JPH09260352A - Plasma processor and plasma processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma processor and a plasma processing method, which obtain a narrow ion energy distribution with excellent controllability to enhance selectivity, etc., of a plasma process. SOLUTION: This plasma processor has a vacuum processing chamber, a sample pedestal 15 for arranging a sample 40 processed in this vacuum processing chamber, and plasma generating means containing a high frequency power source 16. There are provided a pair of parallel plane electrodes 12, 15, electrostatic attracting means 20, 22, 23 for holding the sample 40 on a sample pedestal 15 by electrostatic attracting force, and pulse bias applying means 17 for applying a pulse bias voltage to the sample 40, and a high frequency power source of 20MHz to 500MHz is applied as the high freqency power source 16, and further a vacuum processing chamber 10 is evacuated to 5mTorr to 40mTorr by a vacuum pump 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus and a processing method, and more particularly to a plasma processing apparatus and a processing method suitable for forming a fine pattern in a semiconductor manufacturing process.

[0002]

2. Description of the Related Art In the technical field of performing etching processing and film forming processing of semiconductors using plasma, plasma is applied to a sample table on which an object to be processed (for example, a semiconductor wafer substrate, hereinafter abbreviated as sample) is placed. USP as a processing apparatus provided with a high frequency power source for accelerating ions in the inside and an electrostatic adsorption film for holding a sample on a sample table by electrostatic adsorption force.
5,320,982 and the like.

In the apparatus described in this specification, plasma is generated by microwaves, the sample is held on the sample stage by electrostatic attraction, and a heat transfer gas is interposed between the sample stage and the temperature of the sample. While performing the control, the sine wave output high frequency power source is used as a bias power source, and the power source is connected to the sample stage to control the ion energy incident on the sample.

Further, in Japanese Laid-Open Patent Publication No. 62-280378, a pulsed ion control bias waveform for stabilizing the electric field strength between the plasma electrode and the electrode is generated and applied to the sample stage so that the ion energy incident on the sample is It is described that the distribution width can be narrowed and the processing dimensional accuracy of etching and the etching rate ratio between the film to be processed and the base material can be increased several times.

Further, in JP-A-6-61182,
It is described that plasma is generated by using electron cyclotron resonance, and a pulse bias having a pulse duty of about 0.1% or more is applied to a sample to prevent the generation of a notch.

[0006]

Among the above-mentioned prior arts, the pulse bias power supply method described in JP-A-62-280378 and JP-A-6-61182 is an electrostatic discharge between a sample stage electrode and a sample. When applying a pulse bias to a sample using a dielectric layer for adsorption, no study has been made.If it is applied to the electrostatic adsorption method as it is, the ion energy distribution will be generated due to the change in voltage generated across the electrostatic adsorption film. Therefore, there is a drawback that it is not possible to deal with the necessary fine pattern processing while sufficiently controlling the temperature of the sample.

Further, in the conventional sine wave output bias power supply system described in USP 5,320,982,
When the frequency becomes higher, the impedance of the sheath approaches the impedance of the plasma itself or becomes lower than that, so unnecessary plasma is generated by the bias power supply, it is not used effectively for accelerating ions, and the plasma distribution deteriorates and the bias There is a drawback that the controllability of ion energy by the power source is lost.

Further, in plasma processing, it is important to properly control the amount of ions, the amount of radicals, and the species of radicals in order to improve the performance. Conventionally, a gas serving as an ion source or a radical source is used in the processing chamber. In order to generate ions and radicals at the same time by generating a plasma in the processing chamber, the limit of control is becoming clear as the processing of the sample becomes finer.

The object of the present invention is to control the amount and quality of ions and radicals independently, improve the temperature controllability by electrostatic adsorption of the sample, and perform the required fine pattern processing stably and accurately. It is to provide a processing apparatus and a plasma processing method.

Another object of the present invention is to provide a plasma processing apparatus capable of independently controlling the amounts and qualities of ions and radicals to obtain a narrow ion energy distribution and stably improving the selectivity of plasma processing with good controllability. It is to provide a plasma processing method.

Another object of the present invention is to control the amount and quality of ions and radicals independently, and to process a sample under a relatively low gas pressure, thereby facilitating precise processing of fine patterns and plasma. Improved processing selectivity, etc.
A plasma processing apparatus and a plasma processing method are provided.

Another object of the present invention is to control the amount and quality of ions and radicals independently, and to control the insulating film (eg SiO 2) in the sample.
(2, SiN, BPSG, etc.) It is an object of the present invention to provide a plasma processing apparatus and a plasma processing method in which the selectivity of the plasma processing with respect to (eg, SiN, BPSG) is improved.

[0013]

A feature of the present invention is that a plasma processing has a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating means including a high frequency power source. An apparatus, comprising electrostatic adsorption means for holding the sample on the sample table by electrostatic adsorption force, and pulse bias application means for applying a pulse bias voltage to the sample, to control the quantity and quality of ions and radicals. It is controlled independently.

Another feature of the present invention is a plasma processing apparatus having a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating means including a high frequency power source. An electrostatic attraction means for holding the sample on the sample stage by an electrostatic attraction force and a pulse bias applying means for applying a pulse bias voltage to the sample are provided, and the quantity and quality of ions and radicals are independently controlled. A high frequency voltage of 10 MHz to 500 MHz is applied as the high frequency power source, and the vacuum processing chamber is set to 5 mTorr to 40 mTo.
It is configured to reduce the pressure to rr.

Another feature of the present invention is that a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber,
A plasma processing apparatus having a plasma generating means, the electrostatic attraction means for holding the sample on the sample stage by an electrostatic attraction force, and a pulse bias voltage connected to the sample stage and applied to the sample stage. A pulse bias applying unit and a voltage suppressing unit that suppresses a change in the voltage generated corresponding to the electrostatic attraction capacity of the electrostatic attracting unit when the pulse bias voltage is applied are provided, and the amount of ions and radicals and The quality is controlled independently.

Another feature of the present invention is that a pair of opposed electrodes on one of which electrodes a sample is placed, electrostatic attraction means for holding the placed sample on the electrodes by electrostatic attraction force, A gas introduction means for introducing an etching gas into the atmosphere in which the sample is arranged, a plasma generation means for converting the introduced etching gas into a plasma, and a pulse amplitude of 250 V to 800 V to the one electrode during etching of the sample. And a pulse bias applying means for applying a pulse bias voltage having a duty ratio of 0.05 to 0.4, the amount and quality of ions and radicals are controlled independently, and an insulating film (for example, SiO 2, SiN, BPSG
Etc.) with the plasma.

Another feature of the present invention is that a sample is placed on one of the electrodes facing each other, and the placed sample is held on the electrode by electrostatic attraction.
A step of introducing an etching gas into the atmosphere in which the sample is placed, a step of converting the introduced etching gas into a plasma, a step of etching the sample with the plasma, and a pulse to the one electrode during the etching And a step of applying a bias voltage, which independently controls the amount and quality of ions and radicals.

Another feature of the present invention is that a sample is placed on one of a pair of opposing electrodes provided in the vacuum processing chamber, the sample is held on the electrode by electrostatic attraction, and The step of introducing an etching gas into the atmosphere in which the sample is placed and the atmosphere is set to 5 mTorr
Step of evacuating to ~ 40mTorr and 10MHz ~ 5
Applying a high-frequency voltage of 00 MHz and converting the etching gas into plasma under the pressure; etching the sample with the plasma; and applying a pulse bias voltage to the one electrode,
This is a plasma processing method in which the amount and quality of ions and radicals are controlled independently.

