JP2000058292A - Method and device for plasma treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the time in a pulse plasma process in which the high frequency pulse power for plasma generation remains off while the electric discharging is prevented from becoming unstable. SOLUTION: A spiral electrode 12 is provided on a chamber 10 with a dielectric plate 11 interposed and is supplied with a high frequency pulse power for plasma generation from a high frequency pulse source 13. A specimen stage 14 is provided at the bottom of the chamber 10, and a specimen to be etched 15 is placed on this stage 14. A DC pulse source 17 for biasing is installed under the stage 14 and connected with the stage 14 through a strip line 16. A vacuum ultraviolet source 19 and cylindrical lens 20 are installed on the side face of the chamber 10, and when the high frequency power for plasma generation remains off, vacuum ultraviolet rays are cast onto a plasma generating region 18 from the ultraviolet source 19 through the cylindrical lens 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus and a plasma processing method using high-frequency discharge.

[0002]

2. Description of the Related Art A plasma processing method using high-frequency discharge involves dry etching for fine processing, formation of a thin film such as a nitride film or an oxide film, or formation of an amorphous film using ions or radicals in plasma. It has been used to create a wide variety of new materials, such as the semiconductor industry, and has brought technological innovations in the electronics industry, including the semiconductor industry.

Hereinafter, as an application example of the plasma processing method,
Dry etching suitable for fine processing will be described.
Reactive ion etching (RIE), which is most widely used as a dry etching technique, causes an etching reaction by exposing a sample to be etched in a high-frequency discharge plasma composed of an appropriate reactive gas, thereby causing a surface of the sample to be etched to be etched. Unnecessary parts are removed. A necessary portion of the surface of the sample to be etched, that is, a portion that is not removed is protected by a resist pattern used as a photomask.

[0004] For fine processing, it is necessary to make the directionality of ions uniform, but for that purpose, it is essential to reduce the scattering of ions in plasma. To reduce ion scattering, lower the pressure in the plasma generation chamber,
It is effective to increase the mean free path of ions. However, when the pressure in the plasma generation chamber is reduced, there is a problem that the radical density decreases and the etching rate decreases.

As a countermeasure, a high-density plasma device such as an inductively coupled plasma device or a helicon type plasma device is being introduced. The high-density plasma apparatus can generate plasma of about one to two orders of magnitude higher than a conventional parallel plate type RIE apparatus. For this reason, even when the pressure in the plasma generation chamber is about one to two orders of magnitude lower, the RI
An etching rate equal to or higher than that of the E apparatus is obtained.

However, in the above-described high-density plasma apparatus, since charges, which are electrons or positive ions, accumulate on the substrate to be processed during the plasma processing, abnormalities in the etching shape due to charge-up, micro-loading effects, etc. Or a new problem that the gate insulating film is deteriorated or destroyed due to charging.

Therefore, as a method for solving the above-mentioned problem of the high-density plasma process, a pulse plasma process has been proposed (for example, Ohtake et al., DR 1995).
Y PROCESS SYMPOSIUM Proceedings, p.45, IEEJ). The pulsed plasma process is to supply high-frequency power for plasma generation in a pulsed manner, and when the high-frequency power for plasma generation is turned off or at a low level, a reduction in electrons and generation of negative ions are caused. Since charge accumulation on the substrate to be processed is reduced, abnormalities in the etching shape due to charge-up, a microloading effect, or deterioration or destruction of the gate insulating film due to charging can be prevented.

Hereinafter, an etching apparatus for performing a pulse plasma process will be described with reference to FIG.

A spiral electrode 12 is provided via a dielectric plate 11 on a chamber 10 whose inside is kept in a vacuum, and one end of the spiral electrode 12 supplies a high-frequency pulse power for generating plasma. And the other end of the spiral electrode 12 is grounded. When high-frequency pulse power is applied to the spiral electrode 12, an induction electromagnetic field is generated via the dielectric plate 11, so that high-density plasma is generated inside the chamber 10. A sample stage 14 is provided at the bottom of the chamber 10, and a sample 15 to be etched is placed on the sample stage 14. A high frequency power supply 21 for bias is connected to the sample stage 14 via the strip line 16. The high frequency power supply 21 for biasing accelerates positive ions or negative ions in the plasma generation region 18 toward the sample 15 to be etched.

