JP2017028000A - Plasma processing apparatus and plasma processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma processing apparatus or a plasma processing method which improves the yield of processing.SOLUTION: The plasma processing apparatus includes a processing chamber which is arranged inside a vacuum container and whose inside is decompressed, a sample table on which a wafer to be processed is mounted in the processing chamber, a first high frequency power supply for supplying a first high frequency power for forming a plasma above the sample table in the processing chamber, a second high-frequency power supply for supplying a second high-frequency power for forming a bias potential on the wafer to an electrode disposed in the sample table, and, a matching unit that matches one of the high-frequency powers by using information on one of the high-frequency powers detected at the time when both of the first and second high-frequency powers are output with a high output when it is repeated at a specific cycle that at least one of the first and second high-frequency powers outputs different values of high and low for each predetermined period. The information detected at the point in time is held while at least one of the first and second high-frequency powers is not output at a high output.SELECTED DRAWING: Figure 1

Description

The present invention relates to a plasma processing for processing a substrate-like sample such as a semiconductor wafer to be processed held on a sample stage arranged in a processing chamber using plasma formed in a processing chamber arranged in a vacuum vessel. The present invention relates to an apparatus or a plasma processing method, which relates to a plasma processing apparatus or a plasma processing method for performing an etching process by periodically increasing or decreasing a high-frequency power for generating plasma or a high-frequency power source for forming a bias potential intermittently or with a high or low value.

In the semiconductor manufacturing process, dry etching using plasma is generally performed. With the recent high integration and further three-dimensional structure of semiconductor devices, plasma processing equipment that performs dry etching is required to improve the processing accuracy, improve the etching selectivity, or control the etching shape with high precision. Etc. are required to be improved.

In order to meet such demands, a method has been proposed in which a high-frequency power source for plasma generation is pulsed and the plasma generation is pulsed to improve the controllability of ion density and radical density. In addition, in order to perform etching with a high aspect ratio in a multilayer structure or a three-dimensional structure, the bias application high-frequency power supply is pulsed and the bias application is pulsed to improve the selection ratio effectively using deposition. It has also been proposed to suppress damage by reducing the electronic shading effect.

In Patent Document 1, in order to perform etching at a high selection ratio and a high etching rate, a high-frequency power source for bias application is subjected to power modulation in a frequency range of 0.25 to 100 Hz (low output and high output are alternately output), and a bias is applied. A method of applying is proposed. In Patent Document 1, the bias application high frequency power is stably supplied by controlling the bias application high frequency power supply side matching unit to perform the matching operation only at a high output timing.

JP 2014-96594 A

In the above-described prior art, the following points have been insufficiently considered, causing problems.

That is, as described in Patent Document 1, when the bias applying high frequency power source contributes to plasma generation, the plasma load impedance viewed from the plasma generating high frequency power source side is used for power modulation of the bias applying high frequency power source. Fluctuate synchronously. The matching unit on the high frequency power source for plasma generation performs matching operation against two plasma load impedance conditions when the high frequency power source for bias application is low output and high output. The waves increase and are not constant.

In Patent Document 1, a DC voltage is applied to an electrode to which high-frequency power for plasma generation is applied to stabilize the thickness of the plasma sheath, thereby reducing the increase in reflected waves, but it is not possible to completely suppress the reflected wave. Absent.

An object of the present invention is to perform a stable matching operation in which either or both of a high-frequency power source for generating plasma and a high-frequency power source for forming a bias potential repeatedly output on and off or high and low outputs. It is an object of the present invention to provide a plasma processing apparatus or a plasma processing method that improves the processing yield.

The object is to form a plasma above the sample stage in the processing chamber, a processing chamber in which the inside of the vacuum chamber is evacuated, a sample stage in which the wafer to be processed is placed. A first high-frequency power supply for supplying a first high-frequency power for supplying a second high-frequency power for forming a bias potential on the wafer to an electrode disposed in the sample stage. The first and second high-frequency powers when at least one of the first and second high-frequency powers repeatedly outputs different values of high and low for a predetermined period, respectively, at a specific period. A matching unit that performs matching on the one high-frequency power using information on the one high-frequency power detected at a time when both of the powers are output at a high output, and the first and second high-frequency powers This is achieved by holding the information detected at the time point while at least one of the electric power is not being output at a high output.