Another feature of the present invention is to dispose the sample on one of the electrodes facing each other, to hold the arranged sample on the electrode by electrostatic attraction, and to dispose the sample. Introducing an etching gas into the atmosphere described above, converting the introduced etching gas into plasma, etching the sample with the plasma, and applying 250 V to 800 V to the one electrode during the etching. Pulse amplitude and 0.05
A step of applying a pulse bias voltage having a duty ratio of .about.0.4, the amount and quality of ions and radials are controlled independently, and the insulating film (eg SiO.sub.2,
SiN, BPSG, etc.).

Another feature of the present invention is that, in the above plasma processing method, the high frequency power is used as a high frequency power source for converting the etching gas into plasma by modulating or intermittently switching the high frequency power at a constant cycle.

According to the present invention, the quantity and quality of ions and radials are independently controlled, and a pulsed bias power supply having a predetermined characteristic is provided on a sample stage equipped with electrostatic attraction means having an electrostatic attraction dielectric layer. By applying the voltage, the temperature controllability of the sample can be sufficiently performed, and the required fine pattern processing can be stably performed.

Further, it is possible to independently control the amount and quality of ions and radials, obtain a narrow ion energy distribution, and stably improve the selectivity of plasma treatment with good controllability.

Further, according to the present invention, the quantity and quality of ions and radials are independently controlled, and the change in the voltage generated corresponding to the electrostatic attraction capacity of the electrostatic attraction means with the application of the pulse bias voltage is controlled. As the voltage suppressing means, the voltage change applied to both ends of the dielectric layer by electrostatic attraction during one pulse cycle is configured to be 1/2 or less of the magnitude of the pulse bias voltage. Specifically, the thickness of the dielectric electrostatic chuck film provided on the surface of the lower electrode is reduced, or the dielectric is made of a material having a large relative dielectric constant. Alternatively, a method may be adopted in which the cycle of the pulse bias voltage is shortened to suppress a rise in the voltage applied to both ends of the dielectric layer.

Further, according to the present invention, the amount and quality of ions and radials are independently controlled, and a pulse amplitude of 250 V to 800 V and 0.0 V is applied to the one electrode during etching of the sample.
By applying a pulse bias voltage having a duty ratio of 5 to 0.4, an insulating film (eg, SiO 2) in the sample is applied.
2, SiN, BPSG, etc.) can be improved in the selectivity of the plasma treatment.

According to another feature of the present invention, the amount and quality of ions and radials are independently controlled, a high frequency voltage of 10 MHz to 500 MHz is used as a high frequency power source for plasma generation, and the gas pressure in the processing chamber is controlled. The low pressure is 5 mTorr to 40 mTorr. Thereby, a stable plasma can be obtained. Further, by using such a high-frequency voltage, the ionization of the gas plasma is improved, and the selection ratio control at the time of processing the sample is improved.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.
First, FIG. 1 shows a first embodiment in which the present invention is applied to a facing electrode type plasma etching apparatus. In FIG. 1, a processing chamber 10 as a vacuum vessel includes a pair of opposing electrodes including an upper electrode 12 and a lower electrode 15. The gap between the parallel plate electrodes 12 and 15 is 10 mm to 40 mm.
It is desirable to set the degree. A high frequency power source 16 for supplying high frequency energy is connected to the upper electrode 12 via a high frequency power source modulation signal source 161. On the lower surface of the upper electrode 12, an upper electrode cover 30 as a plate for removing fluorine and oxygen made of silicon, carbon or SiC
Is provided. Further, a gas introduction chamber 34 having a gas diffusion plate 32 that diffuses the gas into a desired distribution is provided above the upper electrode 12. In the processing chamber 10, gas necessary for processing such as etching of a sample is supplied from the gas supply unit 36 through the gas diffusion plate 32 of the gas introduction chamber 34, the holes 38 provided in the upper electrode 12 and the upper electrode cover 30. Supplied. The outer chamber 11 is evacuated by a vacuum pump 18 connected to the outer chamber via a valve 14, and the processing chamber 10 is adjusted to the processing pressure of the sample. A discharge containment ring 37 is provided around the processing chamber 10.

In the present invention, the parallel plate electrodes 12,
It suffices that 15 has a pair of electrodes facing each other, and the parallel plate electrodes 12 and 15 may have a slight concave surface or convex surface in view of requirements such as plasma generation characteristics.

The lower electrode 15 for holding the sample 40 has a structure provided with a two-pole type electrostatic chuck 20. That is, the lower electrode 15 includes the outer first lower electrode 15A,
A dielectric layer for electrostatic adsorption (hereinafter, abbreviated as electrostatic adsorption film) is formed on the upper surface of the first and second lower electrodes by the second lower electrode 15B disposed above the inside thereof with the insulator 21 interposed therebetween. 22) is provided. A DC power supply 23 is connected between the first and second lower electrodes via high frequency component cutting coils 24A and 24B, and the second lower electrode 15 is connected.
A DC voltage is applied between both lower electrodes so that the B side becomes positive. This allows the sample 40 to pass through the electrostatic adsorption film 22.
And Coulomb force acting between both lower electrodes
Are adsorbed and held on the lower electrode 15. Electrostatic adsorption film 22
For example, a dielectric material such as aluminum oxide or a mixture of aluminum oxide and titanium oxide can be used. Also, as the power supply 23, several hundreds of volts
Use the DC power source.

A pulse bias power source 17 for supplying a positive pulse bias of 20V to 800V is connected to the lower electrodes 15 (15A, 15B) via blocking capacitors 19A, 19B for cutting DC components. There is.

When the etching process is performed, the sample 40, which is an object to be processed, is placed on the lower electrode 15 of the processing chamber 10 and adsorbed by the electrostatic chuck 20. On the other hand, a gas necessary for etching the sample 40 is supplied from the gas supply unit 36 to the processing chamber 10 via the gas introduction chamber 34. The outer chamber 11 is evacuated by a vacuum pump 18, and the processing chamber 10 is processed at a sample processing pressure, for example, 5 mTorr to 40 mTorr.
Is exhausted under reduced pressure. Next, from the high frequency power source 16, 20 MHz to 500 MHz, preferably 30 MHz to 200 MHz.
The high frequency power of MHz is output to turn the processing gas in the processing chamber 10 into plasma. On the other hand, the lower electrode 15 has a voltage of 20 V to 800 V and a period of 0.1 μm from the pulse bias power supply 17.
A predetermined pulse bias of s to 10 μs, preferably 0.2 μs to 5 μs is applied to control electrons and ions in plasma to perform a predetermined etching process on the sample 40.

The lower limit of the frequency of the high frequency power source 16 is a frequency at which discharge can be stably maintained at a low pressure, and the upper limit is a frequency at which there is no excessive dissociation of gas.

The etching gas is distributed by the gas diffusion plate 32 to a desired distribution, and then the upper electrode 12 and the upper electrode cover 3 are formed.
It is injected into the processing chamber 10 through a hole 38 drilled.

Further, the upper electrode cover 30 is made of carbon, silicon or a material containing these, and fluorine or oxygen components are removed to improve the selectivity with respect to the base such as resist or silicon.

