JP4123945B2 - Plasma processing apparatus and method for measuring high frequency characteristics of plasma processing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus using a high frequency and a high frequency characteristic measuring method of the plasma processing apparatus.
[0002]
[Prior art]
In plasma processing apparatuses used for semiconductor manufacturing, there are problems such as time-dependent changes in apparatuses and processes that hinder the stable operation of apparatuses, and machine-to-apparatus differences in mass production. However, there is no conventional method for detecting changes over time or machine differences between devices, and it is determined that an abnormality has occurred when a problem has occurred in the actually processed product, and maintenance of the device is performed. is doing.
[0003]
Further, in order not to cause a defect in the product, it has been dealt with by regularly estimating the time when the apparatus / process changes with time and an abnormality occurs based on experience, and regularly maintaining the apparatus.
[0004]
On the other hand, a method of electrically detecting a change in apparatus or process in a plasma processing apparatus has been devised. For example, a directional coupler is inserted between the plasma processing chamber and the high-frequency power source, and signals of phase and amplitude of traveling wave and reflected wave power are respectively taken out by the directional coupler. Then, by processing the extracted signal, the impedance, which is one of the high-frequency characteristics of the plasma processing apparatus, is obtained, and the change over time of the apparatus / process is evaluated from the change, or it is fed back to the plasma processing apparatus and the plasma processed. A method for optimizing processing conditions and achieving stable operation of the apparatus is shown (for example, see Patent Document 1).
[0005]
[Patent Document 1]
JP 2000-195698 A (page 2-4)
[0006]
[Problems to be solved by the invention]
In general, measurement in a wide frequency range is desirable to accurately grasp the high-frequency characteristics of a high-frequency circuit. Furthermore, in order to measure the change in high frequency characteristics with higher accuracy, it is preferable to evaluate in a frequency band where the change in high frequency characteristics is large.
[0007]
However, the preceding example is a method of measuring the impedance of the entire plasma processing apparatus including plasma at a high frequency of an oscillation frequency (for example, 13.56 MHz) of a high frequency power supply. Therefore, the traveling wave and the reflected wave obtained are high frequency signals of 13.56 MHz, and the impedance obtained from the signals is a value at a frequency of 13.56 MHz. Therefore, in the preceding example, only the impedance of the plasma processing apparatus including plasma at a single frequency of the high-frequency power source of the plasma processing apparatus can be obtained. For this reason, there is a problem that the high frequency characteristics cannot be accurately grasped, and the change in the high frequency characteristics cannot be measured with high accuracy.
[0008]
The present invention has been made to solve the above-described problems, and is a plasma processing apparatus capable of measuring high-frequency characteristics with high accuracy, particularly plasma processing capable of accurately measuring high-frequency characteristics during plasma generation. An object of the present invention is to obtain a method for measuring high-frequency characteristics of an apparatus and a plasma processing apparatus.
[0009]
[Problems to be solved by the invention]
The plasma processing apparatus of the present invention has a high-frequency power source that supplies high-frequency power to an electrode installed in a processing chamber, and a directionality that is inserted so that the high-frequency power is transmitted between a transmission line that connects the electrode and the high-frequency power source. A variable frequency generator connected to a terminal coupled to the terminal connected to the electrode of the directional coupler and applying a high frequency signal of a desired frequency to the electrode; and the directional coupler A high-frequency characteristic detector connected to a terminal connected to the electrode and connected to a terminal to measure a reflected wave from the electrode of a high-frequency signal applied from the variable frequency generator. When the plasma is generated in the processing chamber with the high frequency power supplied from the high frequency power source, at least one of the reflected wave and the transmitted wave of the high frequency signal applied from the variable frequency generator is measured by the high frequency characteristic detector. It is characterized by doing.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below.
FIG. 1 is a configuration diagram of a plasma processing apparatus according to the present embodiment. In FIG. 1, a lower electrode 4 and an upper electrode 6 on which a wafer 5 is placed are installed in a processing chamber 1. The lower electrode 4 includes a lower electrode plate 2 formed on the surface, and an insulating member 3 that electrically insulates the lower electrode plate 2 from the processing chamber 1 and vacuum seals it. Here, the lower electrode plate 2 and the upper electrode 6 are installed on parallel plates. The processing chamber 1 is provided with an exhaust port 8 connected to a vacuum pump (not shown) for exhausting to a vacuum and a gas introduction port 7 for introducing an etching gas. Both the upper electrode 6 and the chamber of the processing chamber 1 are at ground potential. The lower electrode plate 2 is connected to a high frequency power source 10. The oscillation frequency of the high frequency power supply 10 is 13.56 MHz. A directional coupler 9 is inserted between the high frequency power supply 10 and the lower electrode 2.