According to the present invention, one or both of the source power source and the bias power source can be pulsed to perform the etching process, so that one load impedance condition to be matched by the source matching device and the bias matching device can be made stable. Alignment can be performed.

It is a longitudinal cross-sectional view of the VHF wave ECR plasma etching apparatus which concerns on this invention. It is a timing chart which shows the flow of operation | movement of the plasma processing apparatus which concerns on the Example shown in FIG. It is a timing chart of the output waveform of the source power supply and bias power supply which concerns on 1st Example of this invention. It is a timing chart of the output waveform of the source power supply and bias power supply which concerns on 1st Example of this invention. It is a timing chart of the output waveform of the source power supply and bias power supply which concerns on 1st Example of this invention. It is a circuit block diagram of the source matching device and bias matching device which concern on the 1st modification of this invention. It is a circuit block diagram of the source matching device which concerns on the 2nd Example of this invention. It is a frequency spectrum of the reflected wave power observed with the source matching device which concerns on the 2nd Example of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal sectional view schematically showing an outline of a configuration of a plasma processing apparatus according to a first embodiment of the present invention.

The plasma processing apparatus 100 shown in FIG. 1 is a processing chamber 101 having a cylindrical shape that is disposed in a vacuum vessel and whose inside is decompressed and plasma is formed inside, and an exhaust at the bottom of the processing chamber 101 connected to the lower portion of the vacuum vessel. A turbo molecular pump 102 for exhausting gas and particles in the processing chamber 101 from the mouth and reducing the pressure to obtain a predetermined degree of vacuum and a vacuum pump including a rotary pump (not shown) for roughing are provided. . In addition, a planar antenna 109 having a circular shape connected by a coaxial cable via a source power source 103 that supplies high-frequency power of a predetermined frequency for forming plasma and a source matching unit 104 is disposed above the processing chamber 101. A circular shower plate 110 having a plurality of gas introduction holes arranged at the center and having a plurality of gas introduction holes into which the processing gas is introduced is arranged in the processing chamber 101.

In the lower part of the processing chamber 101, a wafer 110, which is a substrate-like sample to be etched using plasma, is placed on a circular upper surface covered with the dielectric film, and is adsorbed and held by electrostatic force. A sample stage 111 is arranged. A metal electrode having a disk or a cylindrical shape is arranged in the sample stage 111, and a predetermined high-frequency power for forming a bias potential above the upper surface of the wafer 114 is supplied to the electrode during processing of the wafer 114. A bias power source 105 is connected via a bias matching unit 106 by a coaxial cable.

Inside a cylindrical processing chamber 101 of a vacuum vessel made of a conductive material such as aluminum and grounded, a planar antenna 109, a shower plate 110 for evenly introducing etching gas into the processing chamber, and these There is provided a sample stage 111 which is arranged below and on which the upper surface on which the wafer 114 is placed is opposed to the shower plate 110, and an etching gas can flow into the gap between the shower plate 110 and the planar antenna 109. The processing gas from the gas inlet 112 is introduced, and the gas diffused and filled in the gap is introduced into the processing chamber 101 from a plurality of gas introduction holes arranged at the center of the lower surface of the shower plate 110. A solenoid coil 113 for supplying a magnetic field formed around the side wall and the upper surface of the vacuum chamber surrounding the processing chamber 101 to the processing chamber 101 is aligned with the axis of the vertical cylinder of the processing chamber 101. Alternatively, the processing chamber 101 is arranged in a ring shape.

