JP3838481B2 - Plasma density information measurement method and apparatus, plasma density information measurement probe, plasma generation method and apparatus, plasma processing method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma density information measuring method and apparatus, plasma density information measuring probe, plasma generation method and apparatus, plasma processing method, and plasma density information measuring method in plasma used in thin film element manufacturing processes, particle beam sources or analyzers, etc. In particular, the present invention relates to a technique for easily measuring plasma density information and controlling the plasma density appropriately and easily.
[0002]
[Prior art]
Plasma CVD (chemical vapor deposition), plasma etching, and the like are known as techniques using plasma. For example, the CVD process, the etching process, and the like are performed using high-frequency plasma generated by high-frequency power having a frequency in the microwave band typified by 2.45 GHz from a frequency in the RF band of about 10 MHz. In such a plasma application technology, it is very important for performing appropriate processing to sufficiently grasp information on the plasma density that shows the characteristics of the generated plasma, that is, plasma density information. Useful physical quantities relating to plasma density information include electron density, plasma absorption frequency, plasma surface wave resonance frequency, and the like. That is, the plasma density information can be sufficiently grasped by measuring the electron density and the like.
[0003]
Conventionally, as a method for measuring the electron density in plasma, there are a Langmuir probe method, a microwave interference measurement method, and a relatively recently developed electron beam irradiation type plasma vibration probe method.
[0004]
In the Langmuir probe method, the metal probe is directly exposed to the plasma and the current flowing through the metal probe when a DC bias voltage or a DC bias voltage superimposed with a high frequency voltage is applied to the metal probe. In this method, the electron density is obtained based on the value.
[0005]
In the microwave interferometry, a window facing the plasma is provided in the wall of the plasma generation chamber for generating plasma, and microwaves (for example, monochromatic laser light) are incident on the plasma from one window. This is a method of detecting the microwave passing through the plasma and exiting from the other window, and obtaining the electron density based on the phase difference between the incident and exiting microwaves.
[0006]
The electron beam irradiation type plasma vibration method is a method of obtaining an electron density based on a frequency of plasma vibration generated when a heat filament is placed in a chamber and an electron beam is irradiated from the heat filament to the plasma.
[0007]
By obtaining the electron density from the method described above, the plasma density information is grasped, and then the etching process or the CVD process as described above is performed. When actually performing the above processing using plasma, after obtaining the physical quantity in the plasma density information, the physical quantity related to plasma generation (hereinafter abbreviated as “plasma generation physical quantity” as appropriate), for example, plasma generation power or plasma is generated. In the plasma density information by controlling the pressure of the gas to be processed, or by controlling the processing power supplied to the workpiece in the plasma, the processing voltage, etc. Thus, the physical quantity is controlled, and further the plasma density is controlled, so that the etching process, the CVD process, and the like are appropriately performed.
[0008]
[Problems to be solved by the invention]
However, when the Langmuir probe method described above is applied to reactive plasma, there is a problem that measurement cannot be continued for a long time (that is, the lifetime is short). This is because dirt made of an insulating film adheres to the surface of the metal probe during measurement in a short time, and the current value flowing through the metal probe fluctuates, so that accurate measurement cannot be performed immediately. In order to remove dirt attached to the surface of the metal probe, a method of applying a negative bias voltage to the metal probe and removing the spatter by ions, and a method of evaporating and removing the dirt by making the metal probe red-heated have been tried. The effect is thin and the problem cannot be solved.
[0009]
Further, in the case of the microwave interference measurement method, it is necessary to adjust a large and expensive apparatus and a difficult microwave transmission path, and it is difficult to accurately measure the phase difference between the incident and outgoing microwaves. Another disadvantage is that only average density is required and there is no spatial resolution.
[0010]
Further, in the case of the electron beam irradiation type plasma vibration probe method, there is a problem that the measurement is interrupted due to disconnection of the hot filament in addition to the concern of contamination of the plasma atmosphere by tungsten evaporated from the hot filament. In particular, in the case of plasma using oxygen or chlorofluorocarbon gas, it is difficult to say that the hot filament is suitable for practical use because the hot filament is easily broken and the filament needs to be frequently exchanged.
[0011]
Therefore, the present applicant has previously filed Japanese Patent Application No. 11-058635 and Japanese Patent Application No. 11-058636 in order to solve the above problems. This Japanese Patent Application No. 11-058635 and Japanese Patent Application No. 11-058636 (hereinafter abbreviated as “improved invention” where appropriate) adopt the following constitution to bring about an action.
[0012]
[Principle of improved invention]
FIG. 7 is a partial longitudinal sectional view showing a configuration of an example of a probe for measuring plasma density information according to the improved invention (hereinafter abbreviated as “measurement probe” as appropriate).
As shown in FIG. 7, the measurement probe 101 is provided in the chamber 102 with the tip of the measurement probe 101 inserted. The chamber 102 has a reactive plasma (hereinafter abbreviated as “plasma” as appropriate) PM generated by a plasma generation power source.
[0013]
The measurement probe 101 has a closed end and a rear end open to the atmosphere (outside air). The antenna 103 and the coaxial cable 104 are housed in a dielectric tube 105 so that the antenna 103 comes first. Further, by pulling or pushing the coaxial cable 104 with respect to the longitudinal direction of the tube 105, the measurement probe 101 can easily change the length L from the base of the antenna 103 to the tip of the tube 105. .
[0014]
Plasma density information measurement power (hereinafter, abbreviated as “plasma measurement power” as appropriate) incident from a plasma density information measurement power source (hereinafter abbreviated as “plasma measurement power source” where appropriate) for measuring plasma density information Is transmitted by the measurement probe 101 and emitted from the antenna 103 and absorbed by the plasma load or reflected and returned. FIG. 8 shows the change in the reflectance of the plasma measurement power with respect to frequency (100 kHz to 3 GHz) at each tip length L.
[0015]
The place where the reflectivity greatly decreases is an absorption peak (hereinafter referred to as “absorption point” as appropriate) where strong absorption of power for plasma measurement occurs due to the plasma density. In the curves Ra to Rf in FIG. 8, several absorption points Pa to Pd showing that there is strong absorption of the power for plasma measurement on the plasma load side appear. The frequency at the positions of the absorption points Pa to Pd is the plasma absorption frequency. Since the plasma absorption frequency has a certain correlation with the electron density, useful plasma density information can be obtained. In particular, as shown in FIG. 8, only the absorption point Pa having the lowest frequency appears at the same frequency position even if the tip length L changes. Thus, the plasma absorption frequency that does not depend on the tip length L is the plasma surface wave resonance frequency.
[0016]
If the plasma surface wave resonance frequency is obtained in this way, the electron density of the plasma PM is easily derived, so that it is easy to grasp the characteristics of the generated plasma PM.
[0017]
With the above configuration, since the tube 105 is interposed between the antenna 103 and the coaxial cable 104 and the plasma PM, foreign matter or the like does not enter from the antenna 103 or the coaxial cable 104 into the plasma PM. Cleanliness can be ensured. Further, the presence of the tube 105 prevents the antenna 103 and the coaxial cable 104 from being damaged by the plasma PM. In addition, even if a dirt made of an insulating film adheres thinly on the surface of the tube 105 during measurement, the measurement system does not substantially change because the insulating film is a dielectric, and the measurement due to the dirt on the insulating film. There will be no variation in results. Further, by interposing the tube 105, it is difficult to directly touch the plasma to the antenna 103, and it is possible to prevent a DC overvoltage from being applied or an overcurrent flowing to break the device. Therefore, plasma density information can be measured over a long period of time as compared with the Langmuir probe method described above.
[0018]
Moreover, since the electron density in plasma PM is non-uniform | heterogenous, an electron density changes with places. Therefore, the changed electron density can be measured by moving the measurement probe 101 while being inserted into the chamber 102. Therefore, the spatial resolution of the above density is higher than that of the microwave interferometry method.
[0019]
Furthermore, since the plasma measurement power is supplied from the antenna 103 via the tube 105 and the absorption phenomenon of the resonance plasma measurement power that is easy to measure is captured, the plasma density information can be measured very easily. Furthermore, since it is not a hot filamentless system, there is no need to worry about atmospheric contamination by evaporated tungsten or to perform hot filament replacement unlike the electron beam irradiation type plasma oscillation method.
