JP2004055324A - Plasma density information measuring method and apparatus, plasma density information monitoring method and apparatus, plasma processing method and apparatus - Google Patents

Abstract

A plasma density information measuring method and apparatus, and a plasma density information monitoring method and apparatus, and a plasma processing method capable of efficiently performing plasma density information measurement, plasma density information change monitoring, and plasma processing. And an apparatus thereof.
A measurement probe (7) is configured to be insertable in front of a substrate (W) to be processed with respect to plasma processing, and is inserted and disposed in front of the substrate (W). Therefore, the measurement probe 7 is less likely to be shadowed, so that the measurement of the plasma density information, the monitoring of the change in the plasma density information, and the plasma processing can be performed efficiently.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a plasma density information measuring method and apparatus, a plasma density information monitoring method and apparatus, and a plasma processing method and apparatus used in a manufacturing process of a semiconductor element or a thin film element, a particle beam source, an analyzer, or the like. About.
[0002]
[Prior art]
As techniques using plasma, plasma CVD (chemical vapor deposition), plasma etching, and the like are known. In such a plasma application technique, plasma in a plasma processing chamber (for example, a chamber) for performing a plasma process changes with time, and thus information on the plasma density that indicates the characteristics of the generated plasma, that is, the plasma density information is sufficiently obtained. Is very important for proper processing. Useful physical quantities related to the plasma density information include quantities related to the electron density, that is, an absorption frequency, a plasma surface wave resonance frequency, and the like. By measuring these frequencies and the like, plasma density information can be sufficiently grasped to perform plasma processing.
[0003]
As a technique for measuring plasma density information, the present inventors have previously proposed the invention of Japanese Patent Application Laid-Open No. 2000-100598. In the present invention, as shown in FIG. 11, a plasma density information measurement probe 101 (hereinafter, abbreviated as “measurement probe 101” as appropriate) for measuring plasma density information is inserted into a chamber 102 which is a plasma processing chamber. Then, the power for measuring plasma density information 103 (hereinafter abbreviated as “power for measuring 103”) for measuring plasma density information (hereinafter abbreviated as “power for measurement” as appropriate). Is supplied to the plasma PM in the chamber 102 to perform the measurement. The measurement probe 101 is composed of an antenna 104 for radiating power, a coaxial cable 105 for transmitting power for measurement, and a dielectric tube 106 having a closed end. The antenna 104 and the coaxial cable 105 are connected and inserted.
[0004]
The measurement power is radiated from the measurement power supply 103 to the antenna 104 via the coaxial cable 105 and supplied to the plasma PM in the chamber 102. The measuring power supplied to the plasma PM in the chamber 102 is absorbed by the plasma load due to the plasma density or reflected and returned via the coaxial cable 105. In other words, a surface wave having a wavelength depending on the electron density of the plasma is excited on the surface of the dielectric tube 106 of the measurement probe 101 by the measurement power supplied to the plasma PM, and the region where the surface wave propagates is just When the wavelength becomes an integral multiple of the wavelength, that is, when the surface wave resonates, absorption occurs. At this time, when the frequency of the measurement power is swept, the wavelength changes in proportion to the frequency, so that strong absorption is exhibited only at a certain frequency. By measuring this frequency, the plasma density information is measured.
[0005]
More specifically, the measurement power supply 103 is of a frequency sweep type, and outputs the power for measurement while automatically sweeping at a frequency in a certain frequency band (for example, from 100 kHz to 2.5 GHz). When the measuring power is absorbed or reflected, the reflected power is transmitted in a direction opposite to the direction in which the power is supplied to the plasma PM in the chamber 102, and is disposed between the measuring probe 101 and the measuring power supply 103. The directional coupler 107 is sent to an output device 108 for outputting to a monitor or the like. The frequency of the measurement power output from the measurement power supply 6 is also sequentially sent to the output device 108.
[0006]
The output device 108 obtains a change in the reflectance of the measurement power with respect to the frequency based on the frequency of the measurement power and the detected reflection amount of the measurement power. That is, at the same frequency, an operation of [detection reflection amount of measurement power] ÷ [total output amount of measurement power] is performed to determine the reflectance of the measurement power, and the swept frequency and the reflectance of the measurement power are calculated. Plot them in association. Then, based on the obtained result, an absorption frequency at which strong absorption of the measuring power occurs due to the electron density is obtained. Since the above-mentioned absorption frequency has a certain correlation with plasma density information such as electron density, plasma density information can be easily obtained by obtaining the absorption frequency.
[0007]
[Problems to be solved by the invention]
However, the conventional example having such a configuration has the following problem.
When applied to plasma processing (plasma CVD or plasma etching processing) using the above-described measurement probe 101, an electrode 109 connected to a processing voltage (bias voltage) is provided in a chamber 102 as shown in FIG. The substrate W as an object to be processed is placed on the electrode 109. Since the plasma density information to be measured is measured with high spatial resolution, the result of the measured plasma density information differs depending on the arrangement position of the measurement probe 101. In order to control the plasma processing more precisely, A measurement probe 101 is arranged near W (directly above in FIG. 12) and near the center of the chamber 102.
[0008]
However, when the measurement probe 101 is provided in this manner, the measurement probe 101 becomes a shadow on the substrate W. Therefore, when a bias voltage is applied to the electrode 109 for performing the plasma processing, ions in the plasma move at the same time toward the electrode 109 to which the ions are applied. It does not reach W or electrode 109. As a result, the plasma processing becomes difficult to proceed, which adversely affects the plasma processing.
[0009]
The present invention has been made in view of such circumstances, and a plasma density information measuring method and apparatus capable of efficiently measuring plasma density information, monitoring changes in plasma density information, and performing plasma processing. And a plasma density information monitoring method and apparatus, and a plasma processing method and apparatus therefor.
[0010]
[Means for Solving the Problems]
The present inventors have earnestly studied to solve the above problems, and have obtained the following findings.
A so-called ICP (Inductively Coupled Plasma) type, in which a magnetic field is generated in the antenna by passing a current through an antenna having a coil and an induced electric field is generated by the magnetic field from the antenna, that is, an inductively coupled plasma is taken as an example. Take and explain. The diameter of the chamber is 400 mm. Measurement results of the electron density when the frequency of the generation power is 13.56 MHz and the generation power of 500 W is applied to the coil, and the arrangement position of the above-described measurement probe 101 (see FIGS. 11 and 12) is changed. Is shown in FIG. Further, argon (Ar) is used as a gas for generating plasma, and the gas pressure is set to 4 Pa, 5 Pa, and 6 Pa, respectively. Assuming that the (arrangement) position of the probe is r, when the position r is 200 mm, the probe is arranged at the center of the chamber, and when the position r is 0 mm, the probe is arranged on the wall of the chamber. .
[0011]
As shown in FIG. 13, the electron density continuously decreases toward the wall with the position r peaking at 200 mm (center of the chamber). Even when the position r is 0 mm, that is, the probe is arranged on the wall of the chamber. Is lower by one to two digits than when the position r is 200 mm, ^Fifteen / M ³ The above electron density can be measured. However, 10 ^Fifteen / M ³ Before and after, in the measurement probe 101 shown in FIGS. 11 and 12, the signal intensity (absorption level) of the absorption waveform (reflectance change of the measurement power with respect to the frequency) for confirming the electron density becomes small, making the measurement difficult. Become.
[0012]
Therefore, when the measurement probe (see FIG. 14) according to the invention of Japanese Patent Application Laid-Open No. 2002-043093 previously proposed by the present inventors is used, the relative relationship shown in FIG. 15 and the absorption rate at the absorption frequency shown in FIG. The result is obtained. As shown in FIG. 14, the measurement probe 201 is composed of an antenna 202 for radiating power and a coaxial cable 203 for transmitting power for measurement. The antenna 202 is composed of a central conductor 204 and a flat metal plate. 205 (see the plan view of FIG. 14B). The coaxial cable 203 is connected to one end of the center conductor 204, and the flat plate 205 is connected to the other end of the center conductor 204. Further, the center conductor 204 and the flat plate 205 are covered with a dielectric outer cover 206 as shown in the cross-sectional view of FIG.