[0011]
Here, the directional coupler 9 will be described.
The directional coupler 9 has a total of four terminals: two input terminals 9a and 9b, a coupling terminal 9c coupled to the input terminal 9b, and a coupling terminal 9d coupled to the input terminal 9a. The relationship between the four terminals is as follows. The high frequency incident from the input terminal 9a is transmitted to the input terminal 9b, and at the same time, a part thereof is output to the coupling terminal 9d coupled to the input terminal 9a. However, it is hardly output to the coupling terminal 9c that is not coupled to the input terminal 9a. On the other hand, the high frequency incident from the input terminal 9b is transmitted to the input terminal 9a, and at the same time, a part thereof is output to the coupling terminal 9c coupled to the input terminal 9b. However, it is hardly output to the coupling terminal 9d that is not coupled to the input terminal 9b.
[0012]
The ratio at which the high frequency transmitted from the input terminal 9a is output to the coupling terminal 9d is called the degree of coupling, and is, for example, 60 decibels here. That is, when a high frequency of 1000 W is input to the input terminal 9a, a high frequency signal attenuated to 1 mW is output to the coupling terminal 9d. Similarly, the high frequency incident on the input terminal 9b is also attenuated to the coupling terminal 9c at a rate of 60 decibels and a high frequency signal is output. The difference between the outputs of the coupling terminals 9c and 9d is called the directionality of the directional coupler, and is, for example, 20 decibels here.
[0013]
In the present embodiment, the high frequency power supply 10 and the input terminal 9a of the directional coupler 9 are connected. Further, the lower electrode plate 2 and the input terminal 9b of the directional coupler are connected. A network analyzer 11 is connected to the coupling terminal 9c coupled to the input terminal 9b.
[0014]
Here, the network analyzer will be described. A network analyzer is a measuring apparatus that obtains high-frequency characteristics of a circuit or element by inputting a high-frequency signal to the circuit or element and measuring a reflected wave or a passing wave from the circuit. The configuration of the apparatus has both a variable frequency generator that sweeps and inputs a signal having a frequency in a range to be measured on a measurement object and a high-frequency characteristic detector that measures a reflected wave and a transmitted wave from the measurement object of the swept input signal.
[0015]
With the above configuration, when high-frequency power is supplied from the high-frequency power supply 10, the reflected wave from the lower electrode plate 2 is attenuated by 60 dB and output to the coupling terminal 9 c of the directional coupler 9. . On the other hand, the incident wave from the high frequency power supply is attenuated to 80 decibels, which is the sum of the degree of coupling and the directionality, and is output. Since the incident wave signal output from the coupling terminal 9c is a minute signal attenuated to 80 decibels, it is sufficiently smaller than the reflected wave signal attenuated to 60 decibels, and the reflected wave is not affected by the incident wave. Can be taken out.
[0016]
Note that the degree of coupling and the directionality of the directional coupler are not limited to the above values, and the degree of coupling and the directionality may be appropriately selected in order to obtain a desired output.
[0017]
Next, plasma processing in the plasma processing apparatus having this configuration will be described. The etching gas introduced into the processing chamber 1 from the gas introduction port 7 is exhausted from the exhaust port 8. Etching gas is N ₂ Or an inert gas of Ar or various reactive gases. When high frequency power is supplied from the high frequency power source 10 to the lower electrode plate 2 in this state, discharge is started between the lower electrode plate 2 and the upper electrode 6 to generate plasma. When high-frequency power is supplied from the high-frequency power supply 10, it is generally performed via an impedance matching device, but is omitted here. The wafer 5 is etched by the generated plasma. When the predetermined etching process is completed, the supply of high frequency power is stopped, the etching gas is exhausted, and then the wafer 5 is replaced. By repeating the above operation, the wafer 5 is continuously etched.