[0010]

However, in the conventional pulsed plasma process, the time during which the high-frequency pulse power for plasma generation is off or at a low level in order to sufficiently reduce the accumulation of charges on the substrate to be processed. If it is lengthened, a new problem as described below occurs. That is, as the time during which the high-frequency pulse power for plasma generation is off or at a low level becomes longer, electrons in the chamber continue to decrease due to generation of negative ions and collision with the wall of the chamber. If the power-off or low-level time is longer than the predetermined time, the next time the high-frequency pulse power for plasma generation is turned on or at a high level, the number of electrons is too small and plasma generation does not easily occur and discharge occurs. Is unstable.

When the discharge becomes unstable, there arise problems that the flicker of the discharge is observed, the reproducibility of the process is deteriorated, and in some cases, the gate insulating film is destroyed due to charging.

In view of the above, in the pulse plasma process, the present invention provides a high-frequency plasma generation device that prevents discharge from becoming unstable when high-frequency pulse power for plasma generation is turned on or at a high level. It is an object of the present invention to be able to prolong the time when the pulse power is off or at a low level.

[0013]

In order to achieve the above-mentioned object, the present invention provides a method for irradiating a reactive gas by irradiating a reactive gas with an energy beam when a high-frequency pulse power for plasma generation is off or at a low level. This is to ionize the reactive gas to generate electrons, thereby keeping the number of electrons in the chamber at a predetermined level or more.

[0014] A plasma processing apparatus according to the present invention includes a vacuum chamber provided with a sample stage for holding a substrate to be processed and having a gas introducing means for introducing a reactive gas.
A high-frequency power supply for generating a plasma of a reactive gas in the vacuum chamber by intermittently or repeatedly supplying a predetermined level of high-frequency power to the vacuum chamber or alternately and repeatedly supplying a high-level and low-level high-frequency power to the vacuum chamber Means, an energy beam irradiating means for irradiating the reactive gas with an energy beam during a period in which the high-frequency power supply means does not supply a predetermined level of high-frequency power or a period in which low-level high-frequency power is supplied, And a bias voltage supply means for applying a bias voltage to the power supply.

According to the plasma processing apparatus of the present invention, when the high-frequency power for plasma generation is off or at a low level, the energy beam irradiation means for irradiating the reactive gas with the energy beam is provided. By irradiating the reactive gas with an energy beam when the high-frequency power is off or at a low level, the reactive gas can be ionized to generate electrons.

In the plasma processing apparatus of the present invention, it is preferable that the energy beam irradiation means has a means for emitting vacuum ultraviolet light.

In the plasma processing apparatus according to the present invention, it is preferable that the energy beam irradiation means irradiates the reactive gas with the energy beam substantially parallel to the sample stage.

In the plasma processing apparatus of the present invention, the energy beam irradiation means preferably irradiates the reactive gas with the vacuum ultraviolet light emitted from the deuterium lamp through a cylindrical lens.

In the plasma processing apparatus according to the present invention, the bias voltage supply means is preferably a DC pulse power supply.

In the plasma processing apparatus according to the present invention, the bias voltage supply means is preferably a high frequency power supply.

According to the plasma processing method of the present invention, a reactive gas is supplied to a vacuum chamber in which a sample stage for holding a substrate to be processed is provided, and a reactive gas is supplied to the vacuum chamber.
A plasma generation step of generating a plasma of a reactive gas in a vacuum chamber by intermittently supplying a predetermined level of high-frequency power or alternately repeatedly supplying high-level and low-level high-frequency power; A bias voltage applying step of applying a bias voltage to the reactive gas during a period in which a predetermined level of high-frequency power is not supplied or a period in which low-level high-frequency power is supplied. Energy beam irradiating step of irradiating the light.

According to the plasma processing method of the present invention, when the high frequency power for plasma generation is off or at a low level, the reactive gas is irradiated with an energy beam to ionize the reactive gas to generate electrons. Since the number of electrons in the vacuum chamber can be maintained at a predetermined level or more necessary for easily generating plasma, the next time the high frequency power for plasma generation is turned on or at a high level, In addition, unstable discharge can be prevented.