[0013]
FIG. 15 shows the measurement results of the electron density at the center of the chamber and the absorption frequency at 2.5 mm from the wall when the generation power was changed. FIG. 16 shows the chamber when the generation power was changed. It is a measurement result of the absorptivity at 2.5 mm from the center and the wall. 15, the solid line indicates the electron density when the measurement probe 101 shown in FIGS. 11 and 12 is disposed at the center of the chamber, and the two-dot chain line indicates the absorption when the measurement probe 201 is disposed 2.5 mm from the wall. Frequency. In FIG. 16, the solid line indicates the absorption rate at the absorption frequency when arranged at the center of the chamber, and the two-dot chain line indicates the absorption rate at the absorption frequency when arranged at 2.5 mm from the wall.
[0014]
As described in the invention of Japanese Patent Application Laid-Open No. 2002-043093, the absorption frequency is about 1/10 to 1/100 of the absorption frequency measured by the measurement probe 101 shown in FIGS. The frequency is measured, and the absorption frequency measured by the measurement probe 101 shown in FIGS. 11 and 12 is originally different from the absorption frequency measured by the measurement probe 201 shown in FIG. Therefore, the electron density measured by the measurement probe 101 shown in FIGS. 11 and 12 and the absorption frequency measured by the measurement probe 201 shown in FIG. 14 are originally different from each other. However, the electron density at the center of the chamber measured by the measurement probe 101 shown in FIGS. 11 and 12 and the absorption frequency at 2.5 mm from the wall measured by the measurement probe 201 shown in FIG. However, it can be seen from FIG. Also, as shown in FIG. 16, the absorption rate measured by the measurement probe 201 shown in FIG. 14 is about half that when the probe is arranged at 2.5 mm from the wall as compared with the case where the probe is arranged at the center of the chamber. When the measurement is performed by the measurement probe 201 shown in FIG. 14, the plasma density information such as the absorption frequency is easily measured.
[0015]
For the above reasons, the graph shown in FIG. 13 is used for measurement with the measurement probe 101 shown in FIGS. 11 and 12, and the graph shown in FIG. 15 is used for measurement with the measurement probe 201 shown in FIG. Based on this, plasma density information such as electron density near the substrate at the center of the chamber can be obtained. That is, it is sufficient if the plasma density information is obtained at a position before the object to be processed such as the substrate without obtaining the plasma density information near the substrate at the center of the chamber.
[0016]
Therefore, the present inventors have changed their ideas, and have arrived at obtaining plasma density information at a position in front of an object to be processed such as a substrate. The present invention based on such knowledge has the following configuration.
[0017]
That is, the invention according to claim 1 is a plasma density information measuring method for measuring plasma density information indicating characteristics of plasma, wherein: (a) a plasma density information measuring probe which is a probe for measuring the plasma density information; A step of inserting and disposing a probe for plasma processing in front of an object to be processed related to plasma processing; and (b) a power source for measuring plasma density information from a power source for measuring plasma density information. Supplying the plasma density information to the plasma; and (c) using the plasma density information measurement probe disposed on the front side of the object to be processed, based on the reflection or absorption of the plasma density information measurement power by the plasma load. Measuring the plasma density information.
[0018]
According to the first aspect of the present invention, the plasma density information measuring power supplied from the plasma density information measuring power source (hereinafter abbreviated as "power source for measuring" as appropriate) in the step (b). The power (hereinafter, abbreviated as “measurement power” as appropriate) is absorbed or reflected by the plasma load due to the plasma density and returned through the plasma density information measurement probe. In other words, a surface wave depending on the plasma is excited on the surface of the probe for measuring plasma density information, whereby absorption or reflection by the plasma load occurs. In the process (c), the plasma density information is measured using the plasma density information measurement probe based on the reflection or absorption of the measurement power. Since the plasma density information indicates the characteristics of the plasma, the characteristics of the plasma can be grasped by measuring the plasma density information. In the process (a), the plasma density information measuring probe is inserted and disposed on the front side of the object to be processed related to the plasma processing. The probe is less likely to be shadowed, and the plasma density information can be measured efficiently.
[0019]
The plasma density information measurement probe may be inserted and disposed on the near side of the object to be processed, but preferably, is further on the front side than the wall of the plasma processing chamber located on the front side of the object to be processed. It is inserted and arranged (the invention according to claim 2). Thus, the probe for measuring plasma density information is less likely to be shadowed on the object to be processed, and the measurement of plasma density information can be performed efficiently.
[0020]
Further, the probe for measuring plasma density information is configured to include an antenna for radiating power, a cable for transmitting power for measuring plasma density information, and a dielectric region coupled to plasma. By connecting at one end, at least the antenna is directly covered by the dielectric region (the invention according to claim 3), so that the absorption rate of the absorption waveform is compared with that of another plasma density information measurement probe. And the plasma density information is easily measured.
[0021]
According to a fourth aspect of the present invention, there is provided a plasma density information measuring apparatus for measuring plasma density information indicating characteristics of a plasma, wherein the plasma density information measuring power is supplied to the plasma to measure the plasma density information. Power supply for density information measurement, comprising the plasma density information measurement probe to measure the plasma density information based on the reflection or absorption of the plasma density information measurement power by the plasma load, the plasma density information measurement probe, The plasma processing apparatus is characterized in that it is configured to be able to be inserted in front of an object to be processed related to plasma processing.
[0022]
According to the fourth aspect of the present invention, the plasma density information measuring power (measuring power) input from the plasma density information measuring power source (measuring power source) is a plasma density information measuring probe. , Is absorbed or reflected by the plasma load due to the plasma density and returns. Based on the reflection or absorption of the measurement power, the plasma density information is measured using the plasma density information measurement probe. In addition, since the probe for measuring plasma density information is configured to be insertable on the near side of the object to be processed related to plasma processing, the probe for measuring plasma density information is inserted and installed on the near side of the object to be processed. By arranging them, the plasma density information measurement probe is less likely to be shadowed on the object to be processed, and the plasma density information can be measured efficiently.
[0023]
Further, similarly to the invention according to claim 2, the plasma density information measuring probe is preferably inserted and disposed further on the front side than the wall of the plasma processing chamber located on the front side of the object to be processed. (The invention according to claim 5). Thus, the probe for measuring plasma density information is less likely to be shadowed on the object to be processed, and the measurement of plasma density information can be performed efficiently.
[0024]
Further, the probe for measuring plasma density information is configured to include an antenna for radiating power, a cable for transmitting power for measuring plasma density information, and a dielectric region coupled to plasma. By connecting at one end side, at least the antenna is directly covered by the dielectric region (the invention according to claim 6), so that the absorption rate of the absorption waveform is compared with that of another plasma density information measurement probe. And the plasma density information is easily measured.
[0025]
The invention according to claim 7 is a plasma density information monitoring method for monitoring plasma density information indicating plasma characteristics, wherein: (a) a probe for measuring the plasma density information; (B) inserting the plasma density information measurement power from the plasma density information measurement power source for measuring the plasma density information into the plasma. And (c) ₁ Using the probe for measuring plasma density information disposed on the front side of the object to be processed, monitoring a temporal change in plasma density information based on reflection or absorption of the power for measuring plasma density information by a plasma load. And a step of performing the operation.
[0026]
According to the invention described in claim 7, the plasma density information measurement power (measurement power) supplied from the plasma density information measurement power source (measurement power source) in the process (b) is: Via the plasma density information measuring probe, the light is absorbed or reflected by the plasma load due to the plasma density, and returns. (C ₁ In the process of (2), a temporal change of the plasma density information is monitored using the plasma density information measuring probe based on the reflection or absorption of the measuring power. Since the plasma density information indicates the characteristics of the plasma, by monitoring the temporal change of the plasma density information, the temporal change of the plasma characteristics can be grasped. In the process (a), the plasma density information measuring probe is inserted and disposed on the front side of the object to be processed related to the plasma processing. It is possible to efficiently monitor the change in the plasma density information because the probe is not easily shadowed.
[0027]
Also, as in the second and fifth aspects of the present invention, the plasma density information measuring probe is preferably inserted further in front of the wall of the plasma processing chamber located in front of the object to be processed. (The invention according to claim 8). As a result, the plasma density information measuring probe is less likely to be overshadowed by the object to be processed, and a change in the plasma density information can be monitored efficiently.
[0028]
Further, the probe for measuring plasma density information is configured to include an antenna for radiating power, a cable for transmitting power for measuring plasma density information, and a dielectric region coupled to plasma. By connecting at one end and at least the antenna being directly covered by the dielectric region (the invention according to claim 9), the absorption rate of the absorption waveform is compared with that of other plasma density information measurement probes. And changes in plasma density information can be easily monitored.
