JPH0817807A - Plasma treatment method - Google Patents

Abstract

PURPOSE:To achieve etching with a fine pattern and a large aspect ratio by changing an acceleration voltage for accelerating ions in plasma toward a material to be etched over a critical potential and alternately repeating etching and film formation for the material to be etched. CONSTITUTION:A means for switching the value of an acceleration voltage generated at a sample stand 5a over a critical potential consists of an output voltage control device 16 and an output waveform control device 17. The output voltage control device 16 controls the DC voltage of a DC power supply 15. The output waveform control device 17 controls the timing for changing the DC voltage controlled by the output voltage control device 16. Then, gas is turned into plasma under the same plasma formation conditions (microwave power: 400W, gas flow rate: 70SCCM, pressure: 0.01Torr, high-frequency power: 100W) for etching gases SF6 and C2Cl3F3 and a DC bias voltage applied to a sample stand 5a is changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing method, and more particularly to a plasma processing method suitable for performing processing by alternately performing etching and deposition.

[0002]

2. Description of the Related Art As semiconductor devices become finer, circuit pattern dimension processing systems and low damage processing methods are becoming increasingly important technical issues. In particular, in the device in the submicron region, the device structure has been three-dimensional due to the limitation of the chip area. For this reason, it is required to process a film type having a larger processing depth ratio than the processing dimension width, that is, a film type having a large aspect ratio with high dimensional accuracy.

[0003] As a conventional technique for solving such a demand, there is a technique disclosed in Japanese Patent Application Laid-Open No. 60-50923. This is Si or Poly-Si
In the case of the etching, a mixture of SF ₆ gas contributing to the etching action, N ₂ gas contributing to the formation action of the silicon nitride protective film, and other gases is used as an etching gas. , The concentration is changed periodically. As a result, the etching step and the step of forming a silicon nitride protective film are alternately repeated to perform high-speed etching with high dimensional accuracy.

On the other hand, Japanese Unexamined Patent Publication No. 61-41132 discloses a technique for changing the voltage applied to the electrodes.
And Japanese Unexamined Patent Publication No. 61-13625. In these prior arts, plasma processing is performed by changing the voltage applied to the sample.

[0005]

In the former of the prior art, the etching process is performed by changing the gas composition and concentration of the plasma, so that the state of the plasma changes each time. Therefore, when the gas composition or concentration is changed, the plasma state is changed from the previous plasma state to a new plasma state. That is, it is necessary to quickly exhaust the remaining ions and radicals. However, since the processing container has a certain internal volume, it takes a long time to switch the plasma state, and there is a problem that the entire processing time becomes long. If this is to be improved even a little, the size of the exhaust device is increased in order to shorten the exhaust time. At the same time, it is necessary to separately control the amount of exhaust during processing and during switching, and the apparatus and control technology for that purpose become complicated.

The latter is intended to control the incident energy of ions in the plasma and to simply improve the plasma characteristics such as an etching rate and a selectivity.

It is an object of the present invention to provide a plasma processing method capable of performing etching with a fine pattern and a large aspect ratio.

[0008]

Means for Solving the Problems The present inventors have gained a viewpoint on the present invention only through various experiments. It has the following contents. A certain component gas, which has a component that reacts with the material to be etched of the sample and a component that forms a deposited film, is turned into plasma under predetermined plasma conditions. An acceleration voltage is applied to the ions in the plasma, and the sample is processed using the plasma in which the ions are incident on the sample. At this time, it was found that when the value of the acceleration voltage was changed, there were a potential at which the etching action predominantly occurred and a potential at which the deposition action predominantly occurred due to the reaction with the object. It was also found that this potential had a potential at which the etching action and the deposition action were balanced. Hereinafter, this balanced potential is referred to as “critical potential.” That is, the present invention uses a mixed gas having a component that reacts with the material to be etched and a component that forms a deposited film and also has a critical potential as an etching treatment gas, and performs etching. The process of converting the processing gas into plasma using a microwave ECR under a reduced pressure of about 0.01 Torr, and changing the accelerating voltage for accelerating the ions in the plasma toward the material to be etched across the critical potential, This is achieved by using a method of performing etching with a fine pattern and a large aspect ratio, which has a step of alternately repeating etching and film formation with respect to the etching material.

[0009]

[Function] A gas having a critical potential is generated at a low pressure of 0.01 Torr level to generate a microwave plasma using ECR discharge, and an acceleration voltage for accelerating the ions in the plasma toward the sample is set to the critical potential. Since the ions in the plasma can be drawn into the sample with a small acceleration voltage, the etching action predominantly occurs in the sample when the acceleration voltage is higher than the critical potential, and the acceleration voltage is higher than the critical potential. When the value is small, the deposition action occurs predominantly on the sample, anisotropic etching with little damage can be performed, and a material to be etched having a fine pattern can be processed. As a result, the etching process and the film forming process are alternately performed without switching the processing gas, and a material to be etched having a fine pattern and a large aspect ratio can be processed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a microwave plasma processing apparatus utilizing an ECR discharge, in this case an etching apparatus. A discharge tube 1 made of quartz is provided at the upper opening of the vacuum processing container 4. The lower part of the vacuum processing container 4 is provided with an exhaust part 3 connected to a vacuum exhaust device (not shown). In the vacuum processing container 4, a wafer 6 as a sample
There is provided an electrode 5 having a sample table 5a on which is mounted. A discharge space 7 is formed above the sample table 5a in the discharge tube 1.

A waveguide 9 is provided above the discharge tube 1 so as to surround the discharge tube 1. In this case, at the end of the waveguide 9,
Magnetron 8 for transmitting 2.45 GHz microwaves
Is provided. An electromagnetic coil 10 is provided on the outer peripheral portion of the discharge tube 1 via a waveguide 9.

A gas inlet 2 for supplying an etching gas to the discharge space 7 is provided on a side of the vacuum processing container 4. A gas source (not shown) is connected to the gas introduction unit 2 via a mass flow controller 18.

On the outer circumference of the electrode 5, there is provided a ground electrode 11 which is insulated from the electrode 5, one end of which is located near the periphery of the sample table 5a and the other end of which is grounded. The electrode 5 was connected via a matching box 12. In this case, 13.56
A high frequency power supply 13 that oscillates a high frequency of MHz and a direct current power supply 15 connected via a low pass filter 14 are connected. The other ends of the high-frequency power supply 13 and the DC power supply 15 are grounded. An output voltage controller 16 is connected to the DC power supply 15, and an output waveform controller 17 is connected to the output voltage controller 16. In this case, the matching box 12 is configured by a capacitor coupling. The low-pass filter 14 cuts off the high-frequency voltage from the high-frequency power supply 13.

