JPH11345803A - Method and apparatus for plasma production and processing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of accurately processing a specimen with plasma by controlling ion flux distribution on a specimen carrier in a plasma production processing apparatus by changing frequency of a high-frequency power supply. SOLUTION: A specimen carrier 85 is placed in a plasma production vacuum chamber 81, a variable frequency high-frequency power supply 87 is provided in the specimen carrier 85 to create DC self-bias via an impedance matching circuit 86, a frequency control circuit 91 is also provided to control frequency of the high-frequency power supply 87, and a gas controller 82, an exhaust system 83 and the frequency control circuit 91 are controlled to optimize frequency and gas pressure inside the chamber 81 by a signal of an etching termination detector 90 or a programmed control apparatus 92 placed in the plasma production vacuum chamber 81.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma generating apparatus, in which a sample stage is set in a chamber, and a high frequency power is applied to the sample stage to form a self-bias, whereby ions are directed toward the sample stage. TECHNICAL FIELD The present invention relates to a plasma generation processing method and a plasma generation processing apparatus for processing a sample by mainly or supplementarily using acceleration induction.

[0002]

2. Description of the Related Art Advances in modern high-density semiconductor integrated circuits are bringing about changes that are comparable to the industrial revolution. Higher density has been realized by miniaturization of element dimensions, improvement of devices, enlargement of chip size, and the like. The miniaturization of device dimensions has been progressing to the order of the wavelength of light, and the use of excimer lasers and soft X-rays for lithography is being studied. Dry etching plays an important role along with lithography in realizing fine patterns.

Therefore, dry etching applied to fine processing will be described below. Dry etching is a processing method that uses a chemical or physical reaction between radicals and ions generated by plasma and the solid surface of the material film to be etched to remove unnecessary portions of the material film or substrate. That is. Reactive ion etching (RIE), which is most widely used as a dry etching technique, is such that when a sample is exposed to a high-frequency discharge plasma of an appropriate gas, an unnecessary portion of the sample surface is removed by an etching reaction. At this time, necessary portions are usually protected by a photoresist pattern used as a mask.

In order to form a substantially vertical etching shape in accordance with a mask pattern having a fine size at a high etching rate, a high ion flux is applied to the sample with high energy enough to etch the sample. It is necessary that the light be incident almost perpendicularly. For this purpose, the following two requirements must be satisfied.

[0005] One is that ions generated in the plasma and transported to the sample stage while being accelerated in a sheath region formed near the sample and having energy sufficient to etch the sample are generated in the sheath region. While being transported by neutrons, it is scattered by collisions with neutral particles and has a wide incidence angle distribution as much as possible. In other words, ions that have obtained sufficient energy to perform etching reduce collision scattering with neutral particles during transport of the sheath region as much as possible,
That is, the light is perpendicularly incident on the sample.

The other is the charge of ions having different polarities, that is, ions that enter the sample with a relatively perpendicular angle distribution and electrons that enter the sample with a widened isotropic incidence angle distribution. Due to the difference in the incident angle distribution of ions and electrons having irregularities, the uneven sample surface shows a unique non-uniform positive and negative charging distribution, resulting in a unique sample surface potential distribution. This is to cope with the case where ions having sufficient energy to be applied do not always enter the sample perpendicularly and may be attracted to the resist mask or the side surface of the sample to be etched. In order to prevent this, these surfaces are electrically neutralized and ions are made to be incident perpendicularly to the vicinity of the sample.

[0007] In particular, in order to analyze the solution to the latter problem, some surface charging affecting ion trajectories have been reported by simulation. First,
Arnold and colleagues have investigated the surface potential distribution of a two-dimensional trench shape by ion lens analysis simulation (JCArnold and HHSawi
n: J. Appl. Phys. 70 [No. 10] p. 5314 (1991)). Electrons are assumed to be incident isotropically and ions are incident vertically and at a constant time, respectively, and these incorporate the effect on the ion trajectory of the local electric field created on the surface of the trench pattern assuming an insulator. In addition, there has been reported an example in which a plasma in Maxwell distribution, which is in thermal equilibrium and directly faces an insulator substrate, is simulated by a particle code using the PIC method (H. Naitou, M. Nakaoka,
S.Yamada and O.Fukuyama: Proc.2nd Int. Conf.On Re
active Plasmas and 11th Symp. On Plasma Processin
g, p.439, Yokohama (1994)). The ions are accelerated by the sheath potential, enter the trench at a velocity perpendicular to the substrate, and reach the bottom of the trench. On the other hand, the electrons have an angular distribution and enter the wall near the entrance of the trench. The potential at the bottom of the trench rises until it has a potential energy comparable to the incident energy of the ions.

FIG. 18A shows the charging distribution of the sample surface of the insulator trench 11 and the ion trajectory as a result of the simulation results. Here, + indicates that the battery is positively charged, and − indicates that the battery is negatively charged. FIG. 18B shows this sample surface potential distribution in a form in which the surface of FIG. 18A is developed in a straight line. In particular, the side surface of the insulator resist mask 10 and the upper side surface of the sample to be etched are negatively charged, so that incident ions are near the sample. It is drawn to the upper side surface of the sample to be etched.
As a result, the side surface of the resist mask is shaved or the sample to be etched itself is etched, which causes abnormal dimensions and shapes of the sample to be etched.

On the other hand, the L & S (structure in which a line pattern and a space pattern continuously exist) pattern and a structure in which a wide open area is adjacent to the L & S pattern are used for a sample to be etched with a conductor. Simulations have reported surface charging that affects surface roughness (T. Oomori, M. Taki, K. Nishikawa and H. Oote)
ra: Jpn. J. Appl. Phys. 34 [No.12B] p.6809 (199
Five)). Electrons from the sheath interface are analytic solutions of the Vrazov equation, and ions are launched towards the wafer at a drift velocity. The electrons and ions arrive at and adhere to the pattern surface, and the trajectories of the electrons and ions are recalculated using MC particle simulation near the pattern surface, taking into account the local electric field created by these. A stationary solution is repeatedly obtained until the electron flux and the ion flux are balanced and converged at all points on the pattern surface.

FIG. 19 (a) shows an L & S (structure in which a line pattern and a space pattern are continuously present) pattern shown by the simulation result and an L & S etched sample in a case where a large open area is adjacent to the L & S pattern. FIG. 19 shows the charging distribution of the sample surface during the main etching and the resulting ion trajectory.
(B) shows the charging distribution on the sample surface when the L & S sample to be etched is completed, each line pattern is isolated, and the underlying thermal oxide film as an insulator is exposed (at the time of over-etching); The resulting ion orbitals are shown. Here, in the drawing, 120 is a photoresist pattern, 121 is phosphorus-doped polycrystalline silicon as an L & S etched sample, 122 is a base thermal oxide film, 1
23 is a silicon substrate.