The discharge containment ring 37 localizes the plasma around the sample chamber 40 in the vicinity of the processing chamber 10 to improve the plasma density and to prevent the discharge containment ring 37 from outside the discharge containment ring 37. Minimize unnecessary deposition of deposits on the

As the discharge containment ring 37, it is preferable to use an insulator such as quartz. However, using a semiconductor or conductive material such as carbon, silicon, or SiC,
By connecting to a high frequency power source and causing sputtering by ions, it is possible to reduce deposition of deposits on the ring 37 and also to have an effect of removing fluorine and oxygen.

On the insulator 13 around the sample 40,
When the susceptor cover 39 containing carbon or silicon or these is provided, fluorine and oxygen can be removed, which is useful for improving the selection ratio.

Further, the lower electrode 15 (15A, 15A) is sandwiched by the electric potential of the DC power supply 23 with the electrostatic attraction film 22 of the dielectric material interposed therebetween.
An electrostatic adsorption circuit is formed via B) and the sample 40. In this state, the sample 40 is moved to the lower electrode 15 by electrostatic force.
It is locked and retained by. Sample 4 locked by electrostatic force
A cooling gas such as helium, nitrogen, or argon is supplied to the back surface of 0. The cooling gas fills the concave portion of the lower electrode 15, and the pressure thereof is in the range of several torr to several tens of torr. Note that the electrostatic attraction force is almost zero between the concave portions where the gap is provided, and it can be considered that the electrostatic attraction force is generated only at the convex portion of the lower electrode 15.
However, as will be described later, since the voltage can be appropriately set in the DC power supply 23 and the adsorption force that can sufficiently withstand the pressure of the cooling gas can be set, the sample 40 is moved or skipped by the cooling gas. There is nothing to do.

In order to improve the fine workability of the sample, it is preferable to use a higher frequency power source 16 for plasma generation and to stabilize the discharge in the low gas pressure region. In the present invention, the processing pressure of the sample in the processing chamber 10 is 5 mTorr to 40 mTorr. By reducing the gas pressure in the processing chamber 10 to a low pressure of 40 mTorr or less, the collision of ions in the sheath is reduced. Therefore, in the processing of the sample 40, the directionality of the ions is increased and vertical micromachining is enabled. . At 5 mTorr or less, in order to obtain the same processing speed, the size of the exhaust device and the high-frequency power source are increased, and more than necessary dissociation occurs due to an increase in the electron temperature, which tends to deteriorate the characteristics.

Generally, between the frequency of the power source for plasma generation using parallel plate electrodes and the minimum gas pressure for stable discharge, as shown in FIG. 2, the higher the frequency of the power source, There is a relationship that the minimum gas pressure for stable discharge decreases as the inter-electrode distance increases. In order to avoid the adverse effects of deposits on the surrounding walls and the discharge confinement ring 37, and to effectively function the effect of removing fluorine and oxygen by the upper electrode cover 30, the susceptor cover 39, and the resist in the sample, the maximum gas is used. 2 of mean free path at pressure of 40 mTorr
Corresponding to 5 times or less, it is desirable to set the distance between the electrodes to about 50 mm or less. In addition, the distance between electrodes is 2 to 4 times (4 mm to 8 m) the mean free path at the maximum gas pressure (40 mTorr).
If it is not more than about m), stable discharge becomes difficult.

In the embodiment of the present invention shown in FIG. 1, as the high frequency power source 16 for plasma generation, 20 MHz to 500 MHz,
Since a high frequency power of 30 MHz to 200 MHz is preferably used, stable plasma can be obtained and fine workability can be improved even when the gas pressure in the processing chamber is set to a low pressure of 5 mTorr to 40 mTorr. Further, by using such high-frequency power, the dissociation of gas plasma is improved, and the selectivity control during sample processing is improved.

By the way, the electrostatic adsorption film 22 acts so as to inhibit the action of the pulse bias on the ions. In the present invention, the electrostatic adsorption film 22 is applied with the application of the pulse bias.
One of the features is that the voltage suppressing means is provided in order to suppress the rise of the voltage generated between both ends and to enhance the effect of the pulse bias.

As an example of the voltage suppressing means, the change (V _CM ) of the voltage during one cycle of the bias voltage generated between both ends of the electrostatic adsorption film due to the application of the pulse bias is the magnitude of the pulse bias voltage (V _CM ). _It is preferable to configure it to be 1/2 or less of _p ). Specifically, the electrostatic capacitance of the dielectric is reduced by reducing the thickness of the electrostatic attraction film made of the dielectric provided on the surface of the lower electrode 15 or by using a material having a large dielectric constant. There is a way to increase.

Alternatively, as another voltage suppressing means,
There is also a method of suppressing the rise of the voltage V _CM by shortening the cycle of the pulse bias voltage. Furthermore, a method in which the electrostatic suction circuit and the pulse bias voltage application circuit are separately provided at different positions, for example, at an opposite electrode different from the electrode on which the sample is arranged and held, or at a third electrode separately provided is also considered. Can be

Next, the relationship between the pulse bias voltage and the change (V _CM ) in the voltage generated across the electrostatic attraction film during one cycle of the pulse bias, which should be brought about by the voltage suppressing means in the present invention, will be described with reference to FIGS. This will be described in detail with reference to FIG.

First, an example of a desirable output waveform used in the pulse bias power supply 17 of the present invention is shown in FIG. In the figure, the pulse amplitude is v _p , the pulse period is T ₀ , and the positive direction pulse width is T ₁ .

When the waveform of FIG. 3 (A) is applied to the sample via the blocking capacitor and the electrostatic attraction dielectric layer (hereinafter abbreviated as an electrostatic attraction film), plasma is generated by another power source. The potential waveform on the surface of the sample in the steady state in this state is shown in FIG.

However, the direct current component voltage of the waveform: V _DC floating potential of the plasma: V _f The maximum voltage in one cycle of the voltage generated between both ends of the electrostatic adsorption film: V _CM .

In FIG. 3 (B), the portion (I) where the positive voltage is higher than V _f is the portion that mainly draws only the electron current, and the negative portion from V _f is the ionic current. The part where _Vf is drawn is a part where electrons and ions are balanced ( _Vf is usually several V to ten and several V).

Incidentally, in FIG. 3 (A) and the following description,
It is assumed that the capacity of the blocking capacitor and the capacity of the insulator near the surface of the sample are sufficiently larger than the capacity of the electrostatic attraction film (hereinafter simply referred to as electrostatic attraction capacity).

The value of V _CM is expressed by the following equation (Equation 1).

[0051]

[Equation 1]

However, q: ion current density (average value) flowing into the sample during the period (T ₀ −T ₁ ) c: electrostatic adsorption capacity per unit area (average value) i _i : ion current density, ε _r : Relative permittivity of electrostatic adsorption film d: film thickness of electrostatic adsorption film ε ₀ : dielectric constant (constant) in vacuum K: electrode coverage of electrostatic adsorption film (≦ 1) The pulse duty ratio: (T ₁ / T ₀ ) shows a probability distribution of the potential waveform and ion energy of the sample surface when T ₀ is changed while keeping it constant. Where T ₀₁ ,
T ₀₂ : T ₀₃ : T ₀₄ : T ₀₅ = 16: 8: 4: 2: 1.

As shown in (1) of FIG. 4, the pulse period T ₀
Is too large, the potential waveform on the sample surface deviates greatly from the rectangular wave and becomes a triangular wave, and the ion energy has a constant distribution from the lower side to the higher side, which is not preferable.