[0020]
[Problems of the improved invention to be solved by the present invention]
However, the above-described improved invention also has the following problems.
That is, measurement becomes difficult when the frequency of the power source for plasma measurement is 5 GHz or more.
[0021]
Usually the electron density is 10 ⁸ -10 ¹² cm ^-3 The plasma density information is measured within the range. As described above, the plasma absorption frequency, in particular, the plasma surface wave resonance frequency and the electron density are in a certain correlation, and the electron density is proportional to the square of the plasma surface wave resonance frequency. Therefore, the electron density is low. ⁸ cm ^-3 To 10 ⁹ cm ^-3 In the range up to 1, the plasma surface wave resonance frequency is on the order of several tens of MHz to several hundreds of MHz, but the electron density is 10 which is medium density. ^Ten cm ^-3 To 10 ¹¹ cm ^-3 In this range, the plasma surface wave resonance frequency is about 1 GHz to 2 GHz. Furthermore, the electron density is 10 ¹² cm ^-3 In this state, the plasma surface wave resonance frequency exceeds 5 GHz.
[0022]
Since a normal plasma measurement power source has a frequency of 5 GHz or less, it is difficult to measure plasma density information when the electron density is high. In addition, since the plasma absorption frequency other than the plasma surface wave resonance frequency is higher than the plasma surface wave resonance frequency, measurement of plasma density information is not possible even if the electron density is derived from the plasma absorption frequency other than the plasma surface wave resonance frequency. It becomes more difficult. Therefore, when trying to measure a plasma surface wave resonance frequency of 5 GHz or more, a high-frequency power source having a frequency of 5 GHz or more must be specially used, which complicates the measuring apparatus and makes the apparatus main body expensive.
[0023]
For the above reasons, it is desired to measure plasma density information that can be read in the region of frequencies from 10 MHz to 500 MHz even if the electron density is high. Therefore, the present invention has been made in view of the above circumstances, and a plasma density information measuring method and apparatus capable of measuring plasma density information that can be read in a low frequency range from 10 MHz to 500 MHz, and an apparatus therefor, It is an object of the present invention to provide a probe for measuring plasma density information, a plasma generation method and apparatus, a plasma processing method and apparatus. In the present specification, a frequency region below 500 MHz is defined as a low frequency, and a frequency region above 500 MHz is defined as a high frequency, and the following description is given.
[0024]
[Means for Solving the Problems]
When the measurement probe 51 as shown in FIG. 9 is provided, an absorption point different from the absorption point that appears in the conventional high-frequency region appears in the low-frequency region, and the frequency in the low-frequency region is in the high-frequency region. A phenomenon that the frequency is about 1/10 to 1/100 is known. As shown in FIG. 9, the measurement probe 51 is connected to a metal antenna 52 that radiates power and a coaxial cable 53 for transmitting plasma measurement power. Note that the antenna 52 is not housed in a dielectric tube as in the improved invention, and the antenna 52 remains exposed.
[0025]
The cause of the above phenomenon has not been elucidated so far. Therefore, the present inventor has paid attention to this phenomenon and clarified the cause of the phenomenon, thereby solving the above-mentioned problem.
[0026]
When the measurement probe 51 is inserted into the plasma PM, a layer called “sheath” is generated around the antenna 52. At this time, if the frequency of the plasma measurement power applied to the antenna 52 is changed, a strong electric field that causes resonance in a low frequency region of about 1/10 to 1/100 is applied to the sheath, and absorption occurs there. .
[0027]
On the other hand, in the improved invention, the antenna 103 in the measurement probe 101 is in direct contact with the plasma via the dielectric tube 105 without directly touching the plasma. The probe having a shape like the measurement probe 101 is more easily coupled to plasma than the sheath, and a plasma surface wave is excited on the surface of the tube 105. As a result, absorption occurs in the high frequency region.
[0028]
Thus, depending on the shape of the probe, it may be a probe that is easily coupled to the sheath on the one hand, or a probe that is easily coupled to the plasma on the other hand. In addition, the present inventors have not invented a probe that combines with both the plasma and the sheath, but it is theoretically possible.
[0029]
For the above reasons, the present inventor has conceived to measure plasma density information that can be read in a low frequency range from 10 MHz to 500 MHz by changing the shape of the measurement probe.
[0030]
The present invention created based on the above knowledge has the following configuration.
In other words, the plasma density information measuring method according to the first aspect of the invention is a plasma density information measuring method for measuring plasma density information indicating the characteristics of plasma, and measuring the plasma density information for measuring plasma density information. Power for measuring plasma density information For measuring plasma density information An antenna for radiating power; and a cable for transmitting the power for measuring plasma density information. The antenna and the cable are connected to one end of the antenna, and at least the antenna is directly connected by a dielectric material. Reflecting the plasma density information measurement power by the plasma load, which is supplied to the plasma using the coated plasma density information measurement probe and appears in the frequency range from 10 MHz to 500 MHz. It comprises a plasma density information measurement process for measuring plasma density information based on absorption.
[0031]
A plasma density information measuring apparatus according to a second aspect of the present invention is a plasma density information measuring apparatus for measuring plasma density information indicating characteristics of plasma, and is a power source for measuring plasma density information for measuring plasma density information. And the plasma density based on the reflection or absorption by the plasma load of the plasma density information measuring power supplied from the plasma density information measuring power source, which appears in the frequency range from 10 MHz to 500 MHz. A plasma density information measuring means comprising a plasma density information measuring probe for measuring information, and the plasma density information measuring probe comprises: For measuring plasma density information An antenna for radiating power; and a cable for transmitting the power for measuring plasma density information. The antenna and the cable are connected to one end of the antenna, and at least the antenna is directly connected by a dielectric material. It is characterized by being coated.
[0032]
The plasma density information measuring probe according to claim 3 is the plasma density information measuring probe, wherein the frequency of the plasma density information measuring power source for measuring the plasma density information appears in a frequency region from 10 MHz to 500 MHz. A plasma density information measuring probe for measuring plasma density information based on reflection or absorption by a plasma load of power for measuring plasma density information supplied from a power source, For measuring plasma density information An antenna for radiating power; and a cable for transmitting the power for measuring plasma density information. The antenna and the cable are connected to one end of the antenna, and at least the antenna is directly connected by a dielectric material. It is characterized by being coated.
[0033]
According to a fourth aspect of the present invention, there is provided a plasma density information measuring probe according to the third aspect, wherein the antenna is a flat metal plate.
[0034]
A plasma generation method according to a fifth aspect of the invention is a plasma generation method for controlling plasma density by manipulating a physical quantity related to plasma generation, and a power source for measuring plasma density information for measuring plasma density information Power for measuring plasma density information The , For measuring plasma density information An antenna for radiating power; and a cable for transmitting the power for measuring plasma density information. The antenna and the cable are connected to one end of the antenna, and at least the antenna is directly connected by a dielectric material. Reflecting the plasma density information measurement power by the plasma load, which is supplied to the plasma using the coated plasma density information measurement probe and appears in the frequency range from 10 MHz to 500 MHz. A plasma density information measurement process for measuring plasma density information based on absorption, and an operation process for manipulating a physical quantity related to the plasma generation based on the measured plasma density information.
[0035]
A plasma generator according to the invention described in claim 6 is a plasma generator for controlling plasma density by manipulating a physical quantity related to plasma generation, and a power source for measuring plasma density information for measuring plasma density information And the reflection of the plasma density information measurement power supplied from the plasma density information measurement power supply, which appears in the frequency range from 10 MHz to 500 MHz, or the plasma generation power supply and the plasma density information measurement power supply. Plasma density information measuring means including a plasma density information measuring probe for measuring plasma density information based on absorption, and operation means for operating a physical quantity related to plasma generation based on the measured plasma density information The plasma density information measuring probe is: For measuring plasma density information An antenna for radiating power; and a cable for transmitting the power for measuring plasma density information. The antenna and the cable are connected to one end of the antenna, and at least the antenna is directly connected by a dielectric material. It is characterized by being coated.