At the time of the main etching shown in FIG. 19A, even if there is a temporary unevenness in the sample surface potential due to the difference in the incident angle distribution of ions and electrons having charges of different polarities, the conductive material Since the etching sample is connected, it is electrically neutralized in the sample to be etched by electrons or ions supplied from a wide open area, and the ions are almost perpendicularly incident on the sample. However, especially the side surface of the insulator resist mask is negatively charged by the electrons which are incident almost isotropically. As a result, the ions are subsequently incident on this portion, so that the resist mask is scraped and, as a result, the resist is exposed. This causes abnormal dimensions of the etched sample.

At the time of over-etching shown in FIG. 19B, since each line pattern is isolated, unevenness in the sample surface potential due to the difference in the incident angle distribution of ions and electrons having charges of different polarities is electrically obtained. Not neutralized. As a result, the side surface of the insulator resist mask is negatively charged as in the main etching, and the surface of the base oxide film sample is positively charged. In addition, the side surface facing the wide open area of the L & S etched sample at the end, which is adjacent to the wide open area, has an almost anisotropic side incidence of electrons that fly almost vertically. Since the amount of incident light is larger than the amount of incident light, the side surface on the opposite side is negatively charged almost similarly to the side surface facing the wide open area because the polysilicon sample is a conductor. The inner side L & S sample to be etched, in particular, the bottom side surface is positively charged because the ion incident amount is larger than the side incident amount of the electrons that are flying isotropically. As a result, ions incident on the space portion of the L & S sample to be etched on the inner side are repelled by the positive potential on the surface of the underlying oxide film sample. And is incident vertically. On the other hand, ions incident on the space on the opposite side of the wide open area of the L & S etched sample at the extreme end are repelled by the positive potential on the surface of the base oxide film sample, and the L & S coated on the inner side from the extreme end. The sample is repelled by the positive potential on the side surface of the etched sample, is further attracted to the negative potential on the side surface of the endmost L & S sample to be etched, and enters the side surface. In addition, ions that enter the vicinity of the L & S sample to be etched in the wide open area are attracted to the negative potential on the side surface of the L & S sample to be etched, although the potential in the wide open area is almost neutral. And slightly incident on the side surface. As a result, the resist mask is shaved, causing dimensional anomalies in the sample to be etched.The side surface of the extreme L & S sample to be etched, which is opposite to the wide open area, is etched, causing shape anomalies such as so-called notching. In addition, the L & S etched sample surface at the extreme end of the wide open area is similarly etched to cause shape abnormality.

As the first countermeasure, there is an ECR (Electron Cyclotron Resonance) plasma dry etching apparatus in which high-density plasma discharge is easier at a lower gas pressure P than a parallel plate type (capacitive coupling type) dry etching apparatus. IC
It has been performed using a P (inductively coupled plasma) plasma dry etching apparatus. In an ECR plasma dry etching apparatus or an ICP plasma dry etching apparatus, a high frequency power supply for generating plasma and a self-DC power supply are used.
A high frequency power supply to be applied to the sample stage for forming a bias is provided independently.

On the other hand, as a second countermeasure, conventionally, in order to neutralize the positive potential on the sample surface, in an ECR plasma dry etching apparatus or an ICP plasma dry etching apparatus, a high frequency power supply for generating plasma is turned on / off.
By using the pulse modulation plasma generation method of turning off, the electron temperature sharply decreases during the OFF phase, but the electron density does not decrease so much. Either a method of electrically neutralizing the positive potential of the silicon oxide film or the lower side surface of the sample to be etched, or a method of applying a DC voltage to intermittently generate a positive potential on the sample stage to attract negative ions. I was

[0015]

However, according to the second measure, it has been reported by simulation that in a sufficient afterglow phase at the time of OFF, a state in which charging is relaxed by inflow of electrons and negative ions can be explained. (T. Kinoshita and J.
P.McVittie: Proc. Of 19th Dry Process Symposium,
p.63, Tokyo (1997)) In the short OFF phase, sufficient surface electrical neutralization cannot be achieved, and the most commonly used parallel plate (capacitively coupled) dry etching equipment There was a problem that it was difficult to apply.

Further, the method of applying a DC voltage so that a positive potential is generated intermittently on the sample stage has a problem that the plasma generation efficiency is reduced.

Furthermore, both of these methods have a problem that they do not function sufficiently for the purpose of neutralizing the negative potential generated on the side surface of the resist mask.

In view of the above problems, the present invention controls the energy distribution and the incident angle distribution of ions reaching the sample stage while mitigating the influence of sample surface charging, and performs vertical etching with high throughput. It is a main object to provide a plasma generation processing method to be realized.

[0019]

Means for Solving the Problems To solve the above problems, the plasma processing method and apparatus of the present invention employ the following means.

First, when performing an etching process, a variable frequency high-frequency power for forming a bias on a gas controller, an exhaust system, and a sample stage on which a sample to be etched can be mounted is installed in the plasma generation chamber. Controlling the frequency control circuit of the source, thereby optimizing the frequency and gas pressure inside the plasma generation chamber over time, thereby forming the sheath width and the mean free path of ions formed near the surface of the sample stage, and Control the elapsed time of ions in the sheath, and in the first etching operation mode, increase the degree of monochromaticity of the energy of ions reaching the sample stage in order to improve processing throughput and achieve sufficient etching anisotropy. Means for making the energy substantially equal to a desired value and increasing the perpendicularity of the incident angle distribution to the sample In addition, in the second etching operation mode, after the first etching operation mode operation, the ions having a relatively perpendicular angle distribution and incident on the sample and the spread almost isotropic incidence angle distribution are provided. Due to the difference in the incident angle distribution of ions and electrons having different polarities of electrons incident on the sample, the uneven sample surface shows a unique uneven positive and negative charge distribution. In order to electrically neutralize, use means to make the energy of ions reaching the sample stage spread from low to high components, and to make the incident angle distribution spread from the direction perpendicular to the sample. The dry etching can be performed while switching these two etching means repeatedly over time.