[0029]
Further, as a specific method for monitoring a change in plasma density information, a method according to the present invention described in claim 10 below can be mentioned. That is, according to a tenth aspect of the present invention, in the plasma density information monitoring method according to any one of the seventh to ninth aspects, in the step (b), the frequency is swept from the plasma density information measuring power supply. While sequentially supplying the plasma density information measuring power of each frequency to the plasma, ₁ The step of) is a step of monitoring the temporal change of the plasma density information based on the temporal change of the absorption waveform indicating the change of the reflection or the absorptance of the power for measuring the plasma density information at the swept frequency. It is characterized by the following.
[0030]
According to the tenth aspect of the present invention, in the process (b), the plasma density information measuring power of each frequency is sequentially supplied to the plasma while the frequency is swept from the plasma density information measuring power supply. Thus, an absorption waveform indicating a change in the reflection or absorptance of the power for measuring plasma density information at the swept frequency is obtained. (C ₁ In the process (2), a change in the plasma density information can be monitored based on the temporal change of the absorption waveform.
[0031]
According to the invention of claim 10, (c) ₁ As a further specific example of the step ()), the method according to the invention described in claims 11 to 15 can be mentioned. For example, the temporal change of the absorption rate of the absorption waveform (the invention according to claim 11), the temporal width of the half width which is the frequency width when the reflection or absorption rate of the power for measuring plasma density information becomes half in the absorption waveform. Change (the invention according to claim 12), a temporal change in the Q value (quality factor) indicating the degree of resonance due to the plasma load in the absorption waveform (invention according to claim 13), and the change of the frequency swept in the absorption waveform. Of these, the temporal change in the reflection or absorption rate of the power for measuring plasma density information at the same frequency (the invention according to claim 14), or the maximum or minimum frequency of the frequency derivative of the absorption waveform, or the temporal change in the maximum or minimum value. The temporal change of the plasma density information may be monitored based on the change (the invention according to claim 15) (the invention according to claims 11 to 15). .
[0032]
An invention according to claim 16 is a plasma density information monitoring apparatus for monitoring plasma density information indicating characteristics of a plasma, wherein the plasma density information measuring power is supplied to the plasma to measure the plasma density information. A power source for density information measurement, the plasma density information measurement probe for measuring plasma density information based on reflection or absorption of the plasma density information measurement power by a plasma load, and a plasma density information measurement probe Monitoring means for monitoring a temporal change of the plasma density information from the plasma density information, wherein the plasma density information measuring probe is configured to be able to be inserted in front of an object to be processed related to plasma processing. It is a feature.
[0033]
According to the invention, the power for measuring plasma density information (power for measurement) input from the power source for measuring plasma density (power for measurement) is a probe for measuring plasma density information. , Is absorbed or reflected by the plasma load due to the plasma density and returns. Based on the reflection or absorption of the measuring power, the monitoring means monitors the temporal change of the plasma density information using the plasma density information measuring probe. Since the plasma density information indicates the characteristics of the plasma, by monitoring the temporal change of the plasma density information, the temporal change of the plasma characteristics can be grasped. In addition, since the probe for measuring plasma density information is configured to be insertable on the near side of the object to be processed related to plasma processing, the probe for measuring plasma density information is inserted and installed on the near side of the object to be processed. By arranging, it is possible to efficiently monitor the change in the plasma density information, since the probe for measuring the plasma density information is not easily shadowed on the object to be processed.
[0034]
Also, as in the second, fifth, and eighth aspects of the present invention, the plasma density information measuring probe is preferably located further forward than the wall of the plasma processing chamber located closer to the object to be processed. (The invention according to claim 17). As a result, the plasma density information measuring probe is less likely to be overshadowed by the object to be processed, and a change in the plasma density information can be monitored efficiently.
[0035]
Further, the probe for measuring plasma density information is configured to include an antenna for radiating power, a cable for transmitting power for measuring plasma density information, and a dielectric region coupled to plasma. By connecting at one end, at least the antenna is directly covered by the dielectric region (the invention according to claim 18), so that the absorption rate of the absorption waveform is compared with that of another plasma density information measurement probe. And changes in plasma density information can be easily monitored.
[0036]
The invention according to claim 19 is a plasma processing method for performing plasma processing on an object to be processed in plasma, wherein (a) a plasma density information measuring probe, which is a probe for measuring the plasma density information, (B) supplying plasma density information measuring power to the plasma from a plasma density information measuring power source for measuring the plasma density information; And (c) using the plasma density information measurement probe disposed in front of the object to be processed, based on the reflection or absorption of the plasma density information measurement power by the plasma load. Or measuring (c) ₁ Using the probe for measuring plasma density information disposed on the front side of the object to be processed, monitoring a temporal change in plasma density information based on reflection or absorption of the power for measuring plasma density information by a plasma load. And (d) controlling the plasma processing based on the measured or monitored plasma density information.
[0037]
[Operation / Effect] According to the invention of claim 19, in the process (b), the plasma density information measuring power (measuring power) supplied from the plasma density information measuring power source (measuring power source) is: Through the plasma density information measuring probe, the light is absorbed or reflected by the plasma load due to the plasma density, and returns. (C) or (c ₁ In the process of step (1), the plasma density information is measured using the probe for measuring the plasma density information or the change over time is monitored based on the reflection or absorption of the measuring power. Since the plasma density information indicates the characteristics of the plasma, the plasma processing is controlled in the process (d) by measuring the plasma density information or monitoring its temporal change. In the process (a), the plasma density information measuring probe is inserted and disposed on the front side of the object to be processed related to the plasma processing. The probe is less likely to be shadowed and plasma processing can be performed efficiently.
[0038]
Also, as in the second, fifth, eighth, and seventeenth aspects of the present invention, the plasma density information measuring probe is preferably provided on a wall of the plasma processing chamber located in front of the workpiece. Are also inserted and disposed on the near side (the invention according to claim 20). Thus, the plasma density information measuring probe is less likely to be shadowed on the object to be processed, and the plasma processing can be performed efficiently.
[0039]
Further, the probe for measuring plasma density information is configured to include an antenna for radiating power, a cable for transmitting power for measuring plasma density information, and a dielectric region coupled to plasma. By connecting at one end and at least the antenna being directly covered by the dielectric region (the invention according to claim 21), the absorption rate of the absorption waveform is compared with that of another plasma density information measurement probe. And the plasma processing becomes easier to control.
[0040]
An invention according to claim 22 is a plasma processing apparatus for performing plasma processing on an object to be processed in plasma, wherein plasma density information measurement power is supplied to the plasma to measure plasma density information. A power supply, a plasma density information measuring probe for measuring plasma density information based on reflection or absorption of the plasma density information measuring power by a plasma load, and controlling a plasma process based on the measured plasma density information. The plasma density information measuring probe is configured to be inserted in front of an object related to plasma processing.
[0041]
According to the invention described in claim 22, the power for plasma density information measurement (power for measurement) input from the power supply for plasma density information measurement (power for measurement) is a probe for plasma density information measurement. , Is absorbed or reflected by the plasma load due to the plasma density and returns. Based on the reflection or absorption of the measurement power, the plasma density information is measured using the plasma density information measurement probe. Since the plasma density information indicates the characteristics of the plasma, the plasma processing is controlled by the control unit by measuring the plasma density information. In addition, since the probe for measuring plasma density information is configured to be insertable on the near side of the object to be processed related to plasma processing, the probe for measuring plasma density information is inserted and installed on the near side of the object to be processed. By disposing, the plasma density information measurement probe is less likely to be shadowed on the object to be processed, and the plasma processing can be performed efficiently.
[0042]
In the case where the plasma processing is controlled based on the monitored plasma density information, a monitoring means for monitoring a temporal change of the plasma density information from the plasma density information measured by the plasma density information measuring probe may be provided. Good (the invention according to claim 23).
[0043]
Also, as in the second, fifth, eighth, seventeenth, and twentieth aspects of the present invention, the plasma density information measuring probe is preferably located in front of the workpiece. It is arranged by being inserted further in front of the wall of the room (the invention according to claim 24). Thus, the plasma density information measuring probe is less likely to be shadowed on the object to be processed, and the plasma processing can be performed efficiently.