[0036]
The plasma processing method according to the invention of claim 7 is a plasma processing method for performing plasma processing by placing an object to be processed in plasma whose plasma density is controlled by manipulating a physical quantity related to plasma generation, Power for measuring plasma density information from power source for measuring plasma density information for measuring plasma density information The , For measuring plasma density information An antenna for radiating power; and a cable for transmitting the power for measuring plasma density information. The antenna and the cable are connected to one end of the antenna, and at least the antenna is directly connected by a dielectric material. Reflecting the plasma density information measurement power by the plasma load, which is supplied to the plasma using the coated plasma density information measurement probe and appears in the frequency range from 10 MHz to 500 MHz. A plasma density information measurement process for measuring plasma density information based on absorption, and an operation process for manipulating a physical quantity related to the plasma generation based on the measured plasma density information.
[0037]
A plasma processing apparatus according to an eighth aspect of the present invention is a plasma processing apparatus in which an object to be processed is placed in plasma whose plasma density is controlled by manipulating a physical quantity related to plasma generation. A plasma processing apparatus comprising: a plasma density information measuring power source for measuring plasma density information; a plasma generating power source; and a plasma density information measuring power source having a frequency in a frequency range from 10 MHz to 500 MHz. Plasma density information measuring means comprising a plasma density information measuring probe for measuring plasma density information based on reflection or absorption of plasma density information measuring power supplied from an information measuring power supply by a plasma load; Based on the plasma density information, the physical quantity related to the plasma generation is calculated. And an operating means for work, said plasma density information measuring probe, For measuring plasma density information An antenna for radiating power; and a cable for transmitting the power for measuring plasma density information. The antenna and the cable are connected to one end of the antenna, and at least the antenna is directly connected by a dielectric material. It is characterized by being coated.
[0038]
A plasma processing apparatus according to a ninth aspect of the invention is the plasma processing apparatus according to the eighth aspect, wherein the operating means operates power for generating plasma supplied from the power source for generating plasma. .
[0039]
A plasma processing apparatus according to a tenth aspect of the present invention is the plasma processing apparatus according to the eighth or ninth aspect, wherein the operating means is plasma supplied from a plasma processing power source to a peripheral portion of the object to be processed. It is characterized by operating processing power.
[0040]
[Action]
The operation of the first aspect of the invention will be described.
The power for plasma density information measurement (hereinafter abbreviated as “power for plasma measurement” as appropriate) incident from the power source for plasma density information measurement (hereinafter abbreviated as “power source for plasma measurement” as appropriate) is attributed to the plasma density. Then it is absorbed by the plasma load or reflected back. Based on the reflection or absorption of the plasma measurement power, the plasma density information is measured in the low frequency region where the frequency of the plasma measurement power source is 10 MHz to 500 MHz. Since the plasma density information indicates the characteristics of the plasma, by measuring the plasma density information, the characteristics of the plasma can be grasped even in the low frequency region where the frequency of the power source for plasma measurement is 10 MHz to 500 MHz.
[0041]
According to the second aspect of the present invention, the plasma density information deriving means including the probe for measuring plasma density information is incident from the power source for plasma measurement even in the low frequency range from 10 MHz to 500 MHz. Plasma density information based on reflection or absorption of the measured plasma measurement power is measured, and the characteristics of the plasma are grasped.
[0042]
According to the third aspect of the present invention, the plasma measurement power supplied from the plasma measurement power supply is transmitted to the antenna via the plasma density information measurement probe cable, and is emitted from the antenna and absorbed by the plasma load. Will be reflected or come back through the cable.
[0043]
Further, in the case of a probe for measuring plasma density information that is not directly covered with a dielectric material but is accommodated, the probe is in contact with the plasma through the dielectric material, so that it is more easily coupled to the plasma than the sheath. A plasma surface wave is excited on the surface of the dielectric material. Therefore, in the case of the above-described probe for measuring plasma density information, absorption (or reflection) occurs in a high frequency region.
[0044]
On the other hand, in the case of the probe for measuring plasma density information according to the present invention, at least the antenna is directly covered with the dielectric material, so that the plasma surface wave is excited in the sheath portion around the antenna. Accordingly, the absorption (or reflection) of the plasma load due to the plasma density is combined with the sheath, and as a result, absorption (or reflection) occurs in the low frequency region.
[0045]
In addition, by covering with a dielectric, even if dirt made of an insulating film adheres thinly during measurement, the insulating film is a dielectric, so the measurement system does not change substantially, and the insulating film becomes dirty. The measurement result does not vary due to In addition, by covering the antenna with a dielectric, it is difficult to directly touch the plasma, and it is possible to prevent a DC overvoltage from being applied or an overcurrent flowing to break the device.
[0046]
According to the invention described in claim 4, since the antenna is formed of a flat metal plate, the plasma measurement power is more absorbed by the plasma load. Therefore, the plasma density information is easily measured, and the plasma density information is more easily measured.
[0047]
According to the invention described in claim 5, the plasma density information is measured in the low frequency region where the frequency of the power source for plasma measurement is from 10 MHz to 500 MHz based on the reflection or absorption of the power for plasma measurement caused by the plasma density. Is done. The plasma density is controlled by manipulating the physical quantity related to plasma generation based on the measured plasma density information (hereinafter abbreviated as “plasma generation physical quantity” as appropriate), and the plasma is controlled in a state where the plasma density is further controlled. Will be generated.
[0048]
According to the sixth aspect of the present invention, the plasma density information is measured in the low frequency region where the frequency of the power source for plasma measurement is from 10 MHz to 500 MHz by the plasma density information deriving means equipped with the probe for measuring plasma density information. The Then, the plasma generation physical quantity based on the measured plasma density information is manipulated by the manipulation means. Further, the plasma density is controlled by manipulating the plasma generation physical quantity, and the plasma is generated with the plasma density controlled.
[0049]
According to the invention described in claim 7, the plasma density information is measured in the low frequency region where the frequency of the power source for plasma measurement is from 10 MHz to 500 MHz based on the reflection or absorption of the power for plasma measurement caused by the plasma density. Is done. The plasma density is controlled by manipulating the plasma generation physical quantity based on the measured plasma density information, and the plasma processing is appropriately performed on the workpiece in the plasma with the plasma density controlled. .
[0050]
According to the invention described in claim 8, plasma density information is measured in the low frequency region where the frequency of the power source for plasma measurement is from 10 MHz to 500 MHz by the plasma density information deriving means equipped with the probe for measuring plasma density information. The Then, the plasma generation physical quantity based on the measured plasma density information is manipulated by the manipulation means. Further, the plasma density is controlled by manipulating the plasma generation physical quantity, and the plasma processing is appropriately performed on the object to be processed in the plasma with the plasma density controlled.
[0051]
According to the ninth aspect of the present invention, the operating means operates the power for generating plasma supplied from the power source for generating plasma. The physical quantity becomes the power for plasma generation. Therefore, by operating the plasma generation power, the plasma density is controlled, and the plasma processing is appropriately performed on the workpiece in the plasma with the plasma density controlled.
[0052]
According to a tenth aspect of the present invention, the operating means operates the plasma processing power supplied from the plasma processing power source to the periphery of the workpiece. Therefore, in the case of the invention of the apparatus according to claim 10, the plasma processing is appropriately performed on the workpiece by the operation of the plasma processing power by the operating means.
[0053]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a plasma processing apparatus equipped with an example of a plasma density information measuring probe and a measuring apparatus according to an embodiment.
[0054]
As shown in FIG. 1, the plasma processing apparatus according to the embodiment includes a stainless steel chamber 1 having a diameter of several tens of centimeters having an indoor space S in which plasma PM is generated, and a plasma generating apparatus disposed in the chamber 1. A discharge electrode (discharge antenna) 2, a vacuum exhaust pump 4 communicating with the indoor space S of the chamber 1 via an exhaust pipe 3, and a gas supply pipe 6 provided with a flow rate control valve 5. And a gas source 7 communicating with the indoor space S of the chamber 1. A measuring probe 8 for measuring a physical quantity in plasma density information, in the embodiment, a plasma absorption frequency, is attached to the wall portion of the chamber 1 in a state where only the tip portion is inserted into the chamber 1. The chamber 1 is provided with a workpiece (object to be processed) W for plasma processing and a stage (mounting table) ST on which the workpiece W is placed, and a processing electrode 9 is disposed on the stage ST. ing. In addition, the chamber 1 is also provided with a workpiece W loading / unloading mechanism (not shown). The measurement probe 8 corresponds to the plasma density information measurement probe in the present invention.