Further, according to the plasma processing method of the present invention, it is possible to prolong the time when the high frequency power for plasma generation is off or at a low level while preventing the discharge from becoming unstable. It is possible to alleviate the accumulation of electric charges, which are electrons and positive ions, above.

In the plasma processing method of the present invention, the energy beam is preferably vacuum ultraviolet light.

In the plasma processing method of the present invention, it is preferable that the energy beam irradiating step includes a step of irradiating the reactive gas with the energy beam substantially parallel to the sample stage.

The plasma processing method of the present invention further includes a step of irradiating the reactive gas with an energy beam before starting to supply a predetermined level of high-frequency power or a high-level high-frequency power in the plasma generation step. Is preferred.

[0027] In the plasma processing method of the present invention, the bias voltage applying step is performed during at least a part of a period in which the high frequency power for plasma generation is off or at a low level.
It is preferable to include a step of applying a positive bias voltage to the sample stage.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A dry etching apparatus and a dry etching method according to a first embodiment of the present invention will be described below with reference to FIGS.

FIGS. 1A and 1B are schematic views showing the structure of a dry etching apparatus according to a first embodiment of the present invention. FIG. 1A is a cross-sectional view as viewed from the side. FIG. 1B is a sectional view seen from above. FIG. 1 (a),
In FIG. 2B, reference numeral 10 denotes a chamber which is grounded, has an inner wall covered with an insulating material such as ceramic, Teflon or quartz, and has a vacuum inside. Note that the chamber 10 may have a double structure having an inner chamber made of quartz or the like instead of a structure in which the inner wall is covered with an insulator. The chamber 10 is provided with a well-known gas introducing means for introducing a reactive gas into the chamber 10, but is not shown.

As shown in FIGS. 1A and 1B, a spiral electrode 12 is provided on a chamber 10 via a dielectric plate 11 made of ceramic or the like, and one end of the spiral electrode 12 is provided. Is connected to a high-frequency pulse power source 13 and the other end of the spiral electrode 12 is grounded. When high-frequency pulse power is applied to the spiral electrode 12, an induction electromagnetic field is generated via the dielectric plate 11, so that high-density plasma is generated inside the chamber 10. A metal sample stage 14 whose surface is coated with an insulating material is provided at the bottom of the chamber 10, and a sample to be etched 15 as a substrate to be processed is mounted on the sample stage 14. Is placed. A bias DC pulse power supply 17 is provided near the lower part of the sample stage 14, and the sample stage 14 and the bias DC pulse power source 17 are approximately 30
are connected by a strip line 16 having a length of 10 cm. Strip line 16 is 2cm wide and 0.5m thick
m is a strip of copper, and is covered by a metal square tube with a gap of 2 to 3 cm, thereby suppressing the occurrence of parasitic capacitance. A bias DC pulse power supply 17 accelerates positive ions or negative ions in the plasma generation region 18 toward the sample 15 to be etched. Sample stand 14 and DC
Since the pulse power supply 17 is connected via the strip line 16, an increase in parasitic capacitance or an increase in inductance between the sample stage 14 and the DC pulse power supply 17 can be suppressed.

As a feature of the first embodiment, FIG.
As shown in (a) and (b), a vacuum ultraviolet light source 19 and a cylindrical lens 20 are provided on the side surface of the chamber 10, and the vacuum ultraviolet light emitted from the vacuum ultraviolet light source 19 is Irradiation is performed on the plasma generation region 18 in the chamber 10 via the cylindrical lens 20. As the vacuum ultraviolet light source 19, a light source that emits vacuum ultraviolet light can be widely used.
A deuterium lamp excited by KW microwaves is used.

Hereinafter, a dry etching method according to the first embodiment, which is performed using the dry etching apparatus according to the first embodiment, will be described with reference to FIGS. 1 (a), 1 (b) and 2. FIG. FIG. 2 is a graph showing the change over time of the plasma generating high-frequency power pulse, the bias DC voltage pulse, and the plasma parameters (electron density, negative ion density, and positive ion density) in the chamber 10 in the dry etching method according to the first embodiment. This is indicated by a solid line. In FIG. 2, Td is DC after the high-frequency pulse power supply 13 is turned off.
This shows a delay time until the pulse power supply 17 is turned on. For comparison with the dry etching method according to the present embodiment, in FIG. 2, the time change of plasma parameters (electron density, negative ion density and positive ion density) in the dry etching method without irradiation with vacuum ultraviolet light is shown. This is indicated by a broken line.