Each of the source power source 103 and the bias power source 105 of the present embodiment can output a continuous wave (CW) high-frequency power that continuously outputs a sinusoidal voltage or current at a predetermined frequency, and the predetermined frequency. The high-frequency power is turned on / off at a predetermined period and period, or the pulse-like high-frequency power is repeatedly output by repeatedly increasing / decreasing its intensity by a plurality of values. In this example, the power intensity of the predetermined frequency of the high-frequency power, the output mode, the period (frequency) of the pulse-like output, the on / off or high / low output period, and the ratio (duty) The ratio) is set by the controller 107 that is communicably connected thereto, and the operation is adjusted so as to be the set value. The controller 107 includes a pulse generator 108 that generates a trigger signal corresponding to the pulse frequency and duty ratio at the time of pulse output.

Each of the source power source 103 and the bias power source 105 includes control units 121 and 131, oscillation units 122 and 132, distribution units 123 and 133, amplification units 124 and 134, synthesis units 125 and 135, and high frequency detection units 116 and 136. It is configured. The source power supply 103 and the bias power supply 105 adjust the high-frequency power output from each of the control units 121 and 131 according to the setting input from the controller 107.

That is, in each of the source power supply 103 and the bias power supply 105, high frequency power output from the oscillation units 122 and 132 such as a crystal oscillation circuit is branched by the distribution units 123 and 133, amplified by the amplification units 124 and 134, and then combined. The signals are synthesized by the units 125 and 135 and output from the source power source 103 and the bias power source 105. The control units 121 and 131 feed back the output values detected by the high-frequency detection units 126 and 136, and the outputs are adjusted so as to be set values by comparing the output values with the settings. In the present embodiment, since the output is feedback-controlled in this way, the output of the high-frequency power is received until the high-frequency power output from the oscillation units 122 and 132 is received from the respective power sources upon receiving the command signal from the controller 107. It takes several ms to several tens of ms.

The source power supply 103 and the bias power supply 105 have a function of outputting a pulse in synchronization with an external trigger pulse signal output from the pulse generator 108 and having a pulse frequency of 100 Hz to 10 kHz and a duty ratio of 10 to 90%. . Further, in this embodiment, when either or both of the source power supply 103 and the bias power supply 105 output high-frequency power in pulses, both the source power supply 103 and the bias power supply 105 output in a pulse form (the output is turned on). The external trigger pulse signal synchronized with the timing is input to the source matcher 104 and the bias matcher 106.

The source matching unit 104 and the bias matching unit 106 according to the present embodiment operate based on parameters such as the magnitude and phase difference of high-frequency power detected at a predetermined time or timing for each period during processing of the wafer 114. . Each of these matching units performs a sample and hold operation in accordance with an external trigger pulse signal input from the pulse generator 108.

That is, the source matching unit 104 and the bias matching unit 106 are configured such that each of the source power source 103 and the bias power source 105 generates high-frequency power in a pulse shape with a predetermined period and period or a ratio (duty ratio) between the output ON and OFF periods. When the output is repeatedly turned on and off, the magnitude of the traveling wave power Pf and the reflected wave are only at an arbitrary timing during the period in which the pulsed outputs from both power sources are on (output). Sampling is detected by sampling the magnitude Pr of the power and the phase difference θ between the voltage and current of the traveling wave power. Also, these matching units are the timing immediately before stored in a storage device (not shown) at the timing when either the source power source 103 or the bias power source 105 is not outputting, and the pulse from both power sources. The value of the sampled parameter is held (held) at a timing during the period when the output of is turned on (output). By performing such a sample and hold operation, the source matching unit 104 and the bias matching unit 106 intermittently match the plasma load impedance state at the timing when both the source power source 103 and the bias power source 105 output. The operation can be continued.

Alternatively, the parameter values stored and held in a storage device (not shown) may be read and used at a timing when either the source power supply 103 or the bias power supply 105 is not outputting. For example, when the matching operation of any power source is performed at the timing when any one of them does not output, the corresponding matching unit uses the held data to calculate the load impedance necessary for the matching. The matching operation may be performed based on the calculation or calculation.