[0055]
The indoor space S of the chamber 1 is evacuated by the evacuation pump 4 to maintain an appropriate indoor pressure. Gas is supplied from the gas source 7 at an appropriate flow rate. Examples of the supply gas include argon, helium, nitrogen, oxygen gas, fluorine-based gas, and chlorine-based gas.
[0056]
Further, outside the chamber 1, a plasma generation power source 10 that supplies plasma generation power for generating plasma, and a generation power operation unit 11 for operating the plasma generation power supplied to the discharge electrode 2. And are provided.
[0057]
Similarly, outside the chamber 1, a plasma processing power source 12 that supplies plasma processing power for performing plasma processing of the workpiece W, and a processing for operating the plasma processing power supplied to the processing electrode 9. A power operation unit 13 is provided.
[0058]
Further, outside the chamber 1, a frequency sweep type plasma measurement power supply 14 for supplying plasma measurement power for measuring plasma density information, a coaxial cable 15 for transmitting the plasma measurement power to the measurement probe 8, A probe control unit 16 for controlling the measurement probe 8 is provided, and the measurement probe 8 and the probe control unit 16 are connected via a coaxial cable 15. The probe control unit 16 includes the plasma measurement power source 14, a filter, an attenuator, and the like described later, and the measurement probe 8 and the probe control unit 16 constitute a plasma density information measurement unit 17. .
[0059]
The generation power operation unit 11 and the processing power operation unit 13 correspond to the operation means in the present invention, and the plasma density information measurement unit 17 (that is, the measurement probe 8 and the probe control unit 16) corresponds to the present invention. Corresponds to the plasma density information measuring means in FIG.
[0060]
The generation power operation unit 11 includes an impedance matching unit 11a that adjusts an impedance matching state between the plasma generation power source 10 side and the plasma side, and an electron density setting for setting a target electron density for plasma to be generated in the chamber 1. And a matching unit operation unit 11c that operates the impedance matching unit 11a based on the difference between the set target electron density and the actually measured electron density.
[0061]
Similarly, the processing power operation unit 13 includes an impedance matching unit 13a that adjusts the impedance matching state between the plasma processing power supply 12 side and the plasma side, and plasma processing power that is optimal for the processing electrode 9 to perform plasma processing, That is, the power setting unit 13b for setting the target plasma processing power and the matching unit operation for operating the impedance matching unit 13a based on the difference between the set target plasma processing power and the actually measured plasma processing power. And a power converter 13d that stores in advance the correlation between the electron density and the plasma processing power and converts the measured electron density to the measured plasma processing power based on the correlation.
[0062]
As the impedance matching device 11a or 13a, when the frequency of the plasma generation power source 10 or the plasma processing power source 12 is a frequency on the order of MHz, a matching circuit combining an inductance and a capacitance is used. When the frequency of these power supplies is 1 GHz or higher, an EH tuner or a stub tuner is used.
[0063]
In the case of the embodiment apparatus, the processing power operation unit 13 is used as an operation unit of a plasma CVD method in which a gas raw material is thermally decomposed using plasma to deposit a product on a workpiece W (substrate). That is, the workpiece W is placed on the stage ST on which the processing electrode 9 is disposed, and is inserted into the indoor space S of the chamber 1. By supplying plasma processing power of about 1 kW from the plasma processing power source 12 to the processing electrode 9, electrons and ions in the plasma PM atmosphere are attracted toward the workpiece W and further deposited on the workpiece W. Is done.
[0064]
The voltage of the plasma processing power source 12 or the plasma processing power, and the physical quantity in the plasma density information attracted onto the workpiece W are stored in advance in a storage unit (not shown). For example, a correlation between the plasma processing power and the electron density is stored in advance in the storage unit, and the electron density obtained by measurement based on the correlation is converted into the plasma processing power or the like. In the case of the apparatus according to the present embodiment, the power conversion unit 13 d is provided with the conversion function in the processing power operation unit 13. When the target value and the actually measured value are different, the matching unit operation unit 13c operates the impedance matching unit 13a, and operates the plasma processing power and the like by operating the impedance matching unit 13a. Furthermore, the plasma CVD process of the workpiece W is performed by controlling electrons, ions, and the like in the plasma PM atmosphere that is attracted toward the workpiece W by operating the plasma processing power.
[0065]
If the plasma processing power source 12 is a direct current (DC) power source, the product may be charged up by a product deposited on the workpiece W, and the workpiece W itself may become a capacitor. The power source 12 is preferably an alternating current (AC) power source rather than a direct current (DC) power source. Further, the frequency of not only the plasma processing power supply 12 but also the plasma generation power supply 10 and the like is not particularly limited, in many practical cases there is an example in which a power supply having a frequency of 13.56 MHz is actually used.
[0066]
In addition to the plasma CVD method described above, the plasma processing method is exemplified by plasma processing used for etching processing, a particle beam source, an analyzer, or the like as long as plasma processing is performed by controlling plasma density information. As such, it is not particularly limited.
[0067]
Next, a specific configuration of the plasma density information measurement unit 17, that is, a specific configuration of the measurement probe 8 and the probe control unit 16 will be described. First, a specific configuration of the measurement probe 8 will be described.
[0068]
As shown in the partial vertical cross-sectional view of FIG. 2A and the plan view of FIG. 2B, the measurement probe 8 includes a coaxial cable 15 that transmits plasma measurement power supplied from the plasma measurement power source 14, and A central conductor 18 and a metal flat plate 19 are provided as an antenna for radiating electric power, and the coaxial cable 15 is connected to one end side of the central conductor 18. The metal flat plate 19 is connected to the other end of the central conductor 18. Connected to the side. The central conductor 18 and the flat plate 19 are covered with a dielectric outer skin 20 as shown in FIG. The central conductor 18 and the flat plate 19 correspond to the antenna in the present invention, and the dielectric outer skin 20 corresponds to the dielectric substance in the present invention.
[0069]
Further, in the broken view of the coaxial cable 15, the hatched portion of the left oblique line indicates the center and the external insulator (dielectric) portion, and the black portion indicates the center and the external conductor. In the present embodiment, the dielectric outer sheath 20 covers the central conductor 18 and the flat plate 19, but may be configured to cover the coaxial cable 15.
[0070]
Further, it is not necessary to form the center conductor 18 individually and connect it to the coaxial cable 15, and the outside of the coaxial cable 15 with respect to the distal end portion of the coaxial cable 15 (in the direction opposite to the connection portion of the probe control unit 16). The center conductor of the coaxial cable 15 is the center conductor in this embodiment by cutting the insulator, the outer conductor and the center insulator, and removing the outer insulator, the outer conductor and the center insulator except the center conductor. The function of the conductor 18 is fulfilled. Therefore, the measurement probe 8 including the center conductor 18 and the coaxial cable 15 can be easily created by making the above-described cuts in the coaxial cable 15.
[0071]
By having the above configuration, the measurement probe 8 brings the following actions and effects. That is, by attaching a metal flat plate 19 to the center conductor 18 as an antenna, the absorption of the plasma measurement power by the plasma load described later becomes larger than that of the antenna having only the center conductor 18. Therefore, it is possible to perform measurement more easily than when the absorption point is only the central conductor 18 in the low frequency region where the frequency of the power source for plasma measurement is 10 MHz to 500 MHz.
[0072]
Further, by covering the center conductor 18 and the flat plate 19 with the dielectric outer skin 20, even if the dirt made of the insulating film adheres thinly during the measurement, the insulating film is substantially dielectric, so The measurement system does not change, the measurement result does not fluctuate due to contamination of the insulating film, the center conductor 18 and the flat plate 19 are difficult to directly touch the plasma, and a DC overvoltage is applied or an overcurrent flows. Can be prevented from breaking.
[0073]
Next, a specific configuration of the probe control unit 16 will be described. The probe control unit 16 includes the above-described frequency sweep type plasma measurement power source 14, a directional coupler 21, an attenuator 22, a filter 23, a plasma absorption frequency deriving unit 24, and an electron density conversion unit 25. I have. Further, as described above, the probe control unit 16 is connected to the measurement probe 8 via the coaxial cable 15. Specifically, as shown in FIG. 1, a directional coupler 21, an attenuator 22, and a filter 23 are connected to the measurement probe 8 in order from the plasma measurement power supply 14 side in the probe controller 16. .