That is, the sheath width d on the cathode side formed near the sample stage is:

[0022]

(Equation 1)

As described above, it is proportional to the inverse of the square root of the gas pressure P and the frequency f (K. Harafuji, A. Yamano and
M. Kubota; Jpn. J. Appl. Phys. Vol. 33 (1994) pp. 2212
-2222 and K. Harafuji; Jpn. J. Appl. Phys. Vol. 34 (19
95) pp.1993-2003), and the mean free path λ of ions, mainly derived from elastic collision scattering and charge exchange scattering, between ions and neutral particles is

[0024]

(Equation 2)

By using the proportionality to the reciprocal of the gas pressure P as described above, ions starting from the boundary between the bulk plasma region and the sheath region are transported from the sheath region toward the cathode having the sample stage. In the meantime, the probability η that ions are scattered by collisions with neutral particles in the sheath is, on average,

[0026]

(Equation 3)

## EQU1 ## That is, the gas pressure P is lowered,
Alternatively, the probability of scattering due to collision with neutral particles in the sheath can be reduced by decreasing P / f by increasing the frequency f. This allows
Energy attenuation of ions can be suppressed, ions can be made to be incident on the sample almost perpendicularly with uniform directionality, and attenuation of ion flux density reaching the sample can be suppressed.

As a result, an improvement in processing throughput and a sufficient etching anisotropy can be realized.

Also, by increasing P / f by increasing the gas pressure P or decreasing the frequency f, the probability of scattering due to collision with neutral particles in the sheath can be increased. As a result, the energy of the ions can be attenuated, the directionality of the ions can be made slightly disordered so that the ions are incident on the sample, and the ion flux density reaching the sample can be attenuated.

As a result, the electrons incident on the sample with a spread angular distribution negatively charge especially the side surface of the sample to be etched or the insulating resist mask, and the high-energy ions incident on the surface become negatively charged. In order to prevent the negatively charged insulator resist mask near the sample from being drawn to the side surface of the insulator resist and etching the side surface of the sample,
The surface can be electrically neutralized by low energy positive ions. Ions enter the pattern sidewalls during the etching, but by sufficiently lowering the energy of the ions to such an extent that the sample to be etched by the insulator or the insulator resist mask pattern material itself is not so etched, the following etching process is performed. In this case, the vertical shape of the insulator resist mask pattern and the sample to be etched can be maintained.

Further, when the gas pressure is relatively low,
The ion energy distribution shows a saddle structure (saddle type) distribution having two peaks on the low energy side and the high energy side. When the frequency f is high, the energy width ΔE, which is the difference between the peak on the low energy side and the peak on the high energy side, becomes narrower than when the frequency f is low, and the color becomes more monochromatic. That is, ΔE is approximately

[0032]

(Equation 4)

As described above, it is reported that it is inversely proportional to f (P. Benoit-Cattin and LC Bernard: J. Appl.
Phys. 39 (1968) p.5723).

A program control device capable of preprogramming the switching of the operation mode with the passage of time as described above is installed, and processing is performed in the first etching operation mode by using a signal of the control device. In order to improve the throughput and realize sufficient etching anisotropy, the degree of monochromaticity of the energy of the ions reaching the sample stage is increased so that the energy becomes almost a desired value, and the incident angle distribution for the sample is improved. In the second etching operation mode, after the operation of the first etching operation mode, the ion incident on the sample with a relatively vertical angle distribution and the spread almost isotropically are used. The difference in the incident angle distribution of ions and electrons with different polarities of electrons incident on the sample with the incident angle distribution The uneven sample surface shows a unique uneven positive and negative charge distribution, but in order to electrically neutralize this charged sample, the energy of the ions reaching the sample stage changes from low to high. A means is used to spread the incident angle distribution from the direction perpendicular to the sample, and dry etching is performed while switching these two etching means over time.

According to the present invention, in the parallel plate type reactive ion etching apparatus having the above structure, 10 to 20 P
Even at a medium gas pressure of about a, even in a low-pressure high-density plasma etching apparatus such as ICP or ECR, etching with high processing throughput and sufficient shape anisotropy while overcoming shape defects due to charging However, it is possible to accurately realize the frequency and gas pressure by switching over time.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) A dry etching method performed using a parallel plate type reactive ion etching apparatus according to Embodiment 1 of the present invention will be described below with reference to the drawings.

FIG. 1 shows the dry etching method of the present invention.
It is the schematic which applied to the parallel plate type reactive ion dry etching apparatus. Reactive gas is introduced into the metallic chamber 81 through a gas controller 82, and is controlled to an appropriate pressure by an exhaust system 83. An upper portion of the chamber 81 is provided with an anode (anode) 84, and a lower portion thereof is provided with a sample stage 85 serving as a cathode (cathode). A high frequency power source 87 capable of changing the frequency via an impedance matching circuit 86 is provided on the sample stage 85.
Is connected, and a high-frequency discharge can be generated between the sample stage 85 and the anode 84. The frequency of the high-frequency power source can be changed by the frequency control circuit 91. Further, the etching end point can be determined by an etching end point detector 90 using a spectral method. Further, a signal from the etching end point detector controls the gas controller 82 and the exhaust system 83 to control the gas pressure. It has a function of controlling the frequency of the high-frequency power source via a frequency control circuit in accordance with a signal from the etching end point detector. Further, the gas controller 82, the exhaust system 83, and the frequency control circuit 91
The program control device 92 can also perform control according to a pre-programmed processing flow.

FIG. 2 shows a one-dimensional distribution of physical quantities between a cathode and an anode of plasma generated by the parallel plate type reactive ion etching apparatus shown in FIG.
That is, FIG. 2A shows the electron density distribution, FIG. 2B shows the ion density distribution, and FIG. 2C shows the ion flux density distribution. Similarly, FIG. 3 shows another one-dimensional distribution of the physical quantity between the cathode and the anode. 3A shows the plasma potential distribution, FIG. 3B shows the electric field distribution, and FIG. 3C shows the electron temperature distribution.

2 and 3, the horizontal axis is standardized by the distance L between the cathode and the anode. x / L = 0 corresponds to the cathode, and x / L = 1 corresponds to the anode. In each distribution chart, one cycle of high-frequency power τRF
Is divided into four equal parts, and the graph at each time is shown by changing the line type. As can be understood from these figures, in the vicinity of the cathode serving as the sample stage, a self-bias is formed by the high-frequency power applied to the cathode, and FIG.
The cathode is negatively charged as shown in FIG.
As shown in FIG. 2, a so-called ion sheath in which a strong electric field is formed perpendicular to the sample stage is formed. As a result, in this region, as shown in FIG. The density is almost zero, and FIG.
As shown in (b), the positive ions are transported onto the sample stage so as to be accelerated toward the sample stage.

FIG. 4 shows the maximum value of the ion density and the ion flux transported to the cathode when the frequency of the high-frequency power applied to the cathode is changed in the parallel plate type reactive ion etching apparatus shown in FIG. It shows the maximum value Fmax and the minimum value Fmin of the density, and the maximum value dmax and the minimum value dmin of the sheath width. The sheath width is a value standardized by a distance L between the electrodes surrounded by the anode electrode 84 and the cathode electrode 85, and is indicated by%. From these figures, it can be seen that the maximum ion density and the ion flux density transported to the cathode increase monotonically with increasing frequency, and the sheath width decreases with increasing frequency, as inversely proportional to the square root of frequency. I can understand.