First, 25 sccm of H was used as a reactive gas.
Br gas and 25 sccm Cl ₂ gas were placed in chamber 1
0, and the pressure in the chamber 10 is 1 to 3 Pa
And

Next, the vacuum ultraviolet light source 19 of 1.2 KW
The plasma generation region 18 is irradiated with vacuum ultraviolet light using a deuterium lamp excited by the microwave. Irradiation of the vacuum ultraviolet light is started before supplying the high frequency power pulse from the high frequency pulse power supply 13, and irradiation of the vacuum ultraviolet light is performed continuously regardless of whether the high frequency pulse power supply 13 is on or off. By filling the optical path from the deuterium lamp as the vacuum ultraviolet light source 19 to the cylindrical lens 20 with nitrogen gas, attenuation of light energy due to absorption of vacuum ultraviolet light and generation of ozone are prevented.

Thereafter, from the high frequency pulse power supply 13 for plasma generation, the frequency is 13.56 MHz, the pulse width is 30 to 100 μs, and the time average power is 200 to 1000 W.
Is applied to the spiral electrode 12. Also, from the DC pulse power supply 17 for bias, a negative bias voltage of −50 V is applied to the sample stage 14 5 μs after the high frequency pulse power supply 13 is turned on, and after the high frequency pulse power supply 13 is turned off. After a predetermined delay time Td, 7
A positive bias voltage of 0 V is applied to the sample stage 14 with a pulse width of 5 to 20 μsec. The pulse repetition frequency is 5KH
The delay time Td is set to 10 to 50 μsec in z.

As shown in FIG. 2, when the high-frequency pulse power supply 13 for plasma generation is turned on, molecules of the reactive gas are ionized by collision with high-energy electrons. Increases. Next, when the high-frequency pulse power supply 13 for plasma generation is turned off to enter an afterglow plasma state, the electron temperature is reduced due to the absence of an electron acceleration source, so that electron attachment and dissociation are likely to occur and the plasma is used for etching. Since a reactive gas such as a halogen gas is an electron-negative gas, electron attachment and dissociation occur, so that the electron density rapidly decreases. on the other hand,
Contrary to the decrease in electron density, negative ions increase sharply due to the occurrence of electron attachment and dissociation.

According to the dry etching method according to the first embodiment, as shown by the solid line in FIG. 2, in the state of the afterglow plasma, when the high frequency pulse power supply 13 for plasma generation is initially turned off, the electron density is reduced. Although the drop occurs rapidly, the vacuum ultraviolet light emitted from the vacuum ultraviolet light source 19 is applied to the plasma generation region 18 in the chamber 10 via the cylindrical lens 20, so that the high frequency pulse power supply 13 for plasma generation is turned off. Since the reactive gas molecules are ionized to generate electrons even at a certain time, the electron density is required to be 10 ⁸ / c which is required to easily start discharge when the high frequency pulse power supply 13 is turned on.
m ³ or less. As a result, when the high-frequency pulse power supply 13 for plasma generation is next turned on, the electrons required for plasma generation are sufficiently supplied to stably generate a discharge, so that the discharge flickers and the reproducibility of the process deteriorates. Destruction of the gate insulating film due to charging can be prevented. Further, the time during which the high-frequency pulse power supply 13 for plasma generation is off can be lengthened while preventing the discharge from becoming unstable, so that the accumulation of charges on the sample 15 to be etched can be eased. It is possible to prevent the resulting etching shape from being abnormal.