[0044]
Further, the probe for measuring plasma density information is configured to include an antenna for radiating power, a cable for transmitting power for measuring plasma density information, and a dielectric region coupled to plasma. The connection is made at one end, and at least the antenna is directly covered with the dielectric region (the invention according to claim 25), so that the absorption rate of the absorption waveform is compared with that of another plasma density information measurement probe. And the plasma processing becomes easier to control.
[0045]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a plasma processing apparatus used for a probe for measuring plasma density information according to the present invention. In this embodiment, an ICP (Inductively Coupled Plasma) type, that is, an inductively coupled plasma, and an etching process will be described as an example.
[0046]
As shown in FIG. 1, the etching apparatus according to the present embodiment includes a chamber 1 in which a plasma PM is generated, and an electrode connected to a processing voltage (not shown) in the chamber 1. A substrate W as an object to be processed is placed on the electrode 2. By applying a processing voltage to the electrode 2, the substrate W is etched by the plasma. A quartz plate 3 and a coil 4 are provided in an upper portion of the chamber 1. The coil 4 is connected to a power source 5 for generating plasma PM, and a magnetic field is generated from the quartz plate 3 by passing a current from the power source 5 for generation to the quartz plate 3 via the coil 4. . A dielectric magnetic field is generated by the magnetic field from the quartz plate 3, and plasma PM is generated by heating. In this embodiment, the generation power supplied from the generation power supply 5 is a high frequency of about 500 W and a frequency of about 13.56 MHz.
[0047]
Note that the plasma treatment is not limited to plasma etching, and is not particularly limited as long as it is a process usually performed by plasma, such as plasma CVD or plasma ashing. In addition to the ICP type, the chamber 1 is used for a so-called CCP (Capacitively Coupled Plasma) type in which two electrodes are opposed to each other and a plasma is generated between the two electrodes, that is, a non-magnetic field plasma such as a capacitively coupled plasma. It may be a chamber or a chamber used for a magnetic field plasma such as ECR (Electron Cyclotron Resonance) plasma.
[0048]
The generation power supply 5 is connected to the coil 4 via a generation power control unit 6, and the generation power control unit 6 controls the generation power supplied from the generation power supply 5 to the chamber 1. . The generation power control unit 6 corresponds to a control unit in the present invention.
[0049]
Further, in the chamber 1, in addition to the substrate W and the electrodes 2 described above, a measurement probe 7 for measuring plasma density information in the chamber 1 is inserted. The measurement probe 7 corresponds to the plasma density information measurement probe in the present invention.
[0050]
The measurement probe 7 and a measurement power supply 8 for measuring plasma density information are connected via a coaxial cable 9 and a probe control unit 10. In this embodiment, the electron density is measured as the plasma density information, but other plasma density information includes, for example, ion density, an absorption frequency described later, and a plasma surface wave resonance frequency. The power supply for measurement 8 corresponds to the power supply for measuring plasma density information in the present invention.
[0051]
In addition to the above-described substrate W, electrode 2, and measurement probe 7, the chamber 1 and a gas supply source (tank) 11 for supplying a gas for generating plasma PM are connected to each other via a gas adjusting valve 12. Have been.
[0052]
Next, a specific configuration of the generation power control unit 6 will be described. The generation power control unit 6 includes an etching rate conversion unit 13, an etching time conversion unit 14, an etching time setting unit 15, and an impedance matching unit 16. The etching rate converter 13 is configured to convert the electron density measured by the measurement probe 7 and the probe controller 10 into an etching rate corresponding to the electron density, and the etching time converter 14 converts the electron density. It is configured to convert the etching rate into an etching time according to the electron density. The etching time setting unit 15 is configured to set the etching time, and the impedance matching unit 16 adjusts the supply of the power for generation to the chamber 1 or sets the chamber after the set etching time elapses. 1 is terminated. Note that the etching rate used in this specification refers to a thickness of a film etched per unit time.
[0053]
The etching rate conversion unit 13 and the etching time conversion unit 14 have a function of a calculation unit such as a CPU (central processing unit), and have a certain correlation between the etching rate and the electron density in a unique process. Taking advantage of this, a value obtained by multiplying the measured electron density by a coefficient by the calculation unit is converted as an etching rate, and a value obtained by dividing the thickness of a film to be etched by the etching rate is converted as an etching time. You. In the present embodiment, the etching rate conversion unit 13 and the etching time conversion unit 14 are configured by a calculation unit such as a CPU (central processing unit). However, a storage unit not shown is provided, and the storage unit includes an electronic storage unit. A calibration curve or the like indicating the correlation between the density and the etching rate is stored in advance, and read out from the storage unit at any time according to the measured electron density to derive the etching rate and the etching time. Is also good.
[0054]
The etching time setting unit 15 has a timer and a clock function. The timer is reset almost at the same time as the electron density is measured, and the timer starts counting. When the timer is counted by an amount corresponding to the set etching time, the etching time setting unit 15 supplies the impedance matching unit 16 with a matching circuit in the impedance matching unit 16 so as to end the supply of the power for generation. To operate. In the present embodiment, the etching time setting unit 15 terminates the supply of the power for generation to the plasma PM by operating the impedance matching unit 16, but operates the power supply 5 for generation directly. The etching time setting unit 15 may be configured to directly terminate the application of voltage or the like, or may be configured to directly operate the processing voltage or the like applied to the electrode 2. Is also good. In the case where the substrate W is continuously processed, when the timer is counted by an amount corresponding to the etching time set by the etching time setting unit 15, the substrate W being processed is taken out of the chamber 1, and The substrate W to be processed next may be loaded into the chamber 1.
[0055]
When the frequency of the generation power supply 5 is a frequency on the order of MHz, a matching circuit combining an inductance and a capacitance is used as the impedance matching device 16. When the frequency is 1 GHz or more, an EH tuner or a stub tuner is used.
[0056]
Next, the measurement probe 7 will be described with reference to FIG. The measurement probe 7 is formed by processing and forming the distal end of the coaxial cable 9, and as shown in FIG. 2, after removing the external insulator 9 a and the external conductor 9 b of the coaxial cable 9 at the distal end. It is constituted by covering a dielectric tube 17 having a closed end. In addition, since the outer insulator 9a, the outer conductor 9b, and the center insulator 9c are removed, only the center conductor 9d is provided at the distal end of the coaxial cable 9, and the center conductor 9d is transmitted through the coaxial cable 9. The antenna functions as an antenna that radiates the electric power.
[0057]
The measurement probe 7 is inserted into the plasma PM. Next, measurement power is transmitted from the measurement power supply 8. Then, at the absorption frequency of the measurement probe 7, resonance absorption occurs at the distal end while holding the tube 17, the coaxial cable 9, and the like under boundary conditions. As a result, the electromagnetic wave supplied and transmitted from the measurement power supply 8 is absorbed, and the reflected power at the absorption frequency of the measurement probe 7 is reduced. When the measurement power is absorbed by the plasma PM, the remaining measurement power that is not absorbed is directed toward the measurement power supply 8 in a direction opposite to the direction transmitted from the measurement power supply 8 to the plasma PM. Transmitted. When the measuring power is reflected by the plasma PM, the reflected measuring power is similarly transmitted toward the measuring power supply 8 side. This measuring power corresponds to the plasma density information measuring power in the present invention.
[0058]
The tube 17 is formed of quartz (SiO2) having a relative dielectric constant of about 4 in this embodiment. Examples of the material forming the tube 17 include fluororesin having a relative dielectric constant of 2, alumina (Al2O3) having a relative dielectric constant of 10, zirconia (ZrO2) having a relative dielectric constant of 35, and zirconia (ZrO2). Although not particularly limited, such as anisotropic dielectrics and silicon carbide (SiC) whose relative dielectric constant changes depending on purity but has a relative dielectric constant of about 20 or the like, solid dielectrics are not particularly limited. In view of the fact that the tube 17 is easily formed in such a case, it is preferable that the tube 17 be formed of a substance having a relative dielectric constant of 2 to 50.
[0059]
In addition, as shown in FIG. 2, an outer cylindrical guide portion 18 for guiding the measurement probe 7 to the chamber 1 is provided so as to surround the measurement probe 7. The guide portion 18 has an abutment portion 18a. When the measurement probe 7 is inserted into the chamber 1, the guide portion 18 moves together with the measurement probe 7, and the abutment portion 18a contacts the outer wall 1a of the chamber 1. The guide section 18 stops, and only the measurement probe 7 is inserted into the chamber 1.
