CN1164122A - Plasma processor and its treating method - Google Patents

Abstract

The invention discloses a plasma processing device and the plasma processing method for improving the selection ratio during micromachining in the process of fine pattern precision machining of large-diameter samples. The plasma processing device is provided with a vacuum processing chamber, a sample station and a plasma generating device, as well as a high frequency power of 50 to 200 MH<z>VHF between a pair of electrodes and a magnetic field generating device for generating static magnetic field and low-frequency magnetic field of more than 10 gausses but less than 110 gausses. In order that the maximum part of the components of the magnetic field along a lower electrode direction can be positioned on an upper electrode surface or deviated toward one side of the upper electrode, a magnetic field generating device is arranged appropriately. An electron cyclotron accelerating resonance zone is formed between the pair of electrodes.

Description

Plasma processor and processing method thereof

The present invention relates to a plasma processing machine and a processing method, and more particularly, to a plasma processing machine and a processing method suitable for forming a fine pattern in a semiconductor manufacturing process.

As the integration of semiconductor devices increases, further improvements in microfabrication efficiency and processing speed are required, and for this reason, it is necessary to reduce the gas pressure of plasma processing and increase the plasma density.

There are many ways to reduce the gas pressure and increase the plasma density, for example: (1) the cyclotron resonance (ECR for short) phenomenon of a microwave (2.45GHz) electromagnetic field and a static magnetic field (875 gauss) is utilized; (2) the coil is excited by an RF (radio frequency) power supply to generate an induced electromagnetic field, which generates plasma (ICP for short).

However, when etching oxide film-like thin films with fluorocarbon (fluorocarbon) based gases, the conventional ECR method (1) and ICP method (2) are excessively dissociated, and it is difficult to increase the selectivity to Si or SiN of the underlying layer.

On the other hand, in the conventional method of generating plasma by applying a radio frequency voltage between parallel plates, it is difficult to stably discharge at a pressure of 10Pa or less.

The following two methods are used to solve the above-mentioned difficulties:

(3) the dual-frequency excitation method disclosed in Japanese unexamined patent publication Hei 7-297175 and Japanese unexamined patent publication Hei 3-204925, in which plasma is generated by using a high-frequency voltage of several tens MHz or more, and sample bias control is performed by using a low frequency of several MHz or less;

(4) in the magnetron RIE (M-RIE for short) method disclosed in japanese unexamined patent publication No. 2-312231, a magnetic field B is applied in a direction intersecting a self-bias electric field (E) induced on the surface of a sample, and the electron suppression action by the electron lorentz force is utilized.

In addition, Japanese patent application laid-open No. 56-13480 discloses a method of increasing the plasma density at a low pressure. This is to obtain a high plasma density even at a low gas pressure of 0.1 to 1Pa by flexibly utilizing Electron Cyclotron Resonance (ECR) formed by microwaves (2.45GHz) of electromagnetic waves and a static magnetic field (875 gauss).

On the other hand, in the technology of performing semiconductor etching processing, film forming processing, and the like by plasma, a processing apparatus is used which prepares a high-frequency power supply for accelerating ions in plasma on a sample stage on which a sample to be processed (for example, a semiconductor wafer substrate, hereinafter simply referred to as a sample) is placed, and an electrostatic adsorption film for fixing the sample on the sample stage by electrostatic attraction.

For example, the apparatus described in specification USP5,320,982 controls the ion energy injected into the sample by generating plasma with microwaves, fixing the sample to the sample stage by electrostatic attraction, and controlling the temperature of the sample by a heat conductive gas between the sample and the sample stage, and by connecting a high-frequency power source for outputting a sine wave to the sample stage as a bias power source.

Further, as described in Japanese patent application laid-open No. 62-280378, by generating a pulse-like ion control bias waveform to maintain the electric field strength between the plasma electrodes constant and applying the bias to the sample stage, the distribution width of the ion energy injected into the sample can be reduced, and the etching dimensional accuracy and the etching rate ratio of the film to be processed to the underlying material can be improved several times.

Further, as described in Japanese patent application laid-open No. 6-61182, plasma is generated by electron cyclotron resonance, and a pulse bias having a width such that the duty factor is 0.1% or more is applied to a sample, thereby preventing the formation of "notch".

In the above-mentioned conventional techniques, the plasma generation systems described in Japanese unexamined patent publication No. 7-288195 and Japanese unexamined patent publication No. 7-297175 generate plasma by using high frequencies of 13.56MHz and several tens MHz. With a gas pressure of several tens to 5Pa (pascal), good plasma suitable for oxide film etching can be generated. However, as the pattern size becomes finer (0.2 μm or less), it is more necessary to make the lines of the pattern to be processed vertical. Therefore, the air pressure must be reduced.

However, it is difficult to generate 5X 10 at 4Pa or less (0.4 to 4Pa) by the above-mentioned dual-frequency excitation method and M-RIE method¹⁰cm^-3The above plasma of the desired density. For example, even if the plasma excitation frequency is increased by the above-mentioned dual-frequency excitation method, the plasma density cannot be increased by 50MHz or more, but rather, a decrease phenomenon occurs, and it is difficult to make the plasma density 5X 10 at a low pressure of 0.4 to 4Pa¹⁰cm^-3The above.

Further, in the case of the M-RIE method, electron suppression is caused by the electron Lorentz force generated on the surface of the sample, and the plasma density generated by this effect should be uniform over the entire sample. However, the disadvantage is that drift of E B generally causes plasma density to shift in plane. The density shift of the plasma directly formed on the surface of the sample by the suppression of electrons occurs in the vicinity of the outer film (skin) near the sample having a large electric field strength, and therefore cannot be corrected by a method such as diffusion.

As described in Japanese patent application laid-open No. 7-288195, a magnet is placed in the direction of electron drift caused by E.times.B to reduce the magnetic field strength, so that a uniform plasma without drift can be obtained even when 200 Gauss is added to the maximum value of the magnetic field parallel to the sample. However, the disadvantages are: once the electric field intensity distribution is fixed, the conditions for forming uniform plasma are limited to a specific narrow range, and therefore, it is not easy to make necessary adjustments in accordance with changes in the process conditions. In particular, in a large sample having a diameter of 300mm or more, when the distance between the electrodes is as small as 20mm or less, the pressure at the center of the sample is 10% or more larger than the pressure at the ends of the sample, and it is difficult to set the distance between the sample stage and the opposing electrode to 30mm or more in order to avoid the pressure difference across the sample.

Thus, it is difficult to make 5X 10 at a low pressure of 0.4 to 4Pa by the above-mentioned dual-frequency excitation method and M-RIE method¹⁰cm^-3The plasma density of the sample is uniform in a sample plane with the phi of 300 mm. Therefore, using dual frequencyIn the excitation method and the M-RIE method, it is difficult to process a large wafer having a width of 300mm or more uniformly and efficiently with a line width of 0.2 μ M or less, and it is difficult to increase the selection ratio with respect to the underlying layer (Si or SiN).

On the other hand, in order to greatly increase the plasma density at a low pressure, the method described in the above-mentioned prior art Japanese patent application laid-open No. 56-13480 can be adopted. However, the disadvantages are: when the gas is excessively dissociated (rapidly), and silicon oxide, silicon nitride film, or the like is etched by a gas containing fluorine and carbon, fluorine atoms/molecules and fluorine ions are generated in a large amount, and a desired selectivity ratio to an underlayer (Si or the like) is not obtained. The ICP method using an induced electromagnetic field of radio frequency power also has a disadvantage of too fast dissociation as the ECR method described above.

Further, in the case where the processing gas is discharged from the periphery of the sample, the density of the central portion of the sample is high and the density of the peripheral portion is low, and there is a disadvantage that the uniformity of the processing over the entire surface of the sample is affected. To overcome this drawback, an annular dam (focus ring) was provided around the periphery of the sample to stop the flow of gas. However, the method has a disadvantage that reaction products adhere to the dikes to form impurity sources, thereby reducing the product yield.

On the other hand, in order to control the ionenergy incident to the sample, a radio frequency bias of a sine wave is applied to the electrode on which the sample is placed. The frequency is from hundreds of KHz to 13.56 MHz. In this frequency band, since the ions vary with the electric field in the outer film (sheath), the energy of the injected ions has a double peak shape, i.e., two peaks on the low energy side and the high energy side. The disadvantages are that: the ion treatment speed of the high-energy side is high, and the sample is damaged; the ion processing speed on the low energy side is slow. The speed is reduced to eliminate the damage; damage is caused to the treatment speed. On the other hand, when the rf bias frequency is increased to 50MHz or more, the incident energy distribution is uniform and close to a single peak, most of the energy is used for generating plasma, and the voltage applied to the outer film (skin) is greatly reduced, so that it is difficult to individually control the energy of the incident ions.

In the above-mentioned conventional techniques, the pulse bias power supply system described in japanese patent laid-open nos. 62-280378 and 6-61182 has a disadvantage that it cannot be adapted to a desired fine pattern processing by a method of sufficiently controlling the temperature of a sample because the voltage generated between both ends of an electrostatic adsorption film increases with the inflow of an ion current, the ion acceleration voltage applied between a plasma and the surface of the sample decreases, and the ion energy distribution expands when the system is used in the electrostatic adsorption system without fully examining the application of a pulse bias to the sample by using an electrostatic adsorption medium layer between the electrode of a sample stage and the sample.

In addition, when the conventional sine wave output bias power supply system described in specification USP5,320,982 is used, the impedance of the outer film (sheath) portionis close to or lower than the impedance of the plasma itself when the frequency is increased, and therefore, there are disadvantages in that: unnecessary plasma is generated in the vicinity of the outer layer near the sample by the bias power supply, and the plasma is not effectively used to accelerate ions, and the plasma distribution is also deteriorated, so that the ion energy cannot be controlled by the bias power supply.

Further, in the plasma treatment, it is important to appropriately control the ion amount, the radical amount, and the radical species for improving the performance. However, conventionally, a gas as an ion source and a radical source is introduced into a processing chamber, and plasma is generated in the processing chamber to generate ions and radicals at the same time. Therefore, as the miniaturization of the sample to be processed progresses, the limitation to be imposed on the control becomes more and more significant.

The invention provides a plasma processing apparatus and a plasma processing method, which can obtain uniform plasma in a large wafer range with a diameter of more than 300mm without excessive gas dissociation phenomenon, thereby being easy to precisely process a fine pattern of a large wafer sample.

Another object of the present invention is to provide a plasma processing apparatus and a plasma processing method which can perform oxide film processing uniformly and efficiently, particularly over a large wafer.

Another object of the present invention is to provide a method for improving a sampleMiddle insulating film (e.g. SiO)₂SiN, BPSG, etc.) plasma processing.

It is another object of the present invention to provide a plasma processor and method that has a narrow, stable, low damage, and manageable ion energydistribution, and that improves the selectivity of plasma processing.

Another object of the present invention is to provide a plasma processing apparatus and method for precisely and stably processing a desired fine pattern by improving temperature controllability through electrostatic adsorption of a sample.

It is another object of the present invention to provide a plasma processor and method that can independently control ions and radicals.

The invention is characterized by the following:

the plasma processing machine comprises a vacuum processing chamber, a plasma generating device including a pair of electrodes, a sample stage with a mounting surface for mounting a sample to be processed in the vacuum processing chamber, and a decompression device for decompressing the vacuum processing chamber. The plasma processing machine is further provided with a high-frequency power supply and a magnetic field forming device.

A high-frequency power supply for applying a high-frequency power of a VHF band of 30MHz to 300MHz between the pair of electrodes;

a magnetic field forming device for forming a static magnetic field or a low-frequency magnetic field in a direction intersecting with an electric field generated by the high-frequency power supply between the pair of electrodes or in the vicinity thereof,

thereby forming an electron cyclotron resonance region between the pair of electrodes, the electron cyclotron resonance region being generated by interaction between the magnetic field and the electric field.

The invention is also characterized by having the following:

the plasma processor comprises a vacuum processing chamber, a plasma generating device including a pair of electrodes, and a sample stage which is used for placing a sample processed in the vacuum chamber and also used as one of the electrodes; and a pressure reducing device for evacuating the vacuum processing chamber. The plasma processor is further provided with a high-frequency power supply and a magnetic field forming device.

A high frequency power supply for applying a power supply of a VHF band of 50MHz to 200MHz between the pair of electrodes; and

a magnetic field forming means for forming a static magnetic field or a low-frequency magnetic field portion of 17 Gauss or more and 72 Gauss or less in a direction intersecting with an electric field generated by the high-frequency power supply between the pair of electrodes or in the vicinity thereof,

the largest component of the magnetic field in the direction along the sample stage surface is set on the side opposite to the sample stage so as to be separated from the center of the electrodes, and an electron cyclotron resonance region is formed between the pair of electrodes by the interaction between the magnetic field and the electric field.

Another feature of the present invention is the following:

a plasma processing machine comprises a vacuum processing chamber, a plasma generating device including a pair of electrodes, a sample table which is used as one of the electrodes and is used for placing a sample processed in the vacuum chamber, and a decompression device for decompressing the vacuum chamber.

The method for plasma processing the sample by using the plasma processing device comprises the following steps:

depressurizing the vacuum processing chamber by a depressurizing device;

a part for forming a static magnetic field or a low-frequency magnetic field of 10 gauss to 110 gauss in a direction intersectingwith the electric field between the pair of electrodes by a magnetic field forming means;

a VHF band power supply of 30MHz to 300MHz is added between the pair of electrodes by a high frequency power supply, and an electron cyclotron resonance region is formed between the two electrodes by the interaction of the magnetic field and an electric field generated by the high frequency power supply;

the sample is processed by plasma generated by the electron cyclotron resonance.

According to the present invention, in order to obtain a uniform plasma having a saturated ion current distribution of. + -. 5% or less in a large wafer having a diameter of. + -. 300mm or more without causing excessive gas dissociation, a VHF power source of 30MHz to 300MHz, preferably 50MHz to 200MHz is used as the high-frequency power source for generating plasma. On the other hand, a static magnetic field or a low-frequency magnetic field is formed in a direction intersecting with an electric field generated between the pair of electrodes by the high-frequency power supply. Thus, an electron cyclotron resonance region is formed between the pair of electrodes along the sample mounting surface of the sample stage on the side opposite to the sample stage apart from the center of the electrodes by the interaction between the magnetic field and the electric field. The sample is processed with a plasma generated by electron cyclotron resonance.