[0018]
Next, the operation according to the present embodiment will be described in detail. When performing the plasma processing, high frequency power is supplied from the high frequency power source 10. At the same time, a signal in a frequency range to be measured is output from the network analyzer 11 and a signal is input from the coupling terminal 9c. Here, a signal of 1 to 50 MHz is input. Here, the coupling terminal 9c of the directional coupler 9 is a combination of the high frequency power supplied from the high frequency power supply 10 that passes through the directional coupler 9 and the 1 to 50 MHz signal input from the coupling terminal 9c. The reflected wave is attenuated by 60 dB and output. On the other hand, an incident wave of high-frequency power fed from the input terminal 9 a is hardly output because it is attenuated by 80 dB to the coupling terminal 9 c due to the directionality of the directional coupler 9. By using the directional coupler having this directionality, the reflected wave can be measured without being affected by the input wave. From this measurement result, impedance can be measured by the reflection method.
[0019]
A bandpass filter may be attached to the coupling terminal 9 c of the directional coupler so that a 13.56 MHz signal is not input to the network analyzer 11. In this way, the impedance can be measured without being affected as much as possible by the high frequency of 13.56 MHz.
[0020]
FIG. 2A shows the measurement result of the impedance characteristics at 1 to 50 MHz in the initial state of the apparatus measured by the operation according to the present embodiment. FIG. 2B shows the result of measuring the impedance in the frequency range of 1 to 50 MHz by the same measurement method without generating plasma in the initial state of the apparatus. In addition, a horizontal axis is a measurement frequency and a vertical axis | shaft is an impedance.
[0021]
As shown in FIGS. 2A and 2B, the impedance changes greatly with respect to the frequency. In FIG. 2 (a), a resonance characteristic having a minimum impedance is observed near 27 MHz, and in FIG. 2 (b), the impedance is minimum near 30 MHz.
Here, FIG. 2 (b) is a combination of a high-frequency power source 10, which is a main component of the plasma processing apparatus, and a resistance component, an induction component, and a capacitance component inside the processing chamber 1 including the lower electrode 4 and the upper electrode 6. The impedance characteristics are shown. The resonance in the vicinity of 30 MHz is L and C resonance characteristics due to the electrical induction component and capacitance component in the device. On the other hand, FIG. 2 (A) shows the upper electrode 6 and the lower electrode in the impedance characteristic obtained by synthesizing the resistance component, the induction component, and the capacitance component inside the processing chamber 1 including the high-frequency power source 10 and the lower electrode 4 and the upper electrode 6. The impedance characteristic of plasma generated between the plate 2 and the plate 2 is superimposed.
[0022]
If such a resonance characteristic cannot be obtained due to the configuration of the apparatus, the impedance characteristic in the frequency region where the impedance change is large may be measured. Furthermore, the impedance characteristics may be measured for a plurality of single frequencies, not in the continuous frequency range.
[0023]
Next, FIG. 3A shows impedance characteristics during plasma generation when the etching process is continuously performed for one month. Here, the impedance characteristic in the initial state of the apparatus is also shown in FIG. FIG. 3 (b) shows the same measurement results as FIG. 2 (b). When both are compared, it can be seen that the impedance near the resonance frequency has changed greatly.
[0024]
The impedance characteristic measured here is as described above, and the upper electrode 6 and the lower electrode are combined with the impedance characteristic obtained by synthesizing the resistance component, the induction component, and the capacitance component inside the processing chamber 1 including the high-frequency power source 10 and the lower electrode 4 and the upper electrode 6. The impedance characteristic of plasma generated between the electrode plate 2 and the electrode plate 2 is superimposed.
The large change in the impedance characteristic is the impedance characteristic obtained by synthesizing the resistance component, the induction component, and the capacitance component inside the processing chamber 1 including the high-frequency power source 10 and the lower electrode 4 and the upper electrode 6, or the upper electrode 6 and the lower electrode. It is considered that this occurred due to a change in impedance characteristics of plasma generated between the plate 2 and the plate 2.
[0025]
When such a device change or plasma change occurs, the etching characteristics change, resulting in a problem that the predetermined etching cannot be performed.
Therefore, when such a change in impedance characteristic occurs, it can be determined that it is necessary to stop the etching process and perform inspection and maintenance of the apparatus.