[0060]
At the rear end of the measurement probe 7, a ring-shaped locking member 19 is provided so as to surround the circumference of the measurement probe 7. When the stop member 19 abuts on the side wall at the rear end of the guide portion 18, the insertion of the measurement probe 7 into the chamber 1 can be stopped. When the locking member 19 comes into contact with the rear end side wall of the guide portion 18, the measurement probe 7 is disposed at a position 2.5 mm from the inner wall 1 b of the chamber 1. This prevents the measurement probe 7 from being inserted into the center of the device 1. The substrate W to be processed is disposed at the center of the chamber 1, and the measurement probe 7 is disposed to be inserted closer to the front side than the substrate W. In other words, the measurement probe 7 is configured to be insertable on the near side of the substrate W that is the object to be processed.
[0061]
Subsequently, a specific configuration of the probe control unit 10 will be described. As shown in FIG. 1, the probe control unit 10 includes a directional coupler 20, an attenuator 21, a filter 22, an absorption frequency derivation unit 23, and an electron density conversion unit 24. The directional coupler 20, the attenuator 21, and the filter 22 are connected to the measurement probe 7 via the coaxial cable 9 in order from the measurement power supply 8 side.
[0062]
The measurement power supply 8 is a frequency sweep type, and outputs while automatically sweeping the measurement power at a frequency in a certain frequency band (for example, from 100 kHz to 2.5 GHz). The measurement power output from the measurement power supply 8 is transmitted to the measurement probe 7 via the directional coupler 20, the attenuator 21, and the filter 22 in this order while being transmitted through the coaxial cable 9. On the other hand, when the measuring power is absorbed or reflected, the reflected power is transmitted in the opposite direction as described above, detected by the directional coupler 20, and sent to the absorption frequency deriving unit 23. The frequency of the measurement power output from the measurement power supply 8 is also sequentially sent to the absorption frequency deriving unit 23.
[0063]
The filter 22 has a function of removing power and noise mixed in the probe control unit 10. Further, the attenuator 21 has a function of adjusting the amount of measurement power sent to the measurement probe 7.
[0064]
The absorption frequency deriving unit 23 obtains a change in the reflectance of the measurement power with respect to the frequency based on the frequency of the measurement power and the detected reflection amount of the measurement power. Then, based on the obtained result, an absorption frequency at which strong absorption of the measuring power occurs due to the electron density is obtained. The specific derivation of the absorption frequency will be described later with reference to a flowchart.
[0065]
The electron density conversion unit 24 is configured to convert the electron density into an electron density based on the absorption frequency obtained by the absorption frequency derivation unit 23. Since the above-mentioned absorption frequency has a certain correlation with the electron density, the electron density can be easily obtained by obtaining the absorption frequency.
[0066]
Next, the flow of the etching process in the etching apparatus having the above-described configuration will be described with reference to the flowchart of FIG. At the time of step S1, the switch of the generation power supply 5 for plasma generation is already in the ON state, the gas is already supplied from the gas supply source (tank) 11 into the chamber 1, and the plasma PM is already generated. It is assumed that
[0067]
[Step S1] The switch of the measuring power supply 8 is turned on. The measurement probe 7 is inserted and disposed on the front side of the substrate W which is the object to be processed. Specifically, as described above, when the contact portion 18a of the guide portion 18 contacts the outer wall 1a of the chamber 1, the guide portion 18 stops, and only the measurement probe 7 is inserted into the chamber 1. The measurement probe 7 is disposed at a position 2.5 mm from the inner wall 1 b of the chamber 1 by the engagement of the locking member 19 with the rear end side wall of the guide portion 18. This step S1 corresponds to the step (a) in the present invention.
[0068]
[Step S2] The power for measurement is output from the power supply for measurement 8 while automatically sweeping the power for measurement at a frequency from 100 kHz to 2.5 GHz. In addition, the above-described frequencies are sequentially sent to the absorption frequency deriving unit 23 while automatically sweeping. The output measurement power is supplied to the measurement probe 7 via the coaxial cable 7. This step S2 corresponds to the process (b) in the present invention.
[0069]
[Step S3] The supplied measuring power is absorbed or reflected by a surface wave dependent on the plasma PM, and the measuring power is reflected by the measuring power via the coaxial cable 9 in a direction opposite to that at the time of supply. 8 is transmitted. The amount of reflection of the measurement power is detected by the directional coupler 20 via the filter 22, the attenuator 21, and the directional coupler 20 in this order. Then, it is sent to the absorption frequency deriving unit 23.
[0070]
The absorption frequency deriving unit 23 calculates [reflected amount of measurement power] / [total output amount of measurement power] at the same frequency to obtain the reflectance of the measurement power. By plotting the swept frequency and the reflectance of the measurement power in association with each other, a change in the reflectance of the measurement power versus frequency as shown in FIG. 4 is obtained. As shown in FIG. 4, the place where the reflectance is greatly reduced is an absorption point where strong absorption of the measured power occurs due to the electron density, and the frequency of the absorption point is the absorption frequency.
[0071]
In FIG. 4, two absorption points Pa and Pb appear. Usually, a plurality of absorption points appear, and accordingly, the same number of absorption frequencies as the absorption points exist. Each of these absorption frequencies has a certain correlation with the plasma density information such as the electron density. In particular, among the absorption frequencies, the absorption frequency proportional to the square of the electron density is the plasma surface wave resonance. It is called frequency. The plasma surface wave resonance frequency is one of useful physical quantities when deriving plasma density information such as electron density. This step S3 corresponds to the step (c) in the present invention.
[0072]
In this specification, the absorption frequency at the absorption point where the Q value (quality factor) is the largest is referred to as “zero-order absorption frequency” or “basic absorption frequency”. Then, the absorption frequency is defined as primary, secondary,... In order of absorption. The highest-order absorption frequency, that is, the absorption frequency at the absorption point having the smallest absorption, is the above-described plasma surface wave resonance frequency, which is proportional to the square of the electron density.
[0073]
Therefore, in order to actually measure the plasma density information, an absorption having a large Q value is an absorption having a large absorption (loss due to reflection) and a narrow half-value width. It is usual to measure the next absorption frequency (basic absorption frequency). In this embodiment, the zero-order absorption frequency, that is, the basic absorption frequency (zero-order absorption frequency) at the absorption point where the Q value is the largest is measured.
[0074]
[Step S4] The absorption frequency derived by the absorption frequency derivation unit 23 is sent to the electron density conversion unit 24. The electron density converter 24 obtains a plasma surface wave resonance frequency from the basic absorption frequency, and further converts the plasma surface wave resonance frequency into an electron density.
[0075]
Since the measurement probe 7 is disposed at a position 2.5 mm from the inner wall 1 b of the chamber 1, the electron density obtained here is a value at 2.5 mm from the inner wall 1 b. Since the substrate W is disposed at the center of the chamber 1, the electron density at the center of the chamber 1 must be obtained. Therefore, as described in the section of “Means for Solving the Problems”, based on the graph of FIG. 13, the electron density at the position of 2.5 mm from the inner wall 1 b is changed to the electron density at the center of the chamber 1. You only need to calibrate. In the present embodiment, the electron density conversion unit 24 also has the function of this calibration, but a calibration unit that stores the graph of FIG. 13 and performs calibration may be separately provided.
[0076]
[Step S5] After the electron density is determined, the substrate W is loaded into the chamber 1 and placed on the electrode 2. By applying a processing voltage to the electrode 2, ions and electrons in the plasma PM reach the surface of the substrate W, and the substrate W is etched. Therefore, the timer is reset in the etching time setting section 15 and the counting of the timer is started almost simultaneously with the application of the processing voltage or almost simultaneously with the start of the etching processing. In terms of performing the etching process more precisely, it is preferable that the charging of the substrate W into the chamber 1 and the measurement of the electron density in the step S5 be performed almost simultaneously.
[0077]
[Step S6] On the other hand, the measured electron density is sent to the etching rate conversion unit 13 in the generation power control unit 6, and is converted into an etching rate based on the electron density. As described above, since there is a certain correlation between the etching rate and the electron density, the etching rate can be obtained only by multiplying the measured electron density by a coefficient.