The magnetic field has a static magnetic field of 10-110 Gauss, preferably 17-72 Gauss, or a low-frequency (1KHz or less) magnetic field portion, and the air pressure is set to be 0.4-4 Pa. The distance between the electrodes is 30 to 100mm, preferably 30 to 60 mm. It is to be understood that the area of each of the pair of electrodes should be larger than the area of the sample to be processed.

The frequency f of thehigh-frequency power supply adopts VHF with f being more than or equal to 50MHz and less than or equal to 200MHz, so that the plasma density is reduced by 1-2 orders of magnitude compared with that of the microwave ECR. Also, the dissociation of the gas is reduced and the amount of unwanted oxygen atoms/molecules and ions generated is reduced by about 1 order of magnitude. Due to the adoption of VHF frequency and cyclotron resonance, appropriate high-density plasma with the absolute value of 5 × 10 can be obtained¹⁰cm^-3High speed processing can be performed at low pressures of 0.4-4 Pa. Since the gas dissociation is not excessive, the selectivity to the underlying layer of Si, SiN or the like is not significantly deteriorated.

The gas dissociation was less compared to the past 13.56MHz parallel plate electrode. This slightly increases the number of fluorine atoms/molecules and ions, and can be alleviated by providing a silicon-and-carbon-containing substance on the electrode surface and the wall surface of the processing chamber, and further applying a bias voltage thereto, and by using a hydrogen-containing gas to combine hydrogen with fluorine, and then discharging it.

Further, according to the present invention, the maximum portion of the magnetic field component parallel to the sample stage can be set on the side opposite to the sample stage apart from the center of the two electrodes, and the magnetic field strength parallel to the sample on the sample mounting surface of the sample stage can be set to 30 gauss or less, preferably 15 gauss or less, so that the lorentz force (E × B) acting on electrons in the vicinity of the sample mounting surface can be set to a small value, and the plasma density can be prevented from being uneven due to the ion drift effect caused by the lorentz force on the sample mounting surface.

In accordance with another feature of the present invention, theelectron cyclotron resonance effect is amplified, and the effect of the peripheral portion and the outer side of the sample is made larger than the effect of the center, so that more plasma is generated in the peripheral portion and the outer vicinity of the sample than in the central portion of the sample. The method for reducing the electron cyclotron resonance effect is as follows: enlarging the distance between the cyclotron resonance region and the sample; eliminating a cyclotron resonance region; the degree of orthogonality of the magnetic field and the electric field is reduced.

In addition, when the magnetic field gradient in the vicinity of the cyclotron resonance magnetic field Bc is increased to narrow the ECR resonance region, the cyclotron resonance effect can be reduced. The ECR resonance region is Bc (1-a) to B (1+ a) and Bc (1+ a), but the range of the magnetic field intensity B is changed to 0.05 to a and 0.1.

Ion generation is particularly vigorous because of the strong dissociation forces in the ECR resonance region. On the other hand, the dissociation rate is weaker than that in the ECR resonance region except for the ECR resonance region, and the generation of radicals is vigorous. By adjusting the width of the ECR resonance region and the high-frequency power applied to the upper electrode, the generation of ions and radicals can be controlled more independently, and the ECR resonance region is more suitable for the sample processing requirement.

Another feature of the present invention is the following structure:

the plasma processing machine has a vacuum processing chamber; a sample stage for placing a sample to be processed in the vacuum processing chamber; and a plasma generating apparatus including a high-frequency power supply. The plasma processing apparatus further includes:

an electrostatic adsorption device for fixing a sample on a sample stage by using electrostatic adsorption force; and

a pulse bias device for applying a pulse bias to the sample;

the high-frequency voltage of 10MHz-500MHz is applied as the high-frequency power supply, and the pressure in the vacuum processing chamber is reduced to 0.5-4.0 Pa.

Another feature of the present invention is to provide a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating apparatus. The plasma processor further includes:

an electrostatic adsorption device for fixing the sample on the sample table by means of electrostatic adsorption force;

the pulse bias device is connected to the sample table and is used for applying pulse bias to the sample table; and

and the voltage control device is used for inhibiting the change of the voltage and preventing the voltage from correspondingly changing according to the electrostatic adsorption capacity of the electrostatic adsorption device along with the application of the pulse bias.

Another feature of the present invention is to provide a plasma processing method comprising the following process steps:

placing the sample on one of a pair of electrodes opposed to each other in the vacuum processing chamber;

fixing the sample on the electrode by using electrostatic adsorption force;

feeding a corrosive gas into the processing chamber in which the sample is placed;

vacuumizing the processing chamber to reduce the air pressure to 0.5-4.0 Pa;

applying a high-frequency voltage of 10MHz-500MHz to change theetching gas into plasma under the pressure;

etching the sample with the plasma; and

applying a pulsed bias voltage to said one electrode.

Another feature of the present invention is to apply the following process steps to the insulating film (e.g., SiO) in the sample₂SiN, BPSG, etc.) are plasma treated, the steps are:

placing the sample on one of two electrodes opposed to each other;

fixing the sample on the electrode by electrostatic adsorption force;

introducing a corrosive gas into the ambient atmosphere in the process chamber in which the sample has been placed;

changing the fed etching gas into plasma;

etching the sample with the plasma;

and applying the pulse bias voltage to the one electrode during the etching, wherein the bias voltage has a pulse width of 250-800V and a duty ratio of 0.05-0.4.

According to another feature of the present invention, a pulse bias power supply having a predetermined characteristic can be applied to a sample stage having an electrostatic chuck device with an electrostatic chuck medium layer thereon, so that the temperature of the sample can be sufficiently controlled and a desired fine pattern can be stably processed. That is, the processor has an electrostatic adsorption means for fixing a sample on a sample stage by electrostatic adsorption and a pulse bias means for connecting the sample stage and applying a pulse bias to the sample stage, and the pulse bias having a cycle of one half of the duty ratio of a forward pulse portion of 0.2 to 2 μ s is applied to the sample via a capacitive element.

In accordance with another aspect of the present invention, there is provided avoltage suppressing device for suppressing a voltage change, that is, for preventing a voltage from changing in accordance with an electrostatic chuck capacity of an electrostatic chuck device in response to application of a pulsed bias, comprising: the electrostatic adsorption in one pulse period is used to make the voltage change on two ends of the medium layer less than one half of the bias strength of the pulse. Specifically, a method of reducing the thickness of a dielectric electrostatic film (chuck film) on the surface of the lower electrode may be employed, and a material having a large dielectric constant may be used as the dielectric. Alternatively, the pulse bias period is shortened to suppress a voltage rise on both ends of the dielectric layer.

By adopting another feature of the present invention, a pulse bias of 250V to 1000V in pulse width and 0.05 to 0.4 duty ratio is further applied to one electrode during sample etching, thereby improving the etching rate of an insulating film (e.g., SiO) in a sample₂SiN, BPSG, etc.) and the like.

Another feature of the present invention is the following structure:

a plasma processing machine has a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating device.

The plasma processing apparatus further includes:

an electrostatic adsorption device for fixing a sample on a sample stage by means of electrostatic adsorption force;

biasing means for applying a bias to the sample;

a radical supply device having a device for decomposing a gas for radical generation in advance, for supplying a required number of radicals;

a gas supply device for supplying a gas for generating ions to the vacuum processing chamber;and

a plasma generating device for generating plasma in the vacuum processing chamber,

using SiO₂As a sample.

Another feature of the present invention is a plasma processing apparatus including a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating device including a high-frequency power supply, further including:

the electrostatic adsorption device is used for fixing the sample on the sample table by virtue of electrostatic adsorption force;

a pulse bias device for applying a pulse bias to the sample;

a plasma supply device for radical generation for converting a gas for radical generation into plasma in advance in the vacuum processing chamber and supplying a required number of radicals; and

the plasma generator for generating plasma by supplying a gas for generating ions,

applying 10MHz-500MHz HF voltage to the HF power source while lowering the pressure inside the vacuum treating chamber to 0.5-4.0 Pa.

By adopting the other feature of the present invention, the amount and quality of ions and radicals can be controlled independently, and a pulse-like pulse power source having a predetermined characteristic is applied to a sample stage having an electrostatic adsorption device (in which an electrostatic adsorption medium layer is provided), whereby the temperature of a sample can be controlled sufficiently, and a desired fine pattern can be processed stably.

The quantity and quality of ions and radicals can be further independently controlled, a narrow ion energy distribution can be obtained, and the selectivity of plasma treatment and the like can be stably andaccurately improved.

The voltage control device can independently control the quantity and quality of ions and atomic groups, and can inhibit the voltage from changing corresponding to the electrostatic adsorption capacity of the electrostatic adsorption device along with the application of pulse voltage. Specifically, the thickness of the dielectric electrostatic adsorption film on the surface of the lower electrode can be reduced, and the dielectric is made of a material with a large dielectric constant. Or the pulse bias period is shortened to suppress the voltage rise at both ends of the dielectric layer.

By adopting another feature of the present invention, the quantity and quality of ions and radicals can be controlled independently, and when the sample is etched, a pulse bias voltage of a pulse width of 250V to 1000V and a duty ratio of 0.05 to 0.4 is applied to one electrode, thereby increasing the insulating film (e.g., SiO) in the sample₂SiN, BPSG, etc.) and selectivity of plasma treatment of the underlying layer, etc.

According to another feature of the present invention, the amount and quality of ions and radicals can be controlled independently, a high-frequency voltage of 10MHz to 500MHz is used as a high-frequency power source for generating plasma, and the pressure in the processing chamber is set to 0.5 to 4.0 Pa. Thus, stable plasma can be obtained. Furthermore, the ionization of the gas plasma can be improved by the high-frequency voltage, and the selection ratio during sample processing can be conveniently controlled.

[ FIG. 1]

Is a longitudinal sectional view of a two-electrode type plasma etching apparatus as one embodiment of the present invention.

FIG. 2 shows an example of a change in plasma density when the frequency of a high-frequency power supply for generating plasma is changed while a magnetic field capable of generating electron cyclotron resonance is applied.

[ FIG. 3]

This shows the energy gain K of electrons from the high-frequency electric field at the time of cyclotron resonance and at the time of no resonance.

[ FIG. 4]

The relationship between the magnetic field strength when the upper electrode of the magnetron discharge electrode is grounded and the high frequency power is applied to the lower electrode together with the magnetic field B, the ion acceleration voltage VDC induced in the sample, and the error Δ V of the induced voltage in the sample is shown.

[ FIG. 5]

Is an explanatory view of the magnetic field characteristic of the plasma etching apparatus of FIG. 1.

[ FIG. 6]

Is an explanatory view of an ECR zone of the plasma etching apparatus of fig. 1.

[ FIG. 7]

Is an example of an ideal output waveform used in the pulsed bias power supply of the present invention.

[ FIG. 8]

Is the pulse duty cycle (T)₁/T₀) To be constant, let T₀The potential waveform of the sample surface and the probability distribution map of the ion energy are varied.

[ FIG. 9]

The duty ratio of the pulse is constant, so that T is₀The potential waveform of the sample surface and the probability distribution map of the ion energy are varied.

[ FIG. 10]

Is a pulse break (T)₀-T₁) Maximum voltage V in a period and a period of a voltage generated between both ends of the electrostatic adsorption film_cmA graph of the relationship (c).

[ FIG. 11]

Is the pulse duty ratio sum (V)_DC/V_p) A graph of the relationship (c).

[ FIG. 12]

Shows the etching rates of silicon and oxide film, ESi and ESiO, when ionized by chlorine gas or the like₂Dependence of ion energy of (a).

[ FIG. 13]

Showing an example of etching of an oxide film, when CF is used₄Etching rate of oxide film and silicon ESiO at the time of gas plasmatization₂And ESi and ion energyThe relationship of the cloth.

[ FIG. 14]

Is a longitudinal sectional view of a two-electrode type plasma etching apparatus as another embodiment of the present invention.

[ FIG. 15]

Is a longitudinal sectional view of a two-electrode type plasma etching apparatus as another embodiment of the present invention.

[ FIG. 16]

The magnetic field distribution characteristic of the plasma etching apparatus of fig. 15 is illustrated.

[ FIG. 17]

Is an explanatory view of an ECR zone of the plasma etching apparatus of fig. 15.

[ FIG. 18]

Is a longitudinal sectional view of a plasma etching apparatus as another embodiment of the present invention.

[ FIG. 19]

The magnetic field distribution characteristics of the plasma etching apparatusof FIG. 18 are explained.

[ FIG. 20]

Is a longitudinal sectional view of a two-electrode type plasma etching apparatus as another embodiment of the present invention.

[ FIG. 21]

Is a longitudinal sectional view of a two-electrode type plasma etching apparatus according to another embodiment of the present invention.

[ FIG. 22]

Is an explanatory view of the magnetic field distribution characteristics of the plasma etching apparatus of FIG. 21.

[ FIG. 23]

Is a cross-sectional view of an important part of a two-electrode type plasma etching apparatus as other embodiment of the present invention.

[ FIG. 24]

Is a longitudinal sectional view of the plasma etching apparatus of FIG. 23.

[ FIG. 25]

Are diagrams of other embodiments of a magnetic field forming device.

[ FIG. 26]

Is a longitudinal sectional view of a two-electrode type plasma etching apparatus as another embodiment of the present invention.

[ FIG. 27]

Is a longitudinal sectional view of a two-electrode type plasma etching apparatus as another embodiment of the present invention.

[ FIG. 28]

Is a longitudinal sectional view of a two-electrode type plasma etching apparatus as another embodiment of the present invention.

[ FIG. 29]

The magnetic field distribution characteristics of the plasma etching apparatus of FIG. 28 are explained.

[ FIG. 30]

Is a longitudinal sectional view of a two-electrode type plasma etching apparatus as another embodiment of the present invention.

[ FIG. 31]

Is a longitudinal sectional view of another embodiment of the two-electrode type plasma etching apparatus shown in FIG. 1 after improvement.

