JPH10335308A - Plasma treating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma treating method which more surely controls the deposition of a reaction product on a semiconductor wafer. SOLUTION: A plasma etching apparatus 2 feeds a process gas C4 F8 /Ar/O2 from a gas jet plane 34 of a shower head, converts the process gas into a plasma by high frequency discharge, and etches a semiconductor wafer W on a susceptor 8, using the plasma. During etching, a spectrometer 74 analizes emitted light from the plasma, and a CPU 76 computes the detection value of the ratio of the emitted intensity of the spectra C2 /CF2 and controls the etching process condition, so that the detected value approaches a set reference value, based on the fine workability of etching.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a semiconductor wafer, L
A method for performing processing on a target object such as a CD substrate using plasma generated by discharge,
The present invention relates to a method for etching a silicon oxide film using a plasma obtained from a gas containing carbon and fluorine.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process, for example, a plasma is generated in a processing vessel, and various kinds of plasma processing such as etching is performed on an object to be processed, for example, a semiconductor wafer in this plasma atmosphere. Have been. In recent years, as the miniaturization of patterns to be applied to this type of object has been advanced, it has been required to perform high-precision plasma processing under sub-quarter micron design rules. For this reason, the process pressure has been reduced.

Further, from the viewpoint of increasing productivity, high-density plasma is required, and for this reason, ECR (Ele
ctorn Cyclotron Resonance
e), TCP (Transformer Couple)
d Plasma), ICP (Inductively)
A plasma generation method such as Coupled Plasma) has been proposed. Furthermore, DRM in medium density and medium pressure area
Magnetron plasma and dual-frequency excitation plasma have also been put to practical use.

[0004]

When a silicon oxide film is plasma-etched, a portion to be etched is
Two phenomena, deposition of a reaction product and exfoliation of the reaction product due to ion sputtering, exist in a state in which they compete with each other. Therefore, characteristics such as etching speed, selectivity, and fine workability depend on a delicate balance between the above-mentioned deposition and sputtering. In particular, as the miniaturization of the pattern applied to the object to be processed progresses, conditions under which the portion to be etched can be processed in a vertical shape, conditions under which the portion to be etched bowing, conditions under which the etching stops halfway, etc., are adjacent. In addition, the etching characteristics greatly change due to a slight change in the process conditions. Also,
There is also a need for a process such as a self-aligned contact process in which conditions for obtaining optimum etching characteristics are narrower.

[0005] From such a viewpoint, the input power and the reflected power of the high frequency (RF) system, and the applied voltage (V
pp and Vdc), as well as means for monitoring the high frequency current and voltage downstream of the matcher have recently been developed, allowing more precise control of ion energy and its current.

[0006] On the other hand, the amount or composition of the deposition on the object to be processed tends to change over time as the amount of reaction products deposited and accumulated in the processing chamber increases due to repetition of the processing. Because the reaction products attached to the inside of the processing chamber interact with the plasma, the amount of radicals in the plasma and its ratio change after repeated processing, for example, compared to immediately after cleaning the processing chamber. Because you do. Therefore, accurate monitoring and control of deposition is indispensable for performing stable processing.
Appropriate technology has not yet been established.

[0007] The control of the deposition of the reaction product on the object to be processed is not limited to the etching process.
Other plasma processes such as D, ashing, and sputtering also have a common problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide a plasma processing method capable of more reliably controlling the deposition of a reaction product on an object to be processed. Aim.

[0009]

Means for Solving the Problems Based on this viewpoint,
The present inventor has conducted research on etching a silicon oxide film using a processing gas containing carbon and fluorine, focusing on the relationship between etching characteristics and radicals and ions obtained by dissociation of the processing gas. The following findings were obtained. That is, the C existing in the plasma
The ratio of F ₂ to C ₂ depends on various characteristics of the etching, such as the etching rate, fine workability (the function of penetrating fine contact holes faithfully to design dimensions), and etching selectivity (photoresist or silicon nitride film). (A function of selectively etching the silicon oxide film). Thus, the ratio of CF ₂ and C ₂ can be used as a parameter for determining the state of the plasma with respect to the ability to perform these properties.

