plasma processing is performed as processing on a processing target substrate held by a holding unit based on an electromagnetic wave generation unit that generates an electromagnetic wave and plasma generated based on the electromagnetic wave. An inner circumferential portion corresponding to the placement electrode as a chamber, a placement electrode for placing the processing target substrate in the holding portion, and an electrode provided inside the placement electrode; Supplying a high frequency bias power for applying a high frequency bias voltage to the first electrode and the second electrode at the outer peripheral portion, and the above-mentioned setting electrode and the electrode, and the first electrode is provided as the high frequency bias voltage. A power supply unit that applies a first voltage, applies a second voltage to the second electrode, and applies a third voltage to the placement electrode, and a monitor unit that monitors the first voltage and the second voltage And the above A correction value for the high frequency bias voltage is determined according to the resistivity calculation unit that calculates the resistivity of the substrate to be processed based on the monitor value of the jitter unit, and the correction value is obtained as the correction value. And a correction unit that drives and controls the power supply unit.

  According to a typical embodiment of the present invention, in the plasma processing apparatus, it is possible to realize in-plane uniformity relating to plasma processing and desired distribution adjustment such as an etching rate.

It is a figure which shows the structure of the plasma processing apparatus of Embodiment 1 of this invention. FIG. 2 is a diagram showing configurations of a processing chamber and a power supply unit in Embodiment 1. FIG. 7 is a graph showing characteristics representing the relationship between an inductance value and a voltage value in the first embodiment. FIG. 7 is a diagram showing a sequence of high frequency bias voltage control during plasma processing in the first embodiment. FIG. 7 is a diagram showing characteristics of high frequency bias voltage control and distribution adjustment of etching rate according to the resistivity in the first embodiment. FIG. 5 is a diagram showing an example of DB data in the first embodiment. FIG. 7 is a diagram showing an example of monitor values in the first embodiment. FIG. 7 is a diagram showing an example of a control table in the first embodiment. FIG. 7 is a diagram showing correction of distribution adjustment in the first embodiment. It is a figure which shows the structure of the process chamber and electric power supply part in the plasma processing apparatus of Embodiment 3 of this invention. FIG. 16 is a diagram showing a relationship between a resistivity and a voltage value in a third embodiment. FIG. 17 is a diagram showing an example of a control table in the third embodiment.

  Hereinafter, embodiments of the present invention will be described in detail based on the drawings. Note that, in all the drawings for describing the embodiment, the same reference numeral is attached to the same part in principle, and the repeated description thereof will be omitted.

Embodiment 1
The plasma processing apparatus and the plasma processing method according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 9. The plasma processing method of the first embodiment is a method including the steps performed by the plasma processing apparatus of the first embodiment.

  As the above-mentioned problems, when control of desired distribution adjustment is performed by applying a high frequency bias voltage during plasma processing of a wafer using the distribution adjustment function of a conventional plasma processing apparatus, the wafer being processed The influence of resistivity may change the effect of distribution adjustment. As a result, unlike the intention, the etching rate may be uneven in the radial direction in the plane.

  The reason why the above case occurs is considered as follows. In the electrode holding the wafer, for example, it is assumed that the first voltage is applied to the electrode at the inner peripheral portion and the second voltage is applied to the electrode at the outer peripheral portion. However, electric power propagates between the electrode of the inner peripheral portion and the electrode of the outer peripheral portion through the path between the electrodes. Thereby, on the wafer surface, the voltage value between the first voltage and the second voltage is approached, and the power difference is reduced. It is considered that the reduction of the power difference between the electrodes and the degree of propagation depend mainly on the size of the resistivity of the wafer.

  The basic resistivity of the wafer is determined by the impurity concentration, the plane orientation of the Si crystal of the wafer, and the like. However, with regard to the wafer being subjected to the actual plasma etching process, the process conditions, the process state, and the like are reflected, and due to the influence of the gas or plasma state near the wafer, the resistivity becomes different from the basic resistivity. ing. The actual resistivity during this process may change due to various factors such as the temperature at the wafer and its vicinity, the surface condition, the sample laminated film, the deposit, and the electrostatic adsorption between the wafer and the electrode.

  The plasma processing apparatus of the first embodiment has a function of calculating the resistivity of the wafer being processed in consideration of the above factors, and performing control including suitable distribution adjustment according to the resistivity.

[Plasma processing apparatus (1)]
FIG. 1 shows a functional block configuration of the plasma processing apparatus of the first embodiment. The plasma processing apparatus according to the first embodiment includes a processing chamber 10, a power supply unit 20, a monitor unit 30, an electromagnetic wave generation unit 40, and a control unit 50.

  The processing chamber 10 includes the holding unit 2 and the target substrate 3 held by the holding unit 2. The processing substrate 3 is a processing material such as a wafer, and has a disk shape. The holding unit 2 includes a placement electrode 4 and a conductor film 5 which is an upper surface portion of the placement electrode 4. The processing chamber 10 has a substantially cylindrical shape. The mounting electrode 4 is an electrode for mounting the processing target substrate 3 and has a disk shape corresponding to the processing target substrate 3 such as a wafer. The central axes of the mounting electrode 4 of the processing chamber 10 and the substrate 3 to be processed are indicated by alternate long and short dashed lines.

  The mounting electrode 4 is connected to the high frequency bias power supply 24 of the power supply unit 20 through the power supply line. The third power P3 which is a high frequency bias power supply power is supplied from the high frequency bias power supply 24 to the placement electrode 4, thereby applying a third voltage V3 which is a high frequency bias power supply voltage.

  Inside the conductor film 5, a first electrode 6 and a second electrode 7 are provided as electrodes. The conductor film 5 has a first electrode 6 and a second electrode 7 as conductor films provided separately in two regions. These two electrodes are an electrostatic adsorption electrode (ESC: Electro Static Chuck) which is a bipolar electrode for electrostatic adsorption. The first electrode 6 is an inner circumferential portion ESC, and is an electrode disposed on the inner circumferential portion near the central axis of the disc-shaped surface. The second electrode 7 is an outer peripheral portion ESC, and is an electrode disposed on the outer peripheral portion of the disc-shaped surface.

  The first electrode 6 and the second electrode 7 are each connected to the power supply unit 20 through a power supply line. A first voltage V1 which is a first high frequency bias voltage is applied from the power supply unit 20 to the first electrode 6 based on the supply of the first power P1 which is a first high frequency bias power. A second voltage V2 which is a second high frequency bias voltage is applied from the power supply unit 20 to the second electrode 7 based on the supply of the second power P2 which is a second high frequency bias power.

  The power supply unit 20 includes a switch 21, an LC resonance circuit 22, a control circuit 23, a high frequency bias power supply 24, and the like. The switch 21 is connected to the LC resonant circuit 22 and the first electrode 6 and the second electrode 7, and has a first state connected to the first electrode 6 and a second state connected to the second electrode 7. The switch is a switch that can be switched to a third state not connected to any of the electrodes.

  The LC resonance circuit 22 is a damping circuit and includes a circuit in which a variable inductance by a coil and a fixed capacitance by a capacitor are connected in series, and the inductance value can be controlled. By controlling the inductance value which is a control value, the high frequency bias voltage value applied to the first electrode 6 and the second electrode 7 can be variably controlled.

  The control circuit 23 controls the operation and state of the circuits in the power supply unit 20 according to the drive control value C1 from the control unit 50. The control circuit 23 includes a circuit that variably controls the state of the switch 21 and an inductance value which is a control value of the LC resonance circuit 22.

  The high frequency bias power supply 24 is a power supply that supplies high frequency bias power. The high frequency bias power supply power is power for applying a high frequency bias voltage to the electrode of the holding unit 2. The high frequency bias voltage is a voltage for causing plasma in the processing chamber 10 to act.

  The monitor unit 30 constantly monitors the voltage value related to the high frequency bias voltage of the electrode of the holding unit 2 and the inductance value which is the control value of the LC resonance circuit 22 of the power supply unit 20 during plasma processing. This is given to the resistivity calculator 51 of the controller 50. The monitor unit 30 measures and monitors the first voltage V1 of the first electrode 6, the second voltage V2 of the second electrode 7, and the third voltage V3 of the mounting electrode 4 as voltage values.

  The first voltage V1, the second voltage V2, and the third voltage V3 are peak-to-peak voltages (represented by Vpp) corresponding to the difference between the maximum value and the minimum value of the amplitude of the AC power.

  The electromagnetic wave generation unit 40 is a known element, but is a part that generates an electromagnetic wave and propagates it to the processing chamber 10.

  The control unit 50 includes a resistivity calculation unit 51, a correction unit 52, a DB unit 53, and a processing condition management unit 54. The control unit 50 controls the entire plasma processing apparatus including the electromagnetic wave generation unit 40, the processing chamber 10, the power supply unit 20, and the monitor unit 30. The control unit 50 controls plasma processing on the processing target substrate 3 in the processing chamber 10 in accordance with the processing conditions and processing sequence of plasma processing. The control unit 50 can be configured by, for example, a computer or a circuit board.

  The processing condition management unit 54 manages processing conditions and processing sequences of plasma processing. The processing sequence consists of a plurality of steps. The plurality of processes include various processes such as a transfer process, a wafer holding process, an electromagnetic wave generation process, a gas supply and evacuation process, a high frequency bias voltage application process, and the like according to the process conditions. In each process, there are drive control values corresponding to processing conditions, such as gas pressure value, voltage value, and the like. The processing condition management unit 54 sets or changes the processing conditions based on the operation of the operator, and performs setting relating to the distribution adjustment function, registration of DB data of the DB unit 53, and the like.

  The control unit 50 controls the transfer of the processing target substrate 3 into the processing chamber 10 and the holding of the processing target substrate 3 in the holding unit 2 when controlling the sequence of the plasma processing. The control unit 50 also controls generation and introduction of electromagnetic waves into the processing chamber 10, gas supply and evacuation, application of a high frequency bias voltage, and the like.

  The control unit 50 has a distribution adjustment function, and by using the electrodes of the holding unit 2 and the power supply unit 20, the state of plasma or the like, the etching rate, and the like become uniform in the plane during the plasma etching process. , Control including desired distribution adjustment. This distribution adjustment is to adjust the distribution of plasma density, ion energy, etc. in the radial direction in the plane corresponding to the wafer, etc. to a desired distribution such as flat distribution, concave distribution, convex distribution, etc. . The control unit 50 performs power control so that different high frequency bias voltages are applied to the first electrode 6 in the inner peripheral portion and the second electrode 7 in the outer peripheral portion so as to obtain a desired etching rate.