[0026]
Here, the present invention is compared with the conventional method. The impedance at a frequency of 13.56 MHz on the graph of FIG. 3 is the impedance measured by the conventional method. As is apparent from the graph, the impedance at 13.56 MHz is almost the same between the initial state and after one month of continuous processing. That is, it can be seen that the state of the etching apparatus cannot be determined accurately from the impedance change at a single frequency. On the other hand, according to the present invention, it is possible to measure high frequency characteristics including a resonance frequency region having a large impedance change and impedance characteristics over a wide range of 1 to 50 MHz. Therefore, even a slight change in the state of the plasma processing apparatus can be detected. Therefore, the difference from the normal high-frequency characteristic can be determined with high accuracy.
[0027]
Next, a method for determining whether the change in impedance characteristics is due to the abnormality of the apparatus or the change in plasma characteristics using this method will be described. When the impedance characteristic is significantly different from the initial state, first, the impedance characteristic is measured in the absence of plasma. The measured impedance characteristics in the absence of plasma are compared with the impedance characteristics in the initial state. If the two impedance characteristics match, it can be determined that the state of the apparatus in the absence of plasma has not changed from the initial state.
[0028]
That is, it is considered that the impedance characteristics of the plasma are changing.
When the etching process is performed for a long time, the etching product gradually adheres to the inner wall of the processing chamber 1 including the lower electrode 4 and the upper electrode 6. Alternatively, the members in the processing chamber 1 are consumed by the etching gas. For this reason, the internal state of the processing chamber 1 changes, and the impedance characteristics of the plasma change. Alternatively, it is considered that the impedance characteristics of the plasma are changed because the discharge conditions are changed.
[0029]
In the above case, measures such as confirmation of variation in process conditions and cleaning to return the inner wall of the processing chamber to the initial state may be taken.
[0030]
On the other hand, if the impedance characteristics in the state where the plasma is not generated and the impedance characteristics in the state where the plasma is not generated in the initial state are different when the impedance characteristics during the generation of the plasma are significantly different from the initial state, the etching apparatus It shows that the state of has changed. That is, the resistance component, the induction component, and the capacitance component inside the processing chamber 1 including the high-frequency power source 10 of the etching apparatus and the lower electrode 4 and the upper electrode 6 are changed. In this case, maintenance of the device may be performed to return the device state to a normal state.
[0031]
In the case of the impedance characteristic determined to be abnormal as shown in FIG. 3C, as a result of investigating the cause by the above method, the consumption of the stage member of the plasma processing apparatus, the high frequency power supply 10 and the lower electrode plate 2 are It was found that the cause was the looseness of the tightening part of the connecting cable.
[0032]
As described above, by adopting the configuration of the present embodiment, it is possible to measure the high frequency characteristics of the plasma processing apparatus at an arbitrary frequency. In particular, it is possible to measure high frequency characteristics at an arbitrary frequency even during plasma generation.
[0033]
As a result, it is possible to monitor the high frequency characteristics of a frequency that is sensitive to a change in the state of the apparatus, and to accurately know minute fluctuations in the apparatus state.
[0034]
In addition, the cause of the fluctuation of the high frequency characteristics can be determined immediately and accurately.
[0035]
Embodiment 2. FIG.
FIG. 4 is a configuration diagram of an electron cyclotron resonance (ECR) plasma processing apparatus according to the present embodiment. In FIG. 4, the processing chamber 1 is provided with a vacuum-sealed microwave introduction window 21. The waveguide 22 is installed so that one end face thereof is connected to the microwave introduction window 21, and a microwave generator 23 that generates a microwave of 2.45 GHz is connected to the other end face of the waveguide 22. Yes. Furthermore, a magnetic field generating coil 24 for generating electron cyclotron resonance is provided on the outer periphery of the processing chamber 1.
[0036]
Since the lower electrode 4, the wafer 5, the gas inlet port 6, the exhaust port 8, the directional coupler 9, the high frequency power source 10, and the network analyzer 11 are the same as those in the first embodiment, the description thereof is omitted.
[0037]
The operation in this embodiment will be described.
