JPH03130370A - Device and method for plasma treatment - Google Patents

Abstract

PURPOSE:To simultaneously satisfy the treating condition and desired various working characteristics by providing a DC bias voltage impressing means and a means for synchronizing and mixing RF and DC voltages to a surface treating device for impressing an RF bias voltage on a substrate to be treated. CONSTITUTION:A pulse microwave from its generator 17 is introduced into a plasma producing chamber 3 through a waveguide 1, and the gas supplied is converted to plasma by its resonance effect and an exciting solenoid 6 and forced out into a treating chamber 9 to treat the surface of a substrate 11. A DC generator 32 for impressing a DC bias voltage, a means 40 for synchronizing the generating times of the microwave and RF and DC voltages and a mixing means 41 for impressing both voltages on the substrate 11 without interference are provided to the device. The floating potential generated on the substrate is optionally controlled by independently adjusting the magnitude of the RF and DC voltages. Consequently, the treating condition when a thin film is formed on the substrate or the substrate is etched can be widely changed, and the substrate is treated under optimum conditions.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention applies dry etching or CVD (CVD) using microwave plasma in the manufacture of semiconductor devices.
Chemical Vapor Deposition
The present invention relates to a plasma processing apparatus and a plasma processing method that perform surface treatment such as forming a thin film using the method (1), and particularly relates to a plasma processing apparatus and a plasma processing method that perform surface treatment by applying an RF bias voltage to a processing substrate.

[Conventional technology]

In plasma processing equipment that etches or forms thin films on substrates in order to manufacture semiconductor devices, etching anisotropy is important during etching.

Damage to the substrate surface, etching processing speed, and when forming a thin film, the composition of the film such as the bonding state between atoms, etc.
3. It is required to arbitrarily control the film quality such as aqueous property, the stress applied to the film, and the step coverage. However, it is not easy to realize a device with performance that satisfies each of these conditions at the same time.In recent years, one device that has the possibility of satisfying these conditions is the ECR (Electron Cycler).
Microwave plasma processing apparatuses using Otron Re5onance plasma are attracting attention. ECR plasma is based on the principle of accelerating electrons using the resonance effect of a magnetic field and microwaves, and using the kinetic energy of the electrons to ionize gas to generate plasma.

Electrons excited by microwaves move circularly around magnetic lines of force, and the condition where centrifugal force and Lorentz force are balanced is called the ECR condition. The centrifugal force is srω8. When the Lorentz force is expressed as -qrωB, the condition for their balance is ω/B = q/m. Here ω
is the angular frequency of the microwave, B is the magnetic flux density, and q/m is the specific charge of the electron. The industrially accepted microwave frequency of 2.45 GHz is generally used, and the resonant magnetic flux density in that case is 875 Gauss.

In ECR type plasma etching and CVD equipment, in order to increase the density of plasma and perform efficient etching or thin film formation, the microwaves introduced into the plasma generation chamber to generate plasma must be adjusted to a peak level. It is necessary to apply it in the form of a large power pulse. Furthermore, in etching, in order to perform highly anisotropic processing, an RF bias voltage is applied between the substrate to be processed and the plasma. Furthermore, RF is Radio F.
It is also referred to as high frequency in this field, and is a frequency in the range of approximately 50 KHz to several + MH2. Furthermore, in thin film formation, by applying an RF bias voltage in the same way as in the case of etching, it is possible to uniformly fill grooves and holes on the substrate surface with a dense film. It is possible to eliminate this and create a flat surface.

The reason is that when plasma is generated, the substrate surface (
(or the surface of a thin film formed on a substrate surface), a so-called floating potential is generated due to the difference in mobility between electrons and ions present in the plasma, but when an RF bias voltage is applied, the magnitude of this floating potential is Therefore, the energy of ions directed toward the substrate surface and thin film surface can be controlled. In addition, when an RF bias voltage is applied, an electric field is generated not only perpendicularly to the substrate but also horizontally, and this effectively acts on film formation. One of the reasons is thought to be that the parts become easier to scrape off.