[0078]
[Step S7] When the etching rate is determined, the etching time is determined by the etching time conversion unit 14. For example, when the thickness of the film to be etched is 10 μm and the etching rate is 1 μm / min, the etching time is determined as 10 min obtained by dividing the thickness of the film by 10 μm and the etching rate of 1 μm / min. Can be
[0079]
[Step S8] When the etching time is determined, it is sent to the etching time setting unit 15. When the timer started in step S5 is counted by an amount corresponding to the etching time, that is, when the etching time has elapsed, the etching time setting unit 15 terminates the supply of the generation power to the impedance matching unit 16. Then, the matching circuit in the impedance matching unit 16 is operated. With this operation, the generation power supplied from the generation power supply 5 becomes 0, and the etching process ends. Steps S5 to S8 correspond to the process (d) in the present invention.
[0080]
From the above steps S1 to S8, when the measurement power is supplied from the measurement power supply 8 to the plasma PM in step S2, the measurement power input from the measurement power supply 8 is caused by the plasma density via the measurement probe 7. Then it is absorbed by the plasma load or reflected back. In step S3, the absorption frequency, which is plasma density information, is measured using the measurement probe 7 based on the reflection or absorption of the measurement power. Since the plasma density information indicates the characteristics of the plasma, the plasma etching processing is controlled in steps S5 to S8 by measuring the plasma density information.
[0081]
In addition, since the measurement probe 7 is disposed so as to be inserted in front of the substrate W, which is an object to be processed, the measurement probe 7 is less likely to be shadowed on the substrate W. Therefore, the measurement of the plasma density information and the plasma etching process can be performed efficiently.
[0082]
The present invention is not limited to the above embodiment, but can be modified as follows.
[0083]
(1) In the above-described steps S1 to S8 in the present embodiment, when the etching processing of one substrate W is completed, the generation power supplied from the generation power supply 5 is set to 0. In the case of continuous processing, a procedure may be adopted in which, when the etching time has been reached, one substrate W being processed is removed from the chamber, and a substrate W to be processed next is loaded into the chamber 1. .
[0084]
(2) In this embodiment described above, the etching process is a plasma process. However, for example, a plasma process such as a CVD (Chemical Vapor Deposition) process, an ashing process, or a chamber cleaning process is performed on an object to be processed in a plasma. There is no particular limitation on the processing. In addition, the present invention can be applied not only to plasma processing but also to a plasma density information measuring device that simply measures plasma density information.
[0085]
Similarly, the present invention can be applied to a plasma density information monitoring device that monitors a change in plasma density information, and a plasma processing device using the same. The details will be described below with reference to FIG. Note that the same reference numerals are given to portions common to the present embodiment, and the illustration and description of the portions are omitted.
[0086]
The plasma density information monitoring device and the plasma processing device using the same according to this modification include a monitoring unit 25 as shown in FIG. 5, and the monitoring unit 25 includes a data analysis unit 26 and an output determination unit. It comprises a unit 27, a data storage unit 28, and a display monitor 29. The data analysis unit 26 is connected to a data storage unit 29 via an output determination unit 27, and the data analysis unit 26, the output determination unit 27, and the data storage unit 29 are each connected to a display monitor 29. In the present embodiment, the directional coupler 20 and the measurement power supply 8 are connected to the absorption frequency derivation unit 23, but in this modification, the directional coupler 20 and the measurement power supply 8 are connected to the data analysis unit 26. Have been. Further, in the present embodiment, the etching rate conversion unit 13 in the generation power control unit 6 is connected to the electron density conversion unit 24 in the probe control unit 10, but in this modification, the generation power control unit 6 Is connected to the output determination unit 27 in the monitoring unit 25. The monitoring unit 25 corresponds to a monitoring unit according to the present invention.
[0087]
The data analysis unit 26 and the output determination unit 27 have the function of a calculation unit such as a CPU (Central Processing Unit), and have the same frequency as the absorption frequency derivation unit 23 in this embodiment. It has a function of calculating a change in the reflectance of the measurement power with respect to frequency based on the detected reflection amount of the power for use. In this modification, the change in reflectance of the measurement power with respect to frequency is referred to as an “absorption waveform”. The data analysis unit 26 analyzes the absorption rate indicating the degree of absorption of the absorption waveform, that is, the reflectance of the measurement power, and the output determination unit 27 determines that the absorption rate of the absorption waveform at a certain frequency is higher than the predetermined absorption rate. If it is higher, it is assumed that the measurement power is absorbed / reflected by the plasma load due to the plasma density at that frequency, and that frequency is determined as the absorption frequency. The data analysis unit 26 and the output determination unit 27 perform analysis and determination with time, and monitor a temporal change in the absorption rate of the absorption waveform. Therefore, as shown in FIG. 6, for example, when the absorption frequency, which is one of the plasma density information, changes with time, that is, the previously observed absorption rate becomes smaller than the predetermined absorption rate, and another frequency When the absorption rate of the absorption waveform at becomes larger than the predetermined absorption rate, the output determination unit 27 determines that another frequency is the absorption frequency.
[0088]
The data storage unit 28 stores each data obtained by the data analysis unit 26 and the output determination unit 27. The display monitor 29 displays and outputs each data in the data analysis unit 26, the output determination unit 27, and the data storage unit 28. For example, as shown in FIG. (Absorption waveform) is sequentially displayed and output. Of course, the display monitor 28 may display and output not only the absorption waveform as shown in FIG. 4 but also, for example, the temporal change of the absorption waveform at the same frequency among the swept frequencies.
[0089]
In this modification, the monitoring unit 25 can monitor the time change of the plasma density information. In addition, the result of the output determination unit 27 is provided to the impedance matching unit 16, whereby the power for generation can be controlled, and the plasma processing can be controlled. When monitoring the time change of the plasma density information, the plasma processing can be controlled as long as the time change can be monitored, so that the value of the plasma density information can be accurately measured as in the present embodiment. do not have to. Therefore, it is not necessary to provide the absorption frequency deriving unit 23 as in this embodiment.
[0090]
(3) In the plasma density information monitoring device and the plasma processing device using the same in the modification of the above (2), monitoring was performed based on a temporal change in the absorption rate of the absorption waveform. Temporal change of the half width, which is the frequency width when the reflection or absorption rate of the power for information measurement is halved, temporal change of the Q factor (quality factor), plasma at the same frequency among the frequencies swept in the absorption waveform Monitoring may be performed based on a temporal change in the reflection or absorption rate of the power for density information measurement, or a temporal change in the maximum or minimum frequency or a maximum or minimum value of the frequency derivative of the absorption waveform.
[0091]
In the case of the half-value width, as shown in FIG. ₀ And the frequency at which the reflectivity of the measuring power is halved is f ₁ , F ₂ (However, f ₁ <F ₂ ), The half width, which is the frequency width, is (f) ₂ −f ₁ ). This half width (f ₂ −f ₁ ) Is obtained by the data analysis unit 26, and the output determination unit 27 determines that absorption / reflection of measurement power by the plasma load is occurring due to the plasma density at that frequency if the width is larger than the predetermined half width, and Price range (f ₂ −f ₁ ) To the absorption frequency f ₀ Is determined. In the case of the Q value, Q = f ₀ / (F ₂ −f ₁ ), The data analysis unit 26 obtains the Q value, and if the Q value is larger than the predetermined Q value, the output determination unit 27 determines that absorption / reflection of the measurement power by the plasma load occurs at that frequency due to the plasma density. , That f ₀ Is determined as the absorption frequency. Even in the case of the half width and the Q value, the respective temporal changes are monitored, and the temporal change of the plasma density information is monitored based on the respective temporal changes.
[0092]
In the case of the reflection or absorption rate of the power for measuring plasma density information at the same frequency, as shown in FIG. 8, the temporal change of the absorption waveform at the same frequency is monitored. In this case, the frequency at which the absorption waveform changes greatly with time can be determined as the absorption frequency. Further, when the absorption frequency changes with time, an absorption waveform that changes with time at another frequency is observed, so that the other frequency is determined as the absorption frequency.
[0093]
In the case of the maximum or minimum frequency or the maximum or minimum value of the frequency derivative of the absorption waveform, the maximum or minimum is observed as in the frequency differential waveform shown in FIG. 9B. By observing the maximum or the minimum, the maximum value of the slope of the absorption waveform shown in FIG. 9A is observed. When the maximum frequency or the minimum frequency or the maximum value or the minimum value greatly changes with time, it is determined that the absorption frequency also changes greatly with time.