As shown in (2) to (5) of FIG. 4, as the pulse period T ₀ is reduced, (V _CM / v _p ) becomes a value smaller than 1, and the ion energy distribution also narrows. .

4 and 5, T ₀ = T ₀₁ , TO ₀₂ ,
T ₀₃ , T ₀₄ , and T ₀₅ are (V _CM / v _p ) = 1, 0.63,
It corresponds to 0.31, 0.16, and 0.08.

Next, the pulse off (T ₀ -T ₁ ) period and
FIG. 6 shows the relationship between the maximum voltage V _{CM in} one cycle of the voltage generated across the electrostatic adsorption film.

As the electrostatic adsorption film, a titanium oxide-containing alumina (ε _r = 10) having a thickness of 0.3 mm was used, and the thickness of the electrode was about 50.
% (K = 0.5), the ion current density i _i
The change in the value of V _CM in the medium density plasma of = 5 mA / cm ² is shown by the thick line (standard condition line) in FIG.

As is apparent from FIG. 6, as the pulse off (T ₀ -T ₁ ) period becomes longer, the voltage V _CM generated across the electrostatic adsorption film becomes a larger value in proportion to it, which is normally used. The applied pulse voltage becomes _vp or more.

[0059] For example, in a plasma etching apparatus, damage, selectivity with the base or the mask, typically the shape or the like, in the gate etch 250Volt ≦ a 50volt ≦ v _p ≦ 200volt oxide film etched by 20volt ≦ v _p ≦ 100volt metal etching Limited to v _p ≤ 800 volt.

When the condition of (V _CM / v _p ) ≦ 0.5 described later is to be satisfied, the upper limit of (T ₀ -T ₁ ) is as follows in the standard state. The gate etch (T ₀ -T ₁₎ ≦ 0.15μs the metal etching (T ₀ -T ₁₎ ≦ 0.35μs oxide film in the etching (T ₀ -T ₁₎ ≦ 1.2μs Incidentally, T ₀ is 0. When it approaches 1 μs, the impedance of the ion sheath approaches or falls below the impedance of the plasma, so that unnecessary plasma is generated and the bias power supply is not effectively used for accelerating the ions. Therefore, since the control of the ion energy by the bias power source is degraded, T ₀ is, 0.1 [mu]
s or more, preferably 0.2 μs or more.

Therefore, in a gate etcher or the like in which v _p can be kept low, the dielectric constant of the material of the electrostatic adsorption film is 1
0 to 100 (eg, ε _r = 2 in Ta ₂ O ₃₎
5) or a thin film thickness without lowering the withstand voltage, for example, 10 μm to 400 μm, preferably 10 μm to 10 μm.
It needs to be 0 μm.

In FIG. 6, the electrostatic capacity c per unit area is
V _CM when increased by 2.5 times, 5 times and 10 times respectively
The value of is also shown. Even if the electrostatic adsorption film is improved, at present it is considered that the improvement of the capacitance c by several times is the limit, and V _CM ≦ 3
Assuming that 00 volt and c ≦ 10c ₀ , 0.1 μs ≦ (T ₀ −
T ₁ ) ≦ 10 μs.

The portion effective for plasma treatment by the acceleration of ions is the portion (T ₀ -T ₁ ), and the pulse duty (T ₁ / T ₀ ) is preferably as small as possible.

FIG. 7 shows the plasma processing efficiency estimated by taking (V _DC / v _p ) in consideration of the time average. (T
_It is preferable to decrease ₁ / T ₀ ) and increase (V _DC / v _p ).

As the efficiency of the plasma treatment, 0.5 ≦ (V _DC
/ V _p ) and the following condition, (V _CM / v _p ) ≦ 0.5
, The pulse duty is (T ₁ / T ₀ ) ≦ 0.
It will be about 4.

The smaller the pulse duty (T ₁ / T ₀ ) is, the more effective it is to control the ion energy. However, if it is made smaller than necessary, the pulse width T ₁ becomes a small value of about 0.05 μs, which is several tens of MHz. Therefore, it becomes difficult to separate it from the high frequency component for plasma generation, which will be described later. As shown in FIG. 7, 0 ≦ (T ₁ /
When (T ₀ ) ≦ 0.05, the decrease of (V _DC / v _p ) is slight, and when (T ₁ / T ₀ ) is 0.05 or more, no particular problem occurs.

Here, as an example of gate etching, FIG. 8 shows etching rates ESi and ESiO between silicon and an underlying chloride film when chlorine gas of 10 mT is turned into plasma.
₂ shows the ion energy dependence of ₂ . The silicon etching rate ESi has a constant value at low ion energy. When the ion energy is about 10 V or more, ESi increases as the ion energy increases. On the other hand, the etching rate ESiO ₂ of the underlying oxide film is 0 when the ion energy is about 20 V or less, and when it exceeds about 20 V, ESiO ₂ increases with the ion energy.

As a result, when the ion energy is about 20 V or less, there is a region where the selection ratio ESi / ESiO ₂ to the base is ∞. When the ion energy is about 20 V or more, the selectivity ESi / ESiO ₂ with respect to the base rapidly decreases as the ion energy increases.

FIG. 9 shows an oxide film (Si
As an example of etching (O ₂ , BPSG, HISO, etc.), an etching rate ESiO ₂ and ES of an oxide film and silicon when C 4 F 8 gas 10 mT is turned into plasma
It shows the ion energy distribution of i.

The etching rate ESiO ₂ of the oxide film is
At low ion energies, the value is negative and a depot occurs.
When the ion energy is around 400 V, ESiO ₂ rises rapidly and positively, and thereafter gradually increases. On the other hand, the etching rate ESi of the underlying silicon is ESi
At a place where the ion energy is higher than O ₂ , (−) (etching) is changed to (+) (etching), and gradually increases.

As a result, in the vicinity of the change of ESiO ₂ from (−) to (+), the selection ratio ESiO ₂ / ESi with the base is
、, above which ESiO ₂ / ESi drops rapidly with increasing ion energy.

8 and 9, the values of ESi and ESiO ₂ and ESi / ESi are applied to the actual process.
The ion energy is adjusted to an appropriate value by adjusting the bias power source in consideration of the magnitudes of O ₂ and ESiO ₂ / ESi.

Further, until the just etching (etching until the underlying film appears), the magnitude of the etching rate is given priority, and after the just etching, the ion energy is changed before and after the just etching by giving priority to the magnitude of the selection ratio. If so, better characteristics can be obtained.

The characteristics shown in FIGS. 8 and 9 are characteristics when the ion energy distribution is limited to a narrow portion. When the energy distribution of ions is wide, each etching rate becomes the time average value, so that it cannot be set to the optimum value, and the selectivity is greatly reduced.

According to the experiment, if (V _DC / v _p ) is about 0.3 or less, the spread of ion energy is ± 15%.
It was below the level, and a high selection ratio was obtained with the characteristics shown in FIGS. Further, if (V _DC / v _p ) ≦ 0.5, the selection ratio and the like were improved as compared with the conventional sinusoidal bias method.