As an ECR plasma etching and CVD apparatus as described above, the one shown in FIG. 9, for example, is known. The configuration and operation of this device will be outlined below. First, plasma generation chamber 3. The processing chamber 9 is evacuated by an evacuation means (not shown), and pulsed microwaves generated by the microwave generator 17 are supplied to the plasma generation chamber 3 through which Nt gas, for example, is supplied from the gas supply means 4. The plasma is introduced into the plasma generation chamber 3 via a waveguide l which is a transmission means. Between the waveguide 1 and the plasma generation chamber 3, there is a side of the waveguide 1 under atmospheric pressure and a side of the plasma generation chamber 3 that is evacuated.
A vacuum window 2 is provided to airtightly isolate the A metal plate having a large-diameter open lower center is attached to the lower part of the plasma generation chamber 3, and this metal plate and the plasma generation chamber 3 constitute a semi-open microwave resonator.

An excitation solenoid 6 is arranged outside this resonator,
A magnetic field that satisfies the ECR conditions is generated within the resonator to generate plasma within the resonator. This plasma is pushed into the processing chamber 9 along the transfer path 13 formed by magnetic lines of force,
When monosilane gas (SiH◆), for example, is supplied from the gas supply means 12 into the space facing the substrate table 10 and activated by the plasma, activated species are generated by applying an RF bias voltage by the R1 generator 20. A thin film is formed on the surface of the substrate by reacting with the substrate 11, which is the sample to be processed.

Note that the wiring for applying an RF bias voltage to the substrate 11 is covered with a shield having a ground potential, and the peripheral surface of the substrate 11 is surrounded by a shield having a ground potential.

By supplying etching gas from the gas supply means 4 instead of N3 gas, this apparatus can also be used for etching substrates.

Problems with conventional ECR plasma etching, etching, and CVD apparatuses of this type are as follows. That is, plasma is generated only when microwaves are introduced into the plasma generation chamber. Therefore, when microwaves are not being generated during the microwave pulse period, no plasma is generated.When applying an RF bias voltage, when plasma is being generated, the plasma acts as a load, so impedance matching can be achieved. It is possible to apply appropriate voltages on the substrate. However, when microwaves are not being generated and plasma is not being generated, there is no load from the R1 generator 20's perspective, and matching cannot be achieved.On the other hand, when plasma is being generated, the RF bias voltage is If this is adjusted, a mismatch will inevitably occur when plasma is not generated, and a high voltage will be applied to the substrate. This high voltage may reach about IKV, which causes discharge to occur on the substrate surface, causing a crater on the substrate surface and causing damage (first problem).

Furthermore, during plasma generation, a floating potential is generated on the substrate surface as described above, but this floating potential is controlled by the RF bias voltage, and when the RF bias voltage is applied, the plasma impedance ( (approximately determined by the power of the microwave supplied).

Therefore, when performing substrate surface treatment with ions in plasma under a certain microwave power, the optimal value of floating potential (temporal average value), since ions in plasma are difficult to follow the high frequency RF, When an RF bias is applied, the temporal average value of the floating potential becomes a problem.

), the value (peak value) of the RF bias voltage is uniquely determined to a certain value.On the other hand, in various processes, the optimal value (peak value) of the floating potential controlled by this RF bias voltage is The average value and the optimal value (peak value) of the RF bias voltage itself to bring about that value may not match.In other words, the peak value of the RF bias voltage is determined by the floating potential as the optimal average value. The peak value of the RF bias voltage itself may be an inappropriate value.As a result, etching or CV
There was a process in which it was difficult to set the processing conditions when performing D to satisfy various desired processing characteristics at the same time, and it was difficult to control the results of the process (second problem). for example,
In thin film formation, even if the peak value of the RF bias voltage is the optimum value for film quality, the stress applied to the film may become too large. Similarly, in etching, in order to improve anisotropy, Even if the peak value of the RF bias voltage is optimal for this purpose, the substrate surface may be seriously damaged by ion spatter in the plasma.

Therefore, among the first problem and the second problem,
ECR plasma enching that solves the first problem, C
As a VD device, a device having the configuration shown in FIG. 10 was proposed by the same applicant in Japanese Patent Application No. 63-275786. The configuration and operation of this device will be outlined below.

Note that the same members as in FIG. 9 are designated by the same reference numerals, and their explanations will be omitted.

In the apparatus shown in FIG. 1O, the RF bias voltage is applied to the substrate 11 by a synchronous pulse generation circuit 22 in synchronization with the microwave pulse, and the microwave is generated within the microwave pulse period. No RF bias voltage is applied to the substrate during the time period during which no RF bias voltage is applied.