FIG. 5 shows the frequency dependence of the sheath width shown in FIG. 3 on a schematic sectional view of a parallel plate type reactive ion etching apparatus. That is, the left half of the figure shows a case where the frequency is relatively low, and the right half of the figure shows a case where the frequency is relatively high. The sheath width oscillates around its average value d over one period τRF of the high-frequency power while taking the maximum value dmax and the minimum value dmin, and when the frequency is relatively high, compared to when the frequency is relatively low. , The sheath width becomes shorter. Of the plasma generation region surrounded by the anode electrode 84 and the cathode electrode 85, the region excluding the sheath region is generally called a bulk plasma region.

As shown in FIG. 6, ions starting from the boundary between the bulk plasma and the sheath collide with neutral particles while being transported onto the sample stage while being accelerated toward the sample stage by the sheath width d. And the directionality is disordered, and the ion energy is also attenuated. As a result, for the same gas pressure, the collision between ions and neutral particles is higher at a relatively high frequency where the sheath width d is short than at a relatively low frequency where the sheath width d is long. Scattering is reduced and higher ion fluxes are incident more perpendicularly to the sample at higher energies. On the other hand, the sheath width d
At a relatively low frequency where is longer, the sheath width d
Collisions between ions and neutral particles occur more frequently than at higher frequencies where the ion flux density is reduced, the energy of the ions is reduced, and the ions lose their scattered angular distribution. Bring it in.

FIG. 7 shows the frequency dependence of the energy of the ions reaching the sample stage. That is,
In a frequency region A of about 10 MHz or less, the energy of ions increases as the frequency decreases. This is because the loss of the plasma from the discharge region increases as the traveling distance of one cycle of the ions or electrons increases as the frequency decreases, but in order to compensate for this loss and increase the frequency of sufficient ionization collisions, Secondary electrons generated by the collision of ions with the cathode electrode need to quickly enter the bulk plasma region through the high electric field region in the sheath. For this reason, as the frequency decreases, the voltage between sheaths necessarily increases, and the energy of ions increases. On the other hand, in 71 frequency regions B of about 10 MHz or more, the energy of ions increases as the frequency increases. This is because, as described above, as the frequency increases, collision scattering between ions and neutral particles decreases, and ion energy attenuation is suppressed. Here, the measurement was mainly performed on the frequency domain B.

FIG. 8 shows the frequency dependence of the energy distribution of incident ions when the gas pressure is sufficiently low. The ion energy distribution shows a saddle structure (saddle type) distribution having two peaks on the low energy side and the high energy side. When the frequency f is high, the energy width ΔE, which is the difference between the peak on the low energy side and the peak on the high energy side, becomes narrower than when the frequency f is low, and the color becomes more monochromatic. The energy distribution when f is high and the gas pressure is high is also shown by the dotted line. The peak value of the double peak decreases, and the scattered low energy component increases.

FIG. 9 shows the maximum value of the ion density and the maximum value of the ion flux density transported to the cathode when the gas pressure is changed in the parallel plate type reactive ion dry etching apparatus shown in FIG. It shows the minimum value and the change between the maximum value and the minimum value of the sheath width. From these figures, it can be seen that the maximum value of the ion density and the ion flux density transported to the cathode monotonically increase with increasing gas pressure, and that the sheath width is inversely proportional to the square root of gas pressure, and increases with increasing gas pressure. It can be seen that it decreases.

That is, since the sheath width d on the cathode side formed near the sample stage is proportional to the reciprocal of the square root of the gas pressure P and the frequency f, the sheath width d can be expressed as follows.

[0047]

(Equation 5)

The mean free path λ of ions, which is mainly derived from elastic collision scattering and charge exchange scattering between ions and neutral particles, is inversely proportional to the gas pressure P, and can be expressed as follows.

[0049]

(Equation 6)

Further, an amount η proportional to the probability that ions starting from the boundary between the bulk plasma and the sheath are scattered by collision with neutral particles in the sheath while being transported onto the cathode having the sample stage. Is

[0051]

(Equation 7)

Is as follows. Therefore, by substituting the expressions of d and λ into the expression of η,

[0053]

(Equation 8)

The following relational expression is obtained. Here, K1, K2 and K3 = K1 / K2 are constants, respectively.

That is, the probability of scattering due to collision with neutral particles in the sheath can be reduced by reducing P / f by lowering the gas pressure P and increasing the frequency f. As a result, ion energy attenuation is suppressed, ions are made to be almost perpendicular to the sample with the same directionality, and ion flux density reaching the sample is suppressed, improving etching throughput and achieving sufficient etching. Anisotropy is achieved.

On the other hand, when the gas pressure P is increased and the frequency f
By lowering P / f, the probability of scattering due to collision with neutral particles in the sheath can be increased by increasing P / f. As a result, the ion energy is attenuated, the directionality of the ions is slightly disordered so that the ions are incident on the sample, and the ion flux density reaching the sample is attenuated, thereby alleviating the etching ability.

Further, when the gas pressure is relatively low,
The ion energy distribution shows a saddle structure (saddle type) distribution having two peaks on the low energy side and the high energy side. When the frequency f is high, the average energy is higher than when it is low, and the energy width ΔE, which is the difference between the low energy peak and the high energy peak, is approximately

[0058]

(Equation 9)

As described above, since it is inversely proportional to f, it becomes more monochromatic. The center incident energy of the ion becomes a value corresponding to the self-bias voltage.

The method of switching the etching operation mode that has been specifically performed will be described with two examples.

FIG. 10 shows a first switching method example. While maintaining the gas pressure inside the chamber constant at a low level over time, the high-frequency power frequency f applied to the sample stage is increased by Δt1 at the high frequency f1 in the first etching operation mode.
During the second etching operation mode, the operation is continued at Δt2 at a low frequency f2, and this operation is repeated. 11A and 11B show a method of changing the frequency f. FIG. 11A shows a case where the high frequency f1 and the low frequency f2 are changed stepwise, and FIG. 11B shows a case where the high frequency f1 is changed.
This is a case where the frequency f2 as low as 1 is smoothly changed.

FIG. 12 shows a second example of the switching method. While maintaining the high-frequency power frequency f constant with time, the gas pressure P inside the chamber is maintained at a low gas pressure P1 for Δt1 during the first etching operation mode,
In the second etching operation mode, high gas pressure
This is continued for Δt2 at P2, and this is repeated. FIG.
FIG. 12A shows a case where the low gas pressure P1 and the high gas pressure P2 are changed stepwise, and FIG. 12B shows a case where the low gas pressure P1 and the high gas pressure P1 are changed. This is a case where the gas pressure P2 is smoothly changed.