[0074]
The plasma measurement power supply 14 outputs the plasma measurement power while automatically sweeping the power at a frequency from 10 MHz to 500 MHz. The plasma measurement power output from the plasma measurement power supply 14 is transmitted to the measurement probe 8 via the directional coupler 21, the attenuator 22, and the filter 23 while being transmitted through the coaxial cable 15. In addition, as long as an absorption point can be measured in a low frequency region from 10 MHz to 500 MHz, it may be swept up to a high frequency region above 500 MHz. Therefore, the frequency of the plasma measurement power supply 14 is not necessarily limited to the low frequency region from 10 MHz to 500 MHz, and may be a plasma measurement power supply 14 that outputs a high frequency region of 500 MHz or higher.
[0075]
On the other hand, the power for plasma measurement is not necessarily absorbed by the plasma load by being emitted from the central conductor 18 and the flat plate 19 that are antennas, but may be reflected and returned without being absorbed by the plasma load. The amount of reflection of the plasma measurement power that returns without being absorbed by the plasma load is detected by the directional coupler 21 and sent to the plasma absorption frequency deriving unit 24. The plasma absorption frequency deriving unit 24 also sequentially receives the frequency of the plasma measurement power output from the plasma measurement power supply 14.
[0076]
The filter 23 functions to remove plasma measurement power for plasma generation mixed into the probe control unit 16 via the central conductor 18. The attenuator 22 functions to adjust the amount of plasma measurement power sent to the measurement probe 8.
[0077]
The plasma absorption frequency deriving unit 24 determines a change in the reflectance of the plasma measurement power with respect to frequency based on the frequency of the plasma measurement power and the detected reflection amount of the plasma measurement power. And based on the obtained result, it is the structure which derives | leads-out the plasma absorption frequency in which strong absorption of the electric power for plasma measurement originates in a plasma density. That is, the plasma absorption frequency deriving unit 24 performs an operation of [detected reflection amount of plasma measurement power] / [total output amount of plasma measurement power (a constant amount in the embodiment)] to reflect the plasma measurement power. The rate is obtained and plotted in association with the frequency to be swept, whereby processing for obtaining the change in the reflectance of the plasma measurement power with respect to frequency is performed. The place where the reflectance greatly decreases is an absorption peak at which strong absorption of power for plasma measurement occurs due to the electron density, that is, an absorption point, and the frequency of the absorption point is the plasma absorption frequency. Further, the plasma absorption frequency deriving unit 24 performs processing for automatically detecting an absorption point and deriving the corresponding frequency as a plasma absorption frequency.
[0078]
Here, the reflectivity of the plasma measurement power is [detected reflection amount of plasma measurement power] / [total output power of plasma measurement power], but the absorption characteristic of the line shape caused by the coaxial transmission line, etc. Since there is a spectrum, [detected reflection amount of plasma measurement power when plasma is turned on, that is, when plasma is generated (when plasma measurement power supply 10 is turned on)] ÷ [when plasma is not turned on, that is, plasma is generated. It is desirable to derive the reflectivity of the plasma measurement power when it is not (the detected reflection amount of the plasma measurement power when the plasma measurement power supply 10 is off). In addition, the “detected reflection amount of the power for plasma measurement when plasma is not generated (hereinafter referred to as“ when the plasma is not turned on ”)” is the measurement object of the network analyzer, which is the attenuator 22 in this embodiment. And the detected reflection amount calibrated by calibration means based on the measurement of the filter 23 and the like. That is, when the plasma is not turned on, the measurement probe 8 theoretically totally reflects and returns. Therefore, the reflectance is 100%. However, due to the influence of the measurement object, it does not actually return after being totally reflected. When the reflectance due to the influence of the measurement object is (100−α)%, it seems that absorption occurs as much as α%. Therefore, in consideration of the influence of the measurement object, means for calibrating the reflectance to 100%, which is total reflection, is frequently performed even if the reflectance is (100−α)% when the plasma is not turned on.
[0079]
On the other hand, based on the plasma absorption frequency derived from the plasma absorption frequency deriving unit 24, the electron density conversion unit 25 converts the electron density to derive the electron density. The apparatus according to this embodiment is configured to send the derived electron density to the matching unit operation unit 11c of the generation power operation unit 11 and the power conversion unit 13d of the processing power operation unit 13, respectively.
[0080]
Next, an example of measuring absorption points will be described. As shown in FIGS. 2A and 2B, in this embodiment, a 2 cm × 2 cm square and 0.5 mm thick stainless steel flat plate 19 is connected to the center conductor 18 to cover the flat plate 19. As the dielectric outer skin 20, a fluororesin having a thickness of 0.3 mm or mica (Mica) is used. In addition, the metal material which uses the flat plate 19 is not specifically limited so that not only said stainless steel but copper, aluminum, etc. are illustrated. Moreover, not only the said metal material but conductor materials other than metals, such as carbon, may be sufficient, for example. Further, if the absorption of the plasma measurement power increases and the absorption point can be easily read in addition to the flat plate 19, for example, a ring-shaped metal piece is connected to the other end side of the center conductor 18. The shape is not particularly limited. On the other hand, the material using the dielectric outer skin 20 is not particularly limited as exemplified by quartz, ceramics, insulating tape (Kapton) and the like as well as the above-described fluororesin or mica.
[0081]
Further, argon gas is used as the gas supplied from the gas source 7, and the plasma absorption frequency at which the absorption point occurs is measured by measuring the reflectance of the plasma measurement power under the argon plasma PM atmosphere. The gas pressure ranges from 10 mTorr to 300 mTorr, and in this embodiment, it is 14 mTorr. The frequency of the plasma generation power source 10 is 13.56 MHz, and when 30 W, 40 W, 50 W, 80 W, 150 W, and 200 W of plasma generation power is supplied from the plasma generation power source 10 into the indoor space S of the chamber 1. Changes in the reflectivity of each plasma measurement power versus frequency are observed. The experimental result is as shown in FIG. 3 (the dielectric outer skin 20 uses a fluororesin).
[0082]
The absorption points due to the electron density are observed as at least three spectra at this stage, as shown in the experimental results of FIG. In this specification, the three plasma absorption frequencies are divided into the first absorption frequency f in descending order of frequency. ₁ , Second absorption frequency f ₂ , And the third absorption frequency f _Three And define them respectively.
[0083]
When the power for plasma generation changes, as shown in the experimental results of FIG. 3, it can be seen that the respective plasma absorption frequencies are also shifted. Moreover, since the electron density in plasma PM changes when the power for plasma generation changes, it can be seen from the experimental results in FIG. 3 that the plasma absorption frequency shifts when the electron density in plasma PM changes. .
[0084]
Next, a method for deriving the electron density will be described with reference to FIGS. FIG. 4 shows changes in plasma absorption frequency versus electron density, and FIG. 5 is a block diagram relating to an experimental apparatus for deriving electron density. As described above, the respective plasma absorption frequencies derived by the plasma absorption frequency deriving unit 24 and the first absorption frequency f. ₁ , Second absorption frequency f ₂ , And the third absorption frequency f _Three Is useful plasma density information that has a certain correlation with plasma density, particularly electron density.
[0085]
Although the relational expression between the plasma absorption frequency and the electron density occurring in the low frequency region has not been theoretically explained yet, an actual measurement value as shown in FIG. That is, the change in the plasma absorption frequency with respect to the electron density in the low frequency region is obtained.
[0086]
However, there are the following problems in actually obtaining a change in plasma absorption frequency versus electron density in a low frequency region as shown in FIG. That is, when the measurement probe 8 has the configuration shown in FIG. 2, the absorption is caused by the strong coupling with the sheath portion as described above, so that the absorption point in the low frequency region can be easily observed. can do. However, since the coupling with the plasma portion is weak, it is difficult to determine the absorption point in the high frequency region. On the contrary, in the case of the measurement probe having the shape as in the improved invention, as described above, the absorption is caused by being strongly coupled to the plasma portion, so that the absorption point in the high frequency region can be easily observed. The coupling with the part is weak and it is difficult to determine the absorption point in the low frequency region. Therefore, a probe that strongly binds to both the plasma and the sheath, that is, a probe that can easily measure the absorption point in both the low frequency region and the high frequency region has not been invented at this stage. It is difficult to determine the change in plasma absorption frequency versus electron density in the low frequency region with only one probe.