  The resistivity calculation unit 51 inputs a monitor value from the monitor unit 30 during plasma processing. The resistivity calculating unit 51 calculates the actual resistivity of the processing target substrate 3 being processed based on the voltage value and the control value which are monitor values at that time. This resistivity is referred to as a first resistivity (denoted by R1) in distinction from the basic resistivity. At this time, the resistivity calculating unit 51 calculates the first resistivity R1 using the DB data of the DB unit 53. The resistivity calculating unit 51 provides the correcting unit 52 with information including the calculated first resistivity R1. The first resistivity R1 is a value reflecting the processing conditions, the processing state, and the like.

  The DB unit 53 is constituted by a storage device or the like, and holds a DB in which data used for calculation of resistivity and control information used for control of correction are stored. The DB of the DB unit 53 is registered in advance, and data can also be updated through the processing condition management unit 54.

  In the DB of the DB unit 53, information representing the relationship between a plurality of variable values is stored as a table. The plurality of variable values include the resistivity of the substrate 3 to be processed, the inductance value which is the control value of the LC resonant circuit 22, and the high frequency bias voltage value of each of the first electrode 6 and the second electrode 7. The DB data includes a table representing the relationship between the control value and the high frequency bias voltage value of each electrode for each of the plurality of representative resistivities for wafers of a plurality of samples.

  The correction unit 52 uses the first resistivity R1 calculated by the resistivity calculation unit 51 to determine a voltage correction value that is a suitable correction value of the high frequency bias power value corresponding to the desired distribution adjustment. Further, the correction unit 52 determines a control correction value which is a correction value of the control value corresponding to the voltage correction value. The correction unit 52 operates the power supply unit 20 using a correction value including the determined voltage correction value and control correction value. The correction unit 52 controls driving of the power supply unit 20 using a drive control value C1 corresponding to the correction value.

  Thereby, the power supply unit 20 operates the internal circuit etc. according to the drive control value C1, and the power supply unit 20 responds to the correction value to the first electrode 6 and the second electrode 7 which are the electrodes of the holding unit 2. The corrected high frequency bias voltage is applied. Thereby, control including suitable distribution adjustment in accordance with the first resistivity R1 of the processing target substrate 3 being processed is performed. As a result, the distribution of ion energy and the like can be suitably controlled between the inner and outer peripheral portions in the plane, and stable uniform plasma processing can be realized with high uniformity. As a result, the etching rate can be made uniform in the plane, etc. The effect of

  As described above, the plasma processing apparatus according to the first embodiment calculates the first resistivity R1 based on the monitor value during the plasma etching process of the wafer, and preferably the high frequency according to the first resistivity R1. Real-time control such as correcting the bias voltage value is performed.

  Note that the plasma processing apparatus directly measures and monitors the state of distribution of incident ion energy distribution etc. on the wafer surface with high precision and achieves control in order to achieve in-plane uniformity related to plasma processing. If possible, it is more preferable. However, it may be technically difficult to directly measure and monitor the in-plane distribution with high accuracy. In the configuration of the first embodiment, instead of directly measuring the distribution in the plane, the states are measured at a plurality of radial positions in the plane. In particular, in the present configuration, the monitor unit 30 has a voltage value in a state in which a high frequency bias voltage is applied to the two electrodes of the first electrode 6 at the inner peripheral portion and the second electrode 7 at the outer peripheral portion in the holder 2 The first voltage V1 and the second voltage V2 are measured.

  Then, the control unit 50 calculates a first resistivity R1 of the wafer being processed based on the voltage value of the monitor, and a desired in-plane radial distribution is desired based on the first resistivity R1. The high frequency bias voltage of each electrode is corrected to have a distribution corresponding to the distribution adjustment of, for example, a flat distribution.

[Plasma processing apparatus (2)]
FIG. 2 shows the configuration of the plasma processing apparatus of the first embodiment. The plasma processing apparatus of the first embodiment is an etching apparatus having a function of performing a plasma etching process using microwave electron cyclotron resonance (ECR).

  The processing chamber 10 is a vacuum vessel whose top in the Z direction is open. A vacuum evacuation device (not shown) is connected to the processing chamber 10 via a vacuum evacuation port 110. A shower plate 102 and a window portion 103 are provided in the upper portion of the processing chamber 10. The shower plate 102 has a hole, for example, made of quartz, and introduces the gas for plasma etching processing supplied from the gas supply mechanism 125 into the processing chamber 10 through the hole. A window 103 is provided on the shower plate 102 with a gap for gas supply. The window portion 103 transmits the electromagnetic wave from above and is sealed in the processing chamber 10. The window portion 103 uses a dielectric such as quartz as a material.

  A cavity portion 104 is provided on the window portion 103 for distribution adjustment. The upper portion of the cavity portion 104 is open, and a waveguide 105 extending in the Z direction is connected. A waveguide converter 106 is connected to the top of the waveguide 105, and an X-direction end of the waveguide converter 106 is connected to a waveguide 107 extending in the X direction. There is. The waveguide converter 106 doubles as a waveguide and a corner that bends the direction of the electromagnetic wave by 90 degrees. The waveguide 105, the waveguide 107, and the like are oscillation waveguides that propagate an electromagnetic wave. A source power supply 108 is connected to an end of the waveguide 107 in the X direction.

  The source power supply 108 is a power supply for generating an electromagnetic wave, and generates an electromagnetic wave based on control from the control unit 50. In the first embodiment, a microwave of 2.45 GHz is used as the frequency of the electromagnetic wave. The electromagnetic wave generated by the source power supply 108 propagates in the Z direction through the waveguide 107, the waveguide converter 106, and the waveguide 105, and the inside of the processing chamber 10 through the cavity portion 104, the window portion 103, and the shower plate 102. Introduced to

  A magnetic field generating coil 109 is provided on the outer periphery of the upper portion of the processing chamber 10. The magnetic field generating coil 109 generates a magnetic field in the processing chamber 10 during processing of ECR. The power oscillated from the source power supply 108 generates a high density plasma in the processing chamber 10 by the interaction with the magnetic field generated by the magnetic field generating coil 109.

  A holding unit 2 is provided below the processing chamber 10 so as to face the window unit 103. The holding unit 2 holds the processing target substrate 3 placed on the upper surface. The central axes of the waveguide 105, the holding unit 2 of the processing chamber 10, and the processing substrate 3 coincide with each other. The holding unit 2 mainly includes the placement electrode 4. The placement electrode 4 is made of aluminum or titanium as a material. A conductive film 5 is provided on the upper surface which is a part of the placement electrode 4. A not-shown sprayed film of alumina ceramic or the like is provided on the upper surface of the conductive film 5 of the mounting electrode 4.

  A first electrode 6 and a second electrode 7 are formed inside the conductive film 5 of the mounting electrode 4 as dielectric films which are electrodes divided into two regions of an inner peripheral portion and an outer peripheral portion. . The first electrode 6 and the second electrode 7 are used for the electrostatic adsorption of the processing substrate 3 and for the application of a high frequency bias voltage.

  The power supply unit 20 includes a switch 21, an LC resonance circuit 22, a control circuit 23, a high frequency bias power supply 24, a matching box 210, a high frequency filter 220, DC power supplies 221 and 222, a first voltage detector 201, and a second voltage detector 202. , And a third voltage detector 203.

  The placement electrode 4, the first electrode 6, and the second electrode 7 of the holding unit 2 are connected to the power supply unit 20. The placement electrode 4 is connected to the high frequency bias power supply 24 through the third voltage detection unit 203 and the matching box 210. The first electrode 6 is connected to the LC resonance circuit 22 through the first voltage detection unit 201 and the first terminal of the switch 21. The second electrode 7 is connected to the LC resonant circuit 22 through the second voltage detection unit 202 and the second terminal of the switch 21. A direct current power supply 221 and a direct current power supply 222 are connected to the first electrode 6 and the second electrode 7 via the high frequency filter 220.

[Plasma treatment summary]
An outline of plasma processing in the plasma processing apparatus of the first embodiment is as follows. The to-be-processed substrate 3 such as a wafer is transported into the processing chamber 10 based on the transport control of the control unit 50 and placed on the conductive film 5 of the placement electrode 4 of the holding unit 2. Then, a positive voltage is applied to the first electrode 6 and a negative voltage is applied to the second electrode 7 by the DC power supplies 221 and 222, and the substrate to be processed 3 is placed by the electrostatic force generated thereby. It is electrostatically attracted and held at a predetermined position on the electrode 4.

  Thereafter, based on the gas supply control and the vacuum evacuation control from the control unit 50, the processing chamber 10 is in a vacuum state in which the inside is depressurized. At this time, in detail, a gas for plasma etching is supplied from the gas supply mechanism 125 through a mass flow controller (not shown). Then, the gas passes through the gap between the window portion 103 and the shower plate 102 and is introduced into the processing chamber 10 from the hole of the shower plate 102. The control unit 50 maintains the inside of the processing chamber 10 at a predetermined pressure while controlling the evacuation apparatus.

  The control unit 50 generates an electromagnetic wave from the source power supply 108 based on the electromagnetic wave generation control, and generates a plasma in the processing chamber 10 based on the electromagnetic wave introduced into the processing chamber 10 in a vacuum state.

  At that time, the control unit 50 applies a high frequency bias voltage to the first electrode 6 and the second electrode 7 which are the electrodes of the holding unit 2 in the processing chamber 10 based on the power control and the like for the power supply unit 20. The high frequency bias voltage produces an action of drawing ions from the plasma to the substrate 3 to be processed.

  At that time, in detail, the high frequency bias power supply power is supplied from the high frequency bias power supply 24 to the placement electrode 4, and the high frequency bias voltage is applied to the placement electrode 4. Further, based on the switching control of the switch 21 of the LC resonant circuit 22, the high frequency bias power supply power is supplied to the first electrode 6 and the second electrode 7, and a high frequency bias voltage is applied to each electrode.

  Thereby, the plasma etching process is performed on the surface of the substrate 3 to be processed. At this time, the gas and the reaction product generated by the etching are exhausted through the vacuum exhaust port 110 in the lower part of the processing chamber 10.