Therefore, this device solves the first problem in the device shown in FIG. 9, that is, a high voltage is continuously applied to the substrate, discharge occurs on the substrate surface, and a crater is formed on the substrate surface, resulting in damage. problems can be solved.

[Problem to be solved by the invention]

However, the ECR plasma etching in FIG.
This second problem, which cannot be solved by some CVD apparatuses in the apparatus shown in FIG. 9, will be explained in more detail.

As mentioned above, plasma is generated only when microwaves are introduced into the plasma generation chamber, so the RF bias voltage is applied only when plasma is generated during the microwave pulse period. Then, impedance matching is performed using the plasma as a load, and an appropriate voltage is applied to the substrate. However, in the apparatus shown in FIG. 10, the time width of the RF bias voltage application at this time is the same as the time width of the microwave pulse, and the magnitude is also constant.For example, the RF bias voltage applied to the substrate is If you try to increase the voltage, the time width RF is the same as the microwave pulse.
A high voltage must be output from the generator, however, as mentioned above, there is an optimum value as the average value of the floating potential controlled by the RF bias voltage, and an optimum value of the RF bias voltage itself to produce that value. may not match the peak value of Therefore, in a configuration that simply generates an RF bias voltage with the same duration and constant magnitude as the microwave pulse, as in the device shown in Figure 1O,
In order to generate a predetermined floating potential, an RF bias voltage having a peak value greater than the optimum value must be applied for a longer time than necessary, and as a result, various desired processing characteristics can be simultaneously satisfied. Can not do it,
A specific example thereof will be explained below.

When forming a thin film on a substrate, for example, in order to improve step coverage at a stepped portion on the substrate surface, it is necessary to increase the applied RF bias voltage so that the magnitude of the floating potential generated on the substrate exceeds a certain threshold. , it is necessary to deposit the 'fig film on the sidewalls of the stepped portion by the sputtering effect of ions. However, the value of the floating potential that is controlled by the RF bias voltage and that promotes the sputtering phenomenon for ions is a temporal average value as described above, whereas the voltage that actually appears on the substrate is relatively Has a large amplitude (peak). For this reason, the peak value of the RF bias voltage applied with the same time width and constant magnitude as the microwave pulse is set to a large value that produces a floating potential value (average value) sufficient to produce the sputtering effect. Then, within the so-called sheath that exists between the plasma and the substrate surface, electrons.

Acceleration and deceleration of ions are repeated continuously during the time span, and the quality of the film and the amount of stress applied to the film change. Therefore, if an RF bias voltage with a large amplitude is applied for a longer time than necessary, the stress applied to the film quality, II*, may not be appropriate. In particular, when forming a thin film of silicon nitride, stress on the film tends to become excessive.

The first object of the present invention is to be able to widely control the average value of the floating potential generated on the surface of a substrate to be processed to a desired value, and to control the composition of the film when forming a thin film.

It is an object of the present invention to provide a plasma processing apparatus that can arbitrarily control film quality and stress applied to the film, and in etching, can arbitrarily control anisotropy, damage to the film, and processing speed.

A second object of the present invention is to provide a plasma processing method that can control each of the above characteristics in thin film formation or etching.
It is an object of the present invention to provide a plasma processing method suitable for optimizing the film quality and the stress applied to the film and realizing good step coverage.

(Means for Solving !!lI%Il) In order to achieve the above first object, the present invention provides a microwave generator which is a pulsed microwave generating means, and a microwave transmission means for transmitting the microwave. A waveguide is coupled with the waveguide to introduce the microwave, and the gas supplied through the gas supply means is turned into plasma by the resonance effect with the microwave to generate active atoms. An excitation solenoid that generates magnetic lines of force for generating one molecule or ions is provided, and an opening whose axis coincides with the central axis of the magnetic flux generated by the solenoid is provided on the side opposite to the waveguide that transmits the microwaves. a plasma generation chamber having a plasma generation chamber, and a substrate whose surface is etched or a thin film is formed by the active atom molecule or ion which is coupled to the plasma generation chamber through the opening and flows out from the opening along the lines of magnetic force. Plasma processing comprising: a processing chamber arranged in the substrate; an RF generator serving as an RF generating means for applying an RF bias voltage to the substrate; and a vacuum evacuation system for evacuating the plasma generation chamber and the processing chamber. In the apparatus, the plasma processing apparatus further includes a DC generating means for applying a DC bias voltage in addition to the RF bias voltage, and a generation timing of the pulsed microwave, the RF bias voltage, and the DC bias voltage. The apparatus includes a synchronizing means for synchronizing, and a mixing means for applying the RF bias voltage and the DC bias voltage to the substrate without interference.