[ FIG. 32]

FIG. 32 is a graph of the frequency of the generated plasma power source versus the minimum gas pressure for a stable discharge.

[ FIG. 33]

Is a graphical representation of the relationship between the frequency and the accumulated power of the pulsed bias power supply.

[ FIG. 34]

Is a longitudinal sectional view of an example of an inductively coupled discharge type magnetic field-free plasma etching apparatus using the present invention in an external energy supply discharge type.

[ FIG. 35]

Is a longitudinal sectional view of a plasma etching apparatus as another embodiment of the present invention.

[ FIG. 36]

Is a front view of a partial longitudinal section when the present invention is applied to a microwave plasma processing apparatus.

[ FIG. 37]

Is a longitudinal sectional view of a plasma etching apparatus as another embodiment of the present invention.

[ FIG. 38]

Is a front view of a partial longitudinal section of a plasma processing apparatus according to another embodiment of the present invention.

[ FIG. 39]

Is a longitudinal sectional view of a two-electrode type plasma etching apparatus capable of independently controlling ions and radicals as another embodiment of the present invention.

[ FIG. 40]

Is a detailed view of a part of a two-electrode type plasma etching apparatus capable of individually controlling ions and radicals as another embodiment of the present invention.

The present invention can provide a plasma processing apparatus and a plasma processing method which can easily process a fine and precise pattern on a large-diameter sample having a diameter of 300mm or more and can improve the selection ratio in fine processing. Further, it is possible to provide a plasma processing apparatus and a plasma processing method which can perform a uniform and high-speed processing, particularly an oxide film processing, on the entire surface of a large-diameter sample.

The present invention can also provide a method for improving the performance of an insulating film (e.g., SiO) in a sample₂SiN, BPSG, etc.) and a plasma processing method.

Further, it is possible to provide a plasma processing apparatus and a plasma processing method which are excellent in controllability, narrow in energy distribution, and high in selectivity of plasma processing.

Further, it is possible to provide a plasma processing apparatus and a plasma processing method which are excellent in controllability, narrow in ion energy distribution, high in plasma processing selectivity and the like when using a sample stage having a dielectric layer for electrostatic adsorption.

Further, it is possible to provide a plasma processing apparatus and a plasma processing method which can reduce the pressure inthe processing chamber of the plasma processing apparatus by independently controlling the mass and amount of ions and radicals, facilitate the precision processing of a fine pattern, and improve the selection ratio in the fine processing.

Further, it is also possible to provide a method for improving the quality and quantity of an insulating film (e.g., SiO) in a sample by independently controlling the mass and quantity of ions and radicals₂SiN, BPSG, etc.) and the likeA selective plasma processing apparatus and a plasma processing method for ion processing.

The following describes embodiments of the present invention. First, fig. 1 shows an embodiment 1, i.e., the present invention is applied to a plasma etching apparatus of the opposite electrode type.

In fig. 1, a process chamber 10 as a vacuum chamber has a pair of opposing electrodes consisting of an upper electrode 12 and a lower electrode 15. A sample 40 is placed on the lower electrode 15. In the case of processing a large sample of Φ 300mm or more, the gap between the two electrodes 12 and 15 is preferably set to 30mm or more so that the pressure difference on the sample surface does not exceed 10%. In order to reduce fluorine atoms, molecules and ions, the gap is preferably set to 100mm or less, more preferably 60mm or less, from the viewpoint of effectively utilizing the reaction on the surfaces of the upper and lower electrodes. A high-frequency power supply 16 is connected to the upper electrode 12 to supply high-frequency power through a matching box 162. 161 is a high frequency power modulated signal source. A filter 165 is connected between the upper electrode 12 and the ground, the filter 165 being low impedance to the frequency components of the bias power supply 17; the frequency component to the high frequency power supply 16 is high impedance.

The surface area of the upper electrode 12 is larger than the area of the sample 40 to be processed, and the voltage can be applied to the outer film on the sample surface with high efficiency by the bias power supply 17.

An upper electrode cap 30, which is composed of silicon, carbon or SiC, is provided as a fluorine removal plate on the lower surface of the upper electrode 12. A gas introduction chamber 34 is provided above the upper electrode 12, and includes a gas diffusion plate 32 for diffusing the gas in a predetermined distribution state. Gas necessary for the treatment such as sample etching is supplied from a gas supply unit 36 into the treatment chamber 10 through a gas diffusion plate 32 of a gas introduction chamber 34, the upper electrode 12, and a hole 38 of the upper electrode cover 30. The vacuum pump 18 connected to the outer chamber 11 through the valve 14 evacuates the outer chamber 11 to adjust the pressure in the processing chamber 10 to a pressure required for sample processing. In order to increase the plasma density and to make the reaction in the processing chamber uniform, a discharge suppressing ring 37 is provided around the processing chamber 10. The discharge suppressing ring 37 is provided with a gap for exhaust.

A magnetic field forming device 200 is provided above the upper electrode 12 to form a magnetic field parallel to the surface of the sample 40 and perpendicular to the electric field E formed between the electrodes. The magnetic field forming device 200 has a core 201, an electromagnetic coil 202, and an insulator 203. The structural material of the upper electrode 12 is a non-magnetic conductor, such as aluminum and aluminum alloys. The structural material of the process chamber 10 is a non-magnetic material such as aluminum and aluminum alloys, alumina, quartz, SiC, and the like. The core 201 has an axially rotationally symmetrical structure, has a substantially E-shaped cross section, and is divided into core portions 201A and 201B, and forms a magnetic field B in which magnetic flux is emitted from the central upper portion of the chamber 10 toward the upper electrode 12 and extends in an outer circumferential direction substantially parallel to the upper electrode 12. The magnetic field generated between the electrodes by the magnetic field generator 200 has a static magnetic field of 10 gauss to 110 gauss, preferably 17 gauss to 72 gauss, or a low-frequency magnetic field (1KHz or less) in which cyclotron resonance occurs.

It is known that the magnetic field strength Bc (gaussian) at which cyclotron resonance occurs has a relationship of Bc 0.357 × f (mhz) with the plasma generation high-frequency f (mhz).

The 2 electrodes 12 and 15 in the present invention are a pair of electrodes facing each other, and the two electrodes may be substantially parallel to each other, and the electrodes 12 and 15 may have a certain concave surface or a certain convex surface depending on the requirements such as plasma generation characteristics. The plasma generating device is characterized in that the electric field distribution between the electrodes is easy to be uniform by the double electrodes, and the plasma is easier to be uniformly generated by the cyclotron resonance effect by improving the uniformity of a magnetic field which is orthogonal to the electric field.

The lower electrode 15 on which the test specimen 40 is placed and fixed has a bipolar type electrostatic chuck 20. That is, the lower electrode 15 is composed of a 1 st lower electrode 15A on the outer side and a 2 nd lower electrode 15B provided on the inner upper side thereof via an insulator 21, and an electrostatic adsorbing medium layer (hereinafter, referred to as electrostatic adsorbing film) 22 is provided on the upper surfaces of both the 1 st and 2 nd lower electrodes. Between the 1 stand 2 nd lower electrodes, a dc power supply 23 is connected through coils 24A and 24B for high-frequency component filtering. A DC voltage is applied between the two lower electrodes, and the 2 nd lower electrode 15B side is made positive. Thus, coulomb force acting between the sample 40 and the lower electrodes through the electrostatic adsorption film 22 can adsorb and fix the sample 40 to the lower electrode 15. The electrostatic adsorption film 22 may be made of alumina or a mixture of alumina and titania. The power supply 23 uses a dc power supply of several hundreds volts.

Further, a pulse bias power supply 17 for supplying a pulse bias having a width of 20V to 1000V is connected to the lower electrodes 15(15A, 15B) through DC blocking capacitors 19A, 19B for eliminating DC components, respectively.

Although the electrostatic chuck has been described as bipolar, other electrostatic chucks such as unipolar type and n-polar type (n.gtoreq.3) may be used.

In the etching treatment, a sample 40 to be treated is placed on the lower electrode 15 of the treatment chamber 10 and is attracted by the electrostatic chuck 20. On the other hand, gas necessary for the etching of the sample 40 is supplied from the gas supply unit 36 into the processing chamber 10 through the gas introduction chamber 34. The outer chamber 11 is vacuum-exhausted by the vacuum pump 18 to reduce the pressure of the processing chamber 10 to, for example, 0.4 to 4.0Pa (pascal). Then, a high frequency power of 30MHz to 300MHz, preferably 50MHz to 200MHz is outputted from the high frequency power supply 16, and the processing gas in the processing chamber 10 is changed into plasma.

An electron cyclotron resonance is generated between the upper electrode 12 and the lower electrode 15 by using a high-frequency power of 30 to 300MHz and a static magnetic field of 10 gauss to 110 gauss generated by the magnetic field forming device 200, and at this time, a low-pressure high-density plasma of 0.4 to 4.0Pa is generated.

Further, a pulse bias voltage of 20V to 1000V, a period of 0.1. mu.s to 10. mu.s, preferably 0.2. mu.s to 5. mu.s, and a duty ratio of 0.05 to 0.4 in a positive pulse portion is applied from a pulse bias power supply 17 to the lower electrode 15 to control electrons and ions in the plasma and perform an etching treatment on the sample 40.

The etching gas is injected into the chamber 10 through holes 38 formed in the upper electrode 12 and the upper electrode cover 30 after being distributed as desired by the gas diffusion plate 32.

Further, the upper electrode cap 30 is made of carbon or silicon or a material containing carbon or silicon in order to eliminate fluorine and oxygen components and to increase the selectivity of photoresist or silicon to the underlying layer.

In order to improve the microfabrication efficiency of a large sample, the high-frequency power supply 16 for plasma generation may use a higher frequency to improve the stability of discharge in a low-pressure region. The invention is to use 5X 10 at a low pressure of 0.4Pa-4Pa¹⁰-5×10¹¹cm^-3The plasma density of (3) and the plasma density of (2) are such that a plasma uniform for a large sample is obtained without causing an excessive gas dissociation phenomenon, and a high-frequency power supply 16 for plasma generation is connected to the upper electrode 12. On the other hand, a bias power supply 17 for ion energy control was connected to the lower electrode 15 on which the sample was placed, and the distance between the two electrodes was set to 30 to 100 mm.

The plasma generating high frequency power supply 16 generates electron cyclotron resonance between the upper electrode 12 and the lower electrode 15 byusing the interaction of a static magnetic field or a low frequency (1KHz or less) magnetic field portion of 30MHz to 300MHz, preferably 50MHz to 200MHz, 10 Gauss or more and 110 Gauss or less, preferably 17 Gauss or more and 72 Gauss or less.

Fig. 2 shows an example of a change in plasma density when the frequency of a high-frequency power supply for generating plasma is changed while a magnetic field for generating electron cyclotron resonance is applied. The supplied gas is argon gas added with C₄F₈2-10% of gas, and the pressure of the processing chamber is 1 Pa. The plasma density was 1 in the case of microwave ECR of 2450MHz, which is a standard value. The dotted line in the figure indicates the results obtained in the absence of a magnetic field.

When f is more than or equal to 50MHz and less than or equal to 200MHz, the plasma density is 1-2 orders of magnitude lower than that of the microwave ECR. And less gas dissociation, and less unwanted fluorine atoms/molecules and ions than 1 order of magnitude. By using the frequency of the VHF band and cyclotron resonance, a plasma density of 5X 10 in absolute value can be obtained¹⁰cm^-3Above thatSuitable high density plasma can perform high speed processing at a low pressure of 0.4 to 4 Pa. And, byDoes not excessively dissociate in the gas, and therefore, it is possible to use SiO₂The selectivity of the insulating film to the underlying layer of Si, SiN or the like is not significantly lowered.

When f.ltoreq.f.ltoreq.200 MHz is 50MHz or less, the gas is dissociated slightly more than in the case of the conventional 13.56MHz parallel plate electrode, but fluorine atoms/molecules and ions formed thereby are increased very little, and this situation can be improved by providing a substance containing silicon and carbon on the electrode surface and the container wall surface. Alternatively, the surface of the electrode and the wall surface of the container are further biased to discharge fluorine, carbon and silicon after combination, or hydrogen and fluorine are discharged after combination by a gas containing hydrogen.

When the frequency of the high-frequency power source is 200MHz or more, particularly 300MHz or more, the plasma density is increased, but the gas dissociation is excessive, fluorine atoms/molecules and ions are excessively increased, and the selectivity of Si, SiN, and the like to the underlayer is significantly lowered, which is not desirable.

Fig. 3 shows the energy gain K obtained by electrons from the high-frequency electric field at the time of cyclotron resonance and at the time of no resonance. When the energy obtained by electrons in 1 cycle of high frequency is assumed to be e0 in the case of no magnetic field and the energy obtained by electrons in 1 cycle of high frequency is assumed to be e1 when the cyclotron resonance magnetic field Bc is added to 2 pi f (m/e), e1 and e0 can be calculated by the following equation 1. $e_0=\frac{e^2{\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="A97103106.100581.png,A97103106.100751.png"\; state="\{\{state\}\}">E</figure-callout>}}^2}{2m}\left(\frac{\mathrm{\&gamma;}}{{\mathrm{\&omega;}}^2+{\mathrm{\&gamma;}}^2}\right)$ ${\mathrm{<figure-callout\; id="1"\; label="e"\; filenames="A97103106.100571.png,A97103106.100581.png"\; state="\{\{state\}\}">e</figure-callout>}}_1=\frac{e^2{\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="A97103106.100581.png,A97103106.100751.png"\; state="\{\{state\}\}">E</figure-callout>}}^2\mathrm{\&gamma;}}{4m}(\frac{1}{{\mathrm{\&gamma;}}^2+{(\mathrm{\&omega;}-\mathrm{\&omega;c})}^2}+\frac{1}{{\mathrm{\&gamma;}}^2+{(\mathrm{\&omega;}+\mathrm{\&omega;c})}^2})$ … … formula 1

In the formula: e is the electric field strength

When the ratio thereof (═ e1/e0) is assumed to be K, K can be represented by the following formula. In the formula, m: mass of electrons, e: charge of electron, f: frequency of application

K＝(1/2)(γ²+ω²){1/(γ²+(ω-ωc)²)+(1/(γ²+(ω+ωc)²))}

In the formula: γ: the frequency of the impact is such that,

ω: frequency of excitation angle

ω c: the cyclotron angular frequency is generally such that the value of K increases as the pressure decreases and the frequency increases. FIG. 3 shows that in the case of Ar (argon) gas, when the pressure is 1Pa, f is 50MHz or more, and K is 150 MHz or more, dissociation is promoted even at a low pressure as compared with the case of no magnetic field. The cyclotron resonance effect sharply decreases at a frequency of 20MHz or less when the pressure is 1 Pa. Even from the characteristics shown in fig. 2, it can be seen that the difference from the case of no magnetic field is small at frequencies below 30MHz, and the cyclotron resonance effect is small.