[Power supply unit]
Next, a configuration of a circuit of the power supply unit 20 and a mechanism for applying different high frequency bias voltages to the first electrode 6 and the second electrode 7 of the holding unit 2 from one high frequency bias power supply 24 will be described.

  The switch 21 is connected to both the first state connected to the first electrode 6 by the first terminal, the second state connected to the second electrode 7 by the second terminal, and both the first electrode 6 and the second electrode 7 Three types of states with the third state which is not possible can be switched according to the input of the control terminal.

  The LC resonant circuit 22 includes a series connection of a fixed capacitance by the capacitor 22a and a variable inductance by the coil 22b, and is grounded. The capacitance is indicated by C and the inductance by L. Let L value be an inductance value which is a variable control value.

  At the outlet of the first electrode 6, the second electrode 7, and the high frequency bias power supply 24, voltage detectors are provided. That is, the first voltage detector 201 is provided in the middle of the power supply line at the outlet of the first electrode 6, and the second voltage detector 202 is provided in the middle of the power supply line at the outlet of the second electrode 7. Have. Further, at the exit of the matching box 210 of the high frequency bias power supply 24, a third voltage detector 203 is provided in the middle of the power supply line to the placement electrode 4. Each voltage detector is constituted by an A / D converter or the like, and detects the voltage and its Vpp value with high time resolution.

  The first voltage detector 201 detects Vpp of a first voltage V1 which is a first high frequency bias voltage applied to the first electrode 6. The second voltage detector 202 detects Vpp of the second voltage V2 which is a second high frequency bias voltage applied to the second electrode 7. The third voltage detector 203 detects Vpp of a third voltage V3 which is a third high frequency bias voltage applied to the placement electrode 4.

  Each voltage detector is connected to the monitor unit 30 of FIG. 1 by a line (not shown). The first voltage detector 201 outputs the detected value of the first voltage V1 to the monitor unit 30. The second voltage detector 202 outputs the detected value of the second voltage V2 to the monitor unit 30. The third voltage detector 203 outputs the value of the detected third voltage V3 to the monitor unit 30.

  The L value of the variable inductance of the LC resonance circuit 22 is controlled from the control unit 50 through the control circuit 23 as a control value. By controlling the L value, the magnitudes of the first voltage V1 and the second voltage V2, which are high frequency bias voltages, can be variably controlled. The variable control of the L value can be realized, for example, by changing the rotation angle of the coil 22b by driving a motor (not shown) connected to the coil 22b of the inductance L. Thereby, the L value can be variably controlled at high speed.

  The control circuit 23 includes a drive mechanism such as a motor, and is connected to the coil 22 b of the inductance L of the LC resonant circuit 22. The operation of the control circuit 23 is controlled by the drive control value C1 from the correction unit 52 of the control unit 50. The control circuit 23 variably controls the L value of the inductance L of the LC resonant circuit 22 in accordance with the drive control value C1 from the correction unit 52. Also, the L value can be monitored from the monitor unit 30 through the control circuit 23. The control circuit 23 outputs the L value to the monitor unit 30.

  The monitor unit 30 receives the voltage values {V1, V2, V3}, which are detected values, from each voltage detector of the power supply unit 20, and receives the L value from the control circuit 23, and requires those values. Processing, and outputs monitor values including those values to the resistivity calculation unit 51 of the control unit 50.

  The control circuit 23 is also connected to the control terminal of the switch 21. The control circuit 23 controls switching of the switch 21 in accordance with the drive control value C1 from the correction unit 52. In the first state in which the switch 21 is connected to the first terminal, the capacitor C and the inductance L of the LC resonant circuit 22 are connected to the first electrode 6. In the second state in which the switch 21 is connected to the second terminal, the capacitance C and the inductance L of the LC resonant circuit 22 are connected to the second electrode 7. In the third state in which the switch 21 is not connected to either the first terminal or the second terminal, the LC resonant circuit 22 is not connected to the first electrode 6 and the second electrode 7.

  By controlling the switch 21 and the L value, the first voltage V1 of the first electrode 6 and the second voltage V2 of the second electrode 7 are controlled to have a voltage value corresponding to the L value. The power supply unit 20 can variably control the L value and the magnitude of the high frequency bias power supply voltage based on the control from the control unit 50, and accordingly, the magnitudes of the first voltage V1 and the second voltage V2 It can be variably controlled.

  An L value at which the LC resonance circuit 22 becomes an LC series resonance point is LZ. However, in addition to the fixed capacitance C, the capacitive component of the LC resonant circuit 22 includes the capacitive component of the placement electrode 4 and plasma. The maximum value of the control range for the L value is approximately 1.1 times the value LZ. In the first embodiment, the minimum value of L value is defined as 0%, and the maximum value is defined as 100%. The value LZ which is the LC series resonance point is approximately 90%.

  The matching box 210 is an impedance matching device, and matches the impedance of the high frequency bias power supply 24 on the input side and the placement electrode 4 on the output side.

  It is assumed that a certain amount of power PA (unit: watt) is supplied to the mounting electrode 4 as the high frequency bias power supply of the output from the high frequency bias power supply 24. In this case, for example, 300 V (unit: volt) is measured by the third voltage detector 203 as the third voltage V 3 which is a high frequency bias voltage by the high frequency bias power supply power. When the switch 21 is in the third state, the first voltage V1 of the first electrode 6 and the second voltage V2 of the second electrode 7 are both measured at 250 V by the first voltage detector 201 and the second voltage detector 202. Be done. In this state, the high frequency bias voltage is uniformly applied in the plane corresponding to the substrate 3 to be processed.

  In the first state where the switch 21 is connected to the first electrode 6, when the L value is close to the LC series resonance point (for example, the value LZ = 80%), the impedance of the LC resonance circuit 22 approaches zero. The impedance viewed from the high frequency bias power supply 24 is lowered. As a result, Vpp of the first voltage V1 of the first electrode 6 drops from the above 250V. At this time, Vpp of the second voltage V2 of the other second electrode 7 also decreases from 250V.

  There are two paths between the first electrode 6 and the second electrode 7 through the inside of the mounting electrode 4 and the conductor film 5 of the holding unit 2 and the inside of the substrate 3 to be processed. Since a current flows through the path, the second voltage V2 of the second electrode 7 is dragged to the first voltage V1 of the first electrode 6, and both voltages approach an intermediate value. Therefore, as described above, both the first voltage V1 and the second voltage V2 decrease.

[Inductance characteristics]
(A) of FIG. 3 is a characteristic showing a relationship between the Vpp of the first voltage V1 of the first electrode 6 and the second voltage V2 of the second electrode 7 which are monitor voltage values, and the L value of the variable inductance L. Shows a graph. The characteristics of this graph are called inductance characteristics. In this characteristic, V2> V1 is set as the setting Vpp.

  The control unit 50 increases the L value from zero to a value LZ corresponding to the resonance point. Then, (V2-V1) which is a difference value (referred to as D1) of Vpp between the first voltage V1 and the second voltage V2 gradually increases, and Vpp of V1 and V2 both decrease. When the L value becomes the value LZ, the impedance becomes almost zero and V1 becomes minimum, but the difference value D1 becomes maximum.

  FIG. 3B relates to the characteristic of FIG. 3A, in which the high frequency bias power supply voltage and the first voltage V1 and the second voltage V2, which are monitor voltage values, are fixed when the L value is fixed to a certain value. Fig. 6 shows a graph of a characteristic that represents a relationship with Vpp. The high frequency bias power supply voltage corresponds to the third voltage V3 which is a voltage based on the power of the output of the high frequency bias power supply 24 described above. In this graph, V1 and V2 increase as V3 increases.

  That is, from FIG. 3, by controlling the two parameters of the third voltage V3 which is the high frequency bias power supply voltage and the L value, the high frequency bias voltage which is different in the first electrode 6 and the second electrode 7 is different. The voltage V1 and the second voltage V2 can be applied. The first voltage V1 and the second voltage V2 have a predetermined relationship with the third voltage V3 and the L value. Desired distribution adjustment can be realized by changing the first voltage V1 and the second voltage V2 by controlling the third voltage V3 and the L value.

  Conversely, even in the second state where the switch 21 is connected to the second electrode 7 side, its inductance characteristics do not change except for the positive / negative relationship as compared with the case of the first state. This is because the two regions of the first electrode 6 and the second electrode 7 are designed to have approximately equal areas in order to ensure uniform electrostatic adsorption by the ESC. By switching the switch 21, it is possible to change the magnitude relation between the first voltage V1 and the Vpp of the second voltage V2.

  Assuming that the first voltage V1 and the second voltage V2 are both 250 V, for example, the distribution of the etching rate is a convex distribution. In this case, it is assumed that control of distribution adjustment is performed in order to obtain a better etching rate, ie, to approach a flat distribution. As this control, for the high frequency bias voltage, the first voltage V1 is set to 200 V, and the second voltage V2 is set to 300 V. When performing this control, first, the power supply unit 20 sets the switch 21 to the first state, outputs the high frequency bias power supply power at PA × 1.5 W, thereby setting the third voltage V3 to 400 V, and the L value To 60%.

  However, the above-mentioned inductance characteristics also change depending on the condition and state of plasma processing, the magnitude of the high frequency bias voltage, and the like. Therefore, if the Vpp of the first voltage V1 and the second voltage V2 is determined in advance from the beginning, the L value and the high frequency bias power value of appropriate magnitudes are not determined at one point. In particular, as described above, the actual resistivity of the wafer changes due to the influence of the conditions and conditions of plasma processing and various factors. And the control effect and controllability concerning distribution adjustment change according to the resistivity.

  It is desirable to perform control including distribution adjustment by determining appropriate L value and high frequency bias power value according to the conditions and conditions of plasma processing. Therefore, the first embodiment has a function of calculating the actual resistivity of the wafer undergoing plasma processing, and determining the power value and the L value which is the control value in accordance with the resistivity.

Control sequence
FIG. 4 shows a time-series sequence when performing control to apply a high frequency bias voltage to an electrode during processing of plasma etching processing in the plasma processing apparatus of the first embodiment. The present control example is a control example in the case of setting 200 V as the first voltage V1 to the first electrode 6 and 300 V as the second voltage V2 to the second electrode 7 corresponding to various conditions. In FIG. 4, (a) shows the high frequency bias power supply output from the high frequency bias power supply 24. (B) shows the L value of the variable inductance of the LC resonant circuit 22. (C) shows a detected value of the third voltage V3 which is a high frequency bias power supply voltage based on the power of (a). (D) shows the detection value of the 2nd voltage V2 of perimeter part ESC. (E) shows the detection value of the 1st voltage V1 of inner peripheral part ESC. (F) shows (V2-V1) which is a difference value D1 between the first voltage V1 and the second voltage V2.