Further, in order to achieve the second object, according to the present invention, pulsed microwaves are introduced into a vacuum container in which a DC magnetic field is generated, and a resonance effect between the DC magnetic field and the microwaves is generated. A plasma that converts gas introduced into the vacuum container into plasma, and while transporting the plasma along the DC magnetic field, etches or forms a thin film on a substrate arranged in the transport path and to which an RF bias voltage is applied. In the processing method, the RF bias voltage is applied to the substrate in synchronization with the pulsed microwave, and the magnitude of the RF bias voltage is varied according to a preset time change within the pulse width of the microwave. The surface treatment shall be performed while

[Effect]

By simultaneously applying an RF bias voltage and a DC bias voltage to the substrate, it is possible not only to match the processing conditions to desired conditions, but also to widen the range of processing conditions. That is, when a bias voltage is applied to the substrate, the substrate exhibits a potential such that the total amount of charge on the substrate becomes zero.

Therefore, first, when only an RF bias voltage is applied to the substrate, 74. (Even if tz is about to accumulate, the center of the oscillating potential waveform of the substrate moves so that this accumulation becomes zero. This center potential.

That is, the floating potential varies depending on the magnitude of the RF bias voltage, and since the RF bias voltage is applied, it also depends on the impedance of the plasma. When a DC bias voltage is further applied to the substrate whose floating potential is determined in this way, the substrate potential further moves so that the accumulated charge becomes zero while this DC bias voltage is applied. Therefore, by independently changing the magnitudes of the DC bias voltage and the RF bias voltage, it is possible to control the value of the floating potential over a wide range of I, and as a result, the processing conditions for bottom film or etching can be expanded.

In other words, when the floating potential is controlled by an RF bias voltage, the floating potential felt by ions involved in processing the substrate is a temporal average value, but when the floating potential is sensed by the ions involved in processing the substrate, for example, an RF bias voltage with a large amplitude (peak) is applied to the substrate surface. is applied. As mentioned above, for various processing characteristics, the optimum value (peak value) of the RF bias voltage and the optimum value (average value) of the floating potential due to the application of the RF bias voltage may not match, so this large peak The film quality etc. may be adversely affected by the RF bias voltage having .

However, if a DC bias voltage is also applied at the same time, the DC
Due to the unique effect of the bias voltage, the average value of the floating potential can be shifted independently of the RF bias voltage. Therefore, by simply applying an RF bias voltage with a small peak value, a floating potential (average value) equivalent to that when applying an RF bias voltage with a large peak value can be obtained.
can be caused. Conversely, when it is desired to apply an RF bias voltage having a large peak value, it is also possible to reduce the value (average value) of the floating potential.

Therefore, both the average value of the floating potential and the peak value of the RF bias voltage can be set to optimal values at the same time.

Furthermore, if synchronization with the pulsed microwave is made only with the RF bias voltage and a DC bias voltage is continuously applied to the substrate, when plasma is not generated, the substrate The potential moves and D
The substrate surface may be damaged depending on the magnitude of the C bias voltage. For this reason, there arises a problem that the magnitude of the DC bias voltage applied to the substrate is limited and the range of processing conditions is narrowed. However, in the present invention, the RF bias voltage and the
Both the RF bias voltage and the DC bias voltage are applied in synchronization with pulsed microwaves, and when there is no plasma in the plasma generation chamber, neither the RF bias voltage nor the DC bias voltage is applied to the substrate, so there is no possibility that the substrate surface will be damaged. There is no.

Next, an RF bias voltage to be applied to the substrate is generated in synchronization with the pulsed microwave, and the surface is treated while changing the magnitude of the RF bias voltage according to a preset time change within the pulse width of the microwave. By using a surface treatment method that performs the following, it is possible to widen the range of treatment conditions while preventing discharge on the substrate. In other words, even if it is desired to supply an RF bias voltage with a large peak in order to obtain a sufficient floating potential (average value) for a bottom film, etc., a sufficient floating potential cannot be obtained under conditions where the RF bias voltage can be applied. There may be cases where the desired film quality cannot be obtained. In such a case, if you apply an RF bias voltage whose peak value is shorter than the microwave pulse width, you can apply an RF bias voltage with a high peak value without increasing the average power. This prevents the formation of a dense film on the sides of the width groove. A thin film material deposited on the groove entrance surface is sputtered into the groove so as to close the groove entrance, and R
Film quality can be improved without increasing the average power from the F generator.