The mass flow controller 18 controls the etching gas from a gas source (not shown) at a predetermined flow rate and sends the etching gas into the discharge space 7. The discharge space 7 is depressurized and exhausted by an exhaust device (not shown), and is maintained at a predetermined pressure.

In this case, the means for converting the etching gas introduced into the discharge space 7 into plasma comprises a magnetron 8 and an electromagnetic coil 10. The etching gas in the discharge space 7 is turned into plasma by ECR discharge caused by the action of an electromagnetic field provided by the magnetron 8 and the electromagnetic coil 10.

In this case, the means for applying the incident energy to the wafer 6 to the ions in the plasma, that is, the means for generating the accelerating voltage on the sample stage 5a, is provided by the high frequency power supply 13 and the DC power supply 15. Become. A high-frequency voltage from a high-frequency power supply 13 and a DC voltage from a DC power supply 15 are applied to the sample table 5 a on which the wafer 6 is placed. By applying a high-frequency voltage to the sample stage 5a via the matching box 12 formed by a capacitor coupling, the high-frequency voltage is applied to the sample stage 5a in a DC floating manner, and a DC bias voltage is generated. The ions in the plasma are attracted to the sample stage 5a side, that is, the wafer 6 side by the DC bias voltage. Further, by applying a DC voltage to the sample stage 5a, the value of the DC bias voltage generated on the sample stage 5a is adjusted. This DC bias voltage is an acceleration voltage for accelerating ions in this case.

Further, in this case, the means for switching the value of the acceleration voltage generated on the sample stage 5a with the critical potential interposed therebetween includes an output voltage control device 16 and an output waveform control device 17. The output voltage control device 16 controls a DC voltage value of the DC power supply 15. The output waveform control device 17 controls the timing at which the DC voltage value controlled by the output voltage control device 16 changes. This timing is controlled periodically in this case.

In this case, the wafer 6 is formed by depositing a polysilicon layer as a wiring forming material on a Si substrate. In this case, this etching apparatus uses sulfur hexafluoride (SF ₆ ) and trichlorotrifluoroethane (C ₂ Cl ₃ F _{3 as} trade name CFC-11 as etching gas).
The polysilicon layer of the wafer 6 is etched by using the mixed gas of 3).

Next, both components of the etching gas, that is, S, are etched by the etching apparatus configured as described above.
F ₆ and C ₂ Cl ₃ F ₃ under the same plasma forming conditions (microwave power: 400 W, gas flow rate: 70)
SCCM, pressure: 0.01 Torr, high frequency power: 10
0W), the gas was turned into plasma and the DC bias voltage applied to the sample stage 5a was changed.
It will be described with reference to the drawings.

In the graph of FIG. 2, the vertical axis represents the etching rate, the lower axis represents the deposition rate, and the horizontal axis represents the DC bias voltage.

As is apparent from FIG. 2, SF ₆ always causes an etching phenomenon regardless of the magnitude of the DC bias voltage, and the etching rate increases as the DC bias voltage increases. This is because SF ₆ is separated into S and F components in the plasma, and F ions and F radicals in the reactive ion species and the F component, which is a free radical species, act as an etchant, regardless of the presence or absence of a DC bias voltage. However, it reacts in contact with polysilicon, which is the material to be etched, and a volatile reaction product of SiF ₄ is formed and removed from the sample. When the DC bias voltage is increased, not only F ions on the sample surface, The F ions in the plasma are incident on the sample, and the reaction with the F ions increases, and the F ions collide with the F radicals located near the surface of the sample to increase the contact between the F radicals and the polysilicon. This increases the etching rate.

On the other hand, C ₂ Cl ₃ F ₃ causes a deposition phenomenon in a range where the DC bias voltage is small, and an etching phenomenon in a range where the DC bias voltage is large. this is,
C ₂ Cl ₃ F ₃ is separated into C, Cl and F components in the plasma, and these components are a polymer of C or (CFx).
This is because a deposit as a reaction product of n, CxFy, CClxFy, and CxCly is formed, and the remaining components of Cl and F are present as an etchant. The F component as an etchant reacts with polysilicon as described above. To form a volatile reaction product, SiF ₄ , and the Cl component as an etchant also reacts with the polysilicon in the form of reactive ionic and free radical species to form S
A volatile reaction product of iCl ₄ is formed. here,
The film forming species and the etchant are present in the plasma regardless of the presence or absence of the DC bias voltage, and during the action of the DC bias voltage on the plasma, the deposits formed in the plasma adhere to the sample surface and The incidence of ions in the plasma on the plasma occurs simultaneously. In the range where the DC bias voltage is small, the incidence of ions in the plasma on the sample decreases, and the deposits adhere to the surface of the material to be etched on the sample, and the surface of the material to be etched can contact the etchant in the plasma. It disappears and a deposition phenomenon occurs. In the range where the DC bias voltage is large, the number of ions in the plasma entering the sample increases, and even if the deposits adhere to the surface of the material to be etched of the sample, the reactive ions as the etchant remain on the surface of the material to be etched. Is incident,
In addition to etching away the surface of the material to be etched, it also collides with the deposits to give energy to the deposits and decomposes the deposits into a state before the reaction. The action occurs. At this time, the reactive ions as the etchant and some of the ions of the film-forming species collide with the free radicals as the etchant near the surface of the sample to give energy to promote the reaction with the material to be etched. It acts to let you.

Further, it can be seen that C ₂ Cl ₃ F ₃ has a critical potential (V ₀ ) at which no deposition or etching occurs just at the boundary. The critical potential means a potential at which the deposition phenomenon and the etching phenomenon are reversed when the gas is turned into plasma under a predetermined plasma condition and the DC bias potential is changed. It has been found.

This indicates the following. C ₂ C
When l ₃ F ₃ is turned into plasma, a deposition action and an etching action occur simultaneously. At this time, when the DC bias voltage applied to the sample stage 5a is lower than the critical potential, the deposition effect is dominant. When the DC bias voltage applied to the sample stage 5a is increased within a range smaller than the critical potential, the ions in the plasma are accelerated with the increase in the DC bias voltage, and the etching action gradually increases. The dominance of sedimentation gradually diminishes. When the DC bias voltage increases beyond the critical potential, the ions in the plasma are further accelerated, and the etching action predominates over the deposition action, and the etching action gradually increases. When the DC bias voltage is equal to the critical potential, the deposition action and the etching action are in balance.

Further, SF not having the above-mentioned critical potential
₆ and a mixed gas of C ₂ Cl ₃ F ₃ having a critical potential (1:
A similar experiment was performed using 9). The result was a curve as shown by the broken line in FIG. As is apparent from the broken line curve, the mixed gas has a critical potential V ₀ ′.
And the DC bias voltage lower than the critical potential V ₀ 'predominantly causes the deposition action, and the DC bias voltage higher than the critical potential V ₀ ' predominantly causes the etching action. Moreover, when this mixed gas is used, the above C ₂
It can be seen that the etching rate was much more dependent on the DC bias voltage than when Cl ₃ F ₃ was used alone. From this, it was found that this mixed gas can be used as an etchant having a high bias voltage dependence of the etching rate.