  The control unit 50 controls the power supply unit 20 as follows. First, in the third state in which the switch 21 is not connected to any of the electrodes, the high frequency bias power supply power of (a) is set to a predetermined power PA [W], and the third voltage V3 of (c) is set to 300V. Then, the second voltage V2 of (d) and the first voltage V1 of (e) both become 250V.

  Next, at time t1, the control unit 50 sets the switch 21 to the first electrode 6 side where the setting Vpp is lower, and sets the L value of (b) to 0%, which is the initial value. Increase to the larger one. Then, as described above, while the difference value D1 = (V2−V1) of (f) increases, both the first voltage V1 and the second voltage V2 decrease as a basic characteristic. On the other hand, in this control, the adjustment is performed while raising the high frequency bias power supply power of (a) so as to keep (V1 + V2) / 2 which is the average value of the first voltage V1 and the second voltage V2 constant. As a result, the second voltage V2 of (d) is increased to 300 V and the first voltage V1 of (e) is decreased to 200 V in the period up to the time point t2.

  At the time of control of this adjustment, the adjustment of the high frequency bias power supply power of (a) is performed while calculating an average value of the first voltage V1 and the second voltage V2 through the monitor unit 30 and the control unit 50. . Alternatively, for the adjustment, the third voltage V3 of the third voltage detector 203 is monitored, and the adjustment is performed such that the third voltage V3 is maintained constant as shown in (c).

  The L value is changed until the difference value D1 of (f) becomes the set difference value Dx. The set difference value Dx is a value corresponding to the desired distribution adjustment. Adjustment of the high frequency bias voltage is completed at time t2 after a lapse of about several seconds after the start of application of the high frequency bias voltage from time t1, the first voltage V1 and the second voltage V2 are set to desired Vpp, for example 200V and 300V. be able to. At time t2, the L value becomes a predetermined value Lx.

  In the period after time t2, the high frequency bias power supply voltage, the L value, the first voltage V1, and the second voltage V2 are maintained constant as long as no correction occurs.

  According to the control sequence described above, the first voltage V1 and the second voltage V2 are the same Vpp, and the in-plane distribution of ion energy and the like has a flat distribution without causing a large deviation with respect to the average etching rate of the reference conditions. Only the distribution of the etching rate can be changed. That is, the control sequence of the first embodiment has an advantage that the distribution adjustment and the plasma processing can be suitably realized based on the reference conditions without adversely affecting other elements.

[Characteristics of high frequency bias voltage control according to resistivity]
FIG. 5 shows the characteristics of high-frequency bias voltage control and control of distribution adjustment of the corresponding etching rate corresponding to the difference in resistivity in the plasma processing apparatus of the first embodiment. The etching rate depends on Vpp of the high frequency bias voltage. Also, the etching rate varies depending on the resistivity.

  (A) of FIG. 5 shows the characteristic regarding the distribution of the etching rate in the radial direction in a plane, when the resistivity of the wafer which is the to-be-processed substrate 3 is 10 ohm * cm. As a graph of this characteristic, the horizontal axis indicates the radial position (x) in the plane of the wafer, and the vertical axis indicates the etching rate corresponding to the high frequency bias voltage value of the plasma etching process for the wafer. The resistivity = 10 Ω · cm is a reference resistivity of a representative sample wafer. As for the position x, the position indicated by an alternate long and short dash line corresponds to the inner periphery including the central axis of the wafer, and both sides thereof correspond to the outer periphery.

  A curve K1 is a curve in the case where the first voltage V1 of the inner peripheral portion is 250 V and the second voltage V2 of the outer peripheral portion is 250 V as the first control of the distribution adjustment, and is a convex distribution. A curve K2 is a curve in the case where the first voltage V1 of the inner peripheral portion is 200 V and the second voltage V2 of the outer peripheral portion is 300 V as the second control of the distribution adjustment, and is a substantially flat distribution. The second control corresponds to the condition for setting (V2−V1) which is the difference value D1 to 100V.

  Compared to the first control, as in the second control, the rate is high in the outer peripheral portion where Vpp is raised by 50 V, and the rate is low in the inner peripheral portion where Vpp is lowered by 50 V. Further, the rate in the vicinity of the boundary between the inner peripheral portion and the outer peripheral portion is a value substantially intermediate between the inner peripheral portion and the outer peripheral portion. That is, when the reference resistivity is 10 Ω · cm, in the second control, the in-plane radial characteristic in the etching rate distribution is smoothed from the convex distribution to the flat distribution in the second control, and the outer periphery The part rate is higher, and the in-plane uniformity is improved.

  Next, similarly, (B) of FIG. 5 shows the characteristics when the resistivity is 1 Ω · cm, and (C) of FIG. 5 shows the characteristics when the resistivity is 100 Ω · cm.

  When the resistivity in FIG. 5B is 1 Ω · cm, the distribution of the etching rate can not be sufficiently controlled and the degree of improvement in uniformity is smaller than in FIG. 5A. The curve K3 of FIG. 5B is the same as the curve K1 of FIG. 5A, and although the resistivity is different, the curve K3 has a convex distribution as well. The curve K4 is basically the same as the curve K2 of the second control in FIG. 5A, but has a convex distribution which is a different distribution due to the difference in resistivity.

  The curves K2 and K4 under the condition that the difference value D1 is 100 V are compared with the curves K1 and K3 under the condition that the first voltage V1 and the second voltage V2 are the same. Then, as the resistivity is relatively high, the distribution of the etching rate largely changes as shown by the curve K1 to the curve K2, and approaches a flat distribution. Specifically, while the Vpp difference between the curve K1 and the curve K2 at the position of the central axis in (A) of FIG. 5 is relatively large, the curve K3 at the position of the central axis in (B) of FIG. And the difference in Vpp between the curve K4 and the curve K4 are relatively small. The same applies to the position of the outer peripheral portion. The curve K4 is slightly improved with respect to the convex distribution of the curve K3, but does not reach the flat distribution of the curve K2.

  Similarly, when the first voltage V1 and the second voltage V2 are compared at the same L value, the Vpp difference at the position of each electrode is small when the resistivity is low compared to the case of the reference resistivity. Become.

  That is, in the range of 1 to 10 Ω · cm, it can be said that the controllability of the distribution adjustment regarding the etching rate is higher as the resistivity is higher. When the resistivity is low as in 1 Ω · cm in FIG. 5B, the high frequency bias power is more likely to propagate in the radial direction of the wafer than the plasma side directly above the wafer. As described above, the high frequency bias current mutually propagates between the electrodes through the path between the electrodes. As a result, the first voltage V1 and the second voltage V2 approach the average value of the two at the inner circumferential portion and the outer circumferential portion. Therefore, as described above, the controllability of the rate at each position of the inner peripheral portion and the outer peripheral portion is smaller than in the case of 10 Ω · cm, which is the reference resistivity.

  Conversely, when the resistivity is high as in 100 Ω · cm in FIG. 5C, the degree to which the high frequency bias power propagates in the radial direction of the wafer is suppressed, and the first voltage V1 of the inner peripheral portion and the outer peripheral portion The second voltage V2 is maintained on the wafer and propagates to the plasma immediately above. Therefore, the controllability is enhanced, and the controllability appears as a difference in the resulting etching rate.

  Curve K5 in FIG. 5C is the same condition as curve K1 in FIG. 5A, and curve K6 is basically the same as curve K2 in FIG. Depending on the difference in rate, it has a concave distribution which is a different distribution. That is, in the curve K6, the Vpp difference at each position of the inner peripheral portion and the outer peripheral portion is larger than that of the curve K5, which results in a concave distribution.

  In the range of 10 to 100 Ω · cm, similarly, it can be said that the higher the resistivity, the higher the controllability of the distribution adjustment. Similarly, when the first voltage V1 and the second voltage V2 are compared with the same L value, the Vpp difference at each electrode position is large when the resistivity is large compared to the case of the reference resistivity. Become.

  By plasma processing, the sheath thickness immediately above the wafer is thin at the inner periphery where the first voltage V1 is low, thick at the outer periphery where the second voltage V2 is high, and the impedance to the plasma side also decreases at the inner periphery. It becomes larger at the outer periphery. Further, the LC resonance circuit 22 is connected to the first electrode 6 in the inner peripheral portion, and the impedance of the first electrode 6 is small. These mutual effects increase the Vpp difference at each electrode location. Thus, the curve K6 has a concave distribution beyond the flat distribution of the curve K2.

  In addition, whether the high frequency bias power is likely to propagate in the plasma directly above the electrode or in the radial direction of the wafer depends on the ratio of the impedance to the resistance value depending on the sheath thickness. For example, in the case where the diameter of the wafer is 300 mm and the resistivity is uniformly 1 Ω · cm, the resistance in the circumferential direction in the plane between the position of 50 mm and 100 mm from the central axis in the radial direction of the wafer. Is about 2 Ω. The magnitude of this resistance is directly proportional to the resistivity.

  For example, assuming that a sheath voltage formed with Vpp of about 200 V at a high frequency bias power of 400 kHz and 100 V, and the sheath thickness is calculated from the Debye length is about 0.4 mm. The capacity in this case is about 1500 PF, and the impedance per square cm of unit area is about 0.4 Ω.

  When the wafer resistivity is as low as about 0.1 Ω · cm, the impedance and the resistance value due to the sheath thickness are substantially in the same order, and the degree to which the high frequency bias power propagates in the radial direction is considerably high. As a result, the controllability of the distribution adjustment is considerably reduced. Since the sheath thickness depends on the magnitude of the high frequency bias voltage, the controllability of the distribution adjustment also changes depending on the magnitude of the high frequency bias voltage.

  Also with regard to the inductance characteristic, the resistivity is a factor that determines the Q value (Quality factor value representing the sharpness of the peak of resonance) in the RLC series circuit in which the resistance is added to the LC resonant circuit. Therefore, the inductance characteristic changes according to the resistivity.

  As described above, the controllability, characteristics, and effects in the control of the high frequency bias voltage control and the distribution adjustment differ according to the difference in the resistivity of the substrate 3 to be processed. Therefore, it is effective to correct the contents of control according to the actual resistivity of the substrate 3 to be processed.