That is, as described above, in order to deposit a thin film on the side walls of the groove, that is, the side walls of the stepped portion, with good step coverage, the applied RF bias voltage should have a large peak, and the temporal average value of the floating potential should be adjusted. It is necessary to increase the sputtering effect by ions by increasing the amount of ions. However, the sputtering effect does not occur unless ions are accelerated at an acceleration voltage equal to or higher than a certain threshold (in this case, the floating potential corresponds to the acceleration voltage). This threshold voltage varies depending on the material to be sputtered, but is approximately several tens of volts. If an RF bias voltage of such a magnitude that this sputtering effect can be sufficiently expected is continuously applied to the substrate, the stress applied to the film may become a problem. however,
As mentioned above, if the RF bias average power is kept low and the peak value of the RF bias voltage is increased so that the temporal average value of the short-term floating potential increases only for a short time, stress problems may occur. It is possible to achieve a sufficient six-butter effect.

In this way, according to the method of the present invention, the film quality can be freely controlled without damaging the substrate surface or increasing the average RF power value, and processing conditions can be easily optimized. becomes.

〔Example〕

E, which is a plasma processing apparatus constructed based on the present invention.
An embodiment of CR, type plasma etching, and CVD equipment is shown in FIG. 1. Here, the same parts as in FIG. In the figure, a synchronizing means 40 for synchronizing the generation timing of the pulsed microwave, the RF bias voltage, and the DC bias voltage is connected to a synchronizing pulse generating circuit 22 and a pulse signal transmitting means 31. FIG. 2 shows a block diagram of the synchronous pulse generation circuit 22.
An alternating current is generated at a frequency of approximately 0 tl z, and the pulse generator 222 converts this into a rectangular wave. This rectangular wave is transmitted to the microwave generator 17 by the pulse signal transmission means 31 through the output buffer 223 which has a current amplification function and consists of an operational amplifier and an IC to generate a microwave, and this rectangular wave is transmitted to the RF bias modulation circuit 23. and DC bias modulation circuit 33, these modulation circuits 22.3
3 outputs R with the desired waveform, here the magnitude.
RF bias voltage and DC bias voltage, respectively.
The generator 20 and the DC generator 32 output the microwave simultaneously. Both the RF bias modulation circuit 23 and the DC bias modulation circuit 33 have the circuit configuration shown in FIG. The set data is sent as an electrical signal from the modulation circuit 29 to the RF generator 2 at the subsequent stage via the output circuit 30.
0 and DC generator 32, RF generator 20°D
Bias voltages of desired waveforms, here desired magnitudes, are generated from the C generators 32 at the same time as the microwaves, and are input to the RF-DC bias mixing circuit 41 .

The RF-DC bias mixing circuit 41 is, for example, shown in FIG.
), the input end terminal 41a is connected to the DC generator 32.
The output terminal 41b is connected to the output terminal of the RF generator 20 through the input terminal 41c of this circuit. It resonates with the frequency of the RF wave.It is configured as a parallel resonant circuit consisting of an inductance L8 and a capacitor C8, and serves to guide the DC bias voltage and the RF bias voltage to the substrate without interference.

As a result of adopting the above configuration, in the plasma processing apparatus of this embodiment, the RF bias voltage and the DC bias voltage can be controlled independently, and the average value of the floating potential can be controlled independently of the peak value of the RF bias voltage. can be controlled.

Next, FIG. 5 shows an embodiment of the configuration of a microwave plasma processing apparatus that enables the plasma processing method of the present invention.
In the figure, the same members as in FIG. 10 are given the same reference numerals, and their explanations will be omitted.