[0087]
Therefore, the change in the plasma absorption frequency with respect to the electron density in the low frequency region can be obtained by an experimental apparatus as shown in FIG. That is, the measurement probe 8 having the configuration shown in FIG. 2, that is, the measurement probe 8 dedicated to the low frequency region, and the measurement probe 8a having the shape as in the improved invention, that is, the measurement probe 8a dedicated to the high frequency region Is inserted into the chamber 1. That is, as shown in FIG. 5, the inside of the chamber 1 is such that each of the measurement probes 8 and 8a is located in the same plane in the vicinity of each other and in the plane parallel to the discharge electrode 2 (direction r in FIG. 5). Insert into. While moving both measurement probes 8 and 8a in the chamber 1 at the same time or changing the power for generating plasma while both measurement probes 8 and 8a are fixed, the electron density and the absorption point in the low frequency region And the absorption point in the high frequency region. In the present specification, the r direction indicates the plane direction of the cylindrical coordinate system, and the z direction described later indicates the vertical direction of the cylindrical coordinate system.
[0088]
At this time, when the measurement probe 8 is inserted into the indoor space S of the chamber 1 in the direction as shown in FIG. 5, it is performed in the direction as shown in FIG. As described above, the electron density in the plasma PM is not uniform depending on the location. However, if they are in the same plane with respect to the plane direction (r direction), the electron density is almost the same. Further, since the thickness of the flat plate 19 is 0.5 mm, the change in electron density in the vertical direction (z direction in FIG. 5) can be ignored. On the contrary, when the measurement probe 8 is inserted into the indoor space S of the chamber 1 in the direction as shown in FIG. 2B, the longitudinal direction (z direction) is the diagonal length 2 × √2 cm of the flat plate 19. Therefore, the change in electron density in the vertical direction (z direction) cannot be ignored. Therefore, if it is inserted in the direction as shown in FIG.
[0089]
Moreover, since both the measurement probes 8 and 8a are arrange | positioned so that it may be located in the same surface with respect to a surface direction (r direction), it can be considered that an electron density is substantially the same. First, the plasma absorption frequency in the high frequency region is measured by measuring the absorption point of the measurement probe 8a, and the electron density at that time is derived. By measuring the absorption point of the measurement probe 8 at a position where the electron density is considered to be substantially the same, the plasma absorption frequency in the low frequency region, that is, the plasma absorption frequency (first absorption frequency f) due to the electron density. ₁ , Second absorption frequency f ₂ , And the third absorption frequency f _Three ) And plot the plasma absorption frequency in association with the electron density.
[0090]
Similarly, measurement is performed under different electron densities by moving both measurement probes 8 and 8a in the same plane or changing the power for generating plasma while both measurement probes 8 and 8a are fixed. . When the plasma absorption frequency is plotted in association with the electron density, the change in plasma absorption frequency with respect to electron density as shown in FIG. 4 can be obtained.
[0091]
FIG. 4 shows electron density of each plasma absorption frequency when fluororesin (relative permittivity ε is approximately 2.1) and mica (relative permittivity ε is approximately 5.0) are used as the dielectric outer skin 20. It is a change. The black circle plot in FIG. 4 shows the change in plasma absorption frequency versus electron density when using fluororesin, and the black square in FIG. 4 is the change in plasma absorption frequency vs. electron density when using mica. .
[0092]
In the apparatus of the present embodiment, data on the change in plasma absorption frequency versus electron density as shown in FIG. 4 is stored in advance, and the electron density is calculated from the plasma absorption frequency based on the absorption point derived from the plasma absorption frequency deriving unit 24. It is constructed so as to include an electron density conversion unit 25 for converting to an electron density. Further, each electron density converted by the conversion unit is sent to each operation unit.
[0093]
In addition, the plasma absorption frequency (first absorption frequency f ₁ , Second absorption frequency f ₂ , And the third absorption frequency f _Three ) It is not necessary to previously store data on changes in plasma absorption frequency versus electron density for all, and it is only necessary to store in advance data on changes in plasma absorption frequency versus electron density for at least one plasma absorption frequency. Of course, the above data may be stored for all plasma absorption frequencies in order to derive the electron density more accurately and to control the plasma density information more precisely.
[0094]
In the future, when the relational expression between the plasma absorption frequency and electron density that occurs in the low frequency region is theoretically clarified and the measured plasma absorption frequency and electron density agree with the theoretical value, A mechanism provided in the apparatus of the present embodiment may be an operator that converts the electron density.
[0095]
Next, the flow of plasma processing control in the plasma processing apparatus having the above-described configuration will be described with reference to the flowchart of FIG. The flowchart of FIG. 6 relates to the operation of only the plasma generation power.
[0096]
[Step S1] A switch of the plasma generation power source 10 is turned on. At this time, the indoor space S of the chamber 1 is evacuated by the vacuum exhaust pump 4 and an appropriate flow rate of gas is supplied from the gas source 7 to the indoor space S, and the indoor space S is adjusted to an appropriate atmosphere.
[0097]
[Step S2] The impedance matching unit 11a in the generation power operation unit 11 is set to an appropriate initial state (for example, the tuner position of the impedance matching unit 11a is set to T ₀ Set to).
[0098]
[Step S3] The plasma generation power is supplied from the plasma generation power source 10 to the discharge electrode 2 via the impedance matching unit 11a. ₀ ) To generate plasma PM in the indoor space S of the chamber 1.
[0099]
[Step S4] Based on the absorption of the plasma measurement power from the plasma measurement power source 14, the plasma absorption frequency deriving unit 24 derives the plasma absorption frequency.
[0100]
[Step S5] Based on the derived plasma absorption frequency, the electron density converter 25 converts the plasma absorption frequency into an electron density. The converted electron density is sent to the matching unit operation unit 11c. The procedure up to step S5 corresponds to the plasma density information measurement process in the present invention.
[0101]
[Step S6] The matching unit operation unit 11c sets the target electron density n set by the electron density setting unit 11b. ₀ And an electron density difference Δn (= n) from the electron density converted from the electron density conversion unit 25 in step S5, that is, the actually measured electron density n obtained by measurement. ₀ -N) is derived.
[0102]
[Step S7] It is determined whether the electron density difference Δn is equal to or greater than a certain value. If the electron density difference Δn is less than a certain value, it is determined that the electron density corresponding to the generated plasma density is the target electron density, and the control process is terminated.
[0103]
[Step S8] If the electron density difference Δn is greater than or equal to a certain value, it is determined whether or not all the adjustable ranges of the impedance matching unit 11a have been checked.
[0104]
[Step S9] If all the adjustable ranges of the impedance matching unit 11a are not checked, after the impedance matching unit 11a is readjusted (for example, after changing the tuner position to another position), the process returns to step S4. .
[0105]
[Step S10] Even if the adjustable range of the impedance matching unit 11a is checked, if the electron density difference Δn is still greater than or equal to a certain value, the set value of the plasma generation power from the plasma generation power source 10 is changed. Then, the process returns to step S4. The procedure from step S6 to steps S9 and S10 corresponds to the operation process in the present invention.
[0106]
As described above, in this embodiment, the plasma generation power is set and the impedance matching unit 11a is adjusted so that the measured plasma density (measured electron density) converges to the target plasma density (target electron density). The physical quantity in the plasma density information is controlled.
[0107]
Further, since the measurement probe 8 (the central conductor 18 and the flat plate 19 as an antenna thereof) is covered with the dielectric outer skin 20, it is strongly coupled to the sheath portion and absorption occurs, and the frequency of the plasma measurement power source 14 is increased. The absorption point can be observed in the low frequency region from 10 MHz to 500 MHz. Therefore, even if the electron density is 10 ¹² cm ^-3 Since the absorption point can be easily measured in the low frequency region even at a high density, there is no need to use a high-frequency power supply with a frequency of 5 GHz or more, and the measuring device can be simplified and the price of the device body can be reduced. it can.
[0108]
The present invention is not limited to the above embodiment, and can be modified as follows.