On the other hand, according to the dry etching method of the comparative example in which irradiation with vacuum ultraviolet light is not performed, as shown by a broken line in FIG.
Although the electron density rapidly decreases and varies depending on the type of reactive gas, the electron density is 10 ⁸ / cm within 1 μsec to several tens μsec after the high frequency pulse power supply 13 for plasma generation is turned off. ³ or less. As a result, in the dry etching method of the comparative example without irradiation with vacuum ultraviolet light,
In order to prevent unstable discharge when the high frequency pulse power supply 13 for plasma generation is turned on, it is necessary to set the time during which the high frequency pulse power supply 13 is off to 1 μsec or less. In this case, since the accumulation of charges on the sample 15 to be etched cannot be sufficiently reduced, an abnormality in the etching shape due to charge-up may occur.

Further, according to the dry etching method of the first embodiment, the time during which the high frequency pulse power supply 13 for generating plasma is off can be lengthened while preventing the discharge from becoming unstable. The negative ions increased by the attachment and dissociation can be positively used for the pulsed plasma process. That is, since the time during which the high-frequency pulse power supply 13 for plasma generation is off can be set to several μsec or more, negative ions are drawn into the surface of the sample 15 to be etched by applying a positive bias voltage to the sample table 14. It can be used for etching.

Specifically, as shown by a solid line in FIG. 2, after a predetermined delay time Td from when the high frequency pulse power applied from the high frequency pulse power supply 13 for plasma generation is turned off, the bias DC The pulse power supply 17 is turned on, and a positive bias voltage is applied to the sample stage 14 from the DC pulse power supply 17. Usually, the delay time Td is such that the electron density is equal to or less than a predetermined ratio with respect to the peak value, for example, 1 of the peak value.
It is preferable to set the time so as to decrease to about / 10. If the delay time Td is set so that the bias DC pulse power supply 17 is turned on after the electron density in the plasma becomes equal to or less than a predetermined ratio with respect to the peak value, the delay time Td
After that, when the DC pulse power supply 17 applies a positive bias voltage to the sample stage 14, the electron current flowing into the sample stage 14 is reduced sufficiently because the electron density is sufficiently low and the negative ion density is large. As a result, the negative ion current can be effectively extracted, and the sample 15 can be effectively irradiated with negative ions. As a result, by sufficiently reducing the electron current flowing into the sample stage 14 and effectively extracting the negative ion current, the charge of the sample 15 to be etched due to the positive ions can be eliminated, resulting in charge-up. Since abnormalities in the etching shape can be further prevented, and even when the high-frequency pulse power supply 13 is off, the etching by the negative ions is performed by effectively irradiating the sample 15 with negative ions. The etching rate is improved.

Incidentally, in the dry etching method according to the first embodiment, the following negative ion contribution may be considered as a cause of the reduction in charge-up. When high energy positive ions or negative ions are incident on the sample 15 to be etched, the charge of the incident ions is accumulated on the surface of the sample 15 to be etched, and the ions 15 The effect of secondary electrons emitted from the surface is too large to be ignored. When positive ions are incident, the emission of secondary electrons increases the accumulation of positive charges, but when negative ions are incident, the emission of secondary electrons acts to cancel the accumulation of negative charges. Up is further reduced.

When the phosphorus-doped polycrystalline silicon film deposited on the silicon oxide film was etched using the plasma generated by the dry etching method according to the first embodiment, the etching rate was 200.
８００800 nm / sec, the selectivity with respect to the silicon oxide film was as good as 30 or more, and the anisotropic etching was performed.

Also, there is no discharge instability such as flickering of the discharge during the plasma treatment, and there is no occurrence of abnormalities in the etching shape or breakage of the gate insulating film due to charge-up, and good etching characteristics can be obtained. Was.

The high-frequency pulse power source 1 for plasma generation
3 is off, the DC pulse power supply 1 for bias is used.
Applying a positive bias voltage from 7 to the sample stage 14 increased the etching rate by about 20% or more.

In the first embodiment, the vacuum ultraviolet light source 1
A deuterium lamp was used as 9, but instead of A
A rare gas resonance line lamp such as r, Kr or Xe or an arc discharge lamp may be used. The energy beam applied to the plasma generation region 18 does not necessarily need to be vacuum ultraviolet light, and instead of vacuum ultraviolet light, a short wavelength excimer laser light, X-ray, β-ray, γ-ray, or the like may be used. .