The etching gas introduced into the processing chamber 1 is exhausted from the exhaust port 7. When a microwave is generated from the microwave generator 23 in this state, the microwave is supplied from the waveguide 22 into the processing chamber 1 through the microwave introduction window 21. When a magnetic field coil generates a magnetic field of, for example, 875 Gauss, ECR (electron cyclotron resonance) plasma is generated in the processing chamber 1. Further, when high frequency power is supplied from the high frequency power supply 10 to the lower electrode plate 2, an RF bias is applied to the lower electrode plate 2. When high-frequency power is supplied from the high-frequency power supply 10, it is generally performed through an impedance matching device, but is omitted here. The wafer 5 is etched by the generated ECR plasma and RF bias. When the predetermined etching process is completed, the supply of high-frequency power and the supply of microwave are stopped, the etching gas is exhausted, and the wafer 5 is replaced. By repeating the above operation, the wafer 5 is continuously etched.
[0038]
In such an ECR plasma etching apparatus, impedance is measured by the same method as in the first embodiment. By doing so, even in an etching apparatus using ECR plasma, the high frequency characteristics of the plasma processing apparatus at an arbitrary frequency can be measured. In particular, it is possible to measure high frequency characteristics at an arbitrary frequency even during plasma generation.
[0039]
As a result, it is possible to monitor the high frequency characteristics of a frequency that is sensitive to a change in the state of the apparatus, and to accurately know minute fluctuations in the apparatus state.
[0040]
In addition, the cause of the fluctuation of the high frequency characteristics can be determined immediately and accurately.
[0041]
Embodiment 3 FIG.
FIG. 5 is a configuration diagram of an inductively coupled plasma (ICP) processing apparatus according to the present embodiment. In FIG. 5, the processing chamber 1 is provided with a dielectric bell jar 31 which is vacuum-sealed. An ICP coil 32 is installed on the outer periphery of the dielectric bell jar 31. Further, an ICPRF power source 33 connected to supply high frequency power to the ICP coil 32 is provided.
[0042]
Since the lower electrode 4, the wafer 5, the gas inlet port 6, the exhaust port 8, the directional coupler 9, the high frequency power source 10, and the network analyzer 11 are the same as those in the first embodiment, the description thereof is omitted.
[0043]
Next, the operation in this embodiment will be described.
The etching gas introduced into the processing chamber 1 is exhausted from the exhaust port 7. When high frequency power is supplied from the ICPRF power source 33 to the ICP coil 32 in this state, inductively coupled plasma is generated in the dielectric bell jar 31. Further, when high frequency power is supplied from the high frequency power supply 10 to the lower electrode plate 2, an RF bias is applied to the lower electrode plate 2. When high-frequency power is supplied from the high-frequency power supply 10, it is generally performed through an impedance matching device, but is omitted here. The wafer 5 is etched by the generated ICP plasma and RF bias. When the predetermined etching process is completed, the supply of the high frequency power from the high frequency power supply 10 and the ICPRF power supply 32 is stopped, the etching gas is exhausted, and then the wafer 5 is replaced. By repeating the above operation, the wafer 5 is continuously etched.
[0044]
In such an ECR plasma etching apparatus, impedance is measured by the same method as in the first embodiment. By doing so, even in an etching apparatus using inductively coupled plasma, the high frequency characteristics of the plasma processing apparatus at an arbitrary frequency can be measured. In particular, it is possible to measure high frequency characteristics at an arbitrary frequency even during plasma generation.
[0045]
As a result, it is possible to monitor the high frequency characteristics of a frequency that is sensitive to a change in the state of the apparatus, and to accurately know minute fluctuations in the apparatus state.
[0046]
In addition, the cause of the fluctuation of the high frequency characteristics can be determined immediately and accurately.
[0047]
Embodiment 4 FIG.
FIG. 6 is a configuration diagram of the plasma processing apparatus according to the present embodiment. In the present embodiment, instead of the network analyzer 11 in the first embodiment, a high-frequency current voltage detector 42 is connected to a coupling terminal 9c coupled to the input terminal 9b of the directional coupler 9. Similarly, the variable frequency generator 41 is connected to the coupling terminal 9c. Since others are the same as those of the first embodiment, description thereof is omitted.