Further, although the cyclotron resonance effect is increased when the gas pressure is reduced, the negative effect of excessive dissociation is increased when the electron temperature of the plasma is increased to 1Pa or less. To suppress excessive dissociation of the gas and to increase the plasma density to 5X 10¹⁰cm^-3The gas pressure may be set to 0.4Pa to 4Pa, preferably 1Pa to 4 Pa.

In order to exhibit the cyclotron resonance effect, the K value must be set to several tens or more. It can also be seen from fig. 2 and 3 that: in order to effectively utilize the cyclotron resonance effect without causing excessive gas dissociation, a high frequency power supply for generating plasma must use VHF of 30 to 300MHz, preferably 50 to 200MHz, when the gas pressure is 0.4 to 4 Pa.

Fig. 4 shows a deviation Δ V between an ion acceleration voltage VDC induced in a sample and an induced voltage VDC in the sample when a uniform transverse magnetic field B is applied to a lower electrode and a high frequency power of 68MHz is applied to a conventional magnetron type container, with the upper electrode grounded. When the intensity of the magnetic field B is increased, the lorentz force acting on the electrons decreases the ion acceleration voltage VDC, and the plasma density increases. However, the conventional magnetron discharge type has a drawback that the strength of the magnetic field B is as high as about 200 gauss: the in-plane uniformity of the plasma density is reduced, the variation Δ V of the induced voltage is increased, and the damage of the sample is increased.

In fig. 4, the intensity of the magnetic field B is set to 30 gauss or less, preferably 15 gauss or less, in the vicinity of the sample surface so that Δ V is reduced to 1/5 to 1/10, as compared with the case of 200 gauss in the conventional magnetron discharge type. This is advantageous for eliminating the damage.

The cyclotron resonance region is formed between the upper electrode 12 and the lower electrode 15, and is slightly shifted to the upper electrode side from the middle position of the electrodes. FIG. 5 shows that the horizontal axis represents the distance from the sample surface (lower electrode 15) to the upper electrode 12; the vertical axis is the magnetic field. In the example of fig. 5, the ECR region is formed at a position of about 30mm from the sample surface under the conditions that the applied frequency f1 is 100MHz, the Bc is 37.5G, and the electrode distance is 50 mm.

Thus, according to the present invention, the maximum portion of the magnetic field component between the upper electrode 12 and the lower electrode 15, which portion is parallel to the lower electrode 15 (sample placement surface), is set on the upper electrode surface or is shifted to the upper electrode side from the center of the two electrodes. In this way, by setting the magnetic field strength parallel to the sample on the lower electrode surface to 30 gauss or less, preferably 15 gauss or less, and setting the lorentz force (E × B) acting on electrons in the vicinity of the lower electrode surface to a small value, the in-plane nonuniformity of the plasma density due to the electron drift effect caused by the lorentz force on the lower electrode surface can be eliminated.

When the magnetic field forming apparatus 200 of the embodiment of fig. 1 is used, the ECR region is formed almost at the same height from the lower electrode 15 (sample placement surface) except for the vicinity of the center of the sample as shown in fig. 6. Therefore, the plasma treatment can be uniformly performed for a large sample. However, in the vicinity of the center of the sample, the ECR region is formed at a position higher than the sample mounting surface. Since the ECR region is spaced from the sample stage by a distance of 30mm or more, ions and radicals are diffused in the gap to form an averaged state, and thus there is no problem in the normal plasma processing. However, in order to uniformly perform the plasma processing on the entire sample, it is preferable that the ECR regions are formed at the same height from the entire sample surface, or the ECR regions on the outer side of the sample are formed closer to the sample stage side than the ECR regions near the center. This measure is explained in detail later.

As described above, in the embodiment of the present invention shown in FIG. 1, since the high-frequency power source 16 for generating plasma uses a high-frequency power of 30 to 300Mhz and performs gas dissociation by electron cyclotron resonance, stable plasma can be obtained even at a low pressure of 0.4 to 4Pa in the process chamber 10. Further, since ion collision in the space charge layer is reduced, the directionality of ions can be improved when the sample 40 is processed, and the vertical microfabrication capability can be improved.

The plasma is concentrated near the sample 40 by the discharge suppressing ring 37 around the processing chamber 10 to increase the plasma density and minimize unnecessary deposits adhering to the outer surface of the discharge suppressing ring 37.

The discharge suppressing ring 37 is made of a semiconductor or conductor material such as carbon, silicon, or SiC. When the discharge suppressing ring 37 is connected to a high frequency power source and sputtering is caused by ions, the amount of deposition on the ring 37 can be reduced and the effect of removing fluorine can be obtained.

Further, when a receiver cover 39 containing carbon and silicon or carbon and silicon is provided on the insulator 13 around the sample 40, the SiO is coated with a fluorine-containing gas₂When plasma treatment is performed on the insulating film, fluorine can be removed, which contributes to an improvement in the selectivity. In this case, when the thickness of the insulator 13 at the lower part of the receiver cover 39 is reduced to 0.5 to 5mm, a part of the work of the bias voltage 17 is performedThe ratio is applied to the receiver cover 39, and the sputtering effect of the ions can be utilized to enhance the above effect.

The dielectric electrostatic adsorption film 22 is sandwiched by the potential of the dc power supply 23, and an electrostatic adsorption circuit is formed by the lower electrodes 15(15A, 15B). In this state, the sample 40 is fixed to the lower electrode 15 by the electrostatic force. A heat conductive gas such as helium, nitrogen, or argon is supplied to the back surface of the sample 40 fixed by the electrostatic force. The heat conductive gas is filled in the concave portion of the lower electrode 15. The pressure is set to be several hundreds pascal to several thousands pascal. The electrostatic attraction force can be regarded as almost zero between the concave portions provided with the gaps, and the electrostatic attraction force is generated only at the convex portions of the lower electrode 15. However, as described later, since the voltage is appropriately set in the dc power supply 23 and the appropriate adsorption force can be set so that thesample 40 can sufficiently withstand the pressure of the heat conductive gas, the heat conductive gas does not move or fly out.

However, the action of the electrostatic adsorption film 22 reduces the bias action of the pulsed bias on the ions in the plasma. This effect is also exhibited by the conventional method of biasing with a sine wave power supply. But not so much. However, in the case of the pulse bias, a large problem arises due to the narrow ion energy width which is sacrificed.

One feature of the present invention is that a voltage suppressing device is provided to suppress a voltage rise phenomenon occurring between both ends of the electrostatic adsorption film 22 in response to application of a pulse bias voltage and to enhance the effect of the pulse bias voltage.

As an example of the voltage suppressing means, a structure having an action of generating a voltage change (V) in one cycle of a bias voltage between both ends of the electrostatic adsorption film in accordance with application of a pulse bias voltage can be adopted_cm) Corresponding to the magnitude (V) of the pulse bias_p) 1/2 below. Specifically, the thickness of the electrostatic adsorption film made of a dielectric provided on the surface of the lower electrode 15 is reduced, or a material having a large dielectric constant is used as the dielectric, so that the electrostatic capacitance of the dielectric is increased.

Another voltage suppressing device may be such that the period of the pulse bias is shortened to suppress the rise of the voltage Vcm. Further, the electrostatic adsorption circuit and the pulse bias circuit may be separated from each other and disposed at another position, for example, on another opposite electrode other than the electrode on which the sample is placed and fixed, or on a third electrode disposed separately.

Next, the relationship between the voltage change generated between the two ends of the electrostatic adsorption film in one period of the pulse bias and the pulse bias, which is formed by the voltage suppressing device of the present invention, will be described in detail with reference to fig. 7 to 13.

First, an example of a desired output waveform used in the pulse bias power supply 17 of the present inventionShown in fig. 7. In the figure, let the pulse width be Vp and the frequency period be T₀The forward pulse width is T₁。

When the waveform of fig. 7a is applied to the sample through the dc blocking capacitor and the electrostatic adsorption dielectric layer (hereinafter, abbreviated as electrostatic adsorption film), the waveform of the potential on the surface of the sample in a steady state in which plasma is generated by a separate power source is shown in fig. 7B.

In the figure, V_DC: voltage of waveform of DC component

V_f: drift potential of plasma

V_cm: maximum voltage in one period generated between both ends of the electrostatic adsorption film

In FIG. 7(B), the ratio V_fThe positive voltage (1) portion, mainly the portion that draws only the electron current; ratio V_fThe negative part of (a) is a part into which an ion current is drawn; v_fThe part is a part (V) where electrons and ions are in equilibrium with each other_fUsually a number V to ten-odd (ten-odd) V).

In fig. 7a and the following description, it is assumed that the capacitance of the dc blocking capacitor and the capacitance of the insulator in the vicinity of the sample surface are both much larger than the capacitance of the electrostatic adsorption film (hereinafter referred to as electrostatic adsorption capacitance).

V_cmThe value of (d) can be represented by the following formula (equation 2).

In the formula, q: (T)₀-T₁) Ion current density (average value) flowing into sample during the period

C: electrostatic adsorption capacity per unit area (average value)

i_i: density of ion current

ε_r: dielectric constant of electrostatic adsorption film

d: thickness of electrostatic adsorption film

ε₀: dielectric constant (constant) in vacuum

K: electrode coating (dressing) rate of electrostatic adsorption film (less than or equal to 1)

Fig. 8 and 9 show pulse duty ratios: (T)_i/T₀) At a constant value, when T is changed₀Electricity of the surface of the sampleThe bit waveform and the probability distribution of ion energy. Wherein it is assumed that

T₀₁∶T₀₂∶T₀₃∶T₀₄∶T₀₅＝16∶8∶4∶2∶1

As shown in FIG. 8(1), when the pulse period T is over₀When the voltage is too large, the potential waveform on the surface of the sample greatly deviates from a rectangular waveform and becomes a triangular waveform, and the ion energy is distributed from low to high in a certain manner as shown in fig. 9, so that the effect is poor.

As shown in FIGS. 8(2) to (5), the pulse period T is varied in accordance with the pulse duration₀(V) is reduced_cm/V_p) The ion energy distribution becomes narrower than 1.

In FIGS. 8 and 9, T₀＝T₀₁、T₀₂、T₀₃、T₀₄、T₀₅Corresponding to (V)_cm/V_p)＝1.0、0.63、0.31、0.16、0.08。

Breaking of pulses (T)₀-T₁) Maximum voltage V in one period of the period and the voltage generated between both ends of the electrostatic adsorption film_cmThe relationship of (a) is shown in FIG. 10.

As the electrostatic adsorption film, titanium oxide-containing alumina (ε) having a thickness of 0.03mm was used_r10) is coated on about 50% of the surface of the electrode (K0.5), the ion current density i is increased_i＝5m A/cm²V in medium density plasma_cmThe change in the value is represented by a thick line (line of the standard condition) in fig. 10.

As can be seen in FIG. 10, the interruption (T) with the pulse₀-T₁) Increase of period, voltage V generated between both ends of electrostatic adsorption film_cmIncreases in proportion thereto, exceeds the pulse voltage V which is generally used_p。

For example, in a plasma etcher, the voltage is generally limited to the following range depending on damage, selectivity with respect to an underlayer and a mask, shape, and the like.

V is not more than 20V during grid corrosion_p≤100V

V is not more than 50V when metal is corroded_p≤200V

V is not more than 250V when the oxide film is corroded_p≤1000V

If the following (V) is to be satisfied_cm/V_p) A condition of ≦ 0.5, then in the standard state (T)₀-T₁) The upper limit of (b) is asfollows.

During gate corrosion (T)₀-T₁)≤0.1 5μs

When metal corrodes (T)₀-T₁)≤0.35μs

When the oxide film is etched, it is (T)₀-T₁) 1.2. mu.s or less, however if T₀When the ion energy is close to 0.1 μ s, the impedance of the ion sheath is close to or lower than the plasma impedance, thereby generating unnecessary plasma, and at the same time, the bias power source cannot be effectively utilized by the acceleration of ions, so the effect of controlling the ion energy by the bias power source is reduced, and therefore, T is increased₀Should be higher than 0.1 mus. Most preferably above 0.2. mu.s.

Therefore, when V is_pIn the process of controlling gate corrosion at a low level, the material of the electrostatic adsorption film needs to be changed into a material with a dielectric constant as high as 10-100 (for example, Ta)₂O₃，ε_r25) or the film thickness is made thin without lowering the dielectric breakdown voltage (for example: 10 μm ^ eThe film thickness of 400 μm is preferably as thin as 10 μm to 100 μm).

FIG. 10 also shows V when the capacitance C per unit area is increased by 2.5 times, 5 times, and 10 times, respectively_cmEven if the electrostatic adsorption film is improved, the electrostatic capacity C can be increased by several times at most in the present situation. If V_cmLess than or equal to 300V, c less than or equal to 10c₀If the ratio is more than or equal to 0.1 mu s (T)₀-T₁)≤10μs。

The portion effective for plasma processing by ion acceleration is (T)₀-T₁) In part, as pulse duty cycle (T)₁/T₀) It is desirable to be as small as possible.

Efficiency as plasma treatment plus time averaging in terms of (V)_DC/V_p) The results of the evaluation are shown in fig. 11. It is desirable to reduce (T)₁/T₀) Increasing (V)_DC/V_p)。

The efficiency of plasma treatment is assumed to be 0.5. ltoreq. (V)_DC/V_p) Adding the following condition (V)_cm/V_p) Less than or equal to 0.5, the pulse duty ratio is (T)₁/T₀) Less than or equal to about 0.4.