[0010] The ratio C ₂ / CF ₂ or CF ₂ / C ₂ and CF ₂ and C ₂ that is present in the plasma, and the spectral emission from the plasma, measuring the emission intensity of the spectrum of CF ₂ and C ₂ Can be obtained. For example, CF ₂
And C ₂ have spectra near 260 nm and 516 nm, respectively. Therefore, if the emission intensities of these spectra are measured and the ratio is obtained, the ratio C ₂ / CF ₂ or CF _{2 is obtained.}
It can be calculated ₂ / C _2.

According to a first aspect of the present invention, in a plasma processing method, a step of mounting an object to be processed on a mounting table provided in a processing container, and a step of discharging a processing gas while exhausting the processing container. Supplying the gas into the processing vessel, and the processing gas contains carbon and fluorine, and dissociates CF ₂ by dissociation.
And providing a C _2, the steps of the plasma through discharge the processing gas in the processing container, and a step of performing plasma processing on the object to be processed using the plasma,
Obtaining a detection value of the ratio of the emission intensity of the CF ₂ and C ₂ spectra by spectrally separating the light emitted from the plasma during the plasma processing; and setting based on the detected value and any characteristic of the plasma processing. Determining whether to stop the plasma processing by comparing the calculated reference value with the reference value.

According to a second aspect of the present invention, in a plasma processing method, a step of mounting an object to be processed on a mounting table provided in a processing container, and a step of exhausting the processing gas while exhausting the processing container. Supplying the gas into the processing vessel, and the processing gas contains carbon and fluorine, and dissociates CF ₂ by dissociation.
And providing a C _2, the steps of the plasma through discharge the processing gas in the processing container, and a step of performing plasma processing on the object to be processed using the plasma,
Obtaining the detected value of the ratio of the emission intensities of the CF ₂ and C ₂ spectra by dispersing the emission from the plasma during the plasma processing; and setting the detected value based on any characteristic of the plasma processing. Controlling the process conditions of the plasma processing so as to approach the set reference value.

According to a third aspect of the present invention, in the plasma processing method according to the first or second aspect, the plasma processing is etching of a silicon oxide film. Further, according to the present invention, it is possible to provide a plasma processing apparatus for performing the above-described plasma processing method.

That is, a fourth aspect of the present invention relates to a plasma processing apparatus, comprising: an airtight processing container; a mounting table for supporting a processing object disposed in the processing container; An exhaust system for evacuating and setting a vacuum in the processing container, a processing gas supply system for supplying a processing gas into the processing container, and the processing gas contains carbon and fluorine, and dissociates. Providing CF ₂ and C ₂ by means of: an electric field generating means for generating an electric field for converting the processing gas into plasma via discharge in the processing container; and dispersing light emitted from the plasma. C
Detecting means for obtaining a detected value of the ratio of the emission intensities of the F ₂ and C ₂ spectra; comparing the detected value with a reference value set based on any characteristic of the plasma processing; And control means for determining whether or not to cancel the process and executing the determination.

According to a fifth aspect of the present invention, in a plasma processing apparatus, an airtight processing container, a mounting table provided in the processing container for supporting an object to be processed, and the inside of the processing container are evacuated. An exhaust system for setting the inside of the processing container to a vacuum, a processing gas supply system for supplying a processing gas into the processing container, and the processing gas contains carbon and fluorine. ₂ and C ₂ , an electric field generating means for generating an electric field in the processing vessel for converting the processing gas into a plasma through a discharge, and separating the light from the plasma into CF _2. and a detecting means for obtaining a detection value of the ratio of the emission intensity of the spectrum of C _2, the detection value, so as to approach the reference value set based on any characteristics of the plasma treatment, a professional of the plasma treatment Characterized by comprising control means for controlling the scan conditions, a. According to a sixth aspect of the present invention, in the plasma processing apparatus according to the fourth or fifth aspect, the plasma processing is an etching processing of a silicon oxide film.

[0016]

FIG. 1 is a block diagram showing a plasma etching apparatus 2 which is a plasma processing apparatus according to an embodiment of the present invention. The plasma etching apparatus 2 includes, for example, a processing container 4 having an inner wall surface processed into a cylindrical shape made of a conductive material such as alumite-treated aluminum. The processing container 4 defines an airtight processing chamber and is grounded.