As described above, as a voltage suppressing means for suppressing the voltage change (V _CM ) during one cycle of the pulse voltage generated between both ends of the electrostatic adsorption film, V _CM is the magnitude of the pulse bias voltage v.
It is preferable that the thickness is set to be equal to or less than 1/2 of _p . Specifically, the thickness of the dielectric electrostatic chuck film 22 provided on the surface of the lower electrode 15 is reduced, By using a material having a high rate, the capacity of the dielectric can be increased. Alternatively, the cycle of the pulse bias voltage is set to 0.
1 μs to 10 μs, preferably 0.2 μs to 5 μs (corresponding to a repetition frequency of 0.2 MHz to 5 MHz), and the pulse duty (T ₁ / T ₀ ) is set to 0.05 ≦ (T ₁ /
T ₀ ) ≦ = 0.4 is set to suppress the voltage change across the electrostatic adsorption film.

Alternatively, by combining the film thickness of the electrostatic attraction film of the dielectric and some of the dielectric constant of the dielectric and the period of the pulse bias voltage, the voltage V _CM generated across the electrostatic attraction film is obtained. May satisfy the condition of (V _CM / v _p ) ≦ 0.5 described above.

Next, an example in which the vacuum processing chamber of FIG. 1 is used for etching an oxide film (eg, SiO2, SiN, BPSG) will be described.

As the gas 19, C ₄ F 8: 1 to 5%,
Ar: 90 to 95%, O ₂ : 0 to 5%, or C ₄ F
8: 1~5%, Ar: 70~90 %, O 2: 0~5%,
The composition of CO: 10 to 20% is used. As the high frequency power source 16 for plasma generation, a higher frequency than the conventional one, for example, 40 MHz is used, and 10 mTorr to 30 m
Measures the stabilization of discharge in the low gas pressure region of Torr.

If the dissociation proceeds more than necessary due to the high frequency of the plasma source high frequency power source 16, the output of the high frequency power source 16 is controlled to be turned on / off or level modulated by the high frequency power source modulation signal source 161. About 5 to 50 μs as the ON (or high level during level modulation) time,
1 for off time (or low level during level modulation)
0 to 100 μs and a cycle of about 20 μs to 150 μs are used, whereby unnecessary dissociation can be prevented.

The modulation cycle of the high frequency power source for plasma source is usually longer than the cycle of pulse bias. Therefore, the modulation ratio of the high-frequency power source for plasma source is set to an integral multiple of the period of the pulse bias, and the phase between the two is optimized to improve the selection ratio.

On the other hand, the ion energy is controlled by accelerating and vertically injecting the ions in the plasma into the sample by applying the pulse bias voltage. As the pulse bias power supply 17, for example, a pulse cycle: T = 0.
By using a power source of 65 μs, pulse width: T ₁ = 0.15 μs, and pulse amplitude: Vp = 600 V, the ion energy distribution width becomes ± 15% or less, and
Plasma processing with a good selection ratio of 20 to 50 with respect to SiN or SiN has become possible.

Next, another embodiment of the present invention will be described with reference to FIG. This embodiment has a configuration similar to that of the parallel plate electrode type plasma etching apparatus shown in FIG. 1, but the lower electrode 15 holding the sample 40 is provided with a unipolar electrostatic chuck 20. ing. That is, the lower electrode 1
A dielectric layer 22 for electrostatic attraction is provided on an upper surface of the DC power supply 5, and a lower side of the DC power supply 23 is connected to the lower electrode 15 via a coil 24 for cutting high frequency components. Also, 2
A pulse bias power supply 17 that supplies a positive pulse bias of 0 V to 800 V is connected via a blocking capacitor 19.

The sample 40 to be processed is placed on the lower electrode 15 and the electrostatic chuck 20, that is, the DC charge 23 supplies the positive charge and the negative charge supplied from the plasma to the electrostatic adsorption film 22. It is adsorbed by the Coulomb force generated between both ends.

The operation of this apparatus is the same as that of the parallel plate electrode type plasma etching apparatus shown in FIG. 1. When performing the etching process, the sample 40 to be processed is placed on the sample table 15 and the electrostatic force is applied. The pressure of the processing chamber 10 is reduced to 5 mTorr to 40 mTorr by introducing the processing gas from the gas supply system 36 into the processing chamber 10 at a predetermined flow rate while evacuating the chamber with the vacuum pump 18. Evacuate under reduced pressure. Next, the high frequency power supply 16 is turned on and a high frequency voltage of 20 MHz to 500 MHz, preferably 30 MHz to 100 MHz is applied between the parallel plate electrodes 12 and 15 to generate plasma. On the other hand, 20 V to 800 V from the pulse bias power supply 17 to the lower electrode 15 with a period of 0.1 μs
A positive pulse bias voltage of 10 μs to 10 μs, preferably 0.2 μs to 5 μs is applied to control the plasma in the processing chamber 10 to etch the sample 40.

By applying such a pulse bias voltage, ions in the plasma or ions and electrons are accelerated and vertically incident on the sample, thereby performing highly accurate shape control or selection ratio control. The characteristics required for the pulse bias power supply 17 and the electrostatic attraction film 22 are the same as those in the embodiment of FIG.

In the embodiments of the present invention described above, there is a possibility that interference may occur between the output of the pulse bias power supply and the output of the plasma generating power supply. Therefore,
I will talk about this measure.

First, in an ideal rectangular pulse having a pulse width: T ₁ and a pulse period: T ₀ and an infinite rise / fall speed, as shown in FIG. 11, f ≦ 3f ₀ (f ₀ = (1
/ T ₁ )) includes about 70 to 80% of the power. Since the actually applied waveform has a finite rise / fall speed, the power convergence is further improved, and f ≦ 3
The frequency range of f ₀ can include about 90% or more of electric power.

In order to uniformly apply a pulse bias having a high frequency component of 3f ₀ to the sample surface, a counter electrode substantially parallel to the sample is provided, and 3f ₀ obtained by the following equation 2 is obtained. Therefore, it is desirable to ground the frequency component in the range of f ≦ 3f ₀ .

[0090]

[Equation 2]

FIG. 12 shows an embodiment of the parallel plate electrode plasma etching apparatus shown in FIG. 1 in which measures against interference between the pulse bias power source output and the plasma generating power source output are taken. In this parallel plate electrode plasma etching apparatus, a high frequency power supply 16 for plasma generation is connected to the upper electrode 12 facing the sample 40. In order to bring the upper electrode 12 to the ground level of the pulse bias, the frequency f ₁ of the high frequency power source 16 for plasma generation is set to be larger than the above 3f ₀ , and the impedance in the vicinity of f ≦ f ₁ is large, so that other frequencies are not used. Then, the band eliminator 141 having a low impedance is connected between the upper electrode 12 and the contact level.

On the other hand, a bandpass filter 142 having a low impedance near f = f ₁ and a high impedance at other frequencies is installed between the sample stage 15 and the ground level. With such a configuration, the pulse bias power supply 1
The interference between the output of the sample 7 and the output of the power supply 16 for plasma generation can be suppressed to a level without any problem, and a good bias can be applied to the sample 40.

FIG. 13 shows an example in which the present invention is applied to a plasma etching apparatus of an inductively coupled discharge method and a non-magnetic field type among external energy supply discharge methods. 52
Is a flat coil, 54 is a flat coil with 10 MHz to 250 MHz
It is a high frequency power supply for applying a high frequency voltage of z. Compared with the parallel plate type shown in FIG. 10, the inductively coupled discharge method enables stable plasma generation at a low frequency and low pressure.
On the contrary, since the dissociation easily proceeds, as shown in FIG. 1, the output of the high frequency power source 1 is changed to the high frequency power source modulation signal source 161.
Can be modulated, and unnecessary dissociation can be prevented. The processing chamber 10 as a vacuum vessel includes a sample table 15 on which a sample 40 is placed on the electrostatic attraction film 22.