In addition, the pulse duty ratio (T)₁/T₀) The smaller the ion energy, the more effective the control. However, if the pulse width is too small to be required, the pulse width T is set to be larger than necessary₁The value of (A) becomes small, about 0.05. mu.s, and as a result, many frequency components of several tens of MHz are contained, and as described later, it becomes difficult to separate high frequency components for generating plasma, as shown in FIG. 11, at 0. ltoreq. T₁/T₀) (V) between 0.05 and less_DC/V_p) Very little reduction (T)₁/T₀) Above 0.05 no problems occur.

Here, FIG. 12 shows, as an example of gate etching, the etching rates ESi and ESiO of silicon and the underlying oxide film after plasmatizing chlorine gas at 10mT₂The dependence of the ion energy of (a). The etching rate ESi of silicon is constant at low ion energy. When the ion energy is higher than 10V, ESi increases with the increase of the ion energy, and on the other hand, the etching rate ESiO of the oxide film as the underlayer increases₂0 when the ion energy is less than 20V. If 20V is crossed, then ESiO₂Increasing simultaneously with the ion energy. As a result, when the ion energy is 20V or less, the selection ratio ESi/ESiO to the underlayer is present₂In the ∞ region, if the ion energy is 20V or more, the selection ratio of ESi/ESiO to the underlayer₂With increasing ion energy, the ion energy drops off sharply.

FIG. 13 shows an oxide film (SiO) which is one type of insulating film₂BPSG, HISO, etc.) are shown in the specification₄F₈Etching rate ESiO of oxide film and silicon after gas plasmatization of 1.0Pa₂And ion energy distribution of ESi.

Corrosion rate of oxide film, ESiO₂At low ion energies, negative values result in deposits. When the ion energy is close to 400V, ESiO₂Rising rapidly towards the positive direction. And then slowly increases. In addition, asThe etch rate of the underlying silicon, ESi, and ESiO₂In contrast, at ion energyThe elevation gradually increased from (-) erosion to (+) erosion. As a result, in ESiO₂The selection ratio ESiO from the bottom layer near the position changing from (-) to (+)₂when/ESi becomes infinite, and continues to change, ESiO₂the/ESi decreases rapidly with increasing ion energy.

FIGS. 12 and 13 show that ESi and ESiO are considered for practical processes₂Value and ESi/ESiO₂And ESiO₂After the value of/ESi is large, the bias power supply is adjusted to make the ion energy reach a proper value.

Further, if the etching rate is preferentially considered for the etching before the occurrence of the underlayer film, and the ion energy is changed to the level before and after the occurrence of the underlayer film by preferentially considering the selection ratio after the occurrence of the underlayer film, better characteristics can be obtained.

However, the characteristics shown in fig. 12 and 13 are characteristics when the ion energy distribution is limited to a narrow portion. When the energy distribution of the ions is wide, the respective etching rates are time-averaged values thereof, and therefore, the etching rates cannot be set to appropriate values, and the selectivity is greatly reduced.

After testing, if (V)_DC/V_p) The ion energy distribution width is not more than 0.3, and not more than. + -. 15%. Even the characteristics of fig. 12 and 13 result in a high selection ratio of 30 or more. And if it is (V)_DC/V_p) Less than or equal to 0.5, the selection ratio is improved compared with the prior sine wave bias method.

Thus, the voltage variation (V) in one cycle is suppressed as the pulse bias generated between both ends of the electrostatic adsorption film_cm) Voltage suppressing device of (1), which is constituted by V_cmTo reach the pulse bias voltage V _p1/2 or less is preferable. Specifically, the capacitance of the dielectric can be increased by reducing the thickness of the electrostatic adsorption film 22 of the dielectric provided on the surface of the lower electrode 15, changing the dielectric to a material having a large dielectric constant, or the like. Or the pulse bias period is shortened to 0.1. mu.s to 10. mu.s, preferably to 0.2. mu.s to 5. mu.s (repetition frequency: corresponding to 0.2MHz to 5MHz), and the likePulse duty cycle (T)₁/T₀) Set to 0.05 ≦ (T)₁/T₀) Less than or equal to 0.4 to inhibit the voltage change at two ends of the electrostatic adsorption film.

The voltage V generated between the two ends of the electrostatic adsorption film can be obtained by combining the film thickness of the electrostatic adsorption film with the dielectric constant of the dielectric and the period of the pulse bias_cmCan satisfy the above (V)_cm/V_p) The condition is less than or equalto 0.5.

Next, the insulating film (for example, SiO)₂SiN, BPSG, etc.) of the vacuum processing chamber of fig. 1.

Gas 19 is C₄F₈：1～5％；Ar：90～95％，O₂：0～5％，Or C₄F₈：1～5％；Ar：70～90％，O₂: 0-5%, CO: 10-20% of a gas. The high frequency power source 16 for plasma generation uses a frequency higher than the original frequency, for example, 40MHz, and aims to stably discharge in a low pressure region of 1 to 3 Pa.

When the dissociation occurs more than necessary due to the increase in frequency of the high-frequency power supply 16 for the plasma source, the output of the high-frequency power supply 16 is controlled to be turned on or off or level-modulated by the high-frequency power supply modulation signal source 161. At high levels, ions are generated much more (faster) than radicals. At low levels, more radicals are generated than ions. The ON time (or high level in level modulation) is about 5-50 mu s, the OFF time (or low level in level modulation) is 10-100 mu s, and the period is 20-150 mu s. Thus, unnecessary dissociation can be prevented, and a desired ion radical ratio can be obtained.

In addition, the modulation period of the high frequency power supply for the plasma source is generally longer than the pulse bias period. Therefore, the modulation period of the high-frequency power source for the plasma source is adjusted to an integral multiple of the pulse bias period, and the phase between the two is optimized, thereby improving the selection ratio.

In addition, ions in the plasma are accelerated by applying a pulse bias voltage and vertically injected into the sample, so that the ion energy is carried outAnd (5) controlling. The pulse bias 17 is, for example, a pulse period: t is 0.65; pulse amplitude: t1 ═ 0.15 μ s; pulse width: v_pThe plasma processing can be performed with good characteristics such that the distribution width of ion energy is ± 15% or less and the selection ratio of Si to SiN in the underlayer is 20 to 50, when the power supply is 800V.

Next, a two-electrode type plasma etching apparatus according to another embodiment of the present invention will be described with reference to fig. 14, and this embodiment has the same structure as that shown in fig. 1. But, in contrast, the lower electrode 15 to which the sample 40 is fixed has a unipolar electrostatic chuck 20. The dielectric layer 22 for electrostatic adsorption is provided on the upper surface of the lower electrode 15, the lower electrode 15 is connected to the positive side of a DC power supply 23 via a coil 24 for cutting off high-frequency components, a pulse bias of a positive pulse bias of 20V to 1000V is applied, and the power supply 17 is connected via a DC blocking capacitor.

The processing chamber 10 is provided with discharge suppressing rings 37A and 37B around the circumference thereof. The plasma density is improved and the adhesion of unnecessary deposits on the outer surface portions of the discharge rings 37A, 37B is minimized. In the discharge suppressing rings 37A and 37B of fig. 14, the diameter of the peripheral portion of the discharge suppressing ring 37A on the lower electrode side is smaller than that of the peripheral portion of the discharge suppressing ring 37B on the upper electrode side, so that the distribution of the reaction product around the sample is uniform.

As a material of the discharge suppressing rings 37A and 37B, a semiconductor or an electric conductor such as carbon, silicon, or SiC is used at least on a surface facing the processing chamber. The lower electrode ring 37A is connected to a 100K-13.56MHz discharge suppressing ring bias power supply 17Avia a capacitor 19A, and the upper electrode ring 37B is applied with a partial power of a high frequency power supply 16, thereby reducing deposits released to the rings 37A and 37B by an ion sputtering effect and providing a fluorine removing effect.

In fig. 14, 13A and 13C are insulators made of a material such as alumina, and 13B is a conductive insulator such as SiC, glassy (glass) carbon, or Si.

When the conductive performance of the rings 37A and 37B is low, the rings 37A and 37B are filled with a conductor such as a metal, and the gap between the surface of the rings and the filled conductor is narrowed, so that the high-frequency power is easily radiated from the surfaces of the rings 37A and 37B, and the decrease in the sputtering effect can be reduced.

The upper electrode can 30 is typically secured to the upper electrode 12 only at its periphery by bolts 250. Gas is supplied from the gas supply unit 36 into the upper electrode cover through the gas introduction chamber 34, the gas diffusion plate 32, and the upper electrode 12. The hole provided in the upper electrode cover 30 is made thin and has a diameter of 0.3 to 1mm so that abnormal discharge is not likely to occur in the hole. The gas pressure in the upper portion of the upper electrode cover 30 is from a fraction to about a tenth of 1 gas pressure. For example: a force of 100kg or more is applied to the upper electrode cover 30 having a diameter of 300mm in total. Therefore, the upper electrode cover 30 is formed in a convex shape with respect to the upper electrode 12, and a gap of several hundred micrometers or more is formed near the center.

In this case, when the frequency of the high-frequency source 16 is increased to 30MHz or more, the lateral resistance of the upper electrode cover 30 cannot be ignored, and particularly, the plasma density in the vicinity of the center portion is decreased. In order to improve this situation, the upper electrode cover 30 may be fixed to the upper electrode at a central portion thereof, and in the embodiment of fig. 14, several central portions of the upper electrode cover 30 are fixed to the upper electrode 12 by bolts 251 made of a semiconductor such as SiC or carbon, or an insulator such as alumina, so that the distribution of the high frequency applied from the upper electrode 12 side becomes uniform.

The method of fixing the upper electrode cover 30 to the upper electrode 12 at least near the center is not limited to the above-described methods of fixing with the bolts 251, and the upper electrode cover 30 and the upper electrode 12 may be bonded to each other entirely or at least near the center by a substance having an adhesive action.

In the example of fig. 14, a sample 40 as a processing object is mounted on the lower electrode 15, and the sample 40 is adsorbed by the electrostatic chuck 20, that is, by coulomb force generated between both ends of the electrostatic adsorption film 22 by positive charges generated by the dc power supply 23 and negative charges supplied by plasma.

The apparatus functions similarly to the bipolar plasma etching apparatus shown in fig. 1, and when performing etching, a sample 40 to be processed is placed on a sample stage 15, fixed by electrostatic force, and vacuum-exhausted by a vacuum pump 18 while supplying a process gas from a gas supply system 36 to a process chamber 10 at a predetermined flow rate, and the pressure of the process chamber 10 is reduced to a process pressure of the sample of 0.5 to 4.0 Pa. Then, a high frequency power supply 16 is turned on, and a high frequency voltage of 20MHz to 500MHz is applied between the electrodes 12 and 15. Preferably, a high frequency voltage of 30MHz to 100MHz is applied to generate plasma. On the other hand, a positive pulse bias of 20V to 1000V with a period of 0.1. mu.s to 10. mu.s, preferably 0.2. mu.s to 5. mu.s is applied from a pulse bias power supply 17 to the lower electrode 15, and plasma in the processing chamber 10 is controlled to perform etching processing on the sample 40.

By applying such a pulse bias voltage, ions or ions and electrons in the plasma are accelerated and vertically injected into the sample, and highly accurate shape control and selection ratio control are performed. The characteristics required for the pulse bias power supply 17 and the electrostatic adsorption film 22 are the same as those of the embodiment of fig. 1, and the detailed description thereof will be omitted.

Other embodiments of the present invention will be described below with reference to fig. 15 to 17. This embodiment is the same in structure as the two-electrode type plasma etching apparatus shown in fig. 1, but the structure of the magnetic field forming device 200 is different. The magnetic core 201 of the magnetic field forming device 200 is eccentric, is driven by a motor 204 about an axis corresponding to the center position of the sample 40, and rotates at a speed of several to several tens of revolutions per minute. In addition, the core 201 is grounded.

In order to perform plasma processing on the entire sample with high accuracy, plasma is generated more in the vicinity of the periphery or the outer side of the sample than in the vicinity of the center of the sample, and the electron cyclotron resonance effect can be increased more in the periphery or the outer side than in the center. However, in the case of the example of fig. 1, as shown in fig. 6, there is no ECR region in the vicinity of the center of the sample, and the plasma density is excessively low in the vicinity of the center.

In the embodiment of fig. 15, the distribution of the magnetic field changes with the rotation of the eccentric core 201 ofthe magnetic field forming device 200. Near the center of the sample, if the time T is 0, T is T₀The ECR zone is formed at a position lower than the sample plane,when the time T is 1/2T₀It is formed at a position higher than the sample face. As a result of rotating the core 201 at a rotational speed of several to several tens of revolutions per minute, as shown in fig. 17, the average value of the magnetic field intensity in the direction parallel to the sample surface between the two electrodes is substantially the same, that is, ECR regions are formed at substantially the same height from the sample surface except for the peripheral portion of the sample, due to time averaging by the rotation action.

In the magnetic core 201 of fig. 15, if the magnetic core constituting the magnetic path on the side closer to the eccentric center portion core is reduced in thickness and the magnetic core constituting the magnetic path farther from the eccentric center portion core is increased in thickness, as shown by the broken line, the uniformity of the magnetic field is further improved.

Other embodiments of the present invention are described below with reference to fig. 18 to 19. The structure of this embodiment is the same as that of the two-electrode type plasma etcher shown in fig. 15. However, the magnetic field forming device 200 has a different structure. The magnetic core 201 of the magnetic field forming apparatus 200 has a concave side 201A at a position corresponding to the center of the processing chamber and has other sides 201B at positions corresponding to both sides of the processing chamber. The magnetic flux B has a component in an oblique direction due to the concave side 201A. As a result, the distribution of the magnetic field changes. As shown in fig. 19, the magnetic field strength of the component parallel to the sample surface is more uniform than in the embodiment of fig. 1.

Other embodiments of the present invention are described below with reference to fig. 20. The structure of this embodiment is the same as that of the two-electrode type plasma etcher shown in fig. 15. However, the magnetic field forming apparatus 200 is different in configuration, and the magnetic core 201 of the magnetic field forming apparatus 200 is fixed and forms a magnetic path together with the magnetic core 205 installed at a position corresponding to the center of the processing chamber. The core 205 rotates simultaneously with the insulator 203 about an axis passing through the center of the side 201A. Due to such a structure, the same as the embodiment of fig. 15. The average position of the ECR zone in the vicinity of the center of the sample was formed at a position substantially equal in height to the surface of the sample. I.e. the process is repeated. The ECR region was formed at substantially the same height as the sample surface over the entire surface of the sample.