[0048]
The variable frequency generator 41 oscillates a high frequency signal having a frequency of 1 to 50 MHz and applies the high frequency signal to the lower electrode plate 2 through the directional coupler 9. In the present embodiment, the high-frequency signal to be applied is about microwatts to milliwatts that does not affect the process. And the high frequency current voltage of the reflected wave of the high frequency signal applied in the high frequency current voltage detector 42 is measured. The impedance can be calculated from the current and voltage measurement results. The apparatus state can be grasped from the change in impedance by the method described in the first embodiment.
[0049]
By using the above configuration, impedance characteristics over a wide range of frequencies can be measured by an inexpensive and simple method.
[0050]
Embodiment 5. FIG.
FIG. 7 shows a configuration diagram of the plasma processing apparatus according to the present embodiment. In FIG. 7, the upper electrode 53 includes an upper electrode plate 51 formed on the surface and an insulating member 52 that insulates the upper electrode plate 51 from the processing chamber 1 and vacuum seals it. Since the processing chamber 1 and the lower electrode 4 have the same configuration as that of the first embodiment, description thereof is omitted. The lower electrode plate 2 is connected to the first high frequency power supply 55. The upper electrode plate 51 is electrically connected to the second high frequency power source 57. The oscillation frequencies of the first high frequency power supply 55 and the second high frequency power supply 57 are both 13.56 MHz. A first directional coupler 54 is inserted between the first high frequency power supply 55 and the lower electrode plate 2. Similarly, a second directional coupler 56 is inserted between the second high frequency power source 57 and the upper electrode plate 53.
[0051]
The connection of the first directional coupler 54 is as follows. The first high-frequency power source 55 and the input terminal 54a of the first directional coupler 54 are connected, and the lower electrode plate 2 and the input terminal 54b of the first directional coupler 54 are connected. The network analyzer 11 is connected to a coupling terminal 54c that is coupled to the input terminal 54b of the first directional coupler 54.
The second high frequency power source 57 and the input terminal 56a of the first directional coupler 56 are connected, and the upper electrode plate 51 and the input terminal 56b of the second directional coupler 56 are connected. Yes. Further, the network analyzer 11 is connected to the coupling terminal 56 c coupled to the input terminal 56 b of the second directional coupler 56.
[0052]
Here, the degree of coupling and the directionality between the terminals of the directional coupler are as follows. In the first directional coupler 54, the degree of coupling between the input terminal 54a and the coupling terminal 54d coupled to the input terminal 54a is 60 dB. The degree of coupling between the input terminal 54b and the coupling terminal 54c coupled to the input terminal 54b is also 60 dB. Furthermore, the directivity of the coupling terminal 54c and the coupling terminal 54d is 20 dB. Also in the second directional coupler 56, as in the first directional coupler 54, the degree of coupling between the input terminal 56a and the coupling terminal 56d and the coupling between the input terminal 56b and the coupling terminal 56c. Both degrees are 60 decibels, and the directionality of the coupling terminal 56c and the coupling terminal 56d is 20 decibels.
[0053]
Next, the operation in this embodiment will be described. The plasma processing apparatus according to the present embodiment is a two-frequency excitation parallel plate etching apparatus that feeds a high frequency to both the upper electrode plate 51 and the lower electrode plate 2. In the case of this plasma processing apparatus, high frequency power is supplied from the first high frequency power supply 55 and the second high frequency power supply 57 to generate plasma. At that time, a desired high-frequency signal is applied to the coupling terminal 54 c of the first directional coupler 54 using the network analyzer 11. A part of the applied high frequency signal is output as a reflected wave from the coupling terminal 54 c of the first directional coupler 54. Another part of the applied high-frequency signal propagates through the lower electrode plate 2, plasma, and upper electrode plate 51. The transmitted wave of the high-frequency signal is output from the coupling terminal 56 c of the second directional coupler 56 together with the reflected wave from the upper electrode plate 51. The transmitted wave and reflected wave of the applied high frequency signal are measured by the network analyzer 11.
[0054]
By using this method in a plasma processing apparatus, not only high-frequency reflection characteristics but also transmission characteristics can be measured.
Therefore, it is possible to measure impedance characteristics in a state where there is plasma with higher accuracy. As a result, the state of the apparatus can be determined with higher accuracy.