[0094]
(4) In this embodiment, the plasma processing is controlled by controlling the generation power for generating the plasma. However, for example, in addition to the generation power, the gas pressure for generating the plasma, the gas mixing ratio, and the like are also controlled. The plasma processing may be controlled by any method, and is not particularly limited as long as it is a method used in ordinary plasma control.
[0095]
In this embodiment, the processing time such as the etching time is set in accordance with the electron density, and the power for generation is operated. However, the processing time is fixed, and the power is generated by operating the impedance matching unit 16 or the like. By adjusting the power for use and controlling the electron density in accordance with the processing time, the gas pressure, the gas mixing ratio, and the like are adjusted by the gas adjusting valve 12 in FIG. The electron density may be controlled according to the processing time. In addition, these methods described above can be appropriately combined with each other.
[0096]
(5) In the above-described embodiment, the plasma density information is the absorption frequency and the electron density. However, since the ion density also indicates the characteristics of the plasma, these physical quantities are calibrated and measured to obtain the physical quantities related to the plasma generation. (For example, generation power, gas pressure, gas mixture ratio, etc.) may be operated. For example, after the absorption frequency is determined by the absorption frequency deriving unit 23 in FIG. 1, the power for generation may be operated based on the correlation between the absorption frequency and the etching process.
[0097]
(6) The measurement probe 7 is disposed at a position 2.5 mm from the inner wall 1 b of the chamber 1, and this position is on the near side of the substrate W to be processed, but on the near side of the substrate W. Then, for example, when the diameter of the substrate W is 200 mm, the diameter of the chamber 1 is 400 mm, and the substrate W is disposed at the center (200 mm) of the chamber 1, the distance from the inner wall 1 b is 100 mm (= 200 mm−100 mm). The measurement probe 7 may be inserted and disposed at 99 mm, which is the near side. However, it is preferable that the measurement probe 7 is disposed on the near side in consideration of the influence of the shadow, and is further on the front side than the outer wall 1a or the inner wall 1b of the chamber 1 located on the front side of the substrate W. It may be provided.
[0098]
For example, as shown in FIG. 10, when a seal member 30 such as an O-ring is interposed between the guide portion 18 and the tube 17 of the measurement probe 7, the plasma PM is distributed to the position of the seal member 30. Therefore, the measurement probe 7 can be disposed near the seal member.
[0099]
(7) In the measurement probe 7 according to the present embodiment, as shown in FIG. 2, the center conductor 9 d at the distal end, which corresponds to an antenna, is not directly covered with the dielectric tube 17, and a gap is formed. Intervened. As described in the section of “Means for Solving the Problems”, when the measurement probe 7 is arranged near the wall of the chamber 1 and the measurement is performed, the absorption rate of the absorption waveform becomes as shown in FIG. Small and difficult to measure. Therefore, the measurement probe 7 may be configured as a measurement probe 201 (see FIG. 14) according to the invention of JP-A-2002-043093 previously proposed by the present inventors. The antenna 202 corresponds to the antenna according to the present invention, the coaxial cable 203 corresponds to the cable according to the present invention, and the dielectric sheath 206 corresponds to the dielectric region according to the present invention.
[0100]
The absorption frequency measured by the measurement probe 7 shown in FIG. 2 and the absorption frequency measured by the measurement probe 201 shown in FIG. 14 are originally different from each other. This is because when the measurement probe 201 is inserted into the plasma PM, a layer called “sheath” is generated around the central conductor 204 as the antenna 202 and the metal flat plate 205, and is measured by the measurement probe 7. It is considered that a strong electric field that causes resonance in a low frequency region of about 1/10 to 1/100 of the absorbed frequency is applied to the sheath, and absorption occurs there. On the other hand, in the measurement probe 7, the center conductor 9d at the distal end, which corresponds to the antenna, does not directly contact the plasma, but comes into contact with the plasma via the dielectric tube 17, and the measurement probe 7 has the plasma rather than the sheath. The coupling is easy, and a plasma surface wave is excited on the surface of the tube 17. Thus, the measurement probe 201 shown in FIG. 14 is easily coupled to the sheath, and the measurement probe 7 shown in FIG. 2 is easily coupled to plasma.
[0101]
As described above, the absorption frequency measured by the measurement probe 7 shown in FIG. 2 and the absorption frequency measured by the measurement probe 201 shown in FIG. As shown in FIG. 15, the electron density at the center of the chamber and the absorption frequency at 2.5 mm from the wall measured by the measurement probe 201 have a high correlation with each other. Also, as shown in FIG. 16, the absorption rate measured by the measurement probe 201 shown in FIG. 14 is about half that when the probe is arranged at 2.5 mm from the wall as compared with the case where the probe is arranged at the center of the chamber. When the measurement is performed by the measurement probe 201 shown in FIG. 14, the plasma density information such as the absorption frequency is easily measured.
[0102]
Therefore, when measuring with the measurement probe 201 shown in FIG. 14, after measuring the absorption frequency at 2.5 mm from the wall with the measurement probe 201, based on the graph showing the relative relationship in FIG. What is necessary is just to convert into density.
[0103]
The measurement probe 201 shown in FIG. 14 has a metal flat plate 205 attached to one end of the center conductor 204 to enhance the signal strength. Although the function of the antenna 205 has been performed, only the center conductor 204 may perform the function as the antenna 202. Further, although the antenna 202 is covered with the dielectric outer cover 206, not only the antenna 202 but also the entire coaxial cable 203 may be covered with the dielectric outer cover 206.
[0104]
【The invention's effect】
As is clear from the above description, according to the present invention, the probe for measuring plasma density information is configured to be insertable in front of the object to be processed related to plasma processing. The probe for plasma density information measurement is less likely to be shadowed on the object to be processed, and the plasma density information is measured and the change in the plasma density information is monitored. And plasma processing can be performed efficiently.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of an apparatus according to an embodiment.
FIG. 2 is a partial longitudinal sectional view showing a configuration of a measurement probe according to the present embodiment.
FIG. 3 is a flowchart illustrating a flow of an etching process according to the embodiment.
FIG. 4 is a graph for explaining an absorption frequency.
FIG. 5 is a block diagram illustrating a configuration of a device according to a modification.
FIG. 6 is a graph for explaining monitoring of a temporal change of plasma density information based on a temporal change of an absorption rate of an absorption waveform.
FIG. 7 is a graph for explaining monitoring of a temporal change of plasma density information based on a temporal change of a half width and a Q value.
FIG. 8 is a graph for explaining monitoring of a temporal change of plasma density information based on a temporal change of a reflection or absorption rate of power for measuring plasma density information at the same frequency.
FIG. 9 is a graph used to explain monitoring of a temporal change of plasma density information based on a temporal change of a maximum or a minimum frequency or a maximum or a minimum value of a frequency derivative of an absorption waveform. The graph of the absorption waveform, and (b) is the graph of the frequency derivative.
FIG. 10 is a diagram showing a configuration of an apparatus when a measurement probe according to a further modification is used.
FIG. 11 is a diagram for explaining a conventional method for measuring plasma density information.
FIG. 12 is a diagram provided for explanation of a conventional method for measuring plasma density information.
FIG. 13 is a graph showing the measurement results of the electron density when the positions of the measurement probes are respectively changed.
FIG. 14A is a cross-sectional view of a measurement probe according to a further modification, and FIG. 14B is a plan view thereof.
FIG. 15 is a graph showing measurement results of the electron density at the center of the chamber and the absorption frequency at 2.5 mm from the wall when the power for generation is changed.
FIG. 16 is a graph showing the measurement results of the absorptivity at 2.5 mm from the center of the chamber and the wall when the power for generation is changed.