Next, the case where an etching process is performed using a mixed gas having such characteristics will be described with reference to FIGS.

First, when a polysilicon film having a high aspect ratio is etched with a mixed gas at a bias voltage V ₁ ′ larger than the critical potential V ₀ ′, the undercut C becomes large as shown in FIG. , Dimensional accuracy cannot be ensured. Where 19 is a photoresist,
Reference numeral 20 is polysilicon, and 21 is a Si substrate.

Therefore, as shown in FIG. 3, the DC voltage superimposed on the DC-strayed high frequency voltage is controlled by the output voltage controller 16 and the output waveform controller 17, and the DC bias voltage is mixed for t ₁ seconds. The gas is set to V ₁ (negative potential) higher than the critical potential V ₀ ′, and is set to V ₂ (negative potential) lower than the critical potential V ₀ ′ for t ₂ seconds so as to be changed periodically.

Since the DC bias voltage value is large for the time t ₁ second, etching can be performed while accelerating ions in the plasma toward the wafer 6. Thereby, relatively anisotropic etching can be performed. However, due to the influence of free radicals, a slight undercut C ₀ occurs as shown in FIG. The size of the undercut C ₀ was about 1/5 to 1/10 of the etching amount d in the vertical direction. The time t ₁ is set within the range in which the undercut C ₀ does not exceed the allowable value.

Since the DC bias voltage value is smaller than the critical potential V ₀ ′ during the time t ₂ seconds, deposition can occur. As a result, the progress of the etching is stopped, the plasma polymer begins to be deposited on the entire surface of the wafer 6, and the polysilicon 2
A protective film is formed on the side wall surface of the pattern 0.

After the protective film is formed, a large DC bias voltage V ₁ is again applied to the sample table 5a to perform etching. The ions in the plasma accelerated by the large DC bias voltage V ₁ are perpendicularly incident on the wafer 6. As a result, the protective film deposited on the pattern bottom of the polysilicon 20 formed by the photo resist 19 is quickly removed by the ion sputtering action, and the pattern bottom of the polysilicon 20 is exposed and etching proceeds. Further, the protective film deposited on the pattern side wall surface of the polysilicon 20 is attacked by free radicals having extremely small physical energy, and is gradually removed by a chemical reaction between the free radicals and the components of the protective film.
Therefore, the time t ₂ for depositing a protective film, even if performed etching action between time t _1, the protective film deposited on the pattern side wall of the polysilicon 20 is set so as to leave.
The times t ₁ and t ₂ set in this way are stored in the output waveform control device 17 in advance, and are automatically switched.

In this manner, by alternately repeating the etching step and the deposition step, that is, the film forming step, a polysilicon film having a high aspect ratio as shown in FIG. 6 can be processed with high dimensional accuracy. It became.

As shown in FIG. 2, the large value of the DC bias voltage V ₁ is 1 / (1) of the total amplitude value Vpp of the high frequency voltage in order to prevent the ions from charging up to the sample.
It is smaller than 2. This is because the magnitude of the DC voltage superimposed on the high frequency voltage is restricted in order to obtain a high etching rate and perform etching without damaging elements formed on the sample.

That is, when the DC bias voltage value (negative potential) is larger than 1/2 of the total amplitude value Vpp of the high frequency voltage, the sample always has a negative potential, and only positive ions are attracted to the sample surface to be charged. I do. As a result, the positive ions (reactive ions) in the plasma eventually repel and do not reach the sample. As a result, the etching rate of the sample is significantly reduced. Further, if the charging potential at this time is large, it may cause deterioration or destruction of the gate portion of the element formed on the sample.

Therefore, in this embodiment, a negative DC voltage smaller than 1/2 of the total amplitude value Vpp of the high frequency voltage is applied to the sample table 5.
a of the high frequency voltage so that a part of the waveform of the high frequency voltage remains as a positive potential, and the electrons in the plasma are attracted by the positive potential part to neutralize the positive ions charged on the sample.

Further, in order to solve this charge-up problem, Japanese Patent Publication No. 56-37311 discloses
As described in detail, the transmission frequency of the high-frequency voltage needs to be about 100 kHz or more. There is no particular upper limit on the transmission frequency, but if a commercially available oscillator is used, an oscillation frequency up to about 27 MHz is appropriate.

As described above, according to the present embodiment, the high frequency power source 1
3 applies a high-frequency voltage to the electrode 5, thereby superimposing a direct-current voltage from the direct-current power supply 15 on a direct-current bias voltage generated on the sample table 5 a, and applying the direct-current bias voltage obtained by superimposing the direct-current voltage to the output voltage controller 16 and the output The critical voltage is changed by the waveform controller 17 so that the plasma generated in the discharge space 7 is not changed, that is, etching and deposition are performed on the wafer 6 without switching and supplying gas. That is, since the film formation can be performed alternately, compared to the conventional technique in which the sample is etched by alternately performing the etching and the deposition by switching the gas type, the gas replacement time is eliminated, and at least the gas is replaced. There is an effect that the processing time is shortened by the amount of time required for the replacement. For example, in a vacuum processing container having the same volume (20,000 cm ³ ) as that of the present embodiment, a gas of 70 SCCM is supplied into the vacuum processing container by using an exhaust device having an exhaust capacity of 500 l / sec, and the pressure is reduced to 0. The time required to switch the gas type from the state where the pressure is maintained at 01 Torr to the state described above is about 10 seconds, and the above-described effect increases as the number of times the gas type is switched increases. In other words, since it is not necessary to switch the gas at a high speed as in the related art, the size of the exhaust device can be reduced. Further, since there is no pressure control or switching control by switching the gas type, the apparatus and control technology are simplified.

The wafer 6 is etched by controlling the output voltage control device 16 to apply a DC bias voltage higher than the critical potential to the sample stage 5a, and a DC bias voltage lower than the critical potential is applied to the sample stage 5a. A protective film can be deposited on the wafer 6, and the output waveform control device 17 is controlled to alternately switch the timing of changing the value of the DC bias voltage across the critical potential. It is possible to perform etching step by step while protecting the etching side surface with a protective film, and it is possible to process a material to be etched having a depth or height higher than the pattern dimension width.

Further, since the processing is performed by microwave plasma utilizing ECR discharge, plasma can be generated under a low pressure of the order of 0.01 Torr, and ions in the plasma can be drawn into the wafer 6 with a small acceleration voltage. Therefore, anisotropic etching with less damage can be performed, and a material to be etched having a fine pattern can be processed. Thus, the material to be etched having a fine pattern and a large aspect ratio can be processed in addition to the above effects.