FIG. 14 shows that the switching between the first etching operation mode and the second etching operation mode using the parallel plate type reactive ion etching apparatus according to the method of the present invention is the same as the first switching method described above. FIG. 4 schematically shows a state in which etching is performed using a silicon oxide film trench. That is, the high frequency f1 and the low frequency f2 are temporally changed stepwise. In this case, as a gas introduced into the plasma generator chamber, CH ₂ F ₂ is 10 sccm and CF ₄ is 30 s.
Ccm was introduced, and the pressure in the etching apparatus was set to 10 Pa. The use of a gas based on another hydrofluorocarbon-based gas such as CHF ₃ or a halogen-based gas such as SF ₆ is also sufficiently effective. In the first etching operation mode, the frequency of the high frequency
In the second etching operation mode, the frequency of the high frequency power was 13.56 MHz.

Here, in the figure, reference numeral 60 denotes a photoresist mask pattern, 61 denotes a silicon oxide film, 62 denotes a portion of the photoresist mask which has been removed by sputtering with ions, 63 denotes a silicon oxide film, and a photoresist mask denotes a photoresist mask. This is a silicon oxide film which should not be etched because it was sputtered and cut by ions. Generally, a sputtered photoresist or a reaction product deposited film of a silicon oxide film and a halogen-based gas adheres to the side wall, but these are not shown here. In the drawing, arrows indicate ion orbits, and the length of the orbit indicates the magnitude of ion energy.

FIG. 14A shows the state of etching in the first etching operation mode, FIG. 14B shows the state of etching in the second etching operation mode, and FIG. The state of the etching when the mode is returned to the first etching operation mode is schematically and slightly exaggerated.

In the first etching operation mode shown in FIG. 14A, the distance between the sheaths is shortened, and the collision and scattering of ions with neutral particles is reduced. As a result, the incident angle of the ions immediately before the sample surface is reduced. The energy width ΔE, which is a difference between two peaks on the low energy side and the high energy side of the energy distribution of the ions exhibiting the saddle structure (saddle type) distribution becomes almost vertical, and the self-bias voltage which is almost the desired energy is reduced. Monochromatization is performed to a corresponding value, plasma loss is further reduced, ion density is increased, and the rate of anisotropic etching such as ion-assisted etching is increased. However, as time elapses, the upper portion of the insulator-etched sample and the particularly side surface of the insulator resist mask become negatively charged. It is drawn to the side surface of the insulator resist mask. As a result, the resist mask is shaved or the sample to be etched itself is etched, causing abnormal dimensions and shapes of the sample to be etched.

In the second etching operation mode shown in FIG. 14B, the distance between the sheaths is increased, and the collision and scattering of ions with neutral particles increases. As a result, the incident angle of the ions immediately before the sample surface is reduced. The energy width ΔE, which is the difference between two peaks on the low energy side and the high energy side of the energy distribution of ions having a saddle structure (saddle-shaped) distribution, becomes a distribution slightly scattered from the vertical, and has a value corresponding to the self-bias voltage. It spreads to the center, the low energy component due to scattering increases relatively, and the plasma loss increases,
The ion density decreases, and the rate of anisotropic etching such as ion-assisted etching decreases. As a result, low-energy ions with low etching ability are attracted to the upper surface of the insulator sample to be etched or the negatively charged sample side surface of the insulator resist mask. Neutralize.

In the case of returning to the first etching operation mode of FIG. 14C again, since the charging of the side surface is neutralized, the environment returns to the initial stage of FIG. Also, the distance between the sheaths is shortened again, and the collision and scattering of ions with neutral particles is reduced. As a result, the angle of incidence of the ions immediately before the sample surface becomes almost vertical, and the ions having a saddle structure (saddle type) distribution are observed. The energy width ΔE, which is the difference between the two peaks on the low and high energy sides of the energy distribution, becomes narrower, becomes monochromatic to a value substantially corresponding to the self-bias voltage, further reduces plasma loss, increases ion density, The rate of anisotropic etching such as ion-assisted etching is increased.

As described above, by repeating the first etching operation mode and the second etching operation mode,
The negatively charged resist mask and the resist mask being scraped by ions attracted to the side surface of the sample, or the etching of the sample to be etched itself is minimized,
Vertical etching with high processing throughput, in which the dimensional abnormality and the shape abnormality of the sample to be etched can be almost ignored, is realized.

Here, the first etching operation mode is performed longer by setting the time ratio of each of the first etching operation mode and the second etching operation mode to 3: 1 or more. Is performed at a value exceeding 10 MHz, and one cycle that is the total time of the first etching operation mode and the second etching operation mode is performed at 2 μs to 20 μs, and the gas pressure is performed at 20 Pa or less. It was found that excellent etching performance was obtained. At this time, an etching rate of 500 to 800 nm / min was obtained.

(Embodiment 2) A dry etching method using an ICP (inductively coupled plasma) plasma dry etching apparatus according to Embodiment 2 of the present invention will be described below with reference to the drawings.

FIG. 15 is a schematic diagram in which the dry etching method of the present invention is applied to an ICP (inductively coupled plasma) plasma dry etching apparatus. A high-frequency power supply for generating plasma and a high-frequency power supply for applying a self-DC bias to a sample stage are independently provided.
Reference numeral 95 denotes a high-frequency power supply for generating plasma, and 9
Reference numeral 6 denotes a spiral coil for generating plasma. The other configuration is the same as that of the configuration applied to the parallel plate type reactive ion dry etching apparatus according to the first embodiment of the present invention, and the detailed description thereof will be omitted by retaining the same reference numerals. The qualitative change in the sheath structure and the physical quantity of plasma on the cathode side was qualitatively the same as that in the parallel plate dry etching apparatus according to the first embodiment shown in FIGS. 2 to 9.

FIG. 16 shows that the method of the present invention uses an ICP (inductively coupled plasma) plasma dry etching apparatus to switch between the first etching operation mode and the second etching operation mode in the above-described embodiment. FIG. 1 schematically shows a state in which etching is performed using the first switching method described in 1 with respect to main etching for forming a phosphorus-doped polycrystalline silicon gate having an L & S structure. Here, a large open area exists on the left side of the L & S pattern structure, and the L & S pattern structure continues on the right side. The high frequency f1 and the low frequency f2 are smoothly changed. In this case, Cl ₂ was introduced for 40 s as a gas to be introduced into the plasma generator chamber.
ccm, 20 sccm of SiCl ₄ were introduced, and the pressure in the etching apparatus was 1 Pa. Use of a gas based on another halogen-based gas such as HBr or SF6 is also sufficiently effective. Here, in the figure, 120 is a photoresist pattern, 121 is phosphorus-doped polycrystalline silicon, 122 is a thermal oxide film, and 123 is a silicon substrate. Reference numeral 125 denotes a portion of the photoresist mask which is sputtered and cut by ions, and reference numeral 126 denotes polycrystalline silicon which should not be etched because the photoresist mask is sputtered and cut by ions. Generally, a sputtered photoresist or a reaction product deposited film of silicon and a halogen-based gas adheres to the side wall, but these are not shown here. In the drawing, arrows indicate ion orbits, and the length of the orbit indicates the magnitude of ion energy.