A substantially columnar susceptor 8 for mounting an object to be processed, for example, a semiconductor wafer W, is provided on the bottom of a processing chamber formed in the processing chamber 4 via an insulating plate 6 made of ceramic or the like.
Is arranged. The susceptor 8 is made of a conductive material such as anodized aluminum.

A coolant chamber 10 is provided inside the susceptor 8. A refrigerant for temperature adjustment, such as liquid fluorocarbon, can be introduced into the refrigerant chamber 10 through the refrigerant introduction pipe 12, and the introduced refrigerant is circulated in the refrigerant chamber 10. The cold of the coolant is transferred from the coolant chamber 10 to the wafer W via the susceptor 8 to cool the wafer W. The refrigerant having undergone the heat exchange is discharged from the processing chamber through the refrigerant discharge pipe 14.

Inside the insulating plate 6 and the susceptor 8, a gas passage 18 for supplying a heat transfer medium, for example, He gas, is formed on the back surface of the wafer W to be processed through an electrostatic chuck 16 described later. Is done. The heat transfer medium secures a heat transfer path from the susceptor 8 to the wafer W, and the wafer W can be maintained at a predetermined temperature by the above-described refrigerant.

The susceptor 8 is formed in a disk shape having a convex upper surface center portion, and an electrostatic chuck 16 having substantially the same diameter as the wafer W is disposed thereon. The electrostatic chuck 16 has a configuration in which a conductive layer is sandwiched between two polymer polyimide films. By applying a DC voltage of, for example, 1.5 kV to the conductive layer from a DC high-voltage power supply 20 disposed outside the processing container 4, the wafer W mounted on the upper surface of the electrostatic chuck 16 is It is sucked and held at that position by the Coulomb force. If a structure in which a conductive layer is sandwiched between two layers of alumina ceramics is used instead of the polymer polyimide film, problems such as poor pressure resistance of the electrostatic chuck 16 can be avoided and the life can be extended.

An annular focus ring 22 is arranged around the upper end of the susceptor 8 so as to surround the wafer W mounted on the electrostatic chuck 16. Focus ring 2
2 is made of a material of an insulator for blocking an electric field. Since the reactive ions are not accelerated on the focus ring 22, the reactive ions generated by the plasma effectively enter only the wafer W inside the reactive ions.

A power supply rod 24 is connected to the susceptor 8 so as to penetrate the susceptor 8 while maintaining the insulating state in a downward direction. Power supply rod 24
Through a matching unit 26 including a decoupling capacitor, for example, a high frequency (R
F) A high-frequency power supply 28 that outputs power is connected by a wiring 29, and a self-bias for drawing ions toward the wafer can be applied to the susceptor 8.

On the ceiling of the processing container 4, a disk-shaped shower head 30 also serving as an upper electrode is supported and fixed via an insulating material 32. The shower head 30 has a lower surface parallel to the upper surface of the susceptor 8 and opposed to the upper surface of the susceptor 8 by a distance of about 20 to 40 mm, that is, a gas ejection surface 34.
A large number of gas ejection holes 36 are formed on the gas ejection surface 34 facing the susceptor 8.

The shower head 30 comprises an electrode plate 40 having a gas ejection surface 34 and a head body 42 supporting the electrode plate 40. The electrode plate 40 is made of a conductive material such as SiC or amorphous carbon.
Is made of a conductive material such as aluminum whose surface is anodized.

A diffusion chamber 44 for retaining the processing gas is formed in the head main body 42. A gas introduction pipe 4 is provided at the center of the top of
6 is connected. The gas introduction pipe 46 has four lines 48a.
To the gas supply sources 50a to 50d. Each line 48a-48d has a valve 52a-52
d and mass flow controllers 54a to 54d are provided.

From the gas supply source 50a, C ₄ F ₈ which is a reactive gas for etching, and from the gas supply source 50b, A which is an inert gas for adjusting the dissociation state of radicals and the like.
r, O _{2 as} an auxiliary gas for etching is supplied from a gas supply source 50c, and N ₂ gas as an inert gas for purging is supplied from a gas supply source 50d.