Next, a two-electrode type plasma etching apparatus according to another embodiment of the present invention will be described with reference to fig. 21 and 22. The apparatus of this embodiment is constructed such that the magnetic field forming means 200 has two pairs of coils 210 and 220 around the process chamber 10, and forms a rotating magnetic field by sequentially switching the directions of the magnetic fields on the respective pairs of coils in the directions of the arrows 1, 2, 3, and 4. The center positions O-O of the coils 210 and 220 are located on the upper electrode 12 side higher than the middle position between the electrodes 12 and 15. Thus, the magnetic field strength of the sample 40 is 30 gauss or less, preferably 15 gauss or less.

The distribution of the magnetic field strength can be adjusted in order to increase the amount of plasma generated around the sample or in the vicinity of the outer side thereof by appropriately selecting the positions and the outer diameters of the coil 210 and the coil 220.

Referring to fig. 23 and 24, a bipolar plasma etching apparatus according to another embodiment of the present invention is described, in which a pair of coils 210' are provided as a magnetic field forming device 200 along the circumference of a circular processing chamber 10 in an arc shape in a horizontal plane. The current flowing through the pair of coils 210' is controlled to change the polarity of the magnetic field in a predetermined cycle in the directions (1) and (2) indicated by arrows in fig. 23.

As shown by the broken line in fig. 24, in the vertical plane, the magnetic flux B expands in the center of the processing chamber, and therefore the magnetic field strength in the center of the processing chamber decreases. However, since the pair of coils 210' are bent along the chamber, the magnetic flux B is concentrated on the center portion of the chamber in the horizontal plane. Therefore, the magnetic field strength at the center of the processing chamber can be increased as compared with the example of fig. 22, that is, the magnetic field strength at the center of the processing chamber can be suppressed from decreasing as compared with the example of fig. 22 in the example of fig. 23, and the uniformity of the magnetic field strength on the sample mounting surface mounted on the sample stage can be further improved. And the polarity of the magnetic field is changed according to a certain period, thereby reducing the drift effect of the E multiplied by B.

In addition, two pairs of coils similar to the embodiment of fig. 22 may be used as the magnetic field forming device 200.

As shown in fig. 25, the magnetic field forming apparatus 200 may combine several linear coil portions arranged along the circumference of the circular processing chamber 10 to form a convex coil 210 "instead of the circular-arc coil 210'. In this case, the magnetic flux B is concentrated in the center of the processing chamber in the horizontal plane. The same effect as the embodiment of fig. 23 can be obtained.

The center axes of the pair of coils may be inclined so that the center axes of the coils are close to the sample plane in the center of the processing chamber as in the embodiment of FIG. 26. With this embodiment, the magnetic field intensity at the central portion of the processing chamber can be increased and the magnetic field intensity at the peripheral portion of the processing chamber can be decreased, so that the magnetic field uniformity of the sample mounting surface of the sample stage can be improved. In addition, for uniformity of the magnetic field intensity, it is preferable to adjust the inclination angle θ of the coil central axis to a range of 5 to 25 degrees.

As shown in fig. 27, a coil 210B is mounted beside a pair of coils 210A, and two sets of coil currents are controlled. By doing so, the gradient of the magnetic field in the vicinity of the ECR resonance position changes with the change in the ECR resonance position, the amplitude of the ECR resonance region can also be changed. By optimizing the amplitude of the ECR resonance region for each process sequence, ion/radical ratios suitable for various process sequences can be obtained.

In addition, the above-described embodiments of fig. 23 to 27 are appropriately combined as necessary, whereby the uniformity and controllability of the magnetic field distribution can be further improved.

Next, a two-electrode plasma etching apparatus according to another embodiment of the present invention will be described with reference to fig. 28 to 29. In this embodiment, part of the chamber wall is made of semiconductor, while being grounded. The magnetic field forming apparatus 200 includes coils 230 and 240 around and above the processing chamber 10. The direction of the magnetic flux B formed by the coil 230 and the direction of the magnetic flux B' formed by the coil 230 cancel each other at the center of the processing chamber 10 as shown by the arrows, and overlap each other around and outside the processing chamber 10. As a result, the magnetic field intensity distribution on the sample surface becomes the state shown in fig. 29. In the mounting surface portion of the sample 40, the direction of the electric field component between the upper electrode 12 and the lower electrode 15 is parallel to the direction of the magnetic field component. On the other hand, the outer portion of the mounting surface of the sample 40 generates a longitudinal magnetic field component orthogonal to the transverse electric field component in the peripheral portion of the upper electrode 12 and the portion between the upper electrode 12 and the chamber wall.

Therefore, if the embodiment of fig. 28 is employed, the electron cyclotron resonance effect in the vicinity of the center of the sample can be reduced, thereby improving the plasma generation in the vicinity of the periphery of the sample and the vicinity of the outside thereof. In this way, the plasma density distribution can be made uniform by further increasing the plasma generation in the peripheral portion of the sample and the vicinity outside the peripheral portion.

Other embodiments of the invention are described below with respect to fig. 30. In the two-electrode plasma etching apparatus shown in FIG. 1, when sufficient ion energy cannot be obtained by the high-frequency power f1 applied to the electrode 12 from the high-frequency power supply 16, the ion energy is increased by about 100 to 200V by applying a high-frequency f3 of, for example, 1MHz or less as a bias voltage to the upper electrode 12 from the low-frequency power supply 163, and 164and 165 are filters.

An example of the present invention in the field-free two-electrode type plasma etcher is explained below with reference to fig. 31.

As described above, in order to improve the fine processing workability of the sample, it is preferable to use a power source having a higher frequency as the high-frequency power source 16 for plasma generation to achieve the stability of discharge in the low-pressure region. In the embodiment of the present invention, the sample processing pressure in the processing chamber 10 is set to 0.5 to 4.0 Pa. Since the ion impact in the space charge layer is reduced by reducing the pressure in the processing chamber 10 to a low pressure of 40mTorr or less, the directionality of the ions is enhanced when the sample 40 is processed, and vertical microfabrication can be performed. When the electron temperature is 5mTorr or less, the exhaust apparatus and the high-frequency power supply are increased to obtain the same processing speed, and the electron temperature tends to increase to cause dissociation more than necessary, thereby deteriorating the characteristics.

Generally, there is a relationship between the frequency of the plasma generating power source using a pair of two electrodes and the minimum gas pressure at which discharge is stably performed, that is, as shown in fig. 32, the higher the frequency of the power source, the larger the inter-electrode distance, the lower the minimum gas pressure at which discharge is stably performed, and it is preferable that the inter-electrode distance is set to 50mm or less in correspondence with the maximum gas pressure of 40mTorr, in order to avoid adverse effects of deposits and the like on the peripheral wall and the suppression of the discharge ring 37 and to effectively remove fluorine and oxygen by the upper electrode cover 30, the receiver cover 39, and the photosensitive resist and the like in the sample. Further, if the distance between the electrodes is not 2 to 4 times (4mm to 8mm) the mean free path at the maximum gas pressure (40mTorr), it is difficult to stabilize the discharge.

In the embodiment shown in FIG. 31, since the high frequency power source 16 for plasma generation uses a high frequency of 20MHz to 500MHz, preferably 30MHz to 200MHz, stable plasma can be obtained even when the gas pressure in the processing chamber is reduced to a low pressure of 0.5 to 4.0Pa, and the fine processing workability can be improved. Further, by using such high frequency power, dissociation of plasma is improved, and selection ratio control at the time of sample processing is facilitated.

In the embodiments of the present invention described above, it has also been considered that interference may also occur between the output of the pulsed bias power supply and the output of the plasma generation power supply. Therefore, this countermeasure is discussed below.

First the pulse width is T₁With a pulse period of T₀An ideal rectangular pulse with infinite rise/fall speed, as shown in FIG. 33, at f ≦ 3f₀(f₀＝1/T₁) The frequency range of (A) contains 70-80% of power. The power concentration of the actually added waveform is further improved because the ascending/descending speed is limited, and f is less than or equal to 3f₀Can reach over 90% of power in the frequency range.

To have 3f₀A pulsed bias of a high frequency component is uniformly applied to the sample plane. Preferably, an opposing electrode is provided substantially parallel to the sample. For 3f obtained by the following numerical formula 3₀So that f is less than or equal to 3f₀The frequency components of the range are grounded.

If T is set₁0.2 mus, then 3f₀＝3·10⁶/0.2＝15MHz

If T is set₁0.1 mus, then 3f₀30MHz … equation 3

The embodiment shown in FIG. 31 is forCountermeasures are taken against the interference generated by the output of the pulsed bias power supply and the output of the plasma generation power supply. I.e., on the plasma etcher. A plasma generation high-frequency power supply 16 is connected to the upper power supply 12 facing the sample. The frequency f of the high-frequency power supply 16 for plasma generation is set so that the upper electrode 12 is grounded to a pulsed bias voltage₁Is increased to the above 3f₀Above, and f is not more than f connected between the electrode 12 and the ground level₁ A band resistor 141 having a large nearby impedance and a small impedance at other frequencies.

On the other hand, when f is f₁The band-pass filter 142 having a low impedance in the vicinity and a high impedance at other frequencies is provided between the sample stage 15 and the ground level. With this configuration, the interference between the output of the pulse bias power supply 17 and the output of the plasma generation power supply 16 can be controlled to be milliAt a trouble-free level, a suitable bias is applied to the specimen mount 40.

FIG. 34 is a view showing an example of applying the present invention to a magnetic field-free plasma etcher of an inductively coupled discharge type in which an external energy is supplied to a discharge system. 52 is a planar coil, and 54 is a high-frequency power supply for applying a high-frequency voltage of 10MHz to 250MHz to the planar coil. The inductively coupled discharge method can generate stable plasma under low frequency and low pressure conditions, as compared with the method shown in fig. 10. On the contrary, as shown in FIG. 1, and thus dissociated, the output of the high frequency power supply 1 is modulated by the high frequency power supply modulation signal source 161, and unnecessary dissociation can be prevented. A processing chamber 10 as a vacuum chamber is provided with a sample table 15 for placing a sample 40 on an electrostatic adsorption film 22.

In the etching process, a sample 40 to be processed is placed on a sample stage 15 and fixed by electrostatic power, and while introducing a process gas into the process chamber 10 at a predetermined flow rate from a gas supply system (not shown), the pressure of the process chamber 10 is reduced to 0.5 to 4Pa by evacuating with a vacuum pump. Then, a high-frequency voltage of 13.56MHz is applied to the high-frequency power supply 54, plasma is generated in the processing chamber 10, and the sample 40 is etched by the plasma. In the etching, a pulse bias having a period of 0.1 to 10 μ s, preferably 0.2 to 5 μ s is applied to the lower electrode 15. The width of the pulse bias varies depending on the type of the film, as described in the embodiment of fig. 1. By applying a pulse bias voltage, ions in the plasma are accelerated and vertically incident on the sample, thereby controlling the high precision or selection ratio of the shape. Thus, even if the resist mask pattern is extremely fine, it can be subjected to etching treatment with high accuracy.

In addition, as shown in FIG. 35, in the inductively coupled discharge type magnetic field-free plasma etching apparatus, a Faraday shield 53 with a gap and an insulating plate 54 for protecting a thin shield of 0.5mm to 5mm are provided on the side of the processing chamber 10 where high frequency is induced, and the Faraday shield may be grounded. Since the faraday shield 53 is provided, the capacitance component between the coil and the plasma is reduced, the energy of ions colliding with the quartz plate and the shield plate protecting insulating plate 54 below the coil 52in fig. 34 can be reduced, damage to the quartz plate and the insulating plate can be reduced, and the mixing of foreign matter in the plasma can be prevented.

Further, because the faraday shield 53 also serves as a ground electrode of the pulse bias power supply 17, a pulse bias can be uniformly applied between the sample 40 and the faraday shield 53. In this case, it is not necessary to provide a filter on the upper electrode or the sample stage 15.

FIG. 36 is a front view in longitudinal section of a part of a microwave plasma processing apparatus to which the present invention is applied. A pulse bias power supply 17 and a dc power supply 13 are connected to a lower electrode 15, which is a sample stage 15 on which a sample 40 is placed on an electrostatic adsorption film 22. Reference numeral 41 denotes a magnetron as a microwave oscillation source, 42 denotes a microwave waveguide, and 43 denotes a quartz plate which vacuum-seals the processing chamber 10 and supplies microwaves to the processing chamber 10. Reference numeral 47 denotes a first solenoid coil for supplying a magnetic field, 48 denotes a second solenoid coil for supplying a magnetic field, and 49 denotes a supply system of a process gas, which supplies the process gas used for performing a process such as etching or film formation to the process chamber 10. The processing chamber 10 is evacuated by a vacuum pump (not shown). The necessary characteristics of the bias voltage source 17 and electrostatic chuck 20 are the same as in the embodiment shown in fig. 1. The details are omitted.

In the etching treatment, the sample 40 to be treated is placed on the sample table 15 and fixed by electrostatic force, and the pressure of the treatment chamber 10 is reduced to 0.5 to 4.0Pa by vacuum pumping while introducing a treatment gas into the treatment chamber 10 from the gas supply system 49 at a predetermined flow rate. Then, the magnetron 41 and the first and second solenoid coils 47 and 48 are turned on, and the microwave generated by the magnetron 41 is introduced into the processing chamber 10 through the waveguide 42 to generate plasma. The sample 40 is subjected to an etching process using such plasma. In the etching, a pulse bias having a period of 0.1 to 10 μ s, preferably 0.2 to 5 μ s, is applied to the lower electrode 15.

By applying such a pulse bias, ions in the plasma can be accelerated and vertically incident on the sample, thereby achieving the purpose of controlling the shape and selection ratio with high accuracy. Thus, even if the resist mask pattern of the sample is extremely fine, high-precision etching processing corresponding to the mask pattern can be performed by vertical incidence.