In the transmission method, the state of the upper electrode plate 51 can be accurately grasped by measuring the transmitted wave that has passed through the upper electrode plate 51.
[0055]
Note that the degree of coupling and the directionality of the directional coupler are not limited to the above values, and the degree of coupling and the directionality may be appropriately selected in order to obtain a desired output.
[0056]
Embodiment 6 FIG.
FIG. 8 is a configuration diagram of the plasma processing apparatus according to the present embodiment. In the present embodiment, a correction circuit 81 is inserted between the directional coupler 9 and the lower electrode 2. Further, a control device 82 for controlling the correction circuit 81 is connected so as to appropriately adjust the impedance based on the measurement result of the network analyzer 11. Others are the same as those in the first embodiment, and thus the description is omitted. The correction circuit 81 corrects the impedance characteristic when the impedance characteristic of the plasma processing apparatus is different from the normal state.
[0057]
FIG. 9 is a configuration diagram of the correction circuit 81. The correction circuit 81 includes a changeover switch 92 that switches whether the correction element unit 91, the directional coupler 9, and the upper electrode 2 are directly connected or the correction element unit 91 is inserted.
[0058]
Next, a method for correcting the impedance characteristic by the correction circuit 81 will be described.
In a normal state, the directional coupler 9 and the lower electrode 2 are directly connected by the changeover switch 92 of the correction circuit 81 based on an instruction from the control device 82.
[0059]
Next, when the impedance characteristic is different from the normal impedance characteristic, when the impedance characteristic needs to be corrected, the changeover switch 92 is switched based on an instruction from the control device 82, and the correction element unit 91 is connected to the directional coupler 9. Connect to the lower electrode 2. As a result, the correction element unit 91 is inserted into the high-frequency power feeding system. When the correction element unit 91 is inserted, the impedance characteristic viewed from the directional coupler 9 is a combination of the impedance of the apparatus and the impedance of the correction element unit 91. And the impedance characteristic of the correction | amendment element part 91 is adjusted based on the instruction | indication from the control apparatus 81 so that it may become a normal state impedance characteristic, and the synthetic | combination impedance characteristic is correct | amended.
[0060]
Here, the correction of the impedance characteristic will be described. When the impedance characteristic viewed from the directional coupler is deviated from the normal impedance characteristic and the capacitance component becomes large, the variable inductive element of the correction element unit 91 is changed to cancel the displaced capacitance component amount. On the contrary, when the inductive component becomes large, the variable capacitance element of the correction element unit 91 is changed to cancel the shifted inductive component amount. As a result, the device impedance including the impedance of the correction element unit 91 viewed from the directional coupler becomes the same as the impedance when the device is in a normal state.
[0061]
According to the present embodiment, by correcting the impedance characteristics based on the measured impedance characteristics, stable plasma treatment can be performed over a long period of time, maintenance frequency can be reduced, and the operating rate of the apparatus Can be increased.
[0062]
Here, the correction element unit 91 may be inserted at any position between the high-frequency power source 10 and the lower electrode 2, but the directional coupler 9 and the lower electrode 2 for measuring the impedance characteristics of the plasma processing apparatus. It is desirable to insert between. This is because the measurement error of the impedance characteristic becomes smaller when the correction element portion 91 is inserted between the directional coupler 9 and the lower electrode 2.
[0063]
In the present embodiment, an example in which there is one high-frequency power source is shown, but it is also possible to apply to a two-frequency excitation type plasma etching apparatus that has a high-frequency power source for the opposing electrodes.
[0064]
Furthermore, although an example of a parallel plate type plasma etching apparatus has been described in this embodiment, it can be applied to an ECR plasma etching apparatus or an inductively coupled plasma etching apparatus.
[0065]
Further, in the above description, the correction of the impedance characteristic when the impedance characteristic of the plasma processing apparatus changes with time has been described. However, when the impedance characteristic is different among a plurality of plasma processing apparatuses, the normal impedance characteristic that becomes a reference In addition, the present invention is also applicable when correcting the impedance characteristics of each plasma processing apparatus.
[0066]
Here, when the plasma processing apparatus is newly introduced, the normal impedance characteristic as a reference is considered to be an impedance characteristic at the witness test when delivered to the factory. However, the present invention is not limited to this, and the impedance characteristics of an apparatus that can obtain desired etching characteristics may be appropriately selected.