A coolant chamber 56 is provided in the head body 42 so as to surround the diffusion chamber 44. Refrigerant chamber 56
For example, a refrigerant for temperature adjustment such as liquid fluorocarbon can be introduced through a refrigerant introduction pipe (not shown), and the introduced refrigerant is circulated in the refrigerant chamber 56. The cold of the refrigerant is transferred from the refrigerant chamber 56 to the electrode plate 40, and the electrode plate 40 can be cooled to a desired temperature. The refrigerant having undergone the heat exchange is discharged out of the processing chamber through a refrigerant discharge pipe (not shown). The electrode plate 40 is set at a higher temperature than the surface of the wafer W so as to direct the flow of radicals toward the wafer W and prevent the radicals from depositing on the surface of the electrode plate 40.

A power supply rod 58 is connected to the head main body 42. For example, at 13.56 MHz via a matching unit 60 including a decoupling capacitor,
High-frequency power supply 6 for plasma generation that outputs high-frequency power
2 are connected by a wiring 63.

An exhaust pipe 66 leading to a vacuum exhaust means 67 such as a turbo molecular pump is connected to a lower portion of the processing container 4. With this exhaust means, the processing chamber in the processing container 4 can be evacuated to a predetermined reduced pressure atmosphere.

A load lock chamber 70 is connected to the side wall of the processing container 4 via a gate valve 68 which can be opened and closed in an airtight manner. By the transfer means (not shown) such as a transfer arm disposed in the load lock chamber 70, the wafer W to be processed is transferred from the processing container 4 to the load lock chamber 70.
Conveyed between.

A transparent detection window 72 made of quartz is provided on the side wall of the processing container 4 in an airtight manner. A spectroscope 74 having a photoelectric conversion element is provided facing the detection window 72 in order to split light emitted from plasma generated in the processing container 4. The spectroscope 74 is connected to a central processing unit (CPU) 76, and the detection information is transmitted via the CPU 76 to a display 78.
Will be displayed.

The CPU 76 includes a high-voltage DC power supply 20, valves 52a to 52d, mass flow controllers 54a to 54
d, controlling the entire etching apparatus 2 such as the vacuum exhaust means 67 and the RF power supplies 28 and 62; Therefore, the CPU 7
6 can be set so that the detection information from the spectroscope 74 and the control of each of the above members are linked.

Next, the operation of the plasma etching apparatus 2 configured as described above will be described. Here, a case will be described in which a silicon oxide film on a wafer having a silicon substrate is etched using the plasma etching apparatus 2.

First, after the gate valve 68 is opened, the wafer W to be processed is carried into the processing container 4 from the load lock chamber 70 by the transfer means and placed on the electrostatic chuck 16. . Then, the wafer W is suction-held on the electrostatic chuck 16 by application of the DC high-voltage power supply 20. After the transfer means has retreated into the load lock chamber, the inside of the processing container 4 is evacuated by the exhaust means.

On the other hand, the valves 52a to 52c are opened, and the flow rates thereof are adjusted by the mass flow controllers 54a to 54c.
From 0c, a C ₄ F ₈ gas, an Ar gas, and an O ₂ gas are respectively supplied. These gases are supplied to gas lines 48a-48c,
The gas is introduced into the diffusion chamber 44 in the shower head 30 through the gas introduction pipe 46, and is further uniformly discharged into the processing container 4 through the ejection holes 36 of the electrode plate 40, as indicated by arrows in FIG. 1. You. And during the supply of these gases,
The processing container 4 is evacuated, and the pressure in the processing space becomes, for example, 1
It is maintained at a predetermined pressure of about Pa.

In this state, high-frequency power for plasma generation is applied to the shower head 30 from the high-frequency power supply 62, while high-frequency power for self-bias is applied to the susceptor 8 from the high-frequency power supply 28. In this manner, the C ₄ F ₈ gas, Ar gas, and O ₂ gas are turned into plasma through discharge by the high-frequency electric field generated between the susceptor 8 and the shower head 30, and this plasma causes a silicon oxide film such as SiO _{2 on the} wafer surface. The film is etched. During the etching, the susceptor 8 and the shower head 30 are cooled to a predetermined temperature by the coolant flowing through each.

When the C ₄ F ₈ gas is turned into plasma through discharge by application of a high-frequency voltage, as the voltage application time (discharge duration) becomes longer, the C ₄ F ₈ gas dissociates into smaller and smaller units of radicals and ions. To go. Specifically, C ₄ F ₈ is dissociated to form C ₂ F ₄ , CF ₃ , CF
_{2, CF, C 2, F} 2, C, provides F and the like.