Further, the timing of switching between the etching operation and the deposition operation is set by the output waveform control device so that the undercut of the material to be etched falls within an allowable value during the etching, and the next etching process is performed during the deposition. Since the time is set such that the protective film on the side surface of the inter-etching remains, the processing can be performed with high dimensional accuracy.

Since the plasma generating means utilizing the action of the electromagnetic field and the DC bias voltage applying means provided by the high frequency voltage and the DC voltage, that is, the accelerating voltage applying means, are independent, the DC bias voltage is changed. Even if this is done, the state of plasma generation, that is, the state of electrons, ions, and free radicals in the plasma does not change, and etching can be performed in a state where the emission intensity is stable, and the end point of etching by emission spectroscopy can be easily determined. Can be done.

A high-frequency power supply 13 is connected to the sample stage 5a, and a high-frequency voltage is applied to control the DC voltage of the DC power supply 15 so that the DC bias voltage is の of the total amplitude of the high-frequency voltage generated from the high-frequency power supply 13. Accordingly, even in the case of a sample having an insulating material or an insulating film, electric charge is not accumulated in the sample, and etching can be performed without lowering an etching rate or deterioration or destruction of a gate portion of an element. Also, when a sample having an element structure having a lower MOS gate was etched by the etching method of this embodiment, no damage such as deterioration in breakdown voltage or destruction of the gate portion occurred.

In the microwave plasma processing apparatus for discharging by the ECR method using microwaves as in the present embodiment, the ion sheath width is generally about 0.1 mm. The time required to this ion sheath to pass ions (ti) is somewhat different depending on the type of ion, it is generally about 1~4 × 1/10 ⁷ seconds. On the other hand, 13.56 MHz usually used for industrial use
The half cycle time (tRF) of the high-frequency voltage waveform of 3. is 3.
7 × ¹¹⁰⁸ seconds. Therefore, 13.56MHz
At a high frequency voltage of, the ions cannot follow the ion sheath. Therefore, ions can be accelerated by generating a negative DC bias voltage as in the present embodiment.

The method using such a DC bias voltage is particularly effective when processing a material that can be electrically connected to the electrode 5 such as Si or a metal film. Further, the method using such a DC bias voltage is effective when the half cycle time tRF of the high frequency voltage waveform and the ion sheath passage time ti of the ions have a relationship of tRF <ti. The lower limit of the frequency of the high frequency power source 13 is about 2 MHz (tRF = 2.5 × 1/10 ⁷ seconds), and when the frequency is low, ions follow the AC voltage waveform and are accelerated. 15 reduces the effect of applying a DC voltage to the electrode 5 in a superimposed manner.

When the sample is electrically conductive, the DC power source 1 is used except for the high frequency power source 13 of this embodiment.
The plasma processing apparatus may be controlled only by 5.

Next, a second embodiment of the present invention will be described with reference to FIGS. 7 and 8.

In FIG. 7, the same members as those in FIG. 1 indicate the same members. This figure differs from FIG. 1 in that, in this case, only the high-frequency power source 23 having a frequency of 385 KHz is used as the acceleration voltage applying means. The high frequency power supply 23 is connected to the electrode 5 via the matching box 22. In this case, one end of the circuit of the matching box 22 is grounded, and the electrode 5 is DC-grounded. The high frequency power supply 23 has an output voltage control means 24.
Is connected.

The output voltage control means 24 is a high frequency power source 23.
The waveform of the high frequency voltage output from the
During the time t ₃ , the total amplitude of the high-frequency voltage is controlled to be V _3, and during the next time t ₄ , the total amplitude of the high-frequency voltage is controlled to be V ₄ .

A plasma processing apparatus configured as described above,
In this case, 50 nm on the Si substrate by the etching device
The relationship between the etching rate of polysilicon and the output voltage of the high-frequency power supply 23, that is, the acceleration voltage, under the same conditions as in the above-described embodiment, for a configuration wafer 6a in which polysilicon and photoresist are sequentially laminated via a thin oxide film. As a result, the same tendency as in FIG. 2 was found.

That is, the frequency 2 by the high frequency power source 23
By applying a high-frequency voltage of MHZ or less (385 kHz in this case) to the sample stage 5a so that the ions sufficiently follow the AC voltage waveform, and changing the strength of the AC voltage, that is, the total amplitude of the AC voltage, As in the case of the above-described embodiment, there was a state in which the etching action was dominant, the deposition action was dominant, and neither etching nor deposition proceeded.

[0052] Thus, the output voltage controlled by the means 24 controls the output voltage of the high frequency power source 23 as shown in FIG. 8, a large high-frequency voltage V ₃ than the critical potential for a time t ₃
Is applied to the electrode 5 to etch the polysilicon. Next, during a time t _4, a high-frequency voltage V ₄ smaller than the critical potential is applied to the electrode 5 to form a protective film on the surface (including the etching side surface) of the wafer 6a. By sequentially repeating these two steps, a material to be etched having a high aspect ratio can be processed with high dimensional accuracy, as in the first embodiment. The etching time t ₃ and the deposition time t ₄ may be set in the same manner as the etching time t ₁ and the deposition time t ₂ described in the embodiment.

Hereinafter, according to the second embodiment, the frequency 2
By changing the output voltage of the high-frequency voltage of MHz or less across the critical potential, it is possible to alternately perform the etching step and the deposition step without switching and supplying the gas. Similarly, there is an effect that the processing time can be reduced.

The processing by microwave plasma is performed in the same manner as in the first embodiment, and the time between the etching time and the deposition time is controlled by the output voltage control means 24.
Since the etching side surface is etched stepwise while being protected by the protective film, a film to be etched having a fine pattern and a depth or height higher than the pattern dimension width can be processed with high dimensional accuracy.

Further, as in the case of the first embodiment, since the plasma generation state does not change and the etching can be performed in a state where the emission intensity is stable, the end point of the etching can be easily determined.

Further, since the voltage for accelerating the ions is applied in the negative voltage region of the high frequency voltage of 2 MHz or less, the positive ions accelerated in the negative voltage region and attracted to the surface of the wafer 6a and charged on the wafer 6a. Can be neutralized by the electrons drawn to the surface of the wafer 6a in the next positive voltage region, and dielectric breakdown of the insulating material formed on the wafer 6a can be prevented. Therefore, it is suitable for etching a sample having an insulating material such as Sio ₂ or Si ₃ N ₄ . In this case,
Since a kind of capacitor is formed between the electrode 5 and the wafer 6a and the plasma, if the frequency of the high-frequency voltage is too low, the electric charge is excessively accumulated on the wafer 6a and the acceleration of ions is suppressed, and the etching rate is reduced. A so-called charge-up phenomenon, which is significantly reduced, occurs. The limit frequency for preventing this charge-up phenomenon depends on the type and thickness of the insulating film, but practical values for semiconductor devices are detailed in Japanese Patent Publication No. 56-37311. It is about 100 KHz.