FIG. 16A shows the state of etching in the first etching operation mode, FIG. 16B shows the state of etching in the second etching operation mode, and FIG. The state of etching when returning to the first etching operation mode is schematically exaggerated. Also in this case, as described below, the same effect as the silicon oxide film trench etching described in the first embodiment can be obtained.

In the first etching operation mode shown in FIG. 16A, the distance between the sheaths is shortened, and the collision and scattering of ions with neutral particles is reduced. As a result, the incident angle of ions immediately before the sample surface is reduced. The energy width ΔE, which is the difference between two peaks on the low energy side and the high energy side of the energy distribution of the ions showing the saddle structure (saddle type) distribution becomes narrower, and becomes monochromatic to a value almost equivalent to the self-bias voltage. And the plasma loss is reduced, the ion density is increased, and the rate of anisotropic etching such as ion-assisted etching is increased. However, as the time elapses, particularly the side surface of the insulator resist mask becomes negatively charged, and the incident ions are attracted to the negatively charged side surface of the insulator resist mask near the sample. As a result, the resist mask is etched, causing dimensional abnormality and shape abnormality of the sample to be etched.

In the second etching operation mode shown in FIG. 16B, the distance between the sheaths is increased and the collision and scattering of ions with neutral particles increase. As a result, the incident angle of the ions immediately before the sample surface is reduced. The energy width ΔE, which is the difference between two peaks on the low energy side and the high energy side of the energy distribution of ions having a saddle structure (saddle-shaped) distribution, becomes a distribution slightly scattered from the vertical, and has a value corresponding to the self-bias voltage. It spreads to the center, the low energy component due to scattering increases relatively, and the plasma loss increases,
The ion density decreases, and the rate of anisotropic etching such as ion-assisted etching decreases. As a result, low-energy ions having low etching ability are attracted to the negatively charged side surface of the insulator resist mask, and the insulator resist mask side surface is electrically neutralized.

In the case of returning to the first etching operation mode in FIG. 16C again, since the charge on the side surface is neutralized, the environment returns to the initial stage of FIG. Also, the distance between the sheaths is shortened again, and the collision and scattering of ions with neutral particles is reduced. As a result, the angle of incidence of the ions immediately before the sample surface becomes almost vertical, and the ions having a saddle structure (saddle type) distribution are observed. The energy width ΔE, which is the difference between the two peaks on the low and high energy sides of the energy distribution, becomes narrower, becomes monochromatic to a value substantially corresponding to the self-bias voltage, further reduces plasma loss, increases ion density, The rate of anisotropic etching such as ion-assisted etching is increased.

As described above, by repeating the first etching operation mode and the second etching operation mode,
Etching of the resist mask by ions attracted to the negatively charged resist mask is minimized,
Vertical etching with high processing throughput, in which the dimensional abnormality and the shape abnormality of the sample to be etched can be almost ignored, is realized.

Here, the first etching operation mode is made longer by setting the time ratio of each of the first etching operation mode and the second etching operation mode to 4: 1 or more. Is performed at a value exceeding 13.56 MHz, and one cycle which is the total time of the first etching operation mode and the second etching operation mode is performed at 2 μs to 20 μs,
Further, it was found that when the gas pressure was set to 2 Pa or less, excellent etching performance was obtained. At this time, an etching rate of 600 to 900 nm / min was obtained.

FIG. 17 shows a case where the etching shown in FIG.
9 shows an example in which the same etching operation mode is switched. However, in the second etching operation mode, it is effective to slightly increase the gas pressure. In addition, the end of the main etching is determined using the signal of the etching end point detector installed in the plasma generation chamber, etching is performed under the main etching conditions until the main etching is completed, and thereafter, the above-described main etching is performed. It is programmed so that an automatic two-stage etching can be performed so that etching is performed under over-etching conditions.

FIG. 17A shows the state of etching in the first etching operation mode, FIG. 17B shows the state of etching in the second etching operation mode, and FIG. The state of etching in the first etching operation mode is schematically and slightly exaggerated.

In the first etching operation mode shown in FIG. 17A, the angle of incidence of ions immediately before the sample surface is substantially vertical, and the energy distribution of ions is monochromatic to a value substantially corresponding to the self-bias voltage. In addition, plasma loss is further reduced, ion density is increased, ion energy is increased, and the rate of anisotropic etching such as ion-assisted etching is increased. However, since each line pattern is isolated with the passage of time, unevenness in the sample surface potential due to the difference in the incident angle distribution of ions and electrons having charges of different polarities is not electrically neutralized. As a result, the side surface of the insulator resist mask is negatively charged as in the main etching, and the surface of the base oxide film sample is positively charged. In addition, the side surface facing the wide open area of the L & S etched sample at the end, which is adjacent to the wide open area, has an almost anisotropic side incidence of electrons that fly almost vertically. Since the amount of incident light is larger than the amount of incident light, the side surface on the opposite side is negatively charged almost similarly to the side surface facing the wide open area because the polysilicon sample is a conductor. The inner side L & S sample to be etched, in particular, the bottom side surface is positively charged because the ion incident amount is larger than the side incident amount of the electrons that are flying isotropically. As a result, ions incident on the space portion of the L & S sample to be etched on the inner side are repelled by the positive potential on the surface of the underlying oxide film sample. And is incident vertically. On the other hand, of the L & S etched sample at the extreme end,
Ions entering the space opposite the wide open area are repelled by the positive potential on the surface of the underlying oxide film sample, and further repulsed by the positive potential on the side surface of the L & S etched sample one inward from the extreme end. Then, it is drawn to the negative potential on the side surface of the endmost L & S sample to be etched, and enters the side surface. In addition, the end of L &
S For ions incident near the sample to be etched, the potential in the wide open area is almost neutral, but the L & S at the extreme end
It is drawn to the negative potential on the side surface of the sample to be etched and slightly enters the side surface. As a result, the resist mask is shaved, causing dimensional anomalies in the sample to be etched.The side surface of the extreme L & S sample to be etched, which is opposite to the wide open area, is etched, causing shape anomalies such as so-called notching. In addition, the L & S etched sample surface at the extreme end of the wide open area is similarly etched to cause shape abnormality.