In the plasma etching apparatus of the present invention shown in fig. 1, the dc voltage of the electrostatic chuck circuit and the pulse voltage of the pulse bias power supply circuit may be superimposed on each other to form a general-purpose circuit. Meanwhile, the electrostatic adsorption circuit and the pulse bias power supply circuit can be designed into separate electrodes, so that the pulse bias does not influence the electrostatic adsorption.

The electrostatic chuck circuit in the embodiment of the plasma etching apparatus shown in fig. 1 may be replaced by other apparatuses, such as a vacuum chuck apparatus.

The plasma processing apparatus including the electrostatic adsorption circuit and the pulse bias circuit according to the present invention described above is applicable not only to the above-described etching apparatus but also to a plasma processing apparatus such as a CVD apparatus if a CVD gas or the like is introduced instead of an etching gas.

Next, another embodiment of a plasma etching apparatus capable of performing an extremely fine plasma process by controlling the mass and quantity of ions and radicals generated by overcoming the disadvantages of the example and by using another embodiment of the present invention shown in fig. 37 will be described.

That is, a place where the first plasma can be generated is set at a place different from the vacuum processing chamber on the upstream side of the vacuum processing chamber containing the sample, and the quasi-stable atoms generated at this place are implanted into the vacuum processing chamber, and the second plasma is generated from the vacuum processing chamber. In the plasma etching apparatus shown in fig. 1, a gas supply part 60 for supplying ions and radicals and a plasma generation chamber 62 for generating metastable atoms are separately provided. The upper electrode 12 is provided with a passage for introducing a gas containing metastable atoms into the vacuum processing chamber, and an introduction passage connected to all of the ion and radical sources.

The features of this embodiment are as follows:

① the gas supplied from the gas supply part 36 for generating metastable atoms is plasmatized with high frequency power in the plasma generating chamber 62 for generating metastable atoms, and a predetermined amount of metastable atoms is generated in advance and injected into the processing chamber 10. in order to efficiently generate metastable atoms in the plasma generating chamber 62 for generating metastable atoms, the pressure in the chamber is set at a high pressure of several hundreds mTorr to several tens Torr.

②, a gas supplied from the supply unit 60 for an ion/radical source is introduced into the processing chamber 10.

③, a high frequency with a relatively low power is output by the power supply 16 for generating plasma, and plasma is generated in the processing chamber 10. since ions can be efficiently generated even with low-energy electrons of 5eV or less by injecting metastable atoms, plasma with a low electron temperature (6eV or less, preferably 4eV or less) and with a large reduction in high-energy electrons exceeding 15V or more can be obtained.

Thus, the quality and quantity of ions and radicals generated can be controlled, and excellent performance can be obtained even in the case of extremely fine plasma processing. As a gas for the radical source, according toIn CHF₃、CH₂F₂，C₄F₈Or is CF₄Mixing the fluorocarbon gas with the corresponding C, H-containing gas (C)₂H₄，CH₄，CH₃OH, etc.). As the gas for generating metastable atoms, one to two kinds of rare gases are used as a base gas. Since a rare gas having the following properties or the like is used as the gas for the ion source, ions can be efficiently generated.

The energy level of the gas used for the ion source is lower than the energy level of the metastable atoms, or the ionization energy level of the gas used for the ion source is higher but the difference is small (5eV or less).

The kind of the gas for the ion source may be replaced with the gas for generating metastable atoms and the gas for the radical source without adding any special gas, but the performance is deteriorated.

Next, fig. 38 shows another embodiment in which the mass and amount of ions and radicals generated by the present invention are controlled. It is the same as the basic idea of fig. 37, but in fig. 37, the distance between the plasma chamber 62 for generating metastable atoms and the vacuum processing chamber 10 is long, and the attenuation of metastable atoms therebetween is large, and fig. 38 is an example of a countermeasure for this case. Reference numeral 41 denotes a magnetron as a microwave oscillation source, 42 denotes a microwave waveguide, 43 denotes a quartz plate which vacuum-seals the first plasma generation chamber 45 and passes microwaves, and 44 denotes a quartz plate for dispersing gas. In the first plasma generation chamber 45, plasma is generated by the above-mentioned microwave at a gas pressure of several hundreds mTorr to several tens Torr, thereby generating metastable atoms.

In fig. 38, since the distance between the place where the metastable atoms are generated and the vacuum processing space can be shortened as compared with fig. 37, the metastable atoms can be implanted into the vacuum processing chamber in a high density state, and the ion amount in the vacuum processing chamber 10 can be increased. The processing chamber 10 is maintained at a pressure of 5-50 mTorr, and is generated at 5eV or more, preferably 3eV or less by a high frequency power source 16 of 20MHz or more to generate 10¹⁰～10¹¹/cm³High density low electron temperature plasma, CF capable of preventing the required dissociation energy from being more than 8eV₂The dissociation enables the ionization of the gas used in the ion source. As a result, ions accelerated at several hundred volts by the bias power supply 17 are incident on the surface of the sample 40, and the following main reactions occur:

si, SiN as the underlying material in CF₂And is not etched, so that it is possible to form an oxide film etch with a high selectivity.

Also, due to dissociation of a portion of CF₂F is increased, which can be reduced by the upper electrode cap 30 formed of silicon, carbon, SiC (silicon carbide), or the like.

As described above, by adjusting the radical source gas and the ion source gas, the ratio of ions and radicals in the processing chamber 10 can be controlled substantially independently, and the reaction on the surface of the sample 40 can be easily controlled to a desired level.

The plasma processing apparatus of the present invention, which is provided with the electrostatic adsorption circuit and the pulse bias circuit, is additionally changed by replacing the etching gas with the CVD gas, and thus can be used not only for the above-described etching process but also for other plasma processing apparatuses such as a CVD apparatus.

Next, fig. 39 is another embodiment of the present invention for independently controlling ions and radicals. In FIG. 39, C, H-containing gas (C) is introduced₂H₄、CH₃OH, etc.) may be mixed into CHF as required₃、CH₂F₂、C₄F₈Or CF₄The fluorocarbon gas, which constitutes the portion shown in FIG. 39A, enters the plasma generation chamber 62 where radicals are generated through the valve 70.

In a plasma generating chamber 62 for generating radicals, an output of an RF power supply 63 of several megahertz (MHz) to several tens of megahertz (MHz) is applied to a coil 65, and plasma is generated by a gas pressure of several hundreds mTorr to several tens Torr to mainly generate CF₂A radical of atoms. Concurrent generation of CF₃And F are reduced by the H component.

However, it is difficult to significantly reduce the components such as CF and O in the plasma generation chamber 62 where radicals are generated, and the unnecessary component removal chamber 65 is provided at the rear side thereof. The material of the inner wall of the removal chamber is carbon or silicon (Si) -containing material (carbon, silicon carbide, etc.) to reduce the content of unnecessary components or to convert the unnecessary components into other gases with less adverse effects. An outlet of the unnecessary component removing chamber 65 is connected to a valve 71 to be supplied with CF₂A mixture of the main components.

Further, since a large amount of deposits such as deposits are accumulated between the valves 70 and 71, the valve is frequently cleaned or replaced. Therefore, the evacuation device 74 is connected via the valve 72 so as to facilitate the atmosphere opening and the replacement operation and to shorten the evacuation time at the time of restart. The exhaust unit 74 may also be used as an exhaust unit for the processing chamber 10.

Further, a gas B for ion source (rare gas such as argon gas or xenon gas) is connected to the outlet of the valve 71 through a valve 73, and the gas is supplied into the processing chamber.

The processing chamber 10 is maintained at a pressure of 5-40 mT, and a modulated high frequency power supply 16 of 20MHz or more is used to generate 10 eV or less at 5eV, preferably 3eV or less¹⁰～10¹¹/cm³The high density low electron temperature plasma of (2) can prevent the CF with dissociation energy of more than 8eV₂And ionization of the gas used in the ion source can be performed. As a result, ions accelerated at several hundred volts by the bias power supply 17 are incident on the surface of the sample 40, and the following reactions mainly occur:

thus, Si and SiN as the underlying materials are not CF₂Therefore, the oxide film can be etched with a high selectivity.

In addition, due to a part of CF₂The dissociation of (fluorocarbon) increases F (fluorine), but the upper electrode cap 30 formed of silicon, carbon or silicon carbide (SiC) decreases F (fluorine).

As described above, the radical gas a and the ion source gas B are adjusted to substantially independently control the ratio of ions to radicals in the processing chamber 10. The reaction on the surface of the sample 40 can be easily controlled at its desired level. In addition, unnecessary deposits and the like are removed by the unnecessary component removing chamber 65, and these unnecessary components are not taken into the processing chamber 10 as much as possible, so that deposits in the processing chamber 10 are greatly reduced, and the frequency of cleaning the processing chamber by opening the processing chamber to the atmosphere is also greatly reduced.

Next, fig. 40 shows another example of independently controlling ions and radicals. Hexafluoropropylene gas (CF)₃CFOCF₂Hereinafter abbreviated as HFPO), is introduced from a through a valve 70 into the heating duct portion 66, is mixed with the ion source gas B through the excess (unnecessary) component removing chamber 65 and the valve 71, and is sent to the processing chamber 10. In the heating duct portion 66, HFPO is heated to 800 to 1000 ℃ to be thermally decomposed to produce CF₂。

CF₃CFO is a relatively stable substance which is not easily decomposed, but is partially decomposed to generate unnecessary oxygen (O) and fluorine (F), and therefore an excess component removing chamber 65 is provided behind the heating pipe portion 66 to remove excess components or convert them into substances having no adverse effect. A part of CF not decomposed₃CFOCF₂Flows into the processing chamber 10, but is not problematic because it is not dissociated in plasma having a low electron temperature of 5eVor less.

The use of the valve 72, the exhaust 74 and the reaction in the process chamber 10 are the same as in the case of fig. 39.

The plasma processing apparatus having the electrostatic adsorption circuit and the pulse bias circuit according to the present invention can be used not only for the above-described etching process but also for other plasma processing apparatuses such as CVD, if a CVD gas is used instead of an etching gas.

Claims (31)

1. A plasma processor, comprising:

a vacuum processing chamber;

a plasma generating device comprising a pair of electrodes;

a sample stage having a sample placing surface for placing a sample to be processed in the vacuum processing chamber; and

the plasma processor of the pressure reducing device for vacuum-reducing the vacuum processing chamber is characterized by further comprising:

a high-frequency power supply for applying a high-frequency power of a VHF band of 30MHz to 300MHz between the pair of electrodes; and

a magnetic field forming device for forming a static magnetic field or a low-frequency magnetic field in a direction intersecting with an electric field generated between or in the vicinity of the pair of electrodes by the high-frequency power supply,

an electron cyclotron resonance region is formed between the two electrodes by the interaction between the magnetic field and the electric field.

2. A plasma processor, comprising:

a vacuum processing chamber;

a plasma generating device including a pair of electrodes;

a sample stage which also serves as one of the electrodes and on which a sample to be processed in the vacuum processing chamber is placed; and

the plasma processor of the pressure reducing device for vacuum-pumping and pressure-reducing the vacuum processing chamber is characterized by further comprising:

a high frequency power supply for applying a VHF band power supply of 50MHz to 200MHz between the pair of electrodes; and

a magnetic field forming device for forming a static magnetic field of 17 Gauss or more and 72 Gauss or less or a low-frequency magnetic field in a direction intersecting with an electric field generated between the pair of electrodes or in the vicinity thereof by the high-frequency power supply,

the magnetic field forming means is set so that the maximum component of the magnetic field in the direction along the surface of the sample stage is positioned on the opposite side of the sample stage, i.e., at a position exceeding the center of the two electrodes,

an electron cyclotron resonance region is formed between the pair of electrodes by the interaction between the magnetic field and the electric field.

3. The plasma processor according to claim 1 or 2, wherein the intensity of the magnetic field formed by the magnetic field forming means is adjusted so that a component of the magnetic field parallel to the surface of the sample is 30 gauss or less.

4. A plasma processor, comprising:

a vacuum processing chamber;

a plasma generating device including a pair of electrodes; and

in a plasma processing machine having a sample stage (which also serves as one of the electrodes and is used for placing a sample to be processed in the vacuum processing chamber),

the electrodes are composed of a 1 st electrode connected to a high frequency power supply and a 2 nd electrode, the 2 nd electrode is also used as the sample stage and is connected to a bias power supply for controlling ion energy, the distance between the pair of electrodes is 30-100mm,

further comprising:

a pressure reducing device for reducing the pressure in the vacuum processing chamber to 0.4Pa-4 Pa;

the high-frequency power supply is used for adding a VHF frequency band power supply of 30MHz-300MHz between the pair of electrodes; and

a magnetic field forming means for forming a static magnetic field or a low-frequency magnetic field portion of 10 Gauss or more and 110 Gauss or less in a direction intersecting with the electric field between the pair of electrodes or in the vicinity thereof,

an electron cyclotron resonance region is formed on the 1 st electrode surface or on the 1 st electrode side beyond the center position of the two electrodes by the interaction between the magnetic field and the electric field generated by the high-frequency power supply.

5. The plasma processor according to claim 1, 2 or 4, wherein the density or direction of said magnetic field formed by said magnetic field forming means is adjusted so that said electron cyclotron resonance effect is larger at the periphery and outside of the sample than at the center of said sample, and further, the plasma density is made uniform at positions corresponding to said entire sample placement surface.

6. The plasma processor according to claim 4, wherein the magnetic core in the magnetic field forming device is eccentrically rotated with respect to the center of the sample surface to change the magnetic field, thereby continuously changing the distance of the cyclotron resonance region from the sample.

7. A plasma processor, comprising:

a vacuum processing chamber;

a plasma generating device comprising a pair of electrodes;

a sample stage having a sample placing face for placing a sample to be processed in the vacuum processing chamber; and

in a plasma processor having a vacuum reducing device for vacuum-reducing the vacuum processing chamber, characterized in that,

the electrode comprises the following components: a 1 st electrode connected with a high-frequency power supply, a 2 nd electrode also used as a sample stage, and a processing chamber wall part which is positioned at the outer side of the periphery of the 1 st electrode and is grounded,

the plasma processor further has:

a high-frequency power supply for applying a high-frequency power of a VHF band of 30MHz to 300MHz between the pair of electrodes and between the 1 st electrode and the wall portion of the processing chamber; and

a magnetic field forming device for forming a static magnetic field or a low-frequency magnetic field portion of 10 Gauss to 110 Gauss, the magnetic fields being formed in such directions as to cancel each other near the center of the processing chamber and overlap each other around and outside the processing chamber,

an electron cyclotron resonance region is formed around the sample placement surface and in the vicinity of the outer side of the sample placement surface by the interaction between the magnetic field and the electric field generated by the high-frequency power supply.