In the first embodiment, high-frequency power is intermittently supplied from the high-frequency pulse power supply 13. Instead of intermittently supplying high-frequency power from the high-frequency pulse power supply 13, High-level and low-level high-frequency power may be alternately and repeatedly supplied.

Further, in the first embodiment, the irradiation of the vacuum ultraviolet light is performed continuously irrespective of the on / off state of the high-frequency pulse power supply 13, but the irradiation of the vacuum ultraviolet light is performed with the high-frequency pulse power supply 13 off. It is preferable to do this sometimes. In that case, the vacuum ultraviolet light source 19 may be pulse-driven in synchronization with the high-frequency power pulse of the high-frequency pulse power supply 13.

Second Embodiment Hereinafter, a dry etching apparatus and a dry etching method according to a second embodiment of the present invention will be described with reference to FIG.

FIG. 3 is a sectional view of a dry etching apparatus according to a second embodiment of the present invention as viewed from the side. Second
In this embodiment, the same members as those in the first embodiment shown in FIG.

The difference between the dry etching apparatus according to the second embodiment and the first embodiment is that a high-frequency power supply for bias for applying high-frequency power to the sample table 14 is used instead of the DC pulse power supply 17 for bias. The source 21 is provided. The high-frequency power supply 21 is provided near the lower part of the sample stage 14, and the sample stage 14 and the high-frequency power source 21 for bias are connected by a strip line 16 having a length of about 30 cm. The high frequency power supply 21 for biasing accelerates positive ions or negative ions in the plasma generation region 18 toward the sample 15 to be etched.

Hereinafter, a dry etching method according to the second embodiment, which is performed using the dry etching apparatus according to the second embodiment, will be described with reference to FIG.

First, 25 sccm of H was used as a reactive gas.
Br gas and 25 sccm Cl ₂ gas were placed in chamber 1
0, and the pressure in the chamber 10 is 1 to 3 Pa
And

Next, as the vacuum ultraviolet light source 19, 1.2 KW
The plasma generation region 18 is irradiated with vacuum ultraviolet light using a deuterium lamp excited by the microwave.

Thereafter, from the high frequency pulse power source 13 for plasma generation, the frequency is 13.56 MHz, the pulse width is 30 to 100 μsec, and the pulse repetition frequency is 5 KH.
z, a high-frequency power having a time average power of 200 to 1000 W is applied to the spiral electrode 12. Further, Vpp is supplied from the high frequency power supply source 21 for bias at a frequency of 100 KHz.
A bias voltage (peak-to-peak voltage) of 100 V is applied to the sample stage 14.

According to the dry etching method according to the second embodiment, since the discharge is generated stably, it is possible to prevent the flicker of the discharge, the deterioration of the reproducibility of the process and the destruction of the gate insulating film due to the charging.

When the phosphorus-doped polycrystalline silicon film deposited on the silicon oxide film was etched using plasma generated by the dry etching method according to the second embodiment, the etching rate was 150.
３００300 nm / sec, the selectivity to the silicon oxide film was as good as 30 or more, and the anisotropic etching was performed.

In addition, there is no discharge instability such as flickering of the discharge during the plasma treatment, and there is no occurrence of abnormalities in the etching shape or destruction of the gate insulating film due to charge-up, and good etching characteristics can be obtained. Was.

By applying a bias voltage to the sample table 14 from the high frequency power supply 21 for bias,
The bias voltage could be easily applied.

In the first and second embodiments, the case where the plasma processing method of the present invention is applied to an etching apparatus using high-density plasma has been described. However, instead of this, a plasma CVD apparatus, a sputtering apparatus or an ion The same effect can be obtained by applying the plasma processing method of the present invention to another apparatus using high-density plasma such as an ion source of an implantation apparatus.

[0060]

According to the plasma processing apparatus of the present invention, when the high-frequency power for plasma generation is off or at a low level, the reactive gas is irradiated with an energy beam to ionize the reactive gas to generate electrons. Since the number of electrons can be generated, the number of electrons in the vacuum chamber can be maintained at a predetermined level or more necessary for easily generating plasma, and then the high frequency power for plasma generation is turned on or at a high level. Sometimes, it is possible to prevent the discharge from becoming unstable.