A synchronization pulse generation circuit 22 for synchronizing the application of an RF bias voltage to the substrate 11 with pulsed microwaves includes:
It has a configuration similar to that shown in FIG. 2, and transmits a rectangular wave to the microwave generator 17 and the RF bias modulation circuit 23 through the output buffer 223, and from the RF bias modulation circuit 23, a signal having a preset magnitude is transmitted. A voltage that changes according to time changes is outputted and inputted to the RF generator 20, and the RF generator 2
The size changes from 0 according to the input time change. Outputs a modulated RF lightning voltage. As shown in the block diagram of FIG. 6, the RF bias modulation circuit 23 includes a trigger circuit 27, a modulation signal generation circuit 28a, and a modulation circuit 29.
and an output circuit 30. By inputting the rectangular wave output from the synchronous pulse generation circuit 22 to the trigger circuit 27, the modulation signal generation circuit 28a is activated in synchronization with the microwave pulse. A signal voltage that changes according to a set time change is inputted to the modulation circuit 29,
The waveform shaped by the modulation circuit 29 is input to the RF generator 20 via the output circuit 30 having a current amplification function, and the magnitude is set in advance from the RF generator 20 in synchronization with the microwave pulse. An RF lightning voltage is output that changes with time. The RF bias modulation circuit shown in FIG. 6 is somewhat different from the one shown in FIG. 3, and the RF lightning voltage waveform can be made more complicated by the function of the modulation signal generation circuit 28a. Can be done.

FIGS. 7 and 8 show examples of temporal changes in RF power output from the RF generator 20 in synchronization with microwave pulses.

Figure 7 shows the time period during which microwaves are generated during one period of microwave pulses, and a predetermined bottom, in synchronization with pulsed microwaves with large peak power for efficient etching or *H shadow formation. The peak value of the peak value shows the case where a thin film is formed on the substrate surface by outputting power from the RF generator 20 (Fig. 5) in which the base portion P of the RF power required for the film rate changes to the peak power P1 for a short time. High peak power PI
(Gutter that can cause sputtering effect) is output, the substrate 1
1, a high RF bias voltage is applied, and therefore, the floating potential on the substrate also becomes large during the time when the peak power P is being output. As a result, when the substrate surface has steps or irregularities, for example, a thin film material deposited laterally protruding from the surface of the convex portion is sputtered by ions contained in the plasma or active species accelerated by the ions. The bottom film is applied to the concave portions and side walls without being hindered by the deposited material on the convex portions, and the film thickness is increased over the entire surface of the concave and convex portions and side walls without increasing the average power output from the RF generator 20. A uniform thin film with good step coverage can be formed. That is, when an RF bias voltage that generates a floating potential at which a sufficient sputtering effect can be expected is continuously applied to the substrate, the problem of stress applied to the film was particularly noticeable. nai
As a result of employing the method of the present invention, it is also possible to easily form a material (one of the methods of the present invention, which is used as a puffy basin film, etc.).

Furthermore, since the application of the RF bias voltage to the substrate 11 is performed within the time period in which microwaves are being generated, a high voltage may appear on the substrate surface due to impedance mismatch between the RF generator side and the plasma side. Since no electrical discharge occurs on the substrate surface, no damage to the substrate surface occurs.

Figure 8 shows a time change in which the RF power generated within the time width of microwave generation during one period of a microwave pulse rises at an angle and gradually decays over time. By making a change, the fifth
Although not particularly shown in the figure, the DC cut capacitor interposed between the substrate table 10 and the RF generator 20 prevents non-uniformity in the RF bias voltage caused by changes in time, etc. The bottom film can be formed under different film formation conditions.

〔Effect of the invention〕

As described above, according to the present invention, the configuration of an ECR type plasma etching and CVD apparatus includes a DC generating means for applying a DC bias voltage in addition to an RF bias voltage, a pulsed microwave and an RF The configuration includes a synchronizing means for synchronizing the generation timing of the bias voltage and the DC bias, and a mixing means for applying the RF bias voltage and the DC bias voltage to the substrate without interference, and the RF bias voltage is applied to the substrate. and a DC bias voltage were applied in synchronization with the pulsed microwave, so
Both the RF bias voltage and the DC bias voltage are applied to the substrate only when microwaves are introduced into the plasma generation chamber and plasma is being generated. By independently adjusting the magnitude of each voltage, the floating potential generated on the substrate can be arbitrarily controlled, making it possible to widely change the processing conditions when forming a thin film on the substrate or performing etching. This results in the effect that substrate processing can be performed under optimal conditions.

Therefore, in forming a thin film, the film composition, film quality, stress applied to the film, etc. can be simultaneously controlled to desired properties. In addition, in etching, anisotropy, damage to the film,
Processing speed can be controlled arbitrarily at the same time.