[Resistance calculation unit and DB]
Based on the above recognition, a method for calculating the actual resistivity of the processing target substrate 3 during plasma processing by the resistivity calculating unit 51 of the control unit 50 in the plasma processing apparatus of the first embodiment will be described.

  FIG. 6 shows a configuration example of DB data of the DB unit 53 used for calculation of resistivity. In this DB, the information on the inductance characteristics described above is arranged in advance for each resistivity in a plurality of typical resistivities of the sample wafer serving as a reference for each identical plasma processing condition based on experiments etc. Has been stored. A table of inductance characteristics representing the relationship between the L value and the high frequency bias voltage value of each electrode according to the magnitude of the high frequency bias power source power is stored in the DB as data for each resistivity. For the magnitudes of the high frequency bias power supply power and the power supply voltage, for example, a plurality of typical values may be set.

  In FIG. 6, four values of 100, 10, and 0.1 Ω · cm are shown as representative examples of resistivity. For example, Tables 601 to 602 are provided as tables of a plurality of inductance characteristics according to a plurality of values obtained by changing the value of the high frequency bias power supply power from small to large as data in the case of resistivity = 100 Ω · cm. Table 601 shows a table of inductance characteristics in the case of a predetermined value with a small high frequency bias power supply power. The table 602 shows a table of the inductance characteristics in the case where the high frequency bias power supply power is a predetermined large value. Tables 611 to 612 are provided as a table of a plurality of inductance characteristics according to the value of the high frequency bias power supply as data in the case of resistivity = 10 Ω · cm. Similarly, there is data for each resistivity.

  For example, by performing plasma processing on a dummy wafer of a sample in advance, the respective resistivity {0.1, 1, 10, 100 Ω · cm} and the inductance characteristic at each power supply power can be obtained. The information is stored in advance in the DB.

  During the plasma processing, the resistivity calculation unit 51 calculates a first resistivity R1 which is an actual resistivity of a wafer being processed, using processing conditions, monitor values, and data of the DB. The resistivity calculating unit 51 obtains, from the monitor value, a first voltage V1 at the inner periphery, a second voltage V2 at the outer periphery, and an L value that is a control value, regarding the wafer being processed. The resistivity calculating unit 51 calculates a first resistivity R1 by comparing the values {V1, V2, L values} with corresponding data in DB. The resistivity calculating unit 51 refers to at least a first voltage V1 and a second voltage V2.

  Note that although four values are used as the resistivity in FIG. 6, the present invention is not limited to this, and the actual resistivity can be calculated with higher accuracy if data of a plurality of resistivities is given more finely in DB. is there.

Monitor value
FIG. 7 shows an example of monitor values during plasma processing of a wafer as an example of monitor values of the monitor unit 30 for calculation of resistivity. In the table of FIG. 7, time (T), inductance (L), outer circumference ESC voltage value (V2), inner circumference ESC voltage value (V1), power supply voltage value (V3), and power output ratio as columns. . “Time (T)” indicates a time corresponding to an elapsed time from the start of plasma processing. "Inductance (L)" indicates the aforementioned L value. The “peripheral part ESC voltage value (V2)” indicates the detected value of the second voltage V2 of the second electrode 7 described above. The “inner circumferential portion ESC voltage value (V1)” indicates a detection value of the first voltage V1 of the first electrode 6 described above. “Power supply voltage value (V3)” indicates a detected value of the third voltage V3 based on the power of the high frequency bias power supply 24 described above. The “power output ratio” indicates the ratio of the output to the predetermined power PA in the power of the high frequency bias power supply 24 described above.

[Comparison process]
The resistivity calculating unit 51 calculates the first resistivity R1 by, for example, the following process using the monitor values as shown in FIG. 7 and the DB data as shown in FIG. As monitor values, for example, it is assumed that L value = Lx, V2 = V2x, V1 = V1x, V3 = V3x and the like are obtained at time Tx. The resistivity calculation unit 51 compares and collates the monitor value with DB data, and determines and extracts data closest to the monitor value from the DB data. The resistivity calculation unit 51 may, for example, search the DB data using the monitor value as a search condition at the time of the process of comparison comparison and determination, or, as described below, the closeness between the monitor value and the DB data value An index value (E) representing H may be calculated, and the closest data may be determined by the index value E.

  The resistivity calculation unit 51 calculates, for example, an index value E representing the closeness between the monitor value and the table of the inductance characteristics. This index value can be calculated by applying various known methods. As an example, the resistivity calculating unit 51 calculates, as the index value E, a difference value or a ratio between the monitor value Lx and the L value in the table. Similarly, the resistivity calculating unit 51 calculates the difference value and the ratio between the monitor value V1x and the table V1 and calculates the difference value and the ratio between the monitor value V2x and the table V2. Further, the resistivity calculation unit 51 may perform predetermined calculation using the difference values and ratios thereof, such as addition or selection of the minimum value. The resistivity calculating unit 51 extracts a table of inductance characteristics with the smallest index value E as the closest data.

  As a result of the comparison and judgment, it is assumed that a table of one inductance characteristic is obtained as data closest to DB, for example, resistivity = 100 Ω · cm and high frequency bias power supply power is a predetermined value. That is, the combination of the monitor values Lx, V1x, V2x is assumed to be closest to the specific L value in the table of the inductance characteristics, the value of the combination of V1, V2.

  The resistivity calculation unit 51 calculates the first resistivity R1 using the data of the closest table and the index value E, and also relates to the high frequency bias power supply power value associated therewith, and the L value which is the control value. Calculate etc. The resistivity calculation unit 51 refers to values such as resistivity, power supply power value, L value, etc. in the data of the closest table, and reflects predetermined index value E representing the closeness to those values. Perform calculations, such as multiplication. The resistivity calculating unit 51 obtains a first resistivity R1 as a result of the calculation. Similarly, the resistivity calculating unit 51 obtains an L value related to the first resistivity R1, a high frequency bias power supply power value, and the like.

  In addition, although it was set as the some table stored in DB in FIG. 6 as a structure of the information used for resistivity calculation, it is not limited to this but is applicable. For example, the relationship between a plurality of variable values as shown in FIG. 6 may be arranged in one table. Further, not limited to the table, a formula representing the relationship between a plurality of variable values may be defined and used. In that case, the resistivity calculating unit 51 substitutes the input value into the formula and obtains the first resistivity R1 as the output value.

  The correction unit 52 uses the first resistivity R1 and the like calculated by the resistivity calculation unit 51 to perform correction processing related to control including plasma processing and distribution adjustment on the wafer being processed by processing such as predetermined calculation. decide. The correction unit 52 determines, as the correction value, a correction value of high frequency bias power and voltage, and a correction value of L value.

  Furthermore, data for each time (T) corresponding to the elapsed time of plasma processing or data for each processing step of plasma processing may be stored in the DB in the same manner. In that case, the resistivity calculation unit 51 uses the time (T) during plasma processing or information representing a processing step as one of monitor values, and refers to data corresponding to the time or processing step from the DB, The first resistivity R1 is determined in the same manner as described above.

[Correction section]
In the case of the above processing example, since the L value for control and the power supply voltage value can be obtained together with the first resistivity R1 from the resistivity calculation unit 51, the correction unit 52 determines the correction value using the information. The correction unit 52 determines a drive control value C1 to be provided to the power supply unit 20 using the first resistivity R1, the L value, and the power supply voltage value. The correction unit 52 determines correction values of the first voltage V1 and the second voltage V2, which are high-frequency bias voltages to be applied to each electrode, in accordance with desired distribution adjustment such as concave distribution, flat distribution, convex distribution, etc. Do.

  For example, in the case of controlling the distribution adjustment so that the etching rate has a flat distribution as shown by the curve K2 in FIG. The correction unit 52 sets the first control voltage R1 to 200 V and the second voltage V2 = 300 V at the second control and the resistivity = 10 Ω · cm corresponding to the curve K2 according to the first resistivity R1 before correction. The first voltage V1 and the second voltage V2 after correction are determined. The correction unit 52, for example, multiplies V1 = 200 V and V2 = 300 V by a correction value according to the ratio of the first resistivity R1 to 10 Ω · cm. Thereby, correction values of the first voltage V1 and the second voltage V2 can be obtained.

  The correction unit 52 determines the L value in the drive control value C1 and the high frequency bias power supply power value based on the relationship between the plurality of variable values from the correction value obtained as described above.

  FIG. 8 shows a control table which is an example of information used for the correction process of obtaining a correction value from the first resistivity R1 by the correction unit 52. The control table is, for example, stored in advance in the DB unit 53, and the correction unit 52 performs correction processing with reference to the control table. The control table stores, in advance, information representing the relationship among representative resistivities, controllability relating to distribution adjustment, correction voltage values, and the like corresponding to FIG.

  The table in FIG. 8 shows, as columns, row numbers indicated by #, "resistivity", "controllability ratio", "correction required Vpp difference (flat distribution)", "inner circumference ESC corrected voltage (V1)" , “Peripheral part ESC corrected voltage (V2)”. “Resistance” is a value of a typical resistivity in DB, and in this case, 10 Ω · cm corresponding to (A) of FIG. 5 is specified as the reference resistivity. The “controllability ratio” is a ratio representing the controllability relating to the above-described distribution adjustment of the etching rate, and is set to 1 in the case of 10 Ω · cm. “Correction required Vpp difference (flat distribution)” indicates a value of Vpp difference necessary as a correction when controlling to be a flat distribution, in other words, a uniform rate, as one of distribution adjustment. This value is a difference value between the inner periphery ESC corrected voltage and the outer periphery ESC corrected voltage. The “inner circuit ESC corrected voltage (V1)” indicates a corrected first voltage V1, and the “outer ESC corrected voltage (V2)” indicates a corrected second voltage V2.

  In the table of FIG. 8, in the third row, when the resistivity is 10 Ω · cm as a reference value, the controllability ratio is 1, the correction required Vpp difference is 100 V, and the corrected first voltage V1 is It shows that it is 200V and V2 after correction is 300V. The correction required Vpp difference is (300−200) = 100. This corresponds to the curve K2 of the second control shown in FIG.