[Explanation of symbols]
6 Power generator for generation
7 ... Measuring probe
8 Power supply for measurement
PM… plasma
W… Substrate

Claims (25)

What is claimed is: 1. A plasma density information measurement method for measuring plasma density information indicating characteristics of plasma, comprising: (a) a plasma density information measurement probe, which is a probe for measuring the plasma density information, (B) supplying plasma density information measuring power to the plasma from the plasma density information measuring power supply for measuring the plasma density information, and (c) supplying the plasma density information measuring power to the plasma. Measuring the plasma density information based on reflection or absorption of the plasma density information measurement power by a plasma load using the plasma density information measurement probe disposed on the front side of the object to be processed. A method for measuring plasma density information, characterized in that: 2. The plasma density information measuring method according to claim 1, wherein in the step (a), the plasma density information measuring probe is positioned further forward than a wall of a plasma processing chamber located forward of the workpiece. A plasma density information measuring method, wherein the method is a process of inserting and arranging on a side. 3. The method for measuring plasma density information according to claim 1, wherein the probe for measuring plasma density information is coupled to an antenna that radiates power, a cable that transmits the power for measuring plasma density information, and plasma. A plasma density information measuring method, comprising: a dielectric region; wherein the cable is connected at one end of the antenna, and at least the antenna is directly covered by the dielectric region. A plasma density information measurement device for measuring plasma density information indicating characteristics of plasma, comprising: a plasma density information measurement power supply for supplying plasma density information measurement power to plasma for measuring the plasma density information; and a plasma load. The plasma density information measurement probe for measuring plasma density information based on reflection or absorption of the plasma density information measurement power by the plasma density information measurement probe, wherein the plasma density information measurement probe is located before the object to be processed related to plasma processing. A plasma density information measuring device characterized in that it can be inserted into the side. 5. The plasma density information measurement device according to claim 4, wherein the plasma density information measurement probe is configured to be inserted further in front of a wall of a plasma processing chamber positioned in front of the object to be processed. A plasma density information measuring device, characterized in that: The plasma density information measuring device according to claim 4 or 5, wherein the plasma density information measuring probe is coupled to an antenna that radiates power, a cable that transmits the plasma density information measuring power, and a plasma. A plasma density information measuring device, comprising: a dielectric region, wherein the cable is connected at one end of the antenna, and at least the antenna is directly covered by the dielectric region. A plasma density information monitoring method for monitoring plasma density information indicating characteristics of plasma, comprising: (a) a plasma density information measurement probe that is a probe for measuring the plasma density information; a process to dispose be inserted on the front side, and a step of supplying a plasma power for measuring plasma density information from the plasma density information measuring power supply to measure (b) the plasma density information, (c ₁ Using the probe for measuring plasma density information disposed on the front side of the object to be processed, monitoring a temporal change in plasma density information based on reflection or absorption of the power for measuring plasma density information by a plasma load. And a plasma density information monitoring method. 8. The plasma density information monitoring method according to claim 7, wherein, in the step (a), the plasma density information measuring probe is positioned further forward than a wall of a plasma processing chamber located forward of the workpiece. A plasma density information monitoring method, wherein the method is a process of inserting and arranging the plasma density information on the side. 9. The plasma density information monitoring method according to claim 7, wherein the probe for measuring plasma density information is coupled to an antenna that radiates power, a cable that transmits the power for measuring plasma density information, and plasma. A plasma density information monitoring method, comprising: a dielectric region; wherein the cable is connected at one end of the antenna, and at least the antenna is directly covered by the dielectric region. 10. The plasma density information monitoring method according to claim 7, wherein in the step (b), the power for measuring plasma density information of each frequency is swept while sweeping a frequency from the power source for measuring plasma density information. Is sequentially supplied to the plasma, and the step (c ₁ ) is a step in which a temporal change of an absorption waveform indicating a change in reflection or absorptance of the power for measuring plasma density information at the swept frequency is provided. A method for monitoring a temporal change of plasma density information based on the information. 11. The plasma density information monitoring method according to claim 10, wherein the step (c ₁ ) is a step of monitoring a temporal change of the plasma density information based on a temporal change of an absorption rate of the absorption waveform. A method for monitoring plasma density information, characterized in that: 11. The plasma density information monitoring method according to claim 10, wherein the step (c ₁ ) is a half-width that is a frequency width when the reflection or absorption rate of the power for plasma density information measurement becomes half in the absorption waveform. Monitoring the temporal change of the plasma density information based on the temporal change of the plasma density information. 11. The plasma density information monitoring method according to claim 10, wherein the step (c ₁ ) is performed based on a temporal change of a Q value indicating a degree of resonance due to a plasma load in the absorption waveform. A method for monitoring plasma density information, wherein the method is a step of monitoring a change in temperature. 11. The plasma density information monitoring method according to claim 10, wherein the step (c ₁ ) is a step in which the reflection or absorption rate of the power for measuring plasma density information at the same frequency among the swept frequencies in the absorption waveform is temporally determined. A method for monitoring a temporal change of the plasma density information based on the change. 11. The plasma density information monitoring method according to claim 10, wherein the step (c ₁ ) is performed based on a maximum or minimum frequency of a frequency derivative of the absorption waveform or a temporal change in a maximum or minimum value of the absorption waveform. A method of monitoring plasma density information, which is a process of monitoring a temporal change of density information. A plasma density information monitoring device for monitoring plasma density information indicating characteristics of plasma, comprising: a plasma density information measurement power supply for supplying plasma density information measurement power to plasma for measuring the plasma density information; and a plasma load. The plasma density information measuring probe for measuring the plasma density information based on the reflection or absorption of the plasma density information measuring power, and the time of the plasma density information from the plasma density information measured by the plasma density information measuring probe. And a monitoring means for monitoring a target change, wherein the plasma density information measuring probe is configured to be insertable in front of an object to be processed related to plasma processing. 17. The plasma density information monitoring device according to claim 16, wherein the plasma density information measurement probe is configured to be inserted further in front of a wall of a plasma processing chamber located in front of the object to be processed. A plasma density information monitoring device, comprising: 18. The plasma density information monitoring device according to claim 16, wherein the probe for measuring plasma density information is coupled to an antenna that radiates power, a cable that transmits the power for measuring plasma density information, and plasma. A plasma density monitoring device comprising: a dielectric region; wherein the cable is connected at one end of the antenna, and at least the antenna is directly covered by the dielectric region. A plasma processing method for performing plasma processing on an object to be processed in plasma, wherein (a) a plasma density information measuring probe, which is a probe for measuring the plasma density information, is positioned before an object related to plasma processing. (B) supplying plasma density information measuring power from the plasma density information measuring power supply for measuring the plasma density information to the plasma, and (c) providing the plasma density information measuring power for measuring the plasma density information. Measuring the plasma density information based on the reflection or absorption of the power for measuring the plasma density information by the plasma load, using the probe for measuring the plasma density information disposed on the front side of the processing object, or (c ₁₎ Using the probe for measuring plasma density information disposed on the front side of the object to be processed, and measuring the plasma density by a plasma load. Monitoring the temporal change of the plasma density information based on the reflection or absorption of the information measuring power; and (d) controlling the plasma processing based on the measured or monitored plasma density information. Characteristic plasma processing method. 20. The plasma processing method according to claim 19, wherein, in the step (a), the plasma density information measuring probe is positioned further forward than a wall of a plasma processing chamber located closer to the object to be processed. A plasma processing method, which is a process of inserting and disposing. 21. The plasma processing method according to claim 19, wherein the probe for measuring plasma density information includes an antenna for radiating power, a cable for transmitting power for measuring plasma density information, and a dielectric material coupled to the plasma. And a conductive region, wherein the cable is connected at one end of the antenna, and at least the antenna is directly covered by the dielectric region. A plasma processing apparatus for performing plasma processing on an object to be processed in plasma, comprising: a plasma density information measurement power supply for supplying plasma density information measurement power to plasma for measuring plasma density information; The plasma density information measurement probe for measuring plasma density information based on reflection or absorption in density information measurement power, and control means for controlling plasma processing based on the measured plasma density information, the plasma A plasma processing apparatus characterized in that the density information measuring probe is configured to be insertable in front of an object to be processed related to plasma processing. 23. The plasma processing apparatus according to claim 22, further comprising monitoring means for monitoring a temporal change in plasma density information from plasma density information measured by the plasma density information measuring probe, based on the monitored plasma density information. The control means controls the plasma processing. 24. The plasma processing apparatus according to claim 22 or 23, wherein the plasma density information measuring probe can be inserted further in front of a wall of a plasma processing chamber located in front of the object to be processed. A plasma processing apparatus, comprising: 25. The plasma processing apparatus according to claim 22, wherein the plasma density information measuring probe is coupled to an antenna that radiates power, a cable that transmits the plasma density information measuring power, and a plasma. A plasma processing apparatus, wherein the cable is connected to one end of the antenna, and at least the antenna is directly covered by the dielectric region.

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