The wafer 114 to be etched is processed through the following process. First, a wafer 114, which is another vacuum vessel connected to the side wall of the vacuum vessel and placed on an arm of a robot arranged in the internal transfer chamber, is moved from the transfer chamber into the processing chamber 101 by the expansion and contraction and rotation of the arm. The sample is conveyed, transferred to the sample stage 111, and placed on the upper surface thereof. The wafer 114 is attracted and held on the upper surface of the sample stage 111 by using an electrostatic force formed by DC power applied to an electrode for electrostatic attraction (not shown) disposed in the dielectric film constituting the upper surface of the sample stage 111. In this state, a gas for heat transfer such as He is introduced into the back surface of the wafer 114, and an etching gas is introduced into the processing chamber 101 from the gas introduction hole of the shower plate 110 toward the wafer 114.

When the pressure in the processing chamber 101 is set to a predetermined pressure or degree of vacuum suitable for processing by the balance between the flow rate and speed of exhaust gas by the operation of the vacuum pump and the flow rate and speed of processing gas from the shower plate 110. In addition, a direct current is supplied to the solenoid coil 113 to form a magnetic field in the processing chamber 101, and a high frequency power of a predetermined frequency is supplied from the source power source 103 to the planar antenna 109 to enter the processing chamber 101 from the planar antenna 109. An electric field is supplied. In response to the interaction between these electric and magnetic fields, electron cyclotron resonance (ECR) is generated to excite the atoms or molecules of the gas for processing, and the high-density plasma 115 is formed in the shower plate 110 in the processing chamber 101 or It is generated in the space between the planar antenna 109 and the sample stage 110.

In the state in which the plasma 115 is formed, a bias potential is formed above the upper surface of the wafer 114 by supplying high-frequency power from the bias power source 105 to the electrode in the sample stage 111. A plurality of films including a resist mask formed in advance by the charged particles such as ions in the plasma 115 being attracted to the upper surface of the wafer 114 while controlling the energy according to the potential difference between the bias potential and the potential of the plasma 115. Etching progresses by colliding with the membrane layer to be treated of the membrane structure composed of layers and promoting chemical or physical reaction with the material of the surface by particles having activity such as radicals on the membrane layer surface .

In the process of this embodiment, as described above, the source power supply 103 for forming the plasma 115 or the bias power supply 105 for forming the bias potential is supplied to the planar antenna 109 and the sample stage 111 (inner electrodes). The output of at least one of the high-frequency power of the frequency and the wavelength is repeatedly turned on and off in a pulsed manner at a predetermined cycle, period, or duty ratio. As the ON / OFF repetition is controlled, the progress of the processing of the film layer to be processed on the surface of the wafer 114 is controlled to have a desired processing speed and direction. As a result, the shape of the film layer obtained after the processing, that is, the so-called processed shape can be brought close to the intended one, and the processing accuracy can be improved.

When such an etching process is performed for a predetermined time and the end point of the process is determined by a determination unit using a light detector or the like from a processing chamber (not shown), the high-frequency power for bias formation is stopped and the electric field is Alternatively, the supply of the magnetic field is stopped, the plasma 115 is extinguished, and the process ends. Thereafter, the robot is driven to extend the arm from the transfer chamber, and the processed wafer 114 is transferred to the arm that has entered the processing chamber 101 from the sample stage 111 and is carried out of the processing chamber 101 to be unprocessed. When the wafer 114 is present, this is placed on the sample stage 111. When there is no unprocessed wafer 114, the processing operation in the processing chamber 101 is temporarily stopped.

2 to 5 are timing charts showing the flow of operation of the plasma processing apparatus according to the embodiment of FIG. In particular, it is a timing chart showing pulse output patterns of the source power supply 103 and the bias power supply 105. In these drawings, in accordance with the traveling wave power and reflected wave power of the source power source 103 and the bias power source 105, the external trigger pulse signal input from the pulse generator 108 to the source matching unit 104 and the bias matching unit 106 is matched with each of them. The sample hold operation of the instrument is described.

FIG. 2 shows that the high-frequency power from the source power supply 103 is not turned on and off in a pulsed manner, but a sine waveform is continuously output (CW output), and the output from the bias power supply 105 is turned on and off in a pulsed manner. 5 shows a timing chart when output (pulse output) is performed at a period, a period or a duty ratio. In this figure, the traveling wave power 201 of the source power supply 103, the reflected wave power 202, the sample hold operation 203 of the source matching unit 104, the traveling wave power 204 of the bias power source 105, the reflected wave power 205, and the sample hold operation of the bias matching unit 106 are illustrated. 206 shows the change over time.

The source matching unit 104 and the bias matching unit 106 of the present example have the magnitude of the power Pf of the traveling wave at the timing during the arbitrary sampling state in the figure in each of the sample hold operation 203 and the sample hold operation 206. The parameters used for the matching operation, such as the magnitude Pr of the reflected wave power, the voltage difference between the traveling wave power and the phase difference θ of the current, are detected, and the matching is performed based on these values. The value detected at the timing in the Sampling state is maintained. In this embodiment, since only the bias power source 105 outputs in a pulse shape, the timing and period of the start and end of sampling and holding in each of the sample hold operation 203 and the sample hold operation 206 are made the same and synchronized. doing.

Such a sample-and-hold operation is performed in synchronism with the start and end timing and period of the traveling wave 204 of the pulsed power from the bias power source 105, and in the period when the pulse traveling wave is on. By obtaining the magnitude Pf, the magnitude Pr of the reflected wave power, and the phase difference θ between the voltage and current of the traveling wave power, both the source power source 103 and the bias power source 105 A stable matching operation can be performed with respect to the plasma load impedance condition during output. This sample and hold operation is performed based on an external trigger pulse signal input from the pulse generator 108 to the source matcher 104 and the bias matcher 106.

On the other hand, the reflected wave power 202 of the source power source 103 is generated in the off period when the bias power source 105 is not outputting. However, since the source matching unit 104 maintains an appropriate matching state with respect to the load impedance including the plasma output from the bias power source 105, fluctuations in the reflected wave power 202 of the source power source 103 are also suppressed and reproducibility is reduced. High etching processing can be performed.

FIG. 3 is a timing chart when the high-frequency power from the source power supply 103 and the bias power supply 105 is output in a pulse shape with the same timing, pulse width, and period in the embodiment shown in FIG. In this figure, the traveling wave power 301, the reflected wave power 302 of the source power source 103, the sample hold operation 303 of the source matching device 104, the traveling wave power 304 of the bias power source 105, the reflected wave power 305, and the sample hold operation of the bias matching device 106 are illustrated. The time change of 306 is shown respectively.

In this figure, unlike FIG. 2, the reflected wave power 302 of the source power supply 103 is kept constant at 0 W and does not occur during the off period when the bias power supply 105 is not outputting. On the other hand, the temporal changes of the traveling wave power 301 of the source power source, the sample hold operation 303 of the source matching unit 104, the traveling wave power 304 of the bias power source 105, the reflected wave power 305, and the sample hold operation 306 of the bias matching unit 106 are shown in FIG. Same as 2 ones. In this figure, the sample hold operation 303 of the source matcher 104 is a period during which the sampling hold operation 303 and the sample hold operation 306 are in the arbitrary sampling state in the figure, similarly to the sample hold operation 306 of the bias matcher 106. At the middle timing, parameters used for matching operations such as the magnitude Pf of the traveling wave power, the magnitude Pr of the reflected wave power, and the phase difference θ between the voltage and current of the traveling wave power are detected and set to these values. Matching is performed based on this value, and the value detected at the timing in the Sampling state is maintained at the timing during the Hold period, and matching based on the value is performed.

FIG. 4 is a timing chart when the high-frequency power from the source power source 103 and the bias power source 105 is output in a pulse shape with different timing, pulse width, and period in the embodiment shown in FIG. This example is a timing chart in the case where the pulse power of the bias power source 105 is made longer and backward than the source power source 103 and pulses are output at the same repetition period, and the traveling wave power 401 and the reflected wave power of the source power source 103 are shown. 402 shows the time change of the sample hold operation 403 of the source matching unit 104, the traveling wave power 404 of the bias power source 105, the reflected wave power 405, and the sample hold operation 406 of the bias matching unit 106.

FIG. 5 is a timing chart when the high-frequency power from the source power supply 103 and the bias power supply 105 is output in a pulse shape with different timing, pulse width, and period in the embodiment shown in FIG. In this example, the pulse width of the bias power source 105 is made longer than that of the source power source 103, and the pulse frequency is outputted to the source power source 103 by setting the repetition frequency of the bias power source 105 to ½ times. Time variation of traveling wave power 501 and reflected wave power 502 of the source power source 103, sample hold operation 503 of the source matching unit 104, traveling wave power 504 and reflected wave power 505 of the bias power source 105, and sample hold operation 506 of the bias matching unit 106 Respectively.

Similar to the example shown in FIG. 3, in FIGS. 4 and 5, the sample hold operation 503 of the source matcher 104 and the bias are also applied during the period in which both the pulsed outputs of the source power supply 103 and the bias power supply 105 are turned on. Both of the sample and hold operations 506 of the matching unit 106 are set to the sampling operation, and the periods coincide with each other. At the timing of these periods, parameters used for matching operations such as the magnitude Pf of the traveling wave power, the magnitude Pr of the reflected wave power, and the phase difference θ between the voltage and current of the traveling wave power are detected. Based on these values, load impedance is detected to perform matching of each power source. At the timing during the period of holding, the value detected at the timing in the sampling state is maintained, and matching based on the value is performed. To be implemented.

In the above example, in the period before or after the Sampling period, the reflected wave power 502 of the source power source 103 and the reflected wave powers 405 and 505 of the bias power source 105 are pulsed. In the present embodiment, the source matching unit 104 and the bias matching unit 106 can stably perform the matching operation with respect to the load impedance including the plasma even under such a condition that the power of the reflected wave is generated. 4 and 5, a reflected wave is generated at the timing when only one of the high-frequency power supplies is output. However, the value of the reflected wave is suppressed as in FIG. 2 due to the operation during the holding period, and the reproducibility is high. An etching process can be performed.

As described above, in the above embodiment, when the etching process is performed by outputting either one or both of the source power source 103 and the bias power source 105 and performing the etching process, the timing at which the source power source 103 and the bias power source 105 output is as follows. A signal for sample and hold operation is transmitted and transmitted to the source matcher 104 and the bias matcher 106 from the outside. Based on this timing, a required matching parameter is detected at a timing during the period when both power supplies are outputting, and one load impedance condition to be matched is detected, so that a stable matching operation is performed and processed. As a result, the variation in the processing shape is reduced and the processing yield is improved.

The same matching operation control method can be applied even when the pulse output of the source power supply 103 and the bias power supply 105 is power modulation in which two power levels of high power and low power are alternately repeated.

[Modification 1]
In the first embodiment of the present invention, when performing the etching process by outputting either or both of the source power supply 103 and the bias power supply 105 in a pulsed manner, the timing at which both the high-frequency power supplies are output from the outside. I was typing in. On the other hand, in the modification shown below, the source matching unit 104 and the bias matching unit 106 themselves recognize the timing at which both high-frequency power supplies are output without inputting a trigger signal from the outside, and the sample hold operation is performed. An example of a configuration for performing the above will be described.

A modification of the above embodiment will be described with reference to FIGS. The outline of the configuration of the plasma processing apparatus according to this example is the same as that of the embodiment shown in FIG. 1, and the description of the same configuration as that of this example shown here will be omitted. FIG. 6 is a block diagram schematically showing the outline of the configuration of the matching device provided in the plasma processing apparatus according to this example. This figure is a matching unit used as the source matching unit 104 or the bias matching unit 106 of the apparatus of FIG. 1 in particular, and by adding an RF sensor to the configuration of the source matching unit 104 or the bias matching unit 106, Each has a configuration capable of monitoring not only the high-frequency power output from the power source to be matched but also the presence or absence of high-frequency power output from the other power source.

Although the source matching unit 104 is described in FIG. 6, the bias matching unit 106 can have an equivalent configuration. In this figure, the source matching unit 104 includes an input terminal 601, an RF sensor 602, a first variable capacitor 603, a coil 604, a second variable capacitor 605, a cut filter 606, an output terminal 607, a control unit 608, and a first. A variable capacitor control stepping motor 609, a second variable capacitor control stepping motor 610, and an RF sensor 611 are provided.

The source matching unit 104 detects the traveling wave power Pf and reflected wave power Pr in the RF sensor 602 during processing of the wafer 114, and the phase difference θ between the voltage and current of the traveling wave power, and according to the calculation result in the control unit 608. The first variable capacitor control stepping motor 609 and the second variable capacitor control stepping motor 610 are driven. With this operation, the high frequency power from the source power source 103 is matched so that the load impedance viewed from the input terminal 601 of the source matching unit 104 matches the characteristic impedance of the source power source 103 (bias power source 105).

Further, a cut filter 606 is disposed on the output end side of the source matching unit 104 in order to cut off the high frequency power output from the bias power source 105 (source power source 103). That is, the high frequency power output from the bias power source 105 (source power source 103) flows into the ground by the cut filter 606 in the source matching unit 104. By providing an RF sensor 611 between the cut filter 606 and the ground and inputting a signal to the control unit 608, the control unit 608 can recognize the timing at which both high-frequency power supplies are output.

In this manner, the source matching unit 104 and the bias matching unit 106 themselves can recognize the timing at which both high frequency power supplies are output, so that the first embodiment can be used without inputting a trigger signal from the outside. The matching operation can be performed by the same sample and hold operation. Unlike the first embodiment, since the timing can be defined by the actually output high frequency power, there is no timing shift due to the rise time and fall time of the high frequency power, and the sample hold operation can be performed with high accuracy.

The same control method can be applied even to a matching circuit different from the circuit configurations of the source matching unit 104 and the bias matching unit 106 shown in FIG.

In the modified example, by adding the RF sensor 611 to the source matching unit 104 and the bias matching unit 106, not only the high frequency power to be matched but also the presence or absence of the output of the other high frequency power is recognized, and the trigger signal is externally received. A control method for performing the sample-and-hold operation without input is described. In contrast, in the embodiment described below, a method for recognizing and controlling the timing at which the source power supply 103 and the bias power supply 105 are output without adding the RF sensor 611 will be described. Note that the second embodiment is limited to the source matching unit 104 that is a matching unit for the source power source 103 having a higher frequency than the high frequency power output from the bias power source 105.

A second embodiment of the present invention will be described with reference to FIGS. The plasma processing apparatus according to the second embodiment of the present invention is the same as that of the first embodiment, as shown in FIG. FIG. 7 is a circuit configuration diagram of the source matching device 104 according to the second embodiment of the present invention, in which the RF sensor 611 is removed from the circuit configuration of the matching device according to the first modification of FIG. It is.

For example, when a source power source 103 with a frequency of 200 MHz and a bias power source 105 with a frequency of 4 MHz are used, the reflected wave power Pr observed in the RF sensor 702 of the source matching unit 104 shown in FIG. A side band of 200 MHz ± 4 MHz × n (n is a natural number) is observed. FIG. 8 is an actual measurement result of the frequency spectrum of the reflected wave power Pr observed in the RF sensor 602 of the source matching unit 104.

As shown in FIG. 8, side bands are observed on both sides of 200 MHz. Since only the timing at which both the source power supply 104 and the bias power supply 105 are output is observed in this sideband, the signal level of 196 MHz or 204 MHz is monitored by the control unit 708 of the source matcher 104, whereby the source matcher The timing at which the sample and hold operation 104 is performed can be defined, and the same matching operation as in the first embodiment can be performed.

Note that the same control method can be applied to a matching circuit different from the circuit configuration of the source matching unit 104 shown in FIG. Further, even when the frequency is different from the frequency of the source power supply 103 and the bias power supply 105 described in the example, the RF sensor 702 of the source matching device 104 has a frequency resolution capable of recognizing the observed frequency of the source power supply 103 and the sideband separately. If there is, the same control method can be applied.

DESCRIPTION OF SYMBOLS 101 ... Processing chamber 102 ... Turbo molecular pump 103 ... Source power supply 104 ... Source matching device 105 ... Bias power supply 106 ... Bias matching device 107 ... Controller 108 ... Pulse generator 109 ... Planar antenna 110 ... Shower plate 111 ... Sample stand 112 ... Gas inlet 113 ... solenoid coil 114 ... wafer 115 ... plasma 121 ... source power source control unit 122 ... source power source oscillation unit 123 ... source power source distribution unit 124 ... source power source amplification unit 125 ... source power source synthesis unit 126 ... Source power source high frequency detector 131... Bias power source controller 132... Bias power source oscillator 133... Bias power source distributor 134... Bias power source amplifier 135. ... Matching device input terminal 602 ... Matching pair in matching device RF sensor for high-frequency power 603 ... first variable capacitor 604 of matching device ... coil 605 of matching device ... second variable capacitor 606 of matching device ... cut filter 607 of matching device ... output terminal 608 of matching device ... matching Controller 609... Matching device first variable capacitor control stepping motor 610... Matching device second variable capacitor control stepping motor 611... RF sensor 701 for matching high frequency power in matching device. Input terminal 702... RF sensor for high frequency power 703 to be matched in matching device... First variable capacitor 704 for matching device. Coil 705 for matching device. Second variable capacitor 706 for matching device. Filter 707 ... Matching device output terminal 708 ... Matching device controller 709 ... Matching device first variable capacitor control switch Ppingumota 710 ... stepping motor for the second variable capacitor controlling matching unit

Claims (8)

A processing chamber disposed inside the vacuum chamber and depressurized inside, a sample stage placed in the processing chamber and on which a wafer to be processed is placed, and a first for forming plasma above the sample stage in the processing chamber And a second high-frequency power source for supplying a second high-frequency power for forming a bias potential on the wafer to the electrode disposed in the sample stage. And
In the case where at least one of the first and second high-frequency powers repeatedly outputs different values of high and low for a predetermined period, respectively, at a specific period, both the first and second high-frequency powers have high outputs. And a matching unit that performs matching on the one high-frequency power using information on the one high-frequency power detected at the time of output at the time, and at least one of the first and second high-frequency powers A plasma processing apparatus in which the information detected at the time point is held while not being output at a high output.
The plasma processing apparatus according to claim 1,
The plasma processing apparatus that performs matching for the one high-frequency power based on a result of the matching unit that performs matching for the one high-frequency power detecting the other high-frequency power flowing inside.
The plasma processing apparatus according to claim 1,
A plasma processing apparatus that performs matching for one of the high-frequency powers based on a result of the matching unit that performs matching for the one high-frequency power detecting a reflected wave of one of the high-frequency powers.
A plasma processing apparatus according to any one of claims 1 to 3,
The plasma processing apparatus, wherein the matching unit performs matching in this period using the information held in a period in which at least one of the first and second high-frequency powers is not output at a high output.
A wafer to be processed is placed on a sample stage disposed in a decompressed processing chamber inside the vacuum vessel, and a first high frequency power is supplied into the processing chamber to form plasma in the processing chamber above the sample stage, A plasma processing method of processing a wafer by supplying a second high frequency power to an electrode disposed in the sample stage to form a bias potential on the wafer,
Repeating at a specific cycle that at least one of the first and second high-frequency powers outputs different values of high and low for a predetermined period, respectively,
Performing matching on the one high-frequency power using information on the one high-frequency power detected at a time when both the first and second high-frequency powers are output at a high output; And a step of holding the information detected at the time point while at least one of the first and second high-frequency power is not output at a high output.
The plasma processing method according to claim 5,
A plasma processing method for performing matching for one of the high-frequency powers based on a result of detecting the other high-frequency power flowing in a circuit that performs matching for the one high-frequency power.
The plasma processing method according to claim 5,
A plasma processing method for performing matching for one of the high frequency powers based on a result of detecting a reflected wave of the one of the high frequency powers.
A plasma processing method according to any one of claims 5 to 7,
A plasma processing method comprising a step of performing matching in this period using the information held in a period in which at least one of the first and second high-frequency powers is not output at a high output.

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