Further, according to the present invention, pulsed microwaves are introduced into a vacuum container in which a DC magnetic field is generated, and the gas introduced into the vacuum container is turned into plasma by the resonance effect between the DC magnetic field and the microwaves. While transporting plasma along a DC magnetic field, plasma processing is performed to etch or form a thin film on a substrate placed in a transport path and to which a t'LRF bias voltage is applied, in synchronization with pulsed microwaves. This plasma processing method performs surface treatment while applying an RF bias voltage to the substrate surface and changing the magnitude of the RF bias voltage within the microwave pulse width according to a preset time change. This eliminates the need for high voltages to be applied, making it possible to apply an optimal RF bias voltage to the substrate to perform etching or thin film formation, and without increasing the average power output from the RF generator. By applying a time-varying RF bias voltage corresponding to the desired film quality formation to the substrate, it becomes possible to perform surface treatment in which film quality can be controlled over a wide range.

Therefore, according to the plasma processing method of the present invention, a thin film having good step coverage can be formed by the sputtering effect while ensuring desired film quality and stress applied to the film.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a plasma processing apparatus equipped with DC generator synchronization means and the like according to an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of a synchronous plasma generation circuit constituting the synchronization means, and FIG. The figure is a block diagram showing the circuit configuration of the RF bias modulation circuit and the DC bias modulation circuit, and Figure 4 is the RF-DC
A circuit diagram showing an example of the configuration of a bias mixing circuit, FIG. 5 is an apparatus configuration diagram showing an example of the configuration of a microwave plasma processing apparatus that enables the plasma processing method of the present invention, and FIG. 6 is an RF A block circuit diagram showing the circuit configuration of the bias modulation circuit, FIGS. 7 and 8 are diagrams illustrating temporal changes in RF power output from an RF generator in synchronization with pulsed microwaves, and FIG. 9 respectively. 10 is the configuration of a conventional RF bias voltage application type plasma processing apparatus, and FIG. 10 is a diagram of the apparatus structure of a microwave plasma processing apparatus previously proposed by the applicant of the present application. 1: Waveguide (microwave transmission means) 3: Plasma generation chamber, 6: Excitation solenoid, 9: Processing chamber, 11: Substrate, 13: Transfer path, 17: Microwave generator (microwave generation means), 20: RF generator (RF generation means), 22
: synchronous pulse generation circuit, 23: RF bias modulation circuit,
32: DC generator (DC generation means), 33: DC bias modulation circuit, 41-: RF-DC bias mixing circuit (mixing means)

Claims (1)

[Scope of Claims] 1) A pulsed microwave generating means, a means for transmitting the microwave, and a device coupled to the microwave transmitting means to which the microwave is introduced and supplied via a gas supply means. an excitation solenoid that generates magnetic lines of force for generating active atoms, molecules or ions by converting the gas into plasma by a resonance effect with the microwave, and the axis thereof is the central axis of the magnetic line of force generated by the solenoid. a plasma generation chamber having a matching aperture on the side opposite the microwave transmission means; and the active atoms, molecules or ions coupled to the plasma generation chamber via the aperture and flowing out from the aperture along the magnetic field lines. a processing chamber in which a substrate whose surface is etched or a thin film is formed is disposed, and an RF chamber for applying an RF bias voltage to the substrate;
A plasma processing apparatus comprising a generation means and a vacuum evacuation means for evacuating the plasma generation chamber and the processing chamber, the DC generation means for applying a DC bias voltage in addition to the RF bias voltage; synchronizing means for synchronizing generation timings of the pulsed microwave and the RF bias voltage and the DC bias voltage;
A plasma processing apparatus comprising a mixing means for applying an F bias voltage and the DC bias voltage to the substrate without interference. 2) Pulsed microwaves are introduced into the vacuum vessel in which a DC magnetic field is generated, and the gas introduced into the vacuum vessel is turned into plasma by the resonance effect of the DC magnetic field and the microwaves, and the plasma is converted into plasma. In a plasma processing method that etches or forms a thin film on a substrate arranged in a transfer path and to which an RF bias voltage is applied while being transferred along a DC magnetic field, etching is performed on the substrate in synchronization with the pulsed microwave. While applying the RF bias voltage,
A plasma processing method characterized in that surface treatment is performed while changing the magnitude of the RF bias voltage according to a preset time change within the pulse width of the microwave.