As described above, according to the knowledge obtained by the present inventor, when a silicon oxide film is etched using C ₄ F ₈ gas, the absolute value of CF ₂ present in plasma and C
The ratio of F ₂ to C ₂ depends on various characteristics of the etching, such as the etching rate, fine workability (the function of penetrating fine contact holes faithfully to design dimensions), and etching selectivity (photoresist or silicon nitride film). (A function of selectively etching the silicon oxide film). The ratio of CF ₂ to C ₂ present in the plasma is, for example, the ratio of the emission intensity of the emission spectrum of CF _{2 having} a wavelength of 260 nm and the emission intensity of the emission spectrum of C ₂ having a wavelength of 516 nm, C ₂ / CF ₂ or CF _2. it can be detected as a / C _2.

FIG. 2 is a graph showing the results of an experiment in which the relationship between the emission intensity ratio C ₂ / CF ₂ and the fine workability of etching was examined using the etching rate for fine contact holes as an index. In this experiment, using the plasma etching apparatus 2 shown in FIG. 1, a silicon oxide film having a diameter of 0.15 μm and an aspect ratio (depth / diameter) of 5, 1
1, 18 contact holes were formed. At this time, C ₄
F ₈ / Ar / O ₂ was supplied at 20/500/10 sccm, the pressure in the processing vessel 4 was set to 40 mTorr, and 1
Apply 3.56 MHz high frequency power to showerhead 30
At 000 W, a voltage of 1400 W was applied to the susceptor 8. Further, based on the emission intensities of the CF ₂ and C ₂ spectra separated by the spectroscope 74, the emission intensity ratio C ₂ / C is determined by the CPU 76.
F ₂ was calculated and the same ratio was displayed on the display 78.

In FIG. 2, the vertical axis indicates the relative etching rate ER until the contact hole penetrates. The characteristic lines L1, L2, and L3 show the characteristics when the aspect ratio of the contact hole is 5, 11, and 18, respectively.

From FIG. 2, it can be seen that, for any aspect ratio, the higher the luminous intensity ratio C ₂ / CF ₂ , the worse the fine workability of etching becomes, and especially the higher the aspect ratio, the greater the degree of the deterioration. I understand. That is, the relationship between the emission intensity ratio C ₂ / CF ₂ and the fine workability of etching the contact hole to be etched is obtained in advance from experiments, and if the ratio C ₂ / CF ₂ is monitored during the etching process, the process can be performed. Various actions can be taken for optimization.

For example, the ratio C ₂ /
The detected value of CF _2, compared with the reference value of the ratio C ₂ / CF ₂ set on the basis of the fine processing of the etching CPU76
The CPU determines whether or not to stop the processing based on this.
If the determination is made at step 76 and the determination is performed, so-called interlock control can be performed.

Further, for example, the detected value of the ratio C ₂ / CF ₂ obtained by the monitor is etched by the CPU 76 so as to approach the reference value of the ratio C ₂ / CF ₂ set based on the fine workability of the etching. If the process conditions of the processing are controlled, so-called feedback control can be performed.

FIG. 3 shows the flow rate of Ar gas and the emission intensity ratio C ₂ /
Is a graph showing the experimental result of examining the relationship between the CF _2,
FIG. 4 is a graph showing an experimental result of examining the relationship between the flow rate of Ar gas and the fine workability of etching. These experiments were performed under the same conditions as the experiments whose results are shown in FIG.

FIG. 3 shows that the Ar gas flow rate and the emission intensity ratio C
It can be seen that ₂ / CF ₂ is clearly correlated. This means that the Ar gas flow rate can be used as one parameter for adjusting the ratio C ₂ / CF ₂ .

In FIG. 4, the vertical axis indicates the relative etching rate ER until the contact hole penetrates. The characteristic lines L4, L5, and L6 each have an aspect ratio of 5,
11 and 18 show the characteristics. From FIG. 4, it can be seen that the flow rate of the Ar gas and the fine workability of the etching clearly correlate. That is, the flow rate of Ar gas and the emission intensity ratio C ₂
If the relationship between / CF ₂ and the relationship between the flow rate of Ar gas and the fine workability of the etching for the contact hole to be etched is obtained from experiments, based on the ratio C ₂ / CF ₂ monitored during the etching process, The processing can be optimized by adjusting the flow rate of the Ar gas.