In the second etching operation mode shown in FIG. 17B, the distance between the sheaths is increased, and the collision and scattering of ions with neutral particles increases. As a result, the incident angle of the ions immediately before the sample surface is reduced. The energy width ΔE, which is the difference between two peaks on the low energy side and the high energy side of the energy distribution of ions having a saddle structure (saddle-shaped) distribution, becomes a distribution slightly scattered from the vertical, and has a value corresponding to the self-bias voltage. It spreads to the center, the low energy component due to scattering increases relatively, and the plasma loss increases,
The ion density decreases, and the rate of anisotropic etching such as ion-assisted etching decreases. As a result, low-energy ions having low etching ability are attracted to the negatively charged side surface of the insulator resist mask, and the insulator resist mask side surface is electrically neutralized.

In the case of returning to the first etching operation mode of FIG. 17C again, since the charging of the side surface is neutralized, the environment returns to the environment of the first stage of FIG. Also, the distance between the sheaths is shortened again, and the collision and scattering of ions with neutral particles is reduced. As a result, the angle of incidence of the ions immediately before the sample surface becomes almost vertical, and the ions having a saddle structure (saddle type) distribution are observed. The energy width ΔE, which is the difference between the two peaks on the low and high energy sides of the energy distribution, becomes narrower, becomes monochromatic to a value substantially corresponding to the self-bias voltage, further reduces plasma loss, increases ion density, The rate of anisotropic etching such as ion-assisted etching is increased.

As described above, by repeating the first etching operation mode and the second etching operation mode,
Etching of the resist mask by ions attracted to the negatively charged resist mask is minimized,
Vertical etching with high processing throughput, in which the dimensional abnormality and the shape abnormality of the sample to be etched can be almost ignored, is realized.

Here, the first etching operation mode is made longer by setting the time ratio of each of the first etching operation mode and the second etching operation mode to 3: 1 or more. Is performed at a value exceeding 13.56 MHz, and one cycle which is the total time of the first etching operation mode and the second etching operation mode is performed at 2 μs to 20 μs,
Further, it was found that when the gas pressure was set to 1 Pa or less, excellent etching performance was obtained.

That is, by using the etching processing method based on the plasma generation processing method of the present invention, 1
Even at a medium gas pressure of about 0 Pa, in the first etching operation mode, in order to improve the processing throughput and realize sufficient etching anisotropy, the degree of monochromaticity of the energy of ions reaching the sample stage is increased, Means for making the energy substantially equal to the desired value and using means for increasing the perpendicularity of the incident angle distribution to the sample, and in the second etching operation mode, after the first etching operation mode operation, a relatively perpendicular Due to the difference in the incident angle distribution of ions and electrons with different polarity charges between the ions that enter the sample with an angular distribution and the electrons that enter the sample with a broadly isotropic incident angle distribution. The uneven surface of the sample shows a unique uneven positive and negative charge distribution, but the ions reaching the sample stage to electrically neutralize this charged sample. Energy is to have a spread of high component from a low component, and using means to have a spread from vertical incidence angular distribution to the sample,
It is an object of the present invention to provide a dry etching method which controls these two etching means while switching over time to realize vertical etching with high throughput.

In this embodiment, the case of etching a silicon oxide film and polycrystalline silicon has been described.
Even when etching the metal such as Al, the etching of the resist in the multilayer resist, and the like, a high effect can be obtained by using the apparatus of the present invention. When applied to aluminum etching, BCl ₃ + Cl ₂ , SiCl ₄ + Cl ₂ + CHCl
_Use chlorine-based gas such as ₃ etc., pressure is 0.1 ~ 20P
a. At this time, the etching rate is 400 to 90.
0 nm / min was obtained.

In this embodiment, a parallel plate reactive ion etching apparatus and an IC
Although P is used, the present invention has the most remarkable effect in this case. A high-frequency power source for generating plasma as in the case of ICP, and a high-frequency power source for applying to a sample stage for forming a self-DC bias. Similarly, a sufficiently large effect was also observed for an ECR (Electron Cyclotron Resonance) plasma dry etching apparatus provided independently of the above.

[0090]

As described above, by using the plasma generation processing method of the present invention, the applied frequency of the high-frequency power and the gas pressure inside the chamber can be temporally reduced even at a medium gas pressure of about 10 to 20 Pa. By optimizing, the sheath width and the mean free path of ions formed near the sample stage surface, and the elapsed time of ions in the sheath are controlled,
This makes it possible to control the energy distribution and the incident angle distribution of the ions reaching the sample stage while alleviating the influence of the sample surface charging, thereby realizing vertical etching with high throughput.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a dry etching apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a one-dimensional distribution of physical quantities between a cathode and an anode of plasma generated in a parallel plate reactive ion dry etching apparatus according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a one-dimensional distribution of physical quantities between a cathode and an anode of plasma generated in a parallel plate reactive ion dry etching apparatus according to the first embodiment of the present invention.

FIG. 4 is a diagram showing the dependence of the physical quantity on the frequency of the high-frequency power applied to the cathode in the parallel plate reactive ion dry etching apparatus according to the first embodiment of the present invention.

FIG. 5 is a diagram showing the frequency dependence of a sheath width in a parallel plate type reactive ion dry etching apparatus.

FIG. 6 is a schematic view showing a state in which ions starting from a boundary between a bulk plasma and a sheath are transported toward a sample stage while being scattered by a collision with neutral particles in a sheath region having a sheath width d.

FIG. 7 is a diagram showing a frequency dependence of energy when reaching a sample stage in the parallel plate reactive ion dry etching apparatus according to the first embodiment of the present invention.

FIG. 8 is a diagram showing the frequency dependence of the energy distribution of incident ions when the gas pressure is relatively low.

FIG. 9 is a diagram showing the gas pressure dependence of the physical quantity in the parallel plate type reactive ion dry etching apparatus according to the first embodiment of the present invention.

FIG. 10 is a diagram showing a first switching method of the etching operation mode switching methods.

FIG. 11 is a diagram showing a method of changing a frequency.

FIG. 12 is a diagram showing a second switching method among the etching operation mode switching methods.

FIG. 13 is a diagram showing a method of changing a gas pressure.

FIG. 14 shows a case where switching between a first etching operation mode and a second etching operation mode is performed by using the above-described first switching method using a parallel plate type reactive ion etching apparatus. Schematic diagram showing the situation

FIG. 15 is a schematic diagram in which the dry etching method of the present invention is applied to an ICP (inductively coupled plasma) plasma dry etching apparatus.