Further, according to the plasma processing apparatus of the present invention, the time during which the high-frequency power for plasma generation is off or at a low level can be lengthened while preventing the discharge from becoming unstable. It is possible to alleviate the accumulation of electric charges, which are electrons and positive ions, above.

In the plasma processing apparatus of the present invention, if the energy beam irradiation means has a means for emitting vacuum ultraviolet light, the reactive gas may be irradiated with vacuum ultraviolet light because the energy of the vacuum ultraviolet light is large. Thus, the ionization efficiency of the reactive gas can be improved, and the energy can be emitted more easily than other energy beams such as X-rays, β-rays, and γ-rays.

In the plasma processing apparatus of the present invention, when the energy beam irradiating means irradiates the reactive gas with the reactive gas substantially parallel to the sample table, it is possible to prevent the energy beam from being directly irradiated on the substrate to be processed. Therefore, deterioration of device characteristics can be prevented.

In the plasma processing apparatus according to the present invention, when the energy beam irradiating means irradiates the reactive gas with the vacuum ultraviolet light emitted from the deuterium lamp through the cylindrical lens, the vacuum ultraviolet light is surely emitted by the deuterium lamp. In addition, since the diffusion of the vacuum ultraviolet light can be prevented by the cylindrical lens, the substrate to be processed can be prevented from being directly irradiated with the vacuum ultraviolet light.

In the plasma processing apparatus of the present invention, if the bias voltage supply means is a DC pulse power supply, a positive bias voltage or a negative bias voltage can be applied to the sample stage without fail.

In the plasma processing apparatus of the present invention, when the bias voltage supply means is a high frequency power supply, a bias voltage can be easily applied to the sample stage.

According to the plasma processing method of the present invention, when the high frequency power for plasma generation is turned on or at a high level, the discharge can be prevented from becoming unstable, so that the discharge flickers and the process reproducibility deteriorates. In addition, destruction of the gate insulating film due to charging on the substrate to be processed can be prevented.

Further, according to the plasma processing method of the present invention, the time during which the high-frequency power for plasma generation is off or at a low level can be prolonged while preventing discharge from becoming unstable. In addition to reducing the charge-up phenomenon by relaxing the accumulation of charges that are electrons and positive ions, the time during which the high-frequency power for plasma generation is off or at a low level is extended to several microseconds or more. And negative ions can be used for plasma processing. Therefore, when the plasma processing method of the present invention is used for an etching method, it is possible to prevent an abnormal etching shape due to charge-up, a microloading effect, or deterioration or destruction of a gate insulating film due to charging.

In the plasma processing method of the present invention, if the energy beam is vacuum ultraviolet light, the energy of the vacuum ultraviolet light is large, so that the reactive gas is irradiated with the vacuum ultraviolet light to improve the ionization efficiency of the reactive gas. In addition to the above, it is easier to emit than other energy beams such as X-rays, β-rays or γ-rays.

In the plasma processing method of the present invention, when the energy beam irradiating step includes a step of irradiating the reactive gas with the reactive gas substantially parallel to the sample stage,
Since it is possible to prevent the target substrate from being directly irradiated with the energy beam, deterioration of device characteristics can be prevented.

The plasma processing method of the present invention further comprises a step of irradiating the reactive gas with an energy beam before starting to supply a predetermined level of high-frequency power or a high-level high-frequency power in the plasma generation step. In this case, after the reactive gas is ionized to generate electrons, supply of a predetermined level of high-frequency power or high-level high-frequency power for plasma generation is started. Discharge is stabilized.

In the plasma processing method of the present invention, the bias voltage applying step may be performed at least during a period in which the high frequency power for plasma generation is off or at a low level.
When a step of applying a positive bias voltage to the sample stage is included, electrons adhering to the film to be processed on the substrate to be processed can be drawn into the substrate to be processed, and negative ions in the plasma can be transferred to the substrate to be processed. By drawing into the film to be processed, the charge of the film to be processed on the substrate to be processed due to positive ions can be eliminated, so that the charge-up phenomenon can be further reduced. Therefore, when the plasma processing method of the present invention is applied to an etching method, it is necessary to further prevent an abnormality in an etching shape due to charge-up, a microloading effect, or deterioration or destruction of a gate insulating film due to charging. In addition to the above, etching is performed with negative ions even when the high frequency power for plasma generation is off or at a low level, so that the etching rate is improved.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view of a dry etching apparatus according to a first embodiment of the present invention viewed from a side, and FIG.
1 is a cross-sectional view of a dry etching apparatus according to a first embodiment of the present invention as viewed from above.