  In the second row, when the resistivity is 1 Ω · cm, the controllability ratio is 0.5, the required correction Vpp difference is 200 V, the corrected first voltage V1 is 150 V, and the corrected second voltage It shows that V2 is 350V. The required correction Vpp difference is (350−150) = 200. This corresponds to the correction of the curve K4 in FIG. 5B as a curve K7 in FIG. 9A described later. The corrected curve K7 approaches a flat distribution.

  In the fourth row, when the resistivity is 100 Ω · cm, the controllability ratio is 1.6, the required correction Vpp difference is 60 V, the corrected first voltage V1 is 220 V, and the corrected second voltage It shows that V2 is 280V. The correction required Vpp difference is (280−220) = 60. This corresponds to the correction of the curve K6 of (C) of FIG. 5 as the curve K8 of (B) of FIG. 9 described later. The corrected curve K8 approaches a flat distribution.

  The first row shows the case where the resistivity is 0.1 Ω · cm. However, as described above, when the resistivity is small to a certain degree or less, the controllability of the in-plane radial distribution is small, and the correction is necessary The Vpp difference is increased to, for example, 1000V. In this case, the effectiveness of control of distribution adjustment is low.

  The control table may store not only the information on the four resistivities but also information on a plurality of resistivities divided more finely.

  The correction unit 52 refers to the information in the control table from the first resistivity R1 and corrects the value according to the magnitude of the first resistivity R1 to correct the corrected high frequency bias voltage value. Etc can be obtained. Thereby, a drive control value C1 for control including desired desired distribution adjustment can be obtained.

  The correction unit 52 calculates the correction value by reflecting the index value E representing the above-mentioned closeness to the reference resistivity or the electric power value related thereto by multiplication or the like. May be The correction unit 52 may calculate the correction value using a predetermined calculation formula. Alternatively, the resistivity calculation unit 51 and the correction unit 52 may be integrated into one, and the drive control value C1 may be determined from the monitor value of the input.

  The correction unit 52 immediately supplies the drive control value C1 corresponding to the correction value to the control circuit 23 or the like of the power supply unit 20 during the plasma processing. Thereby, from the power supply unit 20, the first voltage V1 of the first electrode 6, which is an electrode in the processing chamber 10, and the second voltage V2 of the second electrode 7 become the corrected high frequency bias voltage values. it can. As a result of this plasma treatment, a suitable etching rate, for example, a flat distribution can be obtained than before the correction. Although the example of the distribution adjustment is a flat distribution, it can be realized in the same manner as described above even if it is desired to control to have a concave distribution or a convex distribution as another distribution adjustment. Information corresponding to the case of the concave distribution or the case of the convex distribution is provided in the DB control table in the same manner as in FIG.

[Control after correction]
FIG. 9 shows the characteristics of the control after correction in the case where FIG. 5 is the characteristics of the control before the correction. (A) of FIG. 9 shows the case where the resistivity is 1 Ω · cm. A curve K7 shows a curve after correction with respect to the curve K4 of (B) of FIG. 5, and the first voltage V1 after correction of the inner peripheral portion is 150 V and the second voltage V2 after correction of the outer peripheral portion is 350 V. The correction content corresponds to the second line in FIG.

  (B) of FIG. 9 shows the case where the resistivity is 100 Ω · cm. A curve K8 shows a curve after correction with respect to the curve K6 of (C) of FIG. 5, and the first voltage V1 after correction of the inner peripheral portion is 220 V and the second voltage V2 after correction of the outer peripheral portion is 280 V. This correction content corresponds to the fourth line in FIG.

  The corrected etching rates are closer to flatter distribution in both the curve K7 and the curve K8. In the curve K7, the Vpp value is smaller at the position of the inner peripheral portion than the curve K4, and the Vpp value is larger at the position of the outer peripheral portion, and both values are closer. In the curve K8, the Vpp value is larger at the position of the inner peripheral portion than the curve K6, and the Vpp value is smaller at the position of the outer peripheral portion, and both values are close to each other.

  Regarding (A) of FIG. 9, in the control of the curve K4 before correction, (V2−V1) which is the difference value D1 is 100V. At the position of the inner circumference, the Vpp difference from the V1 value of the control to the V1 value of the standard control is (200−250) = − 50V. Similarly, the Vpp difference from the V2 value of the control with respect to the V2 value of the standard control at the position of the outer peripheral part is (300−250) = 50V.

  On the other hand, in the control of the curve K7 after correction, the difference value D1 (V2-V1) is 200V. At the position of the inner periphery, the Vpp difference from the V1 value of the control with respect to the V1 value of the standard control is (150−250) = − 100V. Similarly, at the position of the outer periphery, the Vpp difference between the V2 value of the control and the V2 value of the standard control is (350−250) = 100V.

  That is, with respect to the control curve K4 before the correction, in the control curve K7 after the correction, the difference value D1 and the Vpp difference at each position are twice as large. In this manner, the distribution can be made closer to a flat distribution from a convex distribution by increasing the difference value D1 and the Vpp difference at each position by the correction.

  Regarding (B) of FIG. 9, in the control of the curve K6 before correction, the difference value D1 (V2−V1) is 100V. At the position of the inner circumference, the Vpp difference from the V1 value of the control to the V1 value of the standard control is (200−250) = − 50V. Similarly, at the position of the outer periphery, the Vpp difference between the standard control V2 value and the V2 value of the control is (300−250) = 50V.

  On the other hand, in the control of the curve K8 after correction, the difference value D1 (V2-V1) is 60V. At the position of the inner periphery, the Vpp difference between the V1 value of the control and the V1 value of the standard control is (220−250) = − 30V. Similarly, the Vpp difference from the V2 value of the control with respect to the V2 value of the standard control at the position of the outer peripheral part is (280−250) = 30V.

  That is, in the curve K8 for control after correction, the difference value D1 and the Vpp difference at each position are 0.6 times smaller than the curve K6 for control before correction. In this manner, the distribution can be made closer to a flat distribution from a concave distribution by reducing the difference value D1 and the Vpp difference at each position by correction.

  If the resistivity of the wafer being processed is low, for example, 1 Ω · cm, it is necessary to increase the Vpp difference to some extent at each position of the first electrode 6 and the second electrode 7. The correction unit 52 sets the L value to 80% as the correction corresponding thereto, sets the high frequency bias power supply power for the third voltage V3 to PA × 2.0 W with respect to the predetermined power PA, and the first voltage V1 to 150 V , And the second voltage V2 to 350V. As a result, the in-plane rate can be made to approach uniformly as shown by the curve K7 in FIG.

  When the resistivity of the wafer being processed is as high as, for example, 100 Ω · cm, it is necessary to reduce the Vpp difference to some extent at each position of the first electrode 6 and the second electrode 7. The correction unit 52 sets the L value to 30% as a correction corresponding to this, sets the high frequency bias power supply power for the third voltage V3 to PA × 1.2 W with respect to the predetermined power PA, and the first voltage V1 is 220 V , And the second voltage V2 to 280V. As a result, as in a curve K8 of (B) in FIG.

[Effects, etc.]
As described above, according to the plasma processing apparatus of the first embodiment, desired distribution adjustment such as in-plane uniformity and etching rate related to plasma processing can be realized. According to the first embodiment, the distribution of incident ion energy in the plasma etching process can be controlled with high accuracy. According to the first embodiment, an optimal high frequency bias voltage can be applied according to the resistivity of the substrate to be processed to realize suitable etching.

  In the multiple processing steps of the plasma etching processing sequence, the actual resistivity of the wafer changes during the processing steps. As the factors, in addition to the conditions for each processing step, changes in temperature of the wafer, etching of the conductive film of the laminated film of the wafer, adhesion of deposits to the wafer, and the like can be mentioned.

  The plasma processing apparatus according to the first embodiment performs plasma processing by applying different high-frequency bias voltages to the respective electrodes, and the voltage of each electrode also with respect to the change in the resistivity of the wafer accompanying the progress of the processing step during processing. Is constantly monitored to immediately detect the resistivity and its change. Then, the plasma processing apparatus corrects the high frequency bias voltage corresponding to the distribution adjustment according to the resistivity during processing and the change thereof. Thereby, if the resistivity of the wafer is not too low, for example, about 1 Ω · cm or more, the distribution of the etching rate in the radial direction in the plane can be made to, for example, be uniform.

[Modification]
As a modification of the plasma processing apparatus of the first embodiment, the following can be mentioned. The configuration of the LC resonance circuit 22 may be a combination of variable capacitance and fixed inductance. In that case, the control value is the capacitance value.

  The DB data of the DB unit 53 contains information obtained in advance by experiments and the like. As a modification, the plasma processing apparatus records the result of plasma processing of the wafer as data including DB at that time, including the information of resistivity and voltage value at that time as data in DB of the DB unit 53, and in the subsequent plasma processing. You may use it. That is, the plasma processing apparatus may be provided with a function of automatically updating DB data.

  In the surface corresponding to the placement electrode 4 of the holding portion 2, not only the two electrodes of the inner peripheral portion and the outer peripheral portion but also a form in which three or more electrodes are provided may be provided. The plasma processing apparatus monitors each voltage value of three or more electrodes, calculates the resistivity using the monitored value, and performs control such as correction.

  The method relating to the calculation of the first resistivity R1 and the determination of the correction value is not limited to the method of finely calculating the values of the first resistivity R1 and the voltage correction value. For example, the resistivity and the voltage correction value are set in advance as a plurality of roughly divided values in DB. As the plurality of resistivity values, for example, {1, 2,..., 9, 10 Ω · cm} or {10, 20,..., 90, 100 Ω · cm} are provided. The resistivity calculating unit 51 selects the closest one among the plurality of resistivity values based on the determination of the monitor value. The correction unit 52 selects a voltage correction value associated with the selected resistivity value. In the case of this form, the speed of real-time processing can be increased instead of reducing the control accuracy slightly.

Second Embodiment
A plasma processing apparatus according to a second embodiment of the present invention will be described. The basic configuration of the second embodiment is the same as the configuration of the first embodiment, and portions different from the configuration of the first embodiment in the configuration of the second embodiment will be described below.

  The plasma processing apparatus according to the second embodiment performs predetermined control by calculating the resistivity of the processing target wafer in a state before the plasma etching processing is performed on the wafer which is the processing target substrate 3. The configuration of the second embodiment is the configuration of FIG. 1 and FIG. 2 and the processing content of the control unit 50 is different from that of the first embodiment.