Next, a third embodiment of the present invention will be described with reference to FIGS. 9 and 10.

In FIG. 9, the same members as those in FIG. 7 indicate the same members. 7 is different from FIG. 7 in that, in this case, a high frequency power source 23 having a frequency of 385 KHz and an AC waveform generator 26 are used as the acceleration voltage applying means. The high frequency power supply 23 is connected to the electrode 5 via the synthesizer 25. An AC waveform generator 26 is also connected to the synthesizer 25. Output waveform control means 27 is connected to the AC waveform generator 26.

The synthesizer 25 changes the waveform of the high-frequency voltage output from the high-frequency power supply 23 along the waveform 28 output from the AC waveform generator 26, as shown in FIG.
Output waveform control means 27 adjusts the cycle and amplitude of waveform 28 output from AC waveform generator 26.

A plasma treatment procedure constructed as above,
In this case, if the etching process is performed by the etching apparatus under the same conditions as in the second embodiment, the second
The etching process can be performed stepwise while alternately repeating the etching process and the deposition process as in the embodiment of FIG.

That is, as shown in FIG. 10, during the time t ₅ when the negative voltage waveform is larger than the critical potential V ₀ ′, the etching action predominates, and the negative voltage smaller than the critical potential V ₀ ′ is obtained. During time t ₆ of the waveform, the deposition effect predominates.

The time t _{5 at which} etching takes place and the time t _{6 at} which deposition takes place can be adjusted easily by changing the period of the waveform 28 output from the AC waveform generator 26 by the output waveform control means 27. You. Further, when the etching rate in the etching step is increased, it can be easily achieved by changing the amplitude of the waveform 28 output from the AC waveform generator 26 by the output waveform control means 27.
However, if the etching rate, etching time and deposition time are to be adjusted accurately, the output waveform control means 27
It is necessary to adjust the amplitude and cycle of the waveform 28 at the same time.

As described above, according to the third embodiment, the second
It is possible to obtain the same effect as that of the embodiment.

In the case of the third embodiment, switching between etching and deposition gradually progresses.

Next, a fourth embodiment of the present invention will be described with reference to FIGS. 11 and 12.

In FIG. 11, the same reference numerals as those in FIG. 1 denote the same members. The difference between this figure and FIG. 1 is that the sample table 5
b is grounded and a grid electrode 29 is provided between the wafer 6 and the discharge space 7. The DC power supply 15 is connected to the grid electrode 29.
An output voltage controller 16 is connected to the output voltage controller 16, and an output waveform controller 17 is connected to the output voltage controller 16.

In this case, the means for accelerating the ions in the direction of the wafer 6 is the DC power supply 15 for applying a negative DC voltage to the grid electrode 29. The means for changing the negative DC voltage output from the DC power supply 15, that is, the acceleration voltage across the critical potential, includes an output voltage control device 16 and an output waveform control device 17, and these controls are performed in the above-described embodiment. during the time t ₁ as shown in FIG. 12 the same as controls in the voltage V _1, during the time t ₂ is controlled to a voltage V _2.

A plasma processing apparatus configured as described above,
In this case, a plasma is generated in the discharge space 7 by the etching apparatus under the same conditions as in the first embodiment, and a negative DC voltage is applied to the grid electrode 29 by the DC power supply 15. This causes the ions in the plasma to move to the grid electrode 2
The ions accelerated to the side 9 and passed through the grid electrode 29 reach the wafer 6 and etch the material to be etched on the wafer 6.

At this time, the output voltage control device 16 and the output waveform control device 17 cause the DC power supply 15 to output the acceleration voltage V ₁ greater than the critical potential for a time t ₁ second. As a result, the etching action predominates for the time t ₁ second,
The wafer 6 is etched. Next, an acceleration voltage V ₂ smaller than the critical potential is output from the DC power supply 15 for a time t ₂ seconds. As a result, the deposition effect predominates for the time t ₂ seconds, and a protective film is formed on the surface of the wafer 6 (including the etching side surface). By sequentially repeating these steps, the material to be etched on the wafer 6 can be etched stepwise as in the above-described embodiment.

As described above, according to the fourth embodiment, by applying the acceleration voltage to the grid electrode 29 and changing the acceleration voltage across the critical potential, the etching process can be performed without switching and supplying the gas. And the deposition step can be performed alternately, so that there is an effect that the processing time can be shortened in the same manner as in the first embodiment.

The processing by microwave plasma is performed in the same manner as in the first embodiment, and the time between the etching process and the deposition process is controlled by the output voltage control device 16 and the output waveform control device 17 so that the wafer 6 is processed. Since the etching is performed stepwise while protecting the etching side surface with a protective film,
An etching target material having a fine pattern and a depth or a height higher than the pattern dimension width can be processed with high dimensional accuracy.

Further, as in the case of the above-described embodiment, the etching can be performed in a state where the plasma generation state does not change and the emission intensity is stable, so that the end point of the etching can be easily determined.

The grid electrode 2 is used in the fourth embodiment.
Since a DC voltage is applied to the electrode 9, the sample must be conductive. However, if a power supply is connected to the grid electrode 29 as in the first, second, or third embodiment, Insulating samples can also be processed.

Next, a fifth embodiment of the present invention will be described with reference to FIG.

In FIG. 13, the same symbols as those in FIG. 1 denote the same members. The point that this figure differs from FIG. 1 is that the apparatus shown in this figure is a parallel plate type RIE device having an upper electrode 34 and a lower electrode 33 in a vacuum processing vessel 30, and a parallel plate type RIE device as a plasma generating means. Using the electrodes 33 and 34, the electrode 33
Is connected to a high-frequency power supply 13a for applying a high-frequency voltage (in this case, a frequency of 13.56 MHz).

On the side of the vacuum processing container 30, the gas introduction part 3 is provided.
1 is provided, and a gas source (not shown) is connected as in the case of the first embodiment. An evacuation unit 32 connected to a not-shown evacuation device is provided below the vacuum processing container 30. A lower electrode 33 on which the wafer 6 is mounted is provided on a lower surface in the vacuum processing vessel 30, and an upper electrode 3 disposed opposite to the lower electrode 33 is provided in an upper part in the vacuum processing vessel 30.
4 is provided. The upper electrode 34 is grounded. The lower electrode 33 is attached to the vacuum processing container 30 via an insulating material, and the lower electrode 33 is connected to the high-frequency power supply 13a connected via the matching box 12 as in the first embodiment.
A DC power supply 15 connected via a low-pass filter 14 is connected.