8. The plasma processor according to claim 7, wherein the magnetic field forming means has a plurality of coils and is installed around the processing chamber so that magnetic fluxes are offset from each other in the vicinity of the center of the sample and overlap each other around the sample and outside thereof.

9. The plasma processor according to claim 4, wherein the pulse bias voltage having a period of 0.2 to 5 μ s and a duty ratio of the forward pulse portion of 0.4 or less is applied to the specimen through the capacitive element as the bias current for controlling the ion energy.

10. The plasma processor according to claim 1, 2 or 4, wherein:

an electrostatic adsorption device for fixing the sample on the sample stage by electrostatic adsorption force;

a pulse bias device connected to the sample stage for applying a pulse bias to the sample stage; and

and a voltage suppressing device for suppressing a voltage rise corresponding to the electrostatic adsorption capacity of the electrostatic adsorption device in response to the application of the pulse bias.

11. The plasma processor according to claim 10, wherein the voltage suppressing means is configured to suppress a voltage variation generated in an electrostatic adsorption film of the electrostatic adsorption device in one cycle of the pulse to be below 1/2 of the pulse bias voltage.

12. A plasma processing method is characterized by comprising the following steps:

a vacuum processing chamber;

a plasma generating device comprising a pair of electrodes;

a sample stage which also serves as one of the electrodes and on which a sample to be processed in the vacuum processing chamber is placed; and

the sample processing method of the plasma processor of the pressure reducing device (for reducing the pressure in the vacuum processing chamber) comprises the following program steps:

reducing the pressure in the vacuum processing chamber by using a pressure reducing device;

forming a static magnetic field or a low-frequency magnetic field portion of 10 gauss or more and 110 gauss or less in a direction intersecting the electric field between the pair of electrodes by a magnetic field forming means;

a VHF band power supply of 30MHz-300MHz is added between the pair of electrodes by a high frequency power supply, and an electron cyclotron resonance region is formed between the two electrodes by the interaction of the magnetic field and an electric field formed by the high frequency power supply;

the sample is processed by plasma generated by the electron cyclotron resonance.

13. A plasma processing method for a sample in a plasma processor having a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generator including a pair of electrodes,

the electrode is configured as a pair of electrodes, including: a 1 st electrode connected to the high-frequency power supply, and a 2 nd electrode also used as the sample stage and connected to a bias power supply for ion energy control, wherein the distance between the pair of electrodes is 30-100mm,

comprises the following steps:

reducing the pressure in the vacuum processing chamber to 0.4-4Pa by using a pressure reducing device;

forming a static magnetic field or a low-frequency magnetic field portion of 10 gauss to 110 gauss in a direction intersecting the electric field between the pair of electrodes by a magnetic field forming means;

applying a VHF power source of 30MHz to 300MHz between the pair of electrodes by a high frequency power source, and forming an electron cyclotron resonance region between the pair of electrodes by an interaction between the magnetic field and an electric field generated by the high frequency power source;

the sample is processed by plasma generated by the electron cyclotron resonance.

14. A plasma processor comprising a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generator including a high-frequency power source, the plasma processor comprising: an electrostatic adsorption device for fixing the sample on the sample stage by electrostatic adsorption force; and

a pulse bias device for applying a pulse bias to the sample,

further, a high-frequency voltage of 10MHz to 500MHz is applied as the high-frequency power source, and the pressure in the vacuum processing chamber is reduced to 0.5Pa to 4 Pa.

15. A plasma processor, comprising:

a pair of oppositely mounted electrodes, one of which is provided with a sample;

a gas introducing device for introducing an etching gas into the processing chamber (into the ambient gas) in which the sample is placed;

an exhaust device for reducing the pressure in the processing chamber to 0.5-4 Pa;

a high-frequency power supply for applying a high-frequency voltage of 10MHz to 500MHz to the pair of opposing electrodes;

a plasma generating device for converting the etching gas into plasma (plasmatizing) under the pressure;

a pulse bias device for applying a pulse bias to the 1 electrode when the sample is etched;

the insulating film in the sample is subjected to plasma treatment.

16. A plasma processor is provided, which is capable of processing a plurality of plasma,

a plasma processor comprising a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating device, the plasma processor comprising:

an electrostatic adsorption device for fixing the sample on the sample stage by electrostatic adsorption force;

a pulse bias device connected to the sample stage for applying a pulse bias to the sample stage;

a voltage suppressing device for suppressing a voltage rise corresponding to an electrostatic adsorption capacity of the electrostatic adsorption device in response to application of a pulse bias;

the voltage suppressing device is configured such that a voltage change generated in an electrostatic adsorption film of the electrostatic adsorption device in one cycle of a pulse is suppressed to 1/2 or less of the pulse bias.

17. A plasma processor characterized by comprising:

a pair of electrodes having a gap of 10-50mm and disposed facing each other;

electrostatic adsorption means for fixing a sample to one of the electrodes by means of electrostatic adsorption force;

a gas introducing device for introducing an etching gas into a gas around the sample in the processing chamber in which the sample is placed;

an exhaust means for reducing the air pressure around the sample to 0.5-4.0 Pa;

a plasma generating device for ionizing the etching gas under the pressure by using high-frequency power of 10MHz-500 MHz; and

a pulse bias means for applying a pulse bias to an electrode on which the sample is placed;

further, the insulating film in the sample is subjected to plasma treatment.

18. The plasma processor of claim 16 or 17,

a voltage suppressing means for suppressing a voltage rise generated corresponding to the electrostatic adsorption capacity of the electrostatic adsorption means with the application of the pulse bias,

the period of the pulse bias is set so that the voltage change caused by the electrostatic adsorption film of the electrostatic adsorption device in one period of the pulse is suppressed to 1/2 or less of the pulse bias by the voltage suppressing means.

19. A plasma processing method is characterized by comprising the following processing program steps:

placing the sample on an electrode in a vacuum processing chamber;

fixing the sample on the electrode by using electrostatic adsorption force;

introducing a process gas into the process chamber containing the sample;

reducing the gas pressure around the sample to a pressure required for sample processing;

plasmatizing the process gas at the pressure;

processing the sample with the plasma;

a pulsed bias is applied to the sample.

20. A plasma processing method is characterized by comprising the following processing program steps:

placing the sample on one of a pair of oppositely disposed electrodes having a gap of 10mm to 50 mm;

fixing the sample placed on the electrode to the electrode by using electrostatic adsorption force;

feeding an etching gas into the ambient gas in which the sample is placed;

reducing the pressure of said ambient gas to 0.5-4.0 Pa;

applying a high-frequency power of 10MHz to 500MHz to plasmatize the etching gas under the gas pressure;

etching the sample with the plasma;

a pulse bias is applied to the one electrode while the etching is performed,

thus, the insulating film in the sample is subjected to plasma treatment.

21. A plasma processing method is characterized by comprising the following processing program steps:

placing the sample on one of a pair of electrodes mounted in a vacuum processing chamber;

fixing the sample to the electrode by electrostatic attraction;

sending the corrosive gas into the ambient gas in which the sample is placed;

reducing the pressure of said ambient gas;

plasmatizing the etching gas at the low pressure;

etching the sample by using the plasma;

a pulsed bias voltage is applied to the sample,

in this way, the voltage variation of the electrostatic adsorption film of the electrostatic adsorption device in one pulse period when the pulse bias is applied is suppressed to 1/2 or less of the pulse bias.

22. A plasma processing method is characterized by comprising the following processing program steps;

placing the sample on one of two opposing electrodes;

fixing the placed sample on the electrode by using electrostatic adsorption force;

supplying an etching gas into the gas in the processing chamber containing the sample;

carrying out plasma treatment on the fed corrosive gas;

etching the sample by using the plasma;

when the etching is carried out, a pulse bias voltage of a pulse width of 250V-1000V and a duty ratio of 0.05-0.4 is applied to the one electrode,

thus, the insulating film in the sample is subjected to plasma treatment.

23. A plasma processor is provided, which is capable of processing a plurality of plasma,

the plasma processing apparatus includes a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating device, and further includes:

an electrostatic adsorption device for fixing the sample on the sample stage by electrostatic adsorption force;

a biasing device for applying a bias to the sample stage;

a radical supply device having a device for decomposing a gas for generating radicals in advance, and supplying a required number of radicals into the vacuum processing chamber;

a gas supply device for supplying a gas for generating ions into the vacuum processing chamber; and

a plasma generating device for generating plasma in the vacuum processing chamber,

and, using SiO₂The sample was obtained.

24. A plasma processing machine having a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating device, characterized by further comprising:

an electrostatic adsorption device for fixing the sample on the sample table by means of electrostatic adsorption force;

a pulse bias device for applying a pulse bias to the sample;

a plasma supply device for radical generation for plasmatizing a gas for radical generation in advance in the vacuum processing chamber and supplying a required number of radicals;

a plasma generator for generating plasma by supplying an ion generating gas into the vacuum processing chamber,

and, using SiO₂The samples were used as described above.

25. A plasma processing machine having a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating device including a high-frequency power source, characterized by further comprising:

an electrostatic adsorption device for fixing the sample on the sample stage by electrostatic adsorption force;

a pulse bias device for applying a pulse bias to the sample;

a plasma supply device for radical generation for plasmatizing a gas for radical generation in advance in the vacuum processing chamber and supplying a required number of radicals;

a plasma generator for generating plasma in the vacuum processing chamber by supplying a gas for generating ions,

and, a high frequency voltage of 10MHz to 500MHz is applied to the high frequency power source, and the pressure in the vacuum processing chamber is reduced to 0.5 to 4.0 Pa.

26. A plasma processing apparatus having a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating device, the plasma processing apparatus comprising:

an electrostatic adsorption device for fixing the sample on the sample table by means of electrostatic adsorption force;

a plasma supply device for radical generation for plasmatizing a gas for radical generation in advance in the vacuum processing chamber and supplying a required number of radicals;

a plasma generator for supplying a gas for generating ions and generating plasma in the vacuum processing chamber;

a pulse bias device connected with the sample platform for applying pulse bias to the sample platform; and

and a voltage suppressing device for suppressing a voltage rise corresponding to an electrostatic adsorption capacity of the electrostatic adsorption device with the application of the pulse bias.

27. A plasma processing machine having a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating device, characterized by further comprising:

an electrostatic adsorption device including an electrostatic adsorption film provided on the sample stage for fixing the sample to the sample stage by an electrostatic adsorption force;

a plasma supply device for radical generation for plasmatizing a gas for radical generation in advance in the vacuum processing chamber and supplying a required number of radicals;

a plasma generator for supplying a gas for generating ions and generating plasma in the vacuum processing chamber;

a pulse bias device connected to the sample stage for applying a pulse bias to the sample stage;

a voltage suppressing means for suppressing a voltage generated between both ends of the electrostatic adsorption film in accordance with the application of the pulse bias,

the voltage suppressing device suppresses a voltage generated by the electrostatic attraction film of the electrostatic attraction device to 1/2 or less of the pulse bias.

28. A plasma processing method is characterized by comprising the following processing program steps:

placing the sample on one of a pair of opposing electrodes;

fixing the sample on the electrode by electrostatic adsorption force;

preliminarily plasmatizing a radical generating gas in the ambient gas in which the position of the sample is placed and fixed, and supplying a required numberof radicals;

supplying an ion generating gas to the ambient gas at the position;

reducing the ambient air pressure at said location to 0.5-4.0 Pa;

applying a high-frequency voltage of 10MHz to 500MHz to the pair of opposing electrodes, and plasmatizing the supplied ion generating gas under the above-mentioned gas pressure;

carrying out corrosion treatment on the sample by using the plasma;

a pulse bias is applied to the one electrode while the etching treatment is performed,

and, the above sample uses SiO₂。

29. A plasma processing method is characterized by comprising the following processing program steps:

placing the sample on one of a pair of electrodes mounted in a vacuum processing chamber;

fixing the sample on the electrode by electrostatic adsorption force;

preliminarily plasmatizing a radical generating gas in the ambient gas in which the position of the sample is placed and fixed, and supplying a required number of radicals;

supplying an ion generating gas to the ambient gas at the position;

applying a high-frequency voltage of 30MHz to 100MHz to the ambient gas at the position, and plasmatizing the supplied ion generating gas under the gas pressure;

treating the sample with the plasma;

a pulse voltage is applied to the sample,

and, the above sample uses SiO₂。

30. A plasma processing method is characterized by comprising the following processing program steps:

placing the sample on one of a pair of electrodes in a vacuum processing chamber;

fixing the sample on the electrode by electrostatic adsorption force;

preliminarily plasmatizing a radical generating gas in the ambient gas in which the position of the sample is placed and fixed, and supplying a required number of radicals;

supplying an ion generating gas to the ambient gas at the position;

reducing the ambient air pressure at said location to a pressure required for processing said sample;

plasmatizing the supplied ion generating gas under the gas pressure;

the sample is treated with the plasma as described above,

a pulsed bias voltage is applied to the sample,

the voltage of the electrostatic adsorption device is set to 1/2 or less of the pulse bias.

31. A plasma processing method is characterized by comprising the following processing program steps:

placing the sample on one of a pair of opposing electrodes within a vacuum processing chamber;

fixing the sample on the electrode by using electrostatic adsorption force;

preliminarily plasmatizing a radical generating gas in the ambient gas in which the position of the sample is placed and fixed, and supplying a required number of radicals;

supplying an ion generating gas to the ambient gas at the position;

reducing the ambient gas at said location to 0.5-4.0 Pa;

applying a high-frequency voltage of 30MHz to 100MHz between the pair of opposing electrodes, and plasmatizing the supplied ion generating gas under the gas pressure;

treating the sample with the plasma;

a pulsed bias is applied to the sample.

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