[0109]
(1) The above-described plasma processing according to the present embodiment is performed by operating only the plasma generating power, but may be performed by operating the plasma processing power.
[0110]
That is, plasma processing is performed according to the following procedure. Similar to the plasma processing according to the above-described embodiment, when the indoor space S is adjusted to an appropriate atmosphere, the impedance matching unit 13a in the processing power operation unit 13 is set to an appropriate initial state (for example, impedance matching). T of the tuner of the vessel 13a ₁ Set to).
[0111]
After the plasma PM is generated in the indoor space S of the chamber 1, the target plasma processing power P optimum for the plasma processing is obtained. ₀ Is set from the power setting unit 13b. Then, the target plasma processing power P is supplied from the plasma processing power source 12 to the processing electrode 9 through the impedance matching unit 13a. ₀ Supply.
[0112]
Based on the absorption of the plasma measurement power from the plasma measurement power supply 14, the plasma absorption frequency deriving unit 24 derives the plasma absorption frequency. Then, based on the derived plasma absorption frequency, the electron density conversion unit 25 converts it into an electron density. The converted electron density is sent to the power converter 13d.
[0113]
Based on the electron density converted and sent to the power converter 13d, that is, the actually measured electron density n, the power converter 13d converts it into the actually measured plasma processing power P. The converted actual plasma processing power P is sent to the matching unit operation unit 13c. Similar to the above-described plasma processing according to the present embodiment, the matching unit operation unit 13c uses the target plasma processing power P set by the power conversion unit 13d. ₀ And the plasma processing power difference ΔP (= P) between the measured plasma processing power P converted from the power converter 13d. ₀ -P) is derived.
[0114]
Similar to the plasma processing according to this embodiment described above, it is determined whether or not the plasma processing power difference ΔP is equal to or greater than a certain value. If the plasma processing power difference ΔP is less than a certain value, the control process is terminated. If the plasma processing power difference ΔP is equal to or larger than the certain value, the impedance matching unit 13a and the like are readjusted.
[0115]
As described above, in this modification, the physical quantity in the plasma density information is controlled so that the measured plasma processing power converges to the target plasma processing power by adjusting the impedance matching unit 13a.
[0116]
(2) In addition to the plasma processing according to the above-described embodiment and the plasma processing according to the above-described modification, that is, the plasma processing performed by the operation of the plasma generation / processing power, the plasma generation physical quantity and the object to be processed in the plasma The plasma processing method is not particularly limited as long as the plasma processing is performed by manipulating the processing voltage (voltage of the plasma processing power supply 12 in this embodiment) and the processing current to be supplied. For example, as already described in “Prior Art” in this specification, a useful plasma generation physical quantity is the pressure of a gas that generates plasma. Therefore, the plasma processing apparatus according to the present invention may be configured such that the plasma processing is performed by manipulating the gas pressure. That is, a gas pressure conversion unit (not shown) that converts the electron density converted from the electron density conversion unit 25 to a gas pressure corresponding to the electron density, and a flow rate operation unit (not shown) that operates the flow rate control valve 5. May be provided.
[0117]
In the case of having the above configuration, the gas pressure conversion unit obtains the actually measured pressure of the gas based on the electron density converted from the electron density conversion unit 25. The actually measured pressure of the gas is sent to the flow rate control unit, and the flow rate control unit performs feedback control on the flow rate control valve 5. By adjusting the flow rate adjustment valve 5 to the target pressure, the plasma density information such as the electron density is also converged to the target value.
[0118]
Before plasma processing, each plasma generation physical quantity such as operating plasma generation power, plasma processing power, or gas pressure, and various quantities for plasma processing should be selected appropriately. In addition, a conversational step may be provided so that the selected physical quantity and various quantities can be operated.
[0119]
(3) In the above-described embodiment apparatus, the electron density converted from the electron density conversion unit 25 is sent to each operation unit (generation power operation unit 11 and processing power operation unit 13). Other physical quantities in the plasma density information other than the above may be sent to each operation unit. For example, if the plasma density information is a plasma absorption frequency, this modified apparatus is provided with a plasma absorption frequency setting unit (not shown) instead of the electron density setting unit 11b. Then, the actually measured plasma absorption frequency derived from the plasma absorption frequency deriving unit 24 is sent to, for example, the generation power operation unit 11. At this time, it is desirable that the target value and the actual measurement value are configured to have the same data format. That is, when the actually measured plasma absorption frequency is sent to the matching unit operation unit 11c in the generation power operation unit 11, the plasma absorption frequency setting unit sets a target plasma absorption frequency corresponding to the target plasma density. If the difference between the target plasma absorption frequency and the measured plasma absorption frequency is a constant value, the plasma generation physical quantity or the like may be manipulated.
[0120]
(4) In the above-described embodiment apparatus, the plasma generation power and the impedance matching unit 11a are automatically adjusted. However, at least one plasma generation physical quantity and various quantities for performing plasma processing are manually adjusted. It may be a configuration.
[0121]
【The invention's effect】
As described in detail above, according to the plasma density information measuring method of the first aspect of the invention, the plasma density information can be measured even in the low frequency region where the frequency of the power source for plasma measurement is from 10 MHz to 500 MHz. . Therefore, the plasma characteristics can be easily grasped in the low frequency region.
[0122]
According to the plasma density information measuring apparatus of the second aspect of the present invention, the plasma density information deriving means equipped with the plasma density information plasma measuring probe allows the plasma measuring power source even in the low frequency range from 10 MHz to 500 MHz. Plasma density information can be measured. Accordingly, the plasma characteristics can be easily grasped in the low frequency region, and the measurement apparatus can be simplified without requiring a high frequency plasma measurement power source.
[0123]
According to the probe for measuring plasma density information according to the invention of claim 3, since the power for plasma measurement is reflected or absorbed in the low frequency region where the frequency of the power source for plasma measurement is from 10 MHz to 500 MHz, Plasma density information can be easily measured even in the region.
[0124]
In addition, since the plasma density information measuring probe is covered with a dielectric, foreign matter or the like does not enter the plasma density information measuring probe and can be measured smoothly. In addition, it is possible to prevent the antenna from being directly touched by plasma, and to prevent a DC overvoltage from being applied or an overcurrent flowing to break the device.
[0125]
According to the probe for measuring plasma density information according to the invention of claim 4, since the antenna is formed of a flat metal plate, the absorption of power for plasma measurement by the plasma load can be further increased, Plasma density information can be measured more easily.
[0126]
According to the plasma generation method of the fifth aspect of the invention, plasma density information can be measured even in the low frequency region where the frequency of the power source for plasma measurement is 10 MHz to 500 MHz. Therefore, it becomes possible to manipulate the plasma generation physical quantity based on the plasma density information in the low frequency region, and the plasma density is controlled by the operation of the plasma generation physical quantity, and the plasma is generated with the plasma density controlled. Can do.
[0127]
According to the plasma generator of the sixth aspect of the present invention, the plasma density information is derived by the plasma density information deriving means having the probe for measuring plasma density information, even if the frequency of the power source for plasma measurement is in the low frequency range from 10 MHz to 500 MHz. Can be measured. Therefore, it becomes possible to manipulate the plasma generation physical quantity based on the plasma density information in the low frequency region, and the plasma density is controlled by the operation of the plasma generation physical quantity, and the plasma is generated with the plasma density controlled. In addition, it is possible to simplify the measuring apparatus without requiring a high-frequency plasma measuring power source.
[0128]
According to the plasma processing method of the seventh aspect of the invention, plasma density information can be measured even in the low frequency region where the frequency of the power source for plasma measurement is from 10 MHz to 500 MHz. Accordingly, it is possible to manipulate the plasma generation physical quantity based on the plasma density information in the low frequency region, and the plasma density is controlled by the operation of the plasma generation physical quantity, and the plasma treatment is performed in a state where the plasma density is controlled. Plasma treatment can be appropriately performed on an object.
[0129]
According to the plasma processing apparatus of the eighth aspect of the invention, the plasma density information is derived by the plasma density information deriving means equipped with the plasma density information measuring probe even if the frequency of the power source for plasma measurement is in the low frequency range from 10 MHz to 500 MHz. Can be measured. Accordingly, it is possible to manipulate the plasma generation physical quantity based on the plasma density information in the low frequency region, and the plasma density is controlled by the operation of the plasma generation physical quantity, and the plasma treatment is performed in a state where the plasma density is controlled. Plasma processing can be appropriately performed on an object, and a measurement apparatus is simplified without requiring a high-frequency plasma measurement power source.