  First, an example sequence of a conventional plasma etching process is as follows. After transferring the wafer to the processing chamber, the wafer is electrostatically attracted to the electrode by application of a DC voltage from the DC power source to the electrode, and the wafer is held at a predetermined position of the holder. Next, a gas for etching is introduced into the processing chamber, an electromagnetic wave is generated by applying a voltage to the source power supply, an electromagnetic wave propagated through a waveguide or the like is introduced into the processing chamber, and plasma is generated in the processing chamber. After that, a high frequency bias voltage for causing the plasma to act is applied to the electrodes of the processing chamber by the power control.

  In the second embodiment, the sequence of plasma etching processing is as follows. After holding the wafer by electrostatic adsorption by applying a DC voltage from the DC power sources 221 and 222 to the electrodes in the processing chamber 10, the following processing steps are performed before plasma is generated from electromagnetic waves. In the process step, based on the control of the power supply unit 20 from the control unit 50, the high frequency bias power is applied to the electrodes of the holding unit 2 in a non-plasma state for a few seconds with a predetermined low power, for example 5 W. Apply in time. At that time, the power supply unit 20 increases the L value of the LC resonant circuit 22 from 0% to 100% as a first state in which the switch 21 is connected to the first electrode 6 side.

  In this case, a characteristic close to the characteristic of (A) in FIG. 3 corresponding to the inductance characteristic in the absence of plasma in the first embodiment can be obtained. The monitor unit 30 monitors the values {L value, V1, V2, V3, etc.} related to the characteristic at the time of the processing step. The resistivity calculating unit 51 compares the characteristic with the inductance characteristic created in advance and stored in DB based on the monitor value. Thereby, the resistivity calculating unit 51 obtains a rough resistivity of the wafer before processing as a resistivity before processing. The pre-treatment resistivity is taken as a second resistivity R2. The pre-process resistivity is obtained as a value close to the actual resistivity of the wafer being processed. The correction unit 52 performs control such as predetermined correction using the obtained pre-processing resistivity.

  In the plasma processing apparatus of the second embodiment, a schematic resistivity of the wafer can be obtained before the plasma processing. Therefore, the control unit 50 can perform the following control before the processing. The correction unit 52 of the control unit 50 has a function of performing the control.

  First, when the resistivity before processing is, for example, 0.1 Ω · cm, which is lower than a certain level, the control unit 50 outputs alert such as caution or cancels plasma processing as specific control. . The control unit 50 compares the calculated pre-processing resistivity with a predetermined threshold, and applies the specific control when the calculated resistivity is less than the threshold.

  As described above, for example, in a low resistivity wafer such as a resistivity of 0.1 Ω · cm, the controllability of the distribution adjustment is improved even if different high frequency bias voltages are applied to the first electrode 6 and the second electrode 7. Small, weak effect. Also, significant high frequency bias supply power needs to be provided and power efficiency also needs attention. That is, in this case, the effectiveness of the control is low.

  In this case, the control unit 50 causes the operator to output an alert such as attention based on the calculation and determination of the pre-processing resistivity before the plasma processing is performed, and then causes the processing to be performed. The content of the alert is, for example, a caution that the resistivity of the wafer can not sufficiently control the distribution of the etching rate. The operator acknowledges the alert and continues processing as needed. As another control example, the control unit 50 outputs an alert and cancels the process. The content of the alert is, for example, a caution that the processing is canceled because the resistivity of the wafer can not sufficiently control the distribution of the etching rate.

  As the second control, the control unit 50 is configured to obtain a first voltage V1 and a second voltage V2 for obtaining a uniform rate or the like in processing based on the calculation and determination of the resistivity before processing before the plasma processing. The range of values such as L value and high frequency bias power supply power is narrowed to some extent. The correction unit 52 drives and controls the power supply unit 20 based on the narrowed range. Thus, the accuracy of the high frequency bias voltage can be increased during processing, and the time required for control and correction can be shortened.

  Conventionally, there is also an example in which the wafer resistivity is measured in advance using a commercially available wafer resistance measuring device. However, as described above, the wafer resistivity changes under the influence of various factors such as the temperature of the wafer, the electrostatic adsorption state, the state of the front and back surfaces of the wafer, and the type of wafer sample film. Therefore, as in the second embodiment, by detecting and controlling the resistivity of the wafer immediately before the plasma processing and in the state immediately before the processing, a more desirable effect than in the prior art can be obtained. When calculating the pre-processing resistivity, the resistivity calculating unit 51 calculates the pre-processing resistivity in consideration of processing conditions and monitor values in the plasma processing apparatus. And control part 50 can perform control more suitable than before using the resistivity before processing.

Third Embodiment
A plasma processing apparatus according to a third embodiment of the present invention will be described with reference to FIG. The basic configuration of the third embodiment is the same as the configuration of the first embodiment, and in the following, portions different from the configuration of the first embodiment in the configuration of the third embodiment will be described. In the third embodiment, the configuration of the power supply unit 20 mainly differs from the configurations of FIG. 1 and FIG. 2 of the first embodiment.

  FIG. 10 mainly shows the configurations of the processing chamber 10 and the power supply unit 20 in the plasma processing apparatus of the third embodiment. In the configuration of the power supply unit 20 of FIG. 10, the line extending from the high frequency bias power supply 24 and the matching box 210 is either the placement electrode 4 or the second electrode 7 which is the outer peripheral portion ESC. There is a switch 301 connected to the heel.

  The switch 301 can switch between a first state connected to the placement electrode 4 side and a second state connected to the second electrode 7 by the control terminal. The first terminal of the switch 301 is connected to the mounting electrode 4 through the power supply line, and the second terminal is the second through the power supply line to which the second voltage detector 202 is connected through the capacitor 302. It is connected to the electrode 7. A capacitor 302 is inserted in the line between the switch 301 and the second electrode 7. The capacitor 302 is an element for cutting the DC voltage of the ESC.

  The switch 301 is a switch for applying the high frequency bias power supply voltage to the placement electrode 4 in the first state, and applying it to only one of the first electrode 6 and the second electrode 7 in the second state. The first state of the switch 301 is similar to that of the circuit of the first embodiment. The switching of the control terminal of the switch 301 is controlled by the control circuit 23, for example.

  In the third embodiment, the second electrode 7 is used as one of the electrodes to which the switch 301 is connected. However, in the modification, the first electrode 6 may be used as one of the electrodes. In this case, a high frequency bias power supply voltage is applied to the first electrode 6.

  As in the first embodiment, the plasma processing apparatus of the third embodiment calculates the first resistivity R1 of the processing target substrate 3 during the plasma etching process, and performs correction or the like according to the first resistivity R1. Take control. Moreover, the plasma processing apparatus of Embodiment 3 calculates the pre-processing resistivity of the to-be-processed substrate 3 before processing, and performs control according to the pre-processing resistivity.

  The sequence of the plasma etching process in the third embodiment includes the following process steps. First, a wafer as the substrate to be processed 3 is transferred into the processing chamber 10, and in the first state of the switch 301, a DC voltage from the DC power supplies 221 and 222 is applied to the electrodes of the holding unit 2, It is absorbed. Thereafter, based on the control of the power supply unit 20, the control unit 50 causes the switch 301 to be in the second state in which the switch 301 is connected to the second electrode 7 side before generating the plasma in the processing chamber 10. Also in the third state not connected. In this state, the power supply unit 20 supplies the high frequency bias power from the high frequency bias power supply 24 to the second electrode 7 with a predetermined low power, for example, 5 W. Thereby, the high frequency bias power supply voltage is applied to the second electrode 7. At this time, the second voltage detector 202 detects this high frequency bias power supply voltage as the second voltage V2. The third voltage detector 203 detects this high frequency bias power supply voltage as a third voltage V3.

  At this time, for example, when the resistivity of the wafer is 10 Ω · cm, the first electrode 6, which is the other electrode to which the high frequency bias power supply voltage is not applied, is applied to the second electrode 7 through the path between the electrodes. A voltage of about one tenth of the voltage is applied. The first voltage detector 201 measures and detects the voltage as a first voltage V1.

  When the resistivity of the wafer to be processed is low, the second voltage V2 of the second electrode 7 in the outer peripheral portion tends to be large, and conversely, when the resistivity is high, the second voltage V2 tends to be small. is there.

  The monitor unit 30 monitors the first voltage V1, the second voltage V2, and the third voltage V3 in the processing step. The resistivity calculation unit 51 uses the data of the monitor value to compare and collate with data of voltage values for each typical resistivity stored in advance in the DB, thereby providing a schematic view of the wafer to be processed. The pre-treatment resistivity which is the resistivity is calculated. The contents of this process can be realized in the same manner as in the first embodiment.

  In the third embodiment, as in the first embodiment, the resistivity of the wafer can be calculated even under the conditions with plasma, that is, even during the plasma processing. This is realized, for example, as follows. The power supply unit 20 supplies a predetermined power as a high frequency bias power supply to the first electrode 6 in the inner peripheral portion, and applies a corresponding first voltage V1.

  FIG. 11 shows resistances regarding the first voltage V1 of the first electrode 6 in the inner peripheral portion and the second voltage V2 of the second electrode 7 in the outer peripheral portion when the third voltage V3 by the high frequency bias power supply power is about 100 V. Indicates rate dependency. The abscissa represents the wafer resistivity, and the ordinate represents the monitor voltage values {V1, V2, V3}. A curve 901 shows a V1 value, a curve 902 shows a V2 value, and a curve 903 shows a V3 value. As in the curves 901 and 902, when the resistivity is low, the difference value (V2-V1) of Vpp between the first voltage V1 at the inner peripheral portion and the second voltage V2 at the outer peripheral portion decreases, and the resistivity If it is high, the difference value becomes large.

  On the other hand, for the third voltage V3 corresponding to the high frequency bias power supply voltage, the influence of the impedance matching of the matching box 210 is large, the influence of the resistivity is small, and it hardly appears as a change in voltage value. Therefore, it is difficult to calculate the resistivity from the third voltage V3 corresponding to the high frequency bias power supply voltage.

  For each of the voltages and Vpp differential values measured above, the one due to the cause of the resistivity is distinguished from the one due to other factors such as plasma. Therefore, the monitor unit 30 monitors the three voltage values. The resistivity calculation unit 51 uses the monitor value to divide, for example, the Vpp difference value between ESCs (V2−V1) by the third voltage V3 which is Vpp of the high frequency bias power supply voltage, and is the value The resistivity during processing is calculated from (V2−V1) / V3. This can increase the accuracy of the calculation of the resistivity during processing.