In the above embodiment, C ₄ F ₈ was used as the main reactive gas in the processing gas. However, instead of this, other CF-based gases, for example, CH ₄ , CHF ₃ , CH
₂ F ₂ , CH ₃ F, C ₂ F ₆ , C ₂ H ₂ F ₂ , C ₃ F ₃
Can be used. Further, the reactive gas can contain not only O ₂ described in the embodiment but also CO. Further, as the inert gas, in addition to Ar gas, He,
Xe and Kr gases can be used.

In the above embodiment, the ratio C ₂
As an optional property of the etching process for setting the reference value of / CF ₂ , the fine workability of the etching was mentioned.
The reference value may be set based on other characteristics such as an etching rate and selectivity.

In the above-described embodiment, the parallel plate type plasma processing apparatus has been described as an example. However, the present invention is not limited to this type, and may be applied to an ICP type, ECR type or the like. .

The plasma processing apparatus constructed according to the present invention is not limited to an etching apparatus, but can be applied to a CVD apparatus, an ashing apparatus, a sputtering apparatus and the like. The object to be processed is not limited to a semiconductor wafer, and for example, an LCD substrate can be processed.

[0051]

According to the present invention, the detected value of the ratio of the emission intensity of the CF ₂ and C ₂ spectra obtained by dispersing the emission from the plasma is compared with a reference value, and processing is performed based on this. By deciding whether to cancel,
Unnecessary processing and damage to the object can be prevented beforehand, and the processing yield can be improved.

Further, in the present invention, the process condition of the processing is controlled so that the detected value of the ratio of the emission intensity of the CF ₂ and C ₂ spectra obtained by dispersing the emission from the plasma approaches the reference value. By doing so, the reproducibility can be easily improved even in a process in which the allowable range of the process conditions is narrow, and the process efficiency and the productivity can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a plasma etching apparatus which is a plasma processing apparatus according to an embodiment of the present invention.

FIG. 2 is a graph showing experimental results obtained by examining the relationship between the emission intensity ratio C ₂ / CF _{2 of the} spectrum and the fine workability of etching.

FIG. 3 shows the ratio of the flow rate of Ar gas to the emission intensity C _{2 of the} spectrum.
7 is a graph showing an experimental result of examining the relationship with / CF ₂ .

FIG. 4 is a graph showing experimental results obtained by examining the relationship between the flow rate of Ar gas and the fine workability of etching.

[Explanation of symbols]

2 Plasma etching apparatus, 4 Processing container, 8 Susceptor, 28, 62 High frequency power supply, 30 Shower head, 67 Vacuum exhaust means, 72 Detection window, 74 Spectroscope, 76 CPU.

Claims (3)

[Claims] A step of mounting an object to be processed on a mounting table provided in the processing container; a step of supplying a processing gas into the processing container while exhausting the processing container; The gas contains carbon and fluorine, and provides CF ₂ and C ₂ by dissociation; a step of converting the processing gas into a plasma via a discharge in the processing container; and a step of performing the processing using the plasma. Subjecting the body to a plasma treatment; dispersing emission from the plasma during the plasma treatment to obtain a detection value of a ratio of emission intensities of CF ₂ and C ₂ spectra; Comparing a reference value set based on an arbitrary characteristic of the process with a reference value to determine whether or not to stop the plasma process. A step of mounting a target object on a mounting table provided in the processing container; a step of supplying a processing gas into the processing container while exhausting the processing container; The gas contains carbon and fluorine, and provides CF ₂ and C ₂ by dissociation; a step of converting the processing gas into a plasma via a discharge in the processing container; and a step of performing the processing using the plasma. Subjecting the body to a plasma treatment; and, during the plasma treatment, dispersing light emission from the plasma to obtain a detected value of a ratio of emission intensities of CF ₂ and C ₂ spectra; Controlling a process condition of the plasma processing so as to approach a reference value set based on an arbitrary characteristic of the processing. 3. The plasma processing method according to claim 1, wherein said plasma processing is an etching processing of a silicon oxide film.