When performing the etching process, the sample 40 to be processed is placed on the sample table 15 and held by electrostatic force.
While the processing gas is introduced into the processing chamber 10 from a gas supply system (not shown) at a predetermined flow rate, the pressure in the processing chamber 10 is set to 5 mTorr to 40 m by evacuating by the vacuum pump.
Evacuate to Torr. Next, 13.5 is supplied to the high-frequency power supply 54.
Plasma is generated in the processing chamber 10 by applying a high-frequency voltage of 6 MHz. The sample 40 is etched using the plasma. On the other hand, during etching, the lower electrode 15
The cycle is 0.1 μs to 10 μs, preferably 0.2 μs to 5 μs
Is applied. As described in the embodiment of FIG. 1, the range of the amplitude of the pulse bias voltage differs depending on the type of the film. By applying the pulse bias voltage, ions in the plasma are accelerated and vertically incident on the sample, thereby performing highly accurate shape control or selectivity control. Thus, even if the resist mask pattern of the sample is extremely fine, highly accurate etching can be performed.

FIG. 14 shows a schematic diagram of the inductively coupled discharge type non-magnetic field type plasma etching apparatus shown in FIG.
A Faraday shield plate 53 having a gap 55 and a thin shield plate protection insulating plate 54 of 0.5 mm to 5 mm are installed on the processing chamber side 10 of the induction electric high frequency output, and the Faraday shield plate 53 is grounded. By installing the Faraday shield plate 53, the capacitance component between the coil and the plasma is reduced, and the energy of the ions hitting the quartz plate under the coil 52 in FIG. 13 and the shield plate insulating plate 54 in FIG. 14 can be reduced. It is possible to reduce damage to the quartz plate and the insulating plate and prevent foreign matter from entering the plasma.

Further, since the Faraday shield plate 53 also serves as the ground electrode of the pulse bias power supply 17, the pulse bias can be applied uniformly between the sample 40 and the Faraday shield plate 53. In the example of FIG.
No parallel plate type upper electrode or a filter installed on the sample table 15 is required.

FIG. 15 is a vertical sectional front view of a part of an apparatus in which the present invention is applied to a microwave plasma processing apparatus. A pulse bias power supply 1 is applied to a lower electrode 15 as a sample stage 15 on which a sample 40 is mounted on the electrostatic chucking film 22.
7 and a DC power supply 13 are connected. 41 is a magnetron as a microwave oscillation source, 42 is a microwave waveguide, and 43 is a quartz plate for vacuum-sealing the processing chamber 10 and supplying the microwave to the processing chamber 10. 47
Is a first solenoid coil for supplying a magnetic field, and 48 is a second solenoid coil for supplying a magnetic field. A processing gas supply system 49 supplies a processing gas for performing processing such as etching and film formation into the processing chamber 10. The processing chamber 10
Is evacuated by a vacuum pump (not shown). The characteristics required for the pulse bias power supply 17 and the electrostatic chuck 20 are the same as those of the embodiment of FIG.

When performing the etching process, the sample 40 to be processed is placed on the sample table 15 and held by electrostatic force.
The pressure of the processing chamber 10 is reduced to 5 mTorr to 40 mTorr by evacuating the processing chamber 10 from the gas supply system 49 to the processing chamber 10 at a predetermined flow rate while evacuating the processing chamber 10 by vacuum. Next, the magnetron 41 and the first and second solenoid coils 47 and 48 are turned on, and the microwave generated by the magnetron 41 is passed from the waveguide 42 to the processing chamber 10.
To generate plasma. An etching process is performed on the sample 40 using this plasma. On the other hand, during etching, a period of 0.1 μs to 10 μs is applied to the lower electrode 15.
Preferably, a pulse bias voltage of 0.2 μs to 5 μs is applied.

By applying such a pulse bias voltage, ions in the plasma are accelerated and vertically incident on the sample, thereby performing highly precise shape control or selection ratio control. Thereby, even if the resist mask pattern of the sample is extremely fine, a highly accurate etching process corresponding to the mask pattern can be performed by perpendicular incidence.

In the plasma etching apparatus of the present invention shown in FIG. 1 and subsequent figures, the DC voltage of the electrostatic adsorption circuit and the pulse voltage of the pulse bias power supply circuit are superposed and generated,
The circuit can be configured in common. Alternatively, the electrostatic chuck circuit and the pulse bias power supply circuit may be separately provided on different electrodes so that the pulse bias does not affect the electrostatic chuck.

Instead of the electrostatic attraction circuit in the embodiment of the parallel plate plasma etching apparatus shown in FIG. 1, other attraction means such as vacuum attraction means can be used as shown in FIG. First, set the pressure in the processing chamber to 5 mTorr to 4
Evacuate to 0 mTorr. Next, a high frequency voltage is applied to the high frequency power source to generate plasma in the processing chamber 10. The sample 40 is etched using the plasma. On the other hand,
During etching, the lower electrode 15 has a period of 0.1 μs
A pulse bias voltage of 10 μs to preferably 0.2 μs to 5 μs is applied. By applying such a pulse bias voltage, ions in the plasma are accelerated and vertically incident on the sample, thereby performing highly accurate shape control or selection ratio control.

In this case, as the characteristic of the voltage supplied from the pulse bias power supply circuit, it is not necessary to consider the influence of the electrostatic attraction circuit, and the voltage characteristic suitable for highly accurate shape control or selection ratio control is provided. It should be done. As a result, even if the mask pattern of the sample is extremely fine,
It is possible to perform highly accurate etching processing corresponding to the mask pattern.

Next, a plasma etching apparatus capable of independently controlling ions and radicals according to another embodiment of the present invention shown in FIG. 17 will be described. In plasma processing, it is important to properly control the amount of ions, the amount of radicals, and the radical species for improving the performance. Conventionally, a gas serving as an ion source or a radical source is caused to flow into the processing chamber, plasma is generated in the processing chamber, and ions and radicals are simultaneously generated. However, as the processing of the sample becomes finer, its limit is becoming apparent.

The embodiment of FIG. 17 is intended to improve this conventional defect and to enable ultrafine plasma processing. In addition to the parallel plate plasma etching apparatus shown in FIG. A gas supply source 60 and a plasma generation chamber 62 for generating radicals are provided.

The features of this embodiment are as follows. The radical source gas supplied from the radical source gas supply source 60 is turned into plasma in the radical generating plasma generation chamber 62, and a desired amount of desired radicals is generated in advance. Then, this radical is caused to flow into the processing chamber 10. On the other hand, the ion source gas is caused to flow into the processing chamber 10 from the ion source gas supply source 36.

A high frequency is output from the plasma generation power source 16 to generate plasma having a low electron temperature (5 eV or less, preferably 3 eV or less) in the processing chamber 10 to generate ions. It should be noted that although the introduced radicals are partially dissociated by the plasma generated in the processing chamber 10, by suppressing the electron temperature of the generated plasma to a low value of about 5 eV or less, re-dissociation of the introduced radicals can be prevented. It can be suppressed to a small value.

By providing a plasma generation source for radical generation that generates radicals separately from the plasma generation source of the processing chamber 10 that mainly generates ions, it is possible to independently control ions and radicals to a desired quality and amount. Therefore, good performance can be obtained even in ultrafine plasma processing.