A plasma processing apparatus configured as described above,
In this case, the lower electrode 33 and the upper electrode 34 are inserted by the etching apparatus through the gas introduction part 31 as in the case of the above-described embodiment.
An etching gas is supplied to the discharge space 35 formed between At the same time, the inside of the vacuum processing vessel 30 is evacuated to a predetermined pressure by a vacuum evacuation device (not shown). In this state, the high frequency power supply 13a applies one
A high frequency voltage of 3.56 MHz is applied. This allows
Glow discharge occurs in the discharge space 35, and the etching gas is turned into plasma.

In this state, a DC bias voltage for accelerating ions in the plasma toward the wafer 6 has already been generated at the lower electrode 33 in the same manner as in the first embodiment. This DC bias voltage is changed by the DC power supply 15 across the critical potential in the same manner as in the first embodiment. Thus, the material to be etched of the wafer 6 can be etched stepwise by alternately repeating the etching step and the deposition step as in the case of the first embodiment.

As described above, according to the fifth embodiment, by changing the DC bias voltage by the DC power supply 15 across the critical potential, the gas is not switched and supplied.
Since the etching step and the deposition step can be performed alternately, the processing time can be shortened in the same manner as in the first embodiment.

The high frequency power source 13a is used for the electrode 33.
And 34, a stable plasma can be generated in the discharge space 35, and even if the DC bias voltage is changed by the DC power supply 15, the plasma generation state does not change. In addition, the end point of the etching can be easily determined.

In the same manner as in the first embodiment, a material to be etched having a high aspect ratio can be processed with high dimensional accuracy, and can be processed irrespective of a conductive material or an insulating material.

Next, a sixth embodiment of the present invention will be described with reference to FIG.

In FIG. 14, the same symbols as those in FIGS. 7 and 13 indicate the same members. 13 is different from FIG. 13 in that a high-frequency power source 23a having a frequency of 2 MHz or less (385 kHz in this case) is used as a means for generating plasma, and a frequency of 2 MHz or less is similarly used as a means for accelerating ions. The point is that the high frequency power supply 23a is shared. The high-frequency power supply 23a is connected to the lower electrode 33 via the matching box 22 as in FIG. One end of the circuit of the matching box 22 is grounded, and the lower electrode 33 is set to a DC ground potential. Output voltage control means 24 is connected to the high frequency power supply 23a.

The control contents of the output voltage control means 24 are the same as those in the second embodiment, and the explanation thereof is omitted. The wafer 6a has an insulating material as in the second embodiment.

A plasma processing apparatus configured as described above,
In this case, an etching apparatus supplies an etching gas to the discharge space 35 as in the fifth embodiment, and the inside of the vacuum processing vessel 30 is evacuated to a predetermined pressure. In this state, 385 is applied to the lower electrode 33 by the high frequency power supply 23a.
A high-frequency voltage of kHz is applied to generate a glow discharge in the discharge space 35 to convert the etching gas into plasma.

At this time, the high-frequency voltage output from the high-frequency power supply 23a is changed by the output voltage control means 24 across the critical potential, as in the second embodiment. Thus, the material to be etched of the wafer 6a can be etched stepwise by alternately repeating the etching step and the deposition step as in the second embodiment.

As described above, according to the sixth embodiment, the frequency 2
Since the high-frequency voltage of MHz or more is changed across the critical potential, the etching process and the deposition process can be alternately performed without switching and supplying the etching gas. Similarly, the processing time can be shortened.

In the same manner as in the second embodiment, a material to be etched having a high aspect ratio can be processed with high dimensional accuracy. The sample is suitable for a sample having an insulating material. In this case, since the high-frequency voltage having a frequency of 2 MHz or less, which is also a plasma generating means, is changed,
The state of plasma generation differs between the etching step and the deposition step. For this reason, when the etching end point is determined by using the emission spectroscopy, it is necessary to input only the emission intensity when the etching is occurring to make the determination.

Next, a seventh embodiment of the present invention will be described with reference to FIG.

In FIG. 15, the same symbols as those in FIGS. 9 and 14 indicate the same members. 14 is different from FIG. 14 in that an AC waveform generator 26 is used as a means for changing a high-frequency voltage of a high-frequency power supply 23a having a frequency of 2 MHz or less (385 KHz in this case), which is also a means for accelerating ions, with a critical potential interposed therebetween. This is the point that is used. High frequency power supply 2
3a is the lower electrode 3 through the synthesizer 25 as in FIG.
3 is connected. An AC waveform generator 26 is also connected to the synthesizer 25. Output waveform control means 27 is connected to the AC waveform generator 26.

The control contents of the synthesizer 25, the AC waveform generator 26, and the output waveform control means 27 are the same as in the third embodiment, and the description is omitted.

A plasma processing apparatus configured as described above,
In this case, an etching apparatus supplies an etching gas to the discharge space 35 as in the sixth embodiment, and the inside of the vacuum processing vessel 30 is evacuated to a predetermined pressure. In this state, as in the third embodiment, that is, in the tenth embodiment,
A high-frequency voltage controlled as shown in the figure is applied to the lower electrode 33 to generate a blow discharge in the discharge space 35, thereby turning the etching gas into plasma.

Thus, when the high-frequency voltage is higher than the critical potential, the etching action predominates on the wafer 6a, and when the high-frequency voltage is lower than the high-frequency potential, the protection action is deposited on the surface of the wafer 6a (including the etched side surfaces). Occurs dominantly. This etching step and the deposition step are performed alternately, and the material to be etched of the wafer 6a is etched stepwise.

As described above, according to the seventh embodiment, the sixth
Since the etching step and the deposition step can be performed alternately without switching and supplying the etching gas as in the embodiment, the processing time can be shortened.

In this case, since the high-frequency voltage, which is also the plasma generating means, is constantly changing, the state of plasma generation is not constant. Therefore, there is a problem that it is difficult to set conditions for the etching process.

Next, an eighth embodiment of the present invention will be described with reference to FIGS.

In FIG. 16, the same symbols as those in FIG. 13 denote the same members. 13 is different from FIG. 13 in that it is a plasma generating means. In this case, the output voltage of a high frequency power supply 13a having a frequency of 13.56 MHz can be controlled, and the means for changing ions across a critical potential is also used. The point is The high frequency power supply 13a is connected to the lower electrode 33 through the capacitor 36 and the matching box 12 in order. Output voltage control means 24 is connected to the high frequency power supply 13a.

The output voltage control means 24 is the high frequency power source 13a.
The waveform of the high frequency voltage output as shown in FIG. 17 from the controls total amplitude of the high frequency voltage so during the time t ₇ the bias voltage V ₉ of the DC component V _7, the next time t ₈ during the bias voltage of the DC component to control the total amplitude of the high frequency voltage V ₈ such that V _10.