FIG. 16 shows a method of switching between a first etching operation mode and a second etching operation mode using an ICP (inductively coupled plasma) plasma dry etching apparatus according to the first embodiment of the present invention. Schematic diagram showing a state when etching is performed using the first switching method described in

FIG. 17 is a schematic diagram showing a case where the etching operation mode is switched in a case where etching progresses and over-etching is performed;

FIG. 18 is a diagram showing a charging distribution, ion orbit, and a sample surface potential distribution of a sample surface in an insulator trench.

FIG. 19 is a diagram showing a sample surface charging distribution and an ion trajectory when a line pattern is isolated and a base oxide film as an insulator is exposed when an L & S pattern and a wide open area are adjacent to each other.

[Explanation of symbols]

Reference Signs List 30 Bulk plasma region 32 Sheath region 33 Sample 60 Photoresist mask pattern 61 Silicon oxide film 62 Portion of photoresist mask cut off by ion 63 Photoresist mask of silicon oxide film is sputtered off by ion Therefore, a silicon oxide film that should not be etched 75 silicon substrate 76 silicon oxide film 77 phosphorus-doped polycrystalline silicon film 78 photoresist pattern 81 metallic chamber 82 gas controller 83 exhaust system 84 anode (anode) 85 sample table 86 impedance Matching circuit 87 High-frequency power supply 90 Etching end point detector 91 Frequency control circuit 92 Program controller 93 Photoresist pattern 95 High-frequency power supply 96 Spiral coil 120 Photoresist pattern 121 Phosphorus-doped polycrystalline silicon 122 Thermal oxide film 123 Silicon substrate 125 Portion of photoresist mask cut off by ion 126 Photoresist mask of polycrystalline silicon was sputtered off by ion. Polycrystalline silicon that should not be etched

Claims (18)

[Claims] 1. A sample table is set in a vacuum chamber having a function of introducing a gas to be ionized and generating plasma, and applying a high-frequency power to the sample table to form a self-DC bias. A plasma processing apparatus for processing a sample by accelerating and inducing ions toward a sample stage by optimizing a time change of an applied frequency of a high-frequency power and a gas pressure in a chamber. Controls the width of the sheath and the mean free path of the ions formed near the surface of the sample stage, and the elapsed time of the ions in the sheath. A plasma processing method, wherein a sample is processed by plasma while controlling the temperature. 2. In the first etching operation mode, the degree of monochromaticity of energy of ions reaching the sample stage is increased,
By using the first means for increasing the energy to a substantially desired value and increasing the perpendicularity of the incident angle distribution to the sample, during the second etching operation mode, the energy of the ions reaching the sample stage starts from the low component. Using a second means to have a high component spread, and to make the incident angle distribution spread from the direction perpendicular to the sample,
2. The plasma generation processing method according to claim 1, wherein the dry etching is performed while switching the first and second means over time. 3. A cathode formed in the vicinity of the sample stage by lowering the gas pressure P to increase the mean free path λ of ions and increasing the frequency f of the high-frequency power applied to the sample stage by the first means. Side sheath width d,
By reducing f, the scattering probability due to collision with neutral particles in the sheath is reduced, and the gas pressure P is increased to shorten the mean free path λ of ions by the second means, and to reduce the frequency f. The plasma generation according to claim 2, wherein the probability of scattering due to collision with neutral particles in the sheath is increased by increasing the sheath width d by decreasing the sheath width and increasing P / f. Processing method. 4. By increasing the gas pressure P while keeping the frequency f constant, an amount proportional to the scattering probability η (P /
3. The plasma generation processing method according to claim 2, wherein f) is increased, and dry etching accompanied by switching from the first etching operation mode to the second etching operation mode is performed. 5. An amount proportional to the scattering probability η by decreasing the frequency f while keeping the gas pressure P constant.
The plasma generation processing method according to claim 2, wherein (P / f) is increased, and dry etching accompanied by switching from the first etching operation mode to the second etching operation mode is performed. 6. The gas pressure P is kept constant and the frequency f is reduced, so that the elapsed time of ions in the sheath before reaching the sample stage surface is shortened. The plasma generation processing method according to claim 2, wherein dry etching accompanied by switching to the second etching operation mode is performed. 7. By increasing the gas pressure P while keeping the frequency f constant, an amount proportional to the scattering probability η (P /
3. The plasma generation processing method according to claim 2, wherein f) is increased and dry etching accompanied by switching from the main etching operation mode to the over etching operation mode is performed. 8. An amount proportional to the scattering probability η by reducing the frequency f while keeping the gas pressure P constant.
The plasma generation processing method according to claim 2, wherein (P / f) is increased, and dry etching accompanied by switching from the main etching operation mode to the over etching operation mode is performed. 9. The plasma generation processing method according to claim 2, wherein the switching of the etching operation mode is performed according to a previously programmed processing flow. 10. The plasma generation processing method according to claim 2, wherein switching between the first etching operation mode and the second etching operation mode is performed smoothly in time. 11. The plasma generation processing method according to claim 2, wherein switching between the first etching operation mode and the second etching operation mode is performed stepwise discontinuously in time. 12. The method according to claim 2, wherein the time ratio of each of the first etching operation mode and the second etching operation mode is 3: 1 or more, and the first etching operation mode is performed for a long time. The plasma generation processing method according to the above. 13. The plasma generation processing method according to claim 2, wherein the frequency in the second etching operation mode is set to a value exceeding 10 MHz. 14. The total time of the first etching operation mode and the second etching operation mode is set to 2 μs to 20 μs.
The plasma generation processing method according to claim 2, wherein the method is performed between the steps. 15. The plasma generation processing method according to claim 2, wherein the gas pressure is set to 20 Pa or less. 16. A vacuum chamber having a function of generating a plasma, a sample table provided inside the vacuum chamber, on which a sample to be processed can be mounted, and a self-loading device connected to the sample table via an impedance matching circuit. A variable frequency high frequency power source for forming a DC bias, and a frequency control circuit for controlling the frequency of the high frequency power source, for controlling a gas controller, an exhaust system, and a frequency control circuit provided in the vacuum chamber. In this manner, the gas pressure and frequency inside the plasma generation chamber are temporally optimized, and the sheath width and the mean free path of ions near the sample stage, and the elapsed time of ions in the sheath are controlled. Plasma generation processing equipment. 17. A program control device, which can control a gas controller, an exhaust system and a frequency control circuit in a timely manner according to a pre-programmed processing flow, is installed in the plasma generation chamber, and this signal is installed in the plasma generation chamber. 17. A gas controller, an exhaust system and a frequency control circuit which are controlled.
3. The plasma generation processing apparatus according to claim 1. 18. An end point detector for detecting an end point of etching is provided in a plasma generation chamber, and a signal from the end point detector is supplied to a gas controller, an exhaust system, and a frequency control provided in the plasma generation chamber. 17. The apparatus according to claim 16, wherein the apparatus controls a circuit.