The plasma generation chamber 62 for generating radicals
Is a processing chamber 1 that mainly generates ions in the processing chamber 10.
It may be provided separately from the zero plasma generation source.

Next, FIG. 18 shows another embodiment of the present invention in which ions and radicals are independently controlled. In FIG. 18, a fluorocarbon gas such as CHF3, CH2F2, C4F8, or CF4 is mixed with a gas containing C and H (C2H4, CH3OH, etc.), if necessary, and is introduced from a portion A of FIG. It is placed in the plasma generating chamber 62 for generating radicals.

In the plasma generating chamber 62 for generating radicals,
The output of the RF power supply 63 of several MHz or several tens MHz is applied to the coil 65, and several hundreds mTorr to several tens T
Plasma is generated at a gas pressure of orr, and mainly CF2 radicals are generated. Simultaneously generated CF3 and F are reduced by the H component.

The plasma generation chamber 62 for generating radicals
Therefore, it is difficult to greatly reduce the components such as CF and O, and an unnecessary component removing chamber 65 is provided thereafter. here,
Materials containing carbon or Si (carbon, Si, SiC
Etc.) is installed to reduce unnecessary components or convert them to another gas with less adverse effects. Unnecessary component removal chamber 65
Is connected to a valve 71 to supply a gas composition mainly composed of CF2.

Between the valve 70 and the valve 71,
Since a large amount of deposits such as deposits accumulate, cleaning and replacement are required in a relatively short period of time. For this reason, it is connected to the exhaust device 74 via the valve 72 in order to facilitate opening to the atmosphere and replacement, and to shorten the time required for vacuum startup at the time of restart. Note that the exhaust device 74 may also be used as an exhaust device for the processing chamber 10 and the like.

An ion source gas (a rare gas such as argon gas or xenon gas) B is connected to the outlet of the valve 71 and supplied to the processing chamber via the valve 73.

The processing chamber 10 is maintained at a pressure of 5-40 mT,
By the modulated high frequency power supply 16 of 20 MHz or more,
Ionization of ion source gas while generating high density low electron temperature plasma of 5 eV, preferably 3 eV or less and 10 to the 11th power / cm 3, and avoiding dissociation of CF 2 requiring dissociation energy of 8 eV or more. To progress. As a result, the following reaction mainly progresses on the surface of the sample 40, assisted by the incidence of ions accelerated by the bias power supply 17 at several hundred volts.

SiO2 + 2CF2 → SiF4 ↑ + 2CO ↑ Since Si and SiN, which are the base materials, are not etched by CF2, the oxide film can be etched with a high selectivity.

The increase in F due to partial dissociation of CF2 is reduced by the upper electrode cover 30 made of silicon, carbon, SiC or the like.

As described above, by adjusting the radical source gas A and the ion source gas B, the processing chamber 10
The ratio of ions to radicals in the sample can be controlled almost independently, and the reaction on the surface of the sample 40 can be controlled to a desired one.
Has become easier. Unnecessary depot components and the like are eliminated in the unnecessary component removing chamber 65 so as not to be brought into the processing chamber 10 as much as possible. The frequency of cleaning that is open to the public was also significantly reduced.

Next, FIG. 19 shows another embodiment in which ions and radicals are independently controlled. Hexafluoropropylene oxide (CF3CFOCF2, hereinafter abbreviated as HFPO) from A via the valve 70 and the heating pipe portion 66.
Through the unnecessary component removal chamber 65 and the valve 71, and mixed with the ion source gas B, and sent to the processing chamber 10. In the heating pipe section 66, HFPO is heated to 800 ° C to 1000 ° C, and CF2 is generated by the following thermal decomposition.

CF3CFOCF2 → CF2 + CF3CFO CF3CFO is a relatively stable substance and is difficult to decompose, but since it partially decomposes to generate unnecessary O and F, the heating pipe portion 6
After 6, an unnecessary component removal chamber 65 is provided to remove unnecessary components,
Alternatively, it is converted to a substance that does not cause adverse effects. Some C
Although F3CFOCF2 flows into the processing chamber 10 without being decomposed, it does not cause any problem because it is not dissociated by plasma having a low electron temperature of 5 eV or less.

The method of using the valve 72 and the exhaust device 74 and the reaction in the processing chamber 10 are the same as in the case of FIG.

The plasma processing apparatus of the present invention provided with the electrostatic adsorption circuit and the pulse bias voltage application circuit is limited to the above-mentioned etching processing by making changes such as introducing the CVD gas instead of the etching gas. Instead, it can be applied to a plasma processing apparatus such as a CVD apparatus.

[0122]

According to the present invention, the processing conditions suitable for the object to be processed can be constructed by independently controlling the quality and quantity of the ions and radicals.

Further, by controlling the quantity and quality of ions and radicals independently, a narrow ion energy distribution can be obtained with good controllability, and a plasma processing apparatus and a plasma processing method in which the selectivity of plasma processing is improved. Can be provided.

When a sample table having a dielectric layer for electrostatic adsorption is used, the amount and quality of ions and radicals can be controlled independently to obtain a narrow ion energy distribution with good controllability and to obtain plasma. It is possible to provide a plasma processing apparatus and a plasma processing method with improved processing selectivity and the like.

Further, by independently controlling the amount and quality of ions and radicals, the pressure in the processing chamber of the plasma processing apparatus can be lowered, and precise processing of fine patterns can be performed easily. A plasma processing apparatus and a plasma processing method having an improved ratio can be provided.

By controlling the quantity and quality of the ions and radicals independently, the insulating film (eg SiO2,
It is possible to provide a plasma processing apparatus and a plasma processing method in which the selectivity of plasma processing with respect to SiN, BPSG, etc.) is improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a parallel plate electrode type plasma etching apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a frequency of a power supply for plasma generation and a stable discharge minimum gas pressure.

FIG. 3 is a diagram showing an example of a desirable output waveform used in the pulse bias power supply of the present invention.

FIG. 4 is a diagram showing a probability distribution of an ion energy and a potential waveform on a sample surface when T ₀ is changed while keeping a pulse duty ratio (T ₁ / T ₀ ) constant.

FIG. 5 is a diagram showing a potential distribution on a sample surface and a probability distribution of ion energy when T ₀ is changed while keeping a pulse duty ratio constant.

FIG. 6 is a diagram showing the relationship between the pulse off (T ₀ -T ₁ ) period and the maximum voltage V _CM during one cycle of the voltage generated across the electrostatic adsorption film.

FIG. 7 is a diagram showing a relationship between a pulse duty ratio and (V _DC / v _p ).

FIG. 8 is a diagram showing ion energy dependence of etching rates ESi and ESiO ₂ of silicon and a chloride film when chlorine gas of 5 mT is turned into plasma.

FIG. 9: CF4 gas 5 mT as an example of etching an oxide film
FIG. 3 is a diagram showing an ion energy distribution of an etching rate ESiO ₂ between an oxide film and silicon and ESi when plasma is generated.

FIG. 10 is a vertical cross-sectional view of a parallel plate electrode type plasma etching apparatus according to another embodiment of the present invention.

FIG. 11 is a diagram showing a relationship between a frequency of a pulse bias power supply and accumulated power.

FIG. 12 is a vertical cross-sectional view of another embodiment in which the parallel plate electrode plasma etching apparatus shown in FIG. 1 is improved.