A plasma processing apparatus configured as described above,
In this case, an etching apparatus supplies an etching gas to the discharge space 35 as in the fifth embodiment, and the inside of the vacuum processing vessel 30 is evacuated to a predetermined pressure. In this state, a high frequency voltage is applied to the lower electrode 33 by the high frequency power supply 13a. Thus, the etching gas is turned into plasma in the discharge space 35.

[0100] At this time, during the first 17 hours by the output voltage control means 24 as shown in FIG. T ₇ high-frequency power supply 13a
The total amplitude of the high-frequency voltage output from is controlled to V ₇ . As a result, a bias voltage having a DC component higher than the critical potential is generated at the sample electrode 33, and the material to be etched of the wafer 6 is etched. During the next time t ₈ the high-frequency power source 1
The total amplitude of the high frequency voltage outputted from 3a to control the V _8. As a result, a bias voltage of a DC component smaller than the critical potential is generated at the sample electrode 33, and a protective film is deposited on the surface (including the etching side surface) of the wafer 6. The material to be etched of the wafer 6 is etched stepwise by alternately performing the etching step and the deposition step.

As described above, according to the eighth embodiment, the fifth
Since the etching step and the deposition step can be performed alternately without switching and supplying the etching gas as in the embodiment, the processing time can be shortened.

The output voltage of the high frequency power supply 13a is controlled by the output voltage control means 24, and the DC bias voltage generated at the sample electrode 33 is alternately changed with a critical voltage interposed therebetween. Can be alternately performed, so that a film to be etched having a depth or a height higher than the pattern dimension width can be processed with high dimensional accuracy, as in the fifth embodiment.

Even if the high-frequency voltage is controlled, a part of the high-frequency voltage has a positive voltage range, so that no electric charge is accumulated on the wafer 6 as in the fifth embodiment, and the etching speed is reduced. Etching can be performed without deterioration or deterioration or destruction of the gate portion of the element.

In this case, as in the case of the sixth embodiment, the state of plasma generation changes between the etching step and the deposition step. Therefore, when the etching end point is determined using emission spectroscopy, the etching is stopped. It is necessary to input and determine only the light emission intensity when it occurs.

Next, a ninth embodiment of the present invention will be described with reference to FIG.

In FIG. 18, the same symbols as those in FIGS. 11 and 13 indicate the same members. FIG. 18 differs from FIG. 13 in that a grid electrode is provided between the wafer 6 and the discharge space 35 as in FIG. 11 as means for accelerating ions. DC power supply 15 is applied to the grid electrode 29.
Is connected, and the output voltage control device 1 is connected to the DC power supply 15.
6, and an output waveform controller 17 is connected to the output voltage controller 16.

The control contents of the DC power supply 15, the output voltage control device 16 and the output waveform control device 17 are the same as those in the fourth embodiment, and the description thereof will be omitted.

A plasma processing apparatus configured as described above,
In this case, an etching apparatus supplies an etching gas to the discharge space 35 as in the fifth embodiment, and the inside of the vacuum processing vessel 30 is evacuated to a predetermined pressure. In this state, a high frequency voltage is applied to the lower electrode 33 by the high frequency power supply 13a. As a result, blow discharge occurs in the discharge space 35, and the etching gas is turned into plasma.

In this state, a negative DC voltage is applied to the grid electrode 29 by the DC power supply 35 as in the fourth embodiment. Thus, ions in the plasma are accelerated toward the grid electrode, and the ions passing through the grid electrode 29 reach the wafer 6 and etch the material to be etched on the wafer 6.

At this time, similarly to the fourth embodiment, the output voltage control device 16 and the output waveform control device 17
The acceleration voltage applied to the grid electrode 29 is changed by sandwiching the critical potential. As a result, when the acceleration voltage is higher than the critical potential, the etching action predominates on the wafer 6. When the accelerating voltage is lower than the critical potential, the deposition effect of forming a protective film on the surface of the wafer 6 (including the etching side surface) is predominant. The material to be etched of the wafer 6 is etched stepwise by alternately performing the etching step and the deposition step.

As described above, according to the ninth embodiment, by changing the acceleration voltage applied to the grid electrode 29 across the critical potential, the etching process and the deposition process can be performed without switching and supplying gases. Can be performed alternately, so that the processing time can be reduced as in the fifth embodiment.

Further, as in the fifth embodiment, the wafer 6
Since the etching side surface can be etched stepwise while being protected by the protective film, a material to be etched having a depth or height higher than the pattern dimension width can be processed with high dimensional accuracy.

Further, as in the case of the fifth embodiment, since the plasma generation state does not change and the etching can be performed in a state where the emission intensity is stable, the end point of the etching can be easily determined.

Next, a tenth embodiment of the present invention will be described with reference to FIG.

In FIG. 19, the same symbols as in FIG. 13 indicate the same members. 13 is different from FIG. 13 in that a discharge tube 37 is provided outside the vacuum processing vessel 30 as a plasma generating means, a coil 38 is wound around the outer periphery of the discharge tube 37, and a high-frequency power supply 39 is connected to the coil 38. That is the point.

As in FIG. 13, the lower electrode 33 is provided with DC bias applying means by the high frequency power supply 13a and the DC power supply 15, that is, ion acceleration means. These plasma generating means and DC bias applying means can control their outputs independently of each other. The high frequency power supply 39 has a frequency of, for example, 80 kHz to 13.56.
It outputs high frequency power of MHz. The control contents of the DC bias applying means are the same as those in the fifth embodiment, and the description thereof will be omitted.

A plasma treatment apparatus configured as described above,
In this case, an etching device supplies an etching gas from a gas source (not shown) into the discharge tube 37 via the gas introduction part 31a, and the inside of the vacuum processing vessel 30 and the inside of the discharge tube 37 are reduced to a predetermined pressure by an exhaust device (not shown). Exhaust.
In this state, the high frequency power supply 39 applies a high frequency voltage to the coil 38. Thus, the etching gas in the discharge tube 37 is turned into plasma, and the plasma is introduced into the space 35a of the vacuum processing container 30.

At this time, a high frequency voltage is applied to the lower electrode 33 by the high frequency power supply 13a via the matching box 12. As a result, the high frequency voltage applied to the lower electrode 33 floats like a DC current as in the fifth embodiment and has a DC bias voltage. A DC voltage is superimposed on the lower electrode 33 by the DC power supply 15 together with the high-frequency voltage to control the DC bias voltage.

The output voltage control device 16 controls the DC bias voltage.
And the output waveform control device 17 performs control as in the fifth embodiment. Thus, the etching process and the deposition process are performed alternately, and the material to be etched of the wafer 6 is etched stepwise.

As described above, according to the tenth embodiment, the same effects as those of the fifth embodiment can be obtained.