FIG. 2 is a diagram showing a time change of various parameters in the dry etching method according to the first embodiment of the present invention.

FIG. 3 is a side sectional view of a dry etching apparatus according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view of a conventional dry etching apparatus viewed from a side.

[Explanation of symbols]

 Reference Signs List 10 chamber 11 dielectric plate 12 spiral electrode 13 high-frequency pulse power supply 14 sample table 15 sample to be etched 16 strip line 17 DC bias power supply 18 plasma generation area 19 vacuum ultraviolet light source 20 cylindrical lens 21 high-frequency power supply source

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Mitsunari Yamanaka 1-1 Sachimachi, Takatsuki-shi, Osaka Matsushita Electronics Co., Ltd. F-term (reference) 4K057 DA12 DA16 DB06 DD01 DE01 DE11 DG15 DM04 DM20 DN01 5F004 AA02 AA03 BA04 BA09 BB02 BB05 BD04 DA00 DA04 DB01 DB02

Claims (11)

[Claims] A vacuum chamber provided with a sample stage for holding a substrate to be processed and having a gas introducing means for introducing a reactive gas; and a predetermined level of high-frequency power intermittently and repeatedly supplied to the vacuum chamber. High frequency power supply means for generating a plasma comprising the reactive gas in the vacuum chamber by alternately or repeatedly supplying a high level and a low level high frequency power, and the predetermined level from the high frequency power supply means. Energy beam irradiation means for irradiating the reactive gas with an energy beam during a period in which high-frequency power is not supplied or a period in which the low-level high-frequency power is supplied; and a bias voltage for applying a bias voltage to the sample stage. A plasma processing apparatus comprising: a supply unit. 2. The plasma processing apparatus according to claim 1, wherein said energy beam irradiation means has means for emitting vacuum ultraviolet light. 3. The plasma processing apparatus according to claim 1, wherein said energy beam irradiation means irradiates the reactive gas with the energy beam substantially parallel to the sample stage. 4. The plasma processing apparatus according to claim 1, wherein said energy beam irradiation means irradiates the reactive gas with vacuum ultraviolet light emitted from a deuterium lamp through a cylindrical lens. 5. The plasma processing apparatus according to claim 1, wherein said bias voltage supply means is a DC pulse power supply. 6. The plasma processing apparatus according to claim 1, wherein said bias voltage supply means is a high-frequency power supply. 7. A reactive gas is supplied to a vacuum chamber in which a sample stage holding a substrate to be processed is provided, and a high-frequency power of a predetermined level is repeatedly or intermittently supplied to the vacuum chamber. A plasma generating step of generating plasma comprising the reactive gas in the vacuum chamber by alternately and repeatedly supplying a high-frequency power of a level and a low level, and a bias voltage applying step of applying a bias voltage to the sample stage. The plasma generating step includes an energy beam irradiation step of irradiating the reactive gas with an energy beam during a period in which the predetermined level of high-frequency power is not supplied or a period in which the low-level high-frequency power is supplied. A plasma processing method comprising: 8. The plasma processing method according to claim 7, wherein the energy beam is vacuum ultraviolet light. 9. The plasma processing method according to claim 7, wherein the energy beam irradiating step includes a step of irradiating the reactive gas with the energy beam substantially parallel to the sample stage. 10. The method according to claim 1, further comprising a step of irradiating the reactive gas with an energy beam before starting to supply the predetermined level of high-frequency power or the high-level high-frequency power in the plasma generation step. The plasma processing method according to claim 7, wherein: 11. The method according to claim 11, wherein the bias voltage applying step is performed during at least a part of a period during which the predetermined level of high-frequency power is not supplied or a period during which the low-level high-frequency power is supplied in the plasma generating step. 8. The plasma processing method according to claim 7, further comprising a step of applying a positive bias voltage to said sample stage.