FIG. 13 is a vertical cross-sectional view of an example in which the present invention is applied to a plasma etching apparatus of an inductively coupled discharge method and a non-magnetic field type among external energy supply discharge methods.

FIG. 14 is a vertical sectional view of a plasma etching apparatus according to another embodiment of the present invention.

FIG. 15 is a vertical cross-sectional front view of a part of an apparatus in which the present invention is applied to a microwave plasma processing apparatus.

FIG. 16 is a vertical sectional view of a parallel plate plasma etching apparatus according to another embodiment of the present invention.

FIG. 17 is a vertical cross-sectional view of a parallel plate electrode plasma etching apparatus capable of independently controlling ions and radicals according to another embodiment of the present invention.

FIG. 18 is a vertical cross-sectional view of a parallel plate electrode plasma etching apparatus capable of independently controlling ions and radicals according to another embodiment of the present invention.

FIG. 19 is a partial detailed view of a parallel plate electrode plasma etching apparatus capable of independently controlling ions and radicals according to another embodiment of the present invention.

[Explanation of symbols]

10 processing chamber, 12 upper electrode, 15 lower electrode, 16
... high frequency power supply, 17 ... pulse bias power supply, 20 ... electrostatic chuck, 22 ... electrostatic attraction film, 23 ... DC power supply, 40 ...
sample.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location H05H 1/46 H05H 1/46 M (72) Inventor Toru Otsubo 502 Kandachi-cho, Tsuchiura-shi, Ibaraki Stock Company Hiritsu Seisakusho Mechanical Research Center

Claims (27)

[Claims] 1. A plasma processing apparatus having a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating means, wherein the sample is electrostatically attracted to the sample processing device. Radical for supplying a desired amount of radicals, which has electrostatic attraction means for holding it on a sample stage, bias applying means for applying a bias voltage to the sample, and means for previously decomposing a gas for radical generation in the vacuum processing chamber. Supply means, means for supplying a gas for ion generation to the vacuum processing chamber,
A plasma processing apparatus, comprising: a plasma generating means for generating plasma in the vacuum processing chamber; and using SiO ₂ as the sample. 2. The plasma processing apparatus according to claim 1, wherein the means for decomposing the radical generating gas is 1
A plasma processing apparatus characterized by using a plasma of 00 mTorr to several + Torr. 3. The plasma processing apparatus according to claim 2, wherein the means for generating plasma in the vacuum processing chamber is 5e.
A plasma processing apparatus, which is a plasma having an electron temperature of V or less. 4. The plasma processing apparatus according to claim 1, wherein an unnecessary component removing unit is provided after the unit that decomposes the radical generating gas in advance. 5. The plasma processing apparatus according to claim 4, wherein the means for preliminarily decomposing the gas for radical generation and the means for removing unnecessary components are constructed so that they can be evacuated in a system separate from other parts. And a plasma processing apparatus. 6. A plasma processing apparatus having a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating means, wherein the sample is electrostatically attracted to the sample processing device. An electrostatic attraction means for holding the sample on the sample stage, a pulse bias applying means for applying a pulse bias voltage to the sample, and a radical generating gas for preliminarily plasmaizing a radical generating gas into the vacuum processing chamber to supply a desired amount of radicals. A plasma processing apparatus comprising: a plasma supply means; and a plasma generation means for supplying a gas for ion generation to the vacuum processing chamber to generate plasma, wherein SiO ₂ is used as the sample. 7. A plasma processing apparatus having a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and plasma generating means including a high frequency power source, wherein the sample is electrostatically charged. An electrostatic adsorption means for holding the sample on the sample table by an adsorption force, a pulse bias application means for applying a pulse bias voltage to the sample, and a gas for radical generation are preliminarily plasmatized to the vacuum processing chamber to supply a desired amount of radicals. And a plasma generating means for generating a plasma by supplying an ion generating gas to the vacuum processing chamber, and applying a high frequency voltage of 10 MHz to 500 MHz to the high frequency power source, and Vacuum processing chamber 5mTorr-40mTorr
A plasma processing apparatus, wherein the plasma processing apparatus is configured to reduce the pressure. 8. A pair of opposing electrodes, each of which has a sample placed on one of the electrodes, electrostatic attraction means for holding the placed sample on the electrode by an electrostatic attraction force, and an atmosphere in which the sample is placed. A radical generating plasma supply means for preliminarily plasmaizing the radical generating gas to supply a desired amount of radicals; a means for supplying an ion generating gas to the atmosphere in which the sample is placed; and the introduced ion generating Plasma processing means comprising plasma generating means for converting the working gas into plasma, and pulse bias applying means for applying a pulse bias voltage to the one electrode during etching of the sample, wherein SiO ₂ is used as the sample apparatus. 9. A pair of opposing electrodes having a sample placed on one electrode, and a radical-producing plasma supply for preliminarily plasmaizing a radical-producing gas into an atmosphere in which the sample is placed to supply a desired amount of radicals. Means, means for supplying an ion generating gas to the atmosphere in which the sample is placed, exhaust means for reducing the pressure of the atmosphere to 5 mTorr to 40 mTorr, and a high-frequency voltage of 10 MHz to 500 MHz to the pair of opposed electrodes. A high frequency power supply means for applying, a plasma generating means for converting the ion generating gas introduced under the pressure into plasma, and a pulse bias applying means for applying a pulse bias voltage to the one electrode during etching of the sample. A plasma processing apparatus, wherein SiO ₂ is used as the sample. 10. A plasma processing apparatus comprising a vacuum processing chamber, a sample stage for arranging a sample to be processed in the vacuum processing chamber, and a plasma generating means, wherein the sample is treated by electrostatic attraction. An electrostatic attraction means for holding the sample on the sample stage, a plasma generating means for radical generation that plasma-converts a radical generating gas into the vacuum processing chamber in advance to supply a desired amount of radicals, and an ion generating gas for the vacuum processing chamber. Of the electrostatic attraction means connected to the sample stage and applying a pulse bias voltage to the sample stage, and the plasma generating means for supplying plasma to generate plasma. A plasma processing apparatus comprising: a voltage suppressing unit that suppresses an increase in voltage generated corresponding to the electrostatic adsorption capacity. 11. A plasma processing apparatus having a vacuum processing chamber, a sample stage for placing a sample to be processed in the vacuum processing chamber, and a plasma generating means, the electrostatic treatment being provided on the sample stage. An electrostatic adsorption unit that includes an adsorption film and holds the sample on the sample table by electrostatic adsorption force; and a plasma for radical generation that supplies a desired amount of radicals to the vacuum processing chamber in advance into a plasma for radical generation. Supply means, the plasma processing means for supplying a gas for ion generation to the vacuum processing chamber to generate plasma, a pulse bias applying means connected to the sample stage and applying a pulse bias voltage to the sample stage, Voltage suppression means for suppressing a voltage generated between both ends of the electrostatic adsorption film with application of the pulse bias voltage, the voltage suppression means comprising: The voltage due to electrostatic attraction film, plasma processing apparatus which comprises suppressing less than 1/2 of the pulse bias voltage. 12. The plasma processing apparatus according to claim 6, wherein the voltage of the electrostatic adsorption means is 1 of the pulse bias voltage.
The plasma processing apparatus, wherein the cycle of the pulse bias voltage is set to be equal to or less than / 2. 13. The plasma processing apparatus according to claim 12, wherein