According to the tenth embodiment, the discharge tube 37 can be operated without increasing the high frequency voltage of the high frequency power source 13a.
Since high-density plasma can be generated in the inside, high-speed etching can be performed with less damage than in the fifth embodiment.

The present invention has been described based on the first to tenth embodiments. However, the structure of the present invention is not limited to these embodiments, but includes a plasma generating means, an accelerating voltage applying means, It goes without saying that the acceleration voltage applying means can be variously combined.

In this embodiment, an example is shown in which a mixed gas of SF ₆ having no critical potential and C ₂ Cl ₃ F ₃ having a critical potential is used as the etching gas for polysilicon. It goes without saying that other combinations may be used as long as the gas has the property of: For example, SF ₆ having no critical potential and C ₂ Cl ₃ F ₃ having a critical potential
(Commercial name: Freon 114), a combination with CCl ₄ , C ₄ F ₈ or the like, or a combination using NF ₃ instead of SF ₆ can be similarly performed.

Further, the mixed components of the etching gas are not limited to two, and may be composed of three or more components as long as at least one component has a critical potential. Also, a combination of gases in which all components have a critical potential,
Alternatively, it may be a single gas.

In this embodiment, the example of etching of polysilicon is shown, but the present invention can be applied to the etching of Al wiring film. In this case, as the etching gas, a chlorine gas (Cl ₂ ) as a pure etchant having no critical potential, a Cl component as an etchant and a CCl having a critical potential, which is a C component acting as a part of a film-forming species, are used. A mixed gas of ₄ and a mixed gas of BCl ₃ for etching the oxide film on the surface of the material to be etched at high speed may be used. In this case, a volatile reaction product of AlCl ₃ is generated to etch the material to be etched, and a polymer of C or a reaction product of CxCly is generated as a deposit to form a protective film.
Further, instead of CCl ₄ having a critical potential, CF ₄ , C ₂
F ₆ , C ₄ F ₈ or SiCl ₄ may be used.

Although specific numerical values are not shown in FIG. 2, the etching rate or deposition rate and the critical potential are relatively determined by the type of etching gas, gas pressure, output of plasma generating means, and the like. It is.

In the present embodiment, the pattern of application of the acceleration voltage during the etching process is the same, but at the end of the final etching, control is performed to reduce the acceleration voltage within a range larger than the critical potential. Thereby, etching damage can be further reduced.

In this embodiment, the timing at which the acceleration voltage is changed across the critical potential is automatically switched at a preset time. However, the etching state and the deposition state at each stage are detected. Alternatively, the switching may be automatically performed when the respective detected values reach a predetermined set value. In the case of a process in which the number of times of switching is small, the switching may be manually performed. When these acceleration voltages are set, the acceleration voltage may be detected, the detected value may be displayed, and the predetermined value may be set while observing the value to be adjusted.

Further, in this embodiment, the case where etching is performed has been described. However, the present invention is also applicable to a case where the ratio of time between the etching step and the deposition step, that is, the film forming step is reversed, and the film is formed as a whole. is there. In this case, a smooth film can be formed by alternately performing film formation and etching.

[0130]

According to the present invention, the ions in the plasma can be attracted to the sample with a small acceleration voltage, and when the acceleration voltage is higher than the critical potential, the sample is predominantly etched and the acceleration voltage becomes critical. When the potential is smaller than the potential, the sample is predominantly deposited, and anisotropic etching with less damage can be performed, and the material to be etched having a fine pattern can be processed. Therefore, the etching process and film formation can be performed without switching the processing gas. The steps can be performed alternately, and there is an effect that a material to be etched having a fine pattern and a large aspect ratio can be processed.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a relationship between a bias voltage in a processing gas and an etching rate or a deposition rate.

FIG. 3 is an acceleration voltage application pattern diagram by the apparatus of FIG.

FIG. 4 is a diagram showing an etching state when the bias voltage is not changed.

FIG. 5 is a diagram showing an etching state according to the present invention.

FIG. 6 is a diagram showing an etching state according to the present invention.

FIG. 7 is a configuration diagram showing a plasma processing apparatus that is a second embodiment of the present invention.

FIG. 8 is an acceleration voltage application pattern diagram by the apparatus of FIG.

FIG. 9 is a configuration diagram showing a plasma processing apparatus that is a third embodiment of the present invention.

10 is an acceleration voltage application pattern diagram by the apparatus of FIG. 9. FIG.

FIG. 11 is a configuration diagram showing a plasma processing apparatus that is a fourth embodiment of the present invention.

FIG. 12 is an application pattern diagram of an acceleration voltage by the apparatus of FIG.

FIG. 13 is a configuration diagram showing a plasma processing apparatus that is a fifth embodiment of the present invention.

FIG. 14 is a configuration diagram showing a plasma processing apparatus that is a sixth embodiment of the present invention.

FIG. 15 is a configuration diagram showing a plasma processing apparatus that is a seventh embodiment of the present invention.

FIG. 16 is a configuration diagram showing a plasma processing apparatus that is an eighth embodiment of the present invention.

FIG. 17 is an acceleration voltage application pattern diagram of the apparatus of FIG.

FIG. 18 is a configuration diagram showing a plasma processing apparatus that is a ninth embodiment of the present invention.

FIG. 19 is a configuration diagram showing a plasma processing apparatus that is a tenth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Discharge tube, 5 ... Electrode, 6, 6a ... Wafer, 8 ... Magnetron, 10 ... Electromagnetic coil, 12 ... Matching box, 13, 13a ... High frequency power supply, 15 ... DC power supply, 16
... output voltage control device, 17 ... output waveform control device, 22 ...
Matching box, 23, 23a ... High frequency power source, 24
... output voltage control means, 25 ... synthesizer, 26 ... AC waveform generator, 27 ... output waveform control means, 29 ... grid electrode,
30 ... Vacuum processing container, 33, 34 ... Electrode, 36 ... Capacitor, 37 ... Discharge tube, 38 ... Coil, 39 ... High frequency power supply.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location H01L 21/302 B (72) Inventor Kaido Hirobe 1 Horiyamashita, Hadano, Kanagawa, Japan (72) Inventor Yutaka Kakehi 502 No. 502 Kazutachi-cho, Tsuchiura City, Ibaraki Prefecture

Claims (1)

[Claims] 1. A mixed gas having a component that reacts with a material to be etched and a component that forms a deposited film and has a critical potential is used as an etching treatment gas, and the etching treatment gas is 0.01 To using ECR of microwave.
a step of converting the material into plasma under a reduced pressure of rr level, and changing the acceleration voltage for accelerating the ions in the plasma toward the material to be etched across the critical potential to perform etching and film formation on the material to be etched. And a step of alternately repeating and are performed, and etching is performed with a fine pattern and a large aspect ratio.