[0130]
According to the plasma processing apparatus of the ninth aspect of the invention, the operation means operates the plasma generation power supplied from the plasma generation power source. Therefore, the plasma generation power can be controlled by operating the plasma generation power. With the density controlled, the plasma processing can be appropriately performed on the object to be processed in the plasma with the plasma density controlled.
[0131]
According to the plasma processing apparatus of the tenth aspect of the present invention, the operating means operates the plasma processing power supplied from the plasma processing power source to the peripheral portion of the workpiece. Therefore, in the case of the invention of the apparatus of the tenth aspect, the plasma processing can be appropriately performed on the workpiece by the operation of the plasma processing power.
[Brief description of the drawings]
FIG. 1 is a block diagram of a plasma processing apparatus equipped with an example of a plasma density information measuring probe and a measuring apparatus according to an embodiment.
FIGS. 2A and 2B are a partial longitudinal sectional view and a plan view showing a plasma density information measuring probe (measuring probe) according to an embodiment. FIGS.
FIG. 3 is a diagram illustrating a measurement result of a change in reflectance with respect to frequency of power for plasma measurement according to an example.
FIG. 4 is a diagram showing measurement results of changes in electron density versus plasma absorption frequency when a fluororesin and mica are used.
FIG. 5 is a block diagram relating to an experimental apparatus for deriving an electron density.
FIG. 6 is a flowchart showing a flow of operation of power for generating plasma.
FIG. 7 is a partial longitudinal sectional view showing a configuration of an example of a measurement probe according to an improved invention.
FIG. 8 is a diagram showing a measurement result of a change in reflectance with respect to frequency of power for plasma measurement according to the improved invention.
FIG. 9 is a partial longitudinal sectional view showing a configuration of an example of a measurement probe before the present invention for observing an absorption point in a low frequency region.
[Explanation of symbols]
1 ... Chamber
2… discharge electrode
5… Flow control valve
8… Measuring probe
9 ... Processing electrode
10 ... Power source for plasma generation
11 ... Generation power operation unit
12 ... Power supply for plasma processing
13: Processing power operation unit
11a, 13a: Impedance matching device
11b Electron density setting unit
13b ... Power setting unit
11c, 13c: Matching unit operation unit
13d: Power conversion unit
14 ... Power supply for plasma measurement
15 ... Coaxial cable
16 ... Probe controller
17 ... Plasma density information measurement unit
18… Central conductor
19 ... Flat plate
20… Dielectric outer skin
24 ... Plasma absorption frequency deriving section
25 ... Electron density converter
S ... Indoor space
W ... Workpiece
PM… Plasma
ST… Stage

Claims (10)

A plasma density information measuring method for measuring plasma density information indicating the characteristics of plasma, comprising: supplying power for measuring plasma density information from a power source for measuring plasma density information for measuring plasma density information; The antenna and the cable are connected to one end of the antenna, and at least the antenna is directly covered with a dielectric material. The plasma density information measurement power is supplied to the plasma using the plasma density information measurement probe, and the plasma density information measurement power is reflected or absorbed by the plasma load that appears in a frequency range of 10 MHz to 500 MHz. Measure plasma density information based on Plasma density information measuring method characterized by comprising the that plasma density information measuring process. A plasma density information measuring device for measuring plasma density information indicating plasma characteristics, wherein the frequency of the plasma density information measuring power source for measuring the plasma density information and the frequency of the plasma density information measuring power source is from 10 MHz to 500 MHz. Plasma density information provided with a plasma density information measuring probe for measuring plasma density information based on reflection or absorption of plasma density information measuring power supplied from the plasma density information measuring power source, which appears in the frequency domain, by a plasma load and a measuring means, the plasma density information measuring probe, an antenna for radiating the plasma density information measuring power, together and a cable for transmitting the plasma density information measuring power, the antenna and the cable And are connected at one end of the antenna Ri, at least antennas plasma density information measuring apparatus characterized by being directly coated with a dielectric material. The reflection of the plasma density information measurement power supplied from the plasma density information measurement power supply, which appears in the frequency range from 10 MHz to 500 MHz, in the frequency range of the plasma density information measurement power supply for measuring the plasma density information, or A probe for measuring plasma density information that measures plasma density information based on absorption, comprising an antenna that radiates the power for measuring plasma density information, and a cable that transmits the power for measuring plasma density information A probe for measuring plasma density information, wherein the antenna and the cable are connected at one end of the antenna, and at least the antenna is directly covered with a dielectric material.   4. The plasma density information measuring probe according to claim 3, wherein the antenna is a flat metal plate. A plasma generating method for controlling the plasma density by operating the physical amount related to the plasma generation, a power measuring plasma density information from the plasma density information measuring power for measuring the plasma density information, the plasma density information measuring An antenna for radiating power for use and a cable for transmitting the power for measuring plasma density information, and the antenna and the cable are connected at one end of the antenna, and at least the antenna is directly made of a dielectric material. The plasma density information measuring power is supplied to the plasma using the plasma density information measuring probe coated on the electrode, and the power of the plasma density information measuring power source is reflected in the frequency range from 10 MHz to 500 MHz. Or plasma dense based on absorption Plasma generating method characterized by comprising the plasma density information measuring process for measuring information, and an operation step of operating the physical quantity related to the plasma generated based on the measured plasma density information. A plasma generator for controlling plasma density by manipulating a physical quantity related to plasma generation, a plasma density information measuring power source for measuring plasma density information, a plasma generating power source, and a plasma density information measuring power source Plasma density information measurement for measuring plasma density information based on reflection or absorption of plasma density information measurement power supplied from the plasma density information measurement power supply, which appears in a frequency range from 10 MHz to 500 MHz. It includes a plasma density information measuring means comprises a use the probe, and an operation means for operating the physical quantity related to the plasma generated based on the measured plasma density information, the plasma density information measuring probe, the plasma density an antenna for radiating the power information measured, before And a cable for transmitting power for measuring plasma density information, wherein the antenna and the cable are connected at one end of the antenna, and at least the antenna is directly covered with a dielectric material. A plasma generator. A plasma processing method for performing plasma processing by placing an object to be processed in plasma in which plasma density is controlled by manipulating physical quantities relating to plasma generation, and a power source for measuring plasma density information for measuring plasma density information a power measuring plasma density information from, an antenna for radiating the plasma density information measuring power, together and a cable for transmitting the plasma density information measuring power, one end of the antenna and the cable and the antenna And at least the antenna is supplied to the plasma using a probe for measuring plasma density information in which the antenna is directly covered with a dielectric material, and the frequency of the power source for measuring plasma density information is in a frequency range from 10 MHz to 500 MHz. Appearing plasma density information due to plasma load A plasma density information measurement process for measuring plasma density information based on reflection or absorption of power for measurement, and an operation process for manipulating a physical quantity related to the plasma generation based on the measured plasma density information. A plasma processing method. A plasma processing apparatus for performing plasma processing by placing an object to be processed in plasma whose plasma density is controlled by manipulating physical quantities related to plasma generation, for measuring plasma density information The power for plasma density information measurement, the power for plasma generation, and the power for plasma density information measurement appear in the frequency range from 10 MHz to 500 MHz, and the power for plasma density information measurement supplied from the power source for plasma density information measurement Plasma density information measuring means having a plasma density information measuring probe for measuring plasma density information based on reflection or absorption by a plasma load of the plasma, and manipulating physical quantities related to the plasma generation based on the measured plasma density information The plasma density information. Titration, the probe includes an antenna for radiating the plasma density information measuring power, together and a cable for transmitting the plasma density information measuring power, and the antenna and the cable is connected at one end side of the antenna A plasma processing apparatus, wherein at least the antenna is directly covered with a dielectric material.   9. The plasma processing apparatus according to claim 8, wherein the operating means operates plasma generation power supplied from the plasma generation power source.   10. The plasma processing apparatus according to claim 8, wherein the operating unit operates a plasma processing power supplied from a plasma processing power source to a peripheral portion of the object to be processed. .

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