  Then, in the plasma processing apparatus of the third embodiment, using the calculated resistivity, the correction unit 52 performs control to preferably correct the high frequency bias power and the voltage value during processing, as in the first embodiment. Do. At this time, for example, after the resistivity and the power correction value are determined, the correction unit 52 switches the switch 301 in FIG. 10 to the first state connected to the placement electrode 4 side. Then, as in the first embodiment, correction unit 52 applies the corrected high-frequency bias power to first electrode 6 and second electrode 7 as switching switch 21 between the first state and the second state. Control to

  FIG. 12 shows an example of a control table in the third embodiment. In the table of FIG. 12, the resistivity, the outer periphery ESC voltage value (V2), the internal ESC voltage value (V1), the power supply voltage value (V3), and (V2−V1) / V3 are provided as columns.

  The “resistivity” has a plurality of typical resistivities, as in the control table of FIG. The “peripheral part ESC voltage value (V2)” indicates a second voltage V2 according to the resistivity. "Internal ESC voltage value (V1)" indicates a first voltage V1 corresponding to the resistivity. "Power supply voltage value (V3)" indicates a third voltage V3. "(V2-V1) / V3" shows said calculated value.

  The control table is created and stored in advance in the DB unit 53. The resistivity calculating unit 51 calculates the respective resistivities from the monitor values before and during processing with reference to the control table. In addition, when there are a plurality of processing conditions for plasma processing, information may be similarly prepared for each processing condition, and the information may be used.

  As mentioned above, although this invention was concretely demonstrated based on embodiment, this invention is not limited to the said embodiment, It can change variously in the range which does not deviate from the summary.

  The material to be treated to be the substrate 3 is not limited to a silicon (Si) oxide film, and a poly-Si film, a photoresist film, an antireflective organic film, a silicon nitride oxide film, a silicon nitride film, a low-k material, high- The k material, amorphous carbon film, Si substrate, etc. are also applicable.

  As processing gases, chlorine, hydrogen bromide, methane tetrafluoride, methane trifluoride, methane difluoride, argon, helium, oxygen, nitrogen, carbon dioxide, carbon monoxide, hydrogen, ammonia, octafluoride Propane, nitrogen trifluoride, sulfur hexafluoride, methane, silicon tetrafluoride, silicon tetrachloride and the like can be applied.

  The plasma processing apparatus and the discharge method thereof are not limited to the etching apparatus using microwave ECR discharge, but dry etching apparatus using magnetic field UHF discharge, capacitively coupled discharge, inductively coupled discharge, magnetron discharge, etc. is also applied. It is possible.

  The present invention is suitable for an etching apparatus using microwave ECR discharge and its treatment. The present invention is not limited to this, and is widely applicable to a process having a difference in rate due to a high frequency bias, ie, a process having a correlation between ion energy and a rate, in an apparatus provided with a high frequency bias power supply for ion attraction.

  DESCRIPTION OF SYMBOLS 2 ... holding part, 3 ... processed substrate, 4 ... mounting electrode, 5 ... conductor film, 6 ... 1st electrode, 7 ... 2nd electrode, 10 ... processing chamber, 20 ... power supply part, 21 ... switch, 22: LC resonance circuit, 23: control circuit, 24: high frequency bias power supply, 30: monitor unit, 50: control unit, 51: resistivity calculation unit, 52: correction unit, 53: DB unit, 54: processing condition management unit .

Claims (10)

A plasma processing apparatus,
An electromagnetic wave generator for generating an electromagnetic wave;
A processing chamber in which plasma processing is performed as processing on a processing target substrate held by a holding unit based on plasma generated based on the electromagnetic waves;
A placement electrode for placing the substrate to be processed in the holding portion, and an electrode provided inside the placement electrode, in an inner circumferential portion in a plane corresponding to the placement electrode; 1 electrode, and a second electrode at the outer periphery,
A high frequency bias power for applying a high frequency bias voltage to the placement electrode and the electrode is supplied, a first voltage is applied to the first electrode as the high frequency bias voltage, and a second voltage is applied to the second electrode. A power supply that applies and applies a third voltage to the stationary electrode;
A monitor unit that monitors the first voltage and the second voltage;
A resistivity calculation unit that calculates the resistivity of the processing target substrate based on the monitor value of the monitor unit;
A correction unit configured to determine a correction value related to the high frequency bias voltage according to the resistivity, and drive-control the power supply unit to obtain the correction value;
A plasma processing apparatus comprising: In the plasma processing apparatus according to claim 1,
The power supply unit includes a high frequency bias power supply, and an LC resonant circuit connected to the first electrode and the second electrode via a switch, and the switch and the LC resonant circuit are performed during the processing. Applying the first voltage to the first electrode and applying the second voltage to the second electrode by controlling the variable control value of
The monitoring unit monitors a voltage value including the first voltage and the second voltage, and the control value while the processing is being performed.
The resistivity calculating unit is configured to use the first voltage, the second voltage, and the control value during the execution of the process as a resistivity corresponding to a state during the execution of the process. Calculate the resistivity,
The correction unit determines the control value corresponding to the correction value based on the first resistivity during execution of the process, and drives and controls the power supply unit using the control value. ,
Plasma processing equipment. In the plasma processing apparatus according to claim 2,
The correction unit sets the control value of the LC resonance circuit to a first value during the processing, supplies a predetermined power from the high frequency bias power supply, and in a subsequent period, the first voltage and the second voltage Control to change the control value to a second value until the difference value between the first voltage and the second voltage becomes a predetermined value while keeping the average value of the two constant.
Plasma processing equipment. In the plasma processing apparatus according to claim 2,
The correction unit holds, as a plurality of variable values, control information representing a relationship between a resistivity of the substrate to be processed and a voltage value including the first voltage and the second voltage regarding the high frequency bias voltage. And calculating the resistivity related to the voltage value of the monitor value with reference to the control information based on the voltage value of the monitor value.
Plasma processing equipment. In the plasma processing apparatus according to claim 4,
Have a DB part to hold the DB,
The DB stores, as the control information, information representing the relationship between the first voltage and the voltage value including the second voltage for each of the resistivities at a plurality of resistivities,
The resistivity calculation unit compares and collates the voltage value of the monitor value with the voltage value of the DB to obtain the closest voltage value and the resistivity related thereto, and the resistivity or the resistivity A resistivity obtained by correcting the resistivity according to the proximity is obtained as the first resistivity,
Plasma processing equipment. In the plasma processing apparatus according to claim 2 ,
The power supply unit supplies the high frequency bias power and applies the first voltage and the second voltage in accordance with the in-plane distribution adjustment corresponding to the target substrate related to the processing rate.
The correction unit determines a correction value including the first voltage and the second voltage in accordance with the distribution adjustment.
When the first resistivity is smaller than a reference resistivity, the correction unit sets each voltage value of the first voltage and the second voltage as the correction value in the case of the reference resistivity. Correction is made to become larger than the voltage value to be applied, and conversely, when the first resistivity is larger than the reference resistivity, the first voltage and the second voltage to be the correction value are used. Correct each voltage value to be smaller than the voltage value applied in the case of the reference resistivity,
Plasma processing equipment. In the plasma processing apparatus according to claim 1,
The power supply unit includes a high frequency bias power supply, and an LC resonant circuit connected to the first electrode and the second electrode via a switch, and the processing substrate is mounted on the placement electrode. After that, before performing the processing, the first voltage is applied to the first electrode by controlling the variable control value of the switch and the LC resonant circuit, and the second voltage is applied to the second electrode. Apply,
The monitor unit monitors a voltage value including the first voltage and the second voltage, and the control value before performing the process.
The resistivity calculating unit is configured to use a second voltage corresponding to a state before the processing of the processing target substrate using the first voltage, the second voltage, and the control value before the processing is performed. Calculate the resistivity,
The correction unit determines the control value corresponding to the correction value based on the second resistivity before performing the process, and drives and controls the power supply unit using the control value. ,
Plasma processing equipment. In the plasma processing apparatus according to claim 1,
The power supply unit includes an LC resonant circuit connected to the first electrode and the second electrode via a first switch, the one electrode of the placement electrode, the first electrode, and the second electrode. A high frequency bias power supply connected via a second switch, and a voltage detector connected to an outlet of the high frequency bias power supply,
Before execution of the processing, the second switch is connected to the one electrode, and the first switch is not connected to any of the electrodes, the predetermined power from the high frequency bias power supply Is supplied to the one electrode,
The monitor unit monitors a voltage value including the first voltage and the second voltage before execution of the process.
The resistivity calculating unit calculates the resistivity corresponding to the state before the execution of the process using the voltage value before the execution of the process.
The correction unit performs control related to the process using the resistivity before performing the process.
Plasma processing equipment. In the plasma processing apparatus according to claim 8 ,
While the processing is being performed, the second switch is connected to the placement electrode, and the variable control value of the first switch and the LC resonance circuit is controlled to control the first electrode. Applying the first voltage and applying the second voltage to the second electrode;
The monitor unit monitors the voltage value and the control value while the process is being performed,
The resistivity calculating unit calculates a resistivity corresponding to a state in which the process is being performed while the process is being performed,
The correction unit performs control regarding the process using the resistivity while the process is being performed.
Plasma processing equipment. A plasma processing method in a plasma processing apparatus, comprising:
The plasma processing apparatus is
An electromagnetic wave generator for generating an electromagnetic wave;
A processing chamber in which plasma processing is performed as processing on a processing target substrate held by a holding unit based on plasma generated based on the electromagnetic waves;
A placement electrode for placing the substrate to be processed in the holding portion, and an electrode provided inside the placement electrode, in an inner circumferential portion in a plane corresponding to the placement electrode; 1 electrode, and a second electrode at the outer periphery,
Equipped with
The plasma processing method may include, as steps performed by the plasma processing apparatus,
A high frequency bias power for applying a high frequency bias voltage to the placement electrode and the electrode is supplied, a first voltage is applied to the first electrode as the high frequency bias voltage, and a second voltage is applied to the second electrode. Applying and applying a third voltage to the stationary electrode;
Monitoring the first voltage and the second voltage;
Calculating the resistivity of the substrate to be processed based on the monitor value of the monitor;
Determining a correction value relating to the high frequency bias power according to the resistivity, and performing drive control so as to be the correction value;
Having a plasma processing method.

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