[0067]
【The invention's effect】
As described above, according to the present invention, the high frequency characteristics of the plasma processing apparatus at an arbitrary frequency can be measured. In particular, it is possible to measure high frequency characteristics at an arbitrary frequency even during plasma generation.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a plasma processing apparatus according to a first embodiment.
FIG. 2 is a diagram showing impedance characteristics in the initial state of the plasma processing apparatus according to the first embodiment.
FIG. 3 is a diagram showing impedance characteristics during plasma generation in the plasma processing apparatus according to the first embodiment.
FIG. 4 is a configuration diagram of a plasma processing apparatus according to a second embodiment.
FIG. 5 is a configuration diagram of a plasma processing apparatus according to a third embodiment.
FIG. 6 is a configuration diagram of a plasma processing apparatus according to a fourth embodiment.
FIG. 7 is a configuration diagram of a plasma processing apparatus according to a fifth embodiment.
FIG. 8 is a configuration diagram of a plasma processing apparatus according to a sixth embodiment.
FIG. 9 is a configuration diagram of a correction circuit according to a sixth embodiment.
[Explanation of symbols]
1 processing chamber, 2 lower electrode plate, 4 lower electrode, 6 upper electrode, 9 directional coupler, 9a 9b 54a 54b 56a 56b input terminal, 9c 9d 54c 54d 56c 56d coupling terminal, 10 high frequency power supply, 11 network analyzer, 21 Microwave introduction window, 22 waveguide, 23 microwave generator, 24 magnetic field generating coil, 31 dielectric bell jar, 32 ICP coil, 33 ICPRF power supply, 41 variable frequency generator, 42 high frequency current voltage detector, 51 upper electrode Plate, 53 Upper electrode, 54 First directional coupler, 55 First high frequency power supply, 56 Second directional coupler, 57 Second high frequency power supply, 81 Correction circuit, 82 Control device, 91 Correction element section , 92 selector switch.

Claims (3)

A high-frequency power source for supplying high-frequency power to an electrode installed in the processing chamber;
A directional coupler inserted to transmit high-frequency power between transmission lines connecting the electrode and the high-frequency power source;
A variable frequency generator connected to a terminal coupled to a terminal connected to the electrode of the directional coupler, and applying a high frequency signal of a desired frequency to the electrode;
A high-frequency characteristic detector connected to a terminal coupled to a terminal connected to the electrode of the directional coupler, and measuring a reflected wave from the electrode of a high-frequency signal applied from the variable frequency generator;
Have
While plasma is generated in the processing chamber with high-frequency power supplied from the high-frequency power source,
A plasma processing apparatus, wherein at least one of a reflected wave and a transmitted wave of a high frequency signal applied from the variable frequency generator is measured by the high frequency characteristic detector. A first high-frequency power source for supplying high-frequency power to a first electrode installed in the processing chamber;
A second high-frequency power source for supplying high-frequency power to a second electrode provided at a position facing the first electrode in the processing chamber;
A first directional coupler inserted so as to transmit high-frequency power between transmission lines connecting the first electrode and the first high-frequency power source;
A second directional coupler inserted so as to transmit high-frequency power between transmission lines connecting the second electrode and the second high-frequency power source;
A variable frequency generator connected to a terminal coupled to a terminal of the first directional coupler connected to the first electrode, and applying a high frequency signal of a desired frequency to the first electrode;
Connected to a terminal coupled to a terminal of the first directional coupler connected to the first electrode and a terminal coupled to a terminal of the second directional coupler connected to the second electrode A high-frequency characteristic detector,
Have
While plasma is generated in the processing chamber with high-frequency power supplied from the high-frequency power source,
A plasma processing apparatus, wherein at least one of a reflected wave and a transmitted wave of a high frequency signal applied from the variable frequency generator is measured by the high frequency characteristic detector. While plasma is generated in the processing chamber of the plasma processing apparatus by supplying high frequency power from a high frequency power source to the electrodes in the processing chamber,
A method for measuring high-frequency characteristics of a plasma processing apparatus, wherein a desired high-frequency signal is applied to the electrode to which high-frequency power is applied, and at least one of a reflected wave and a transmitted wave of the applied high-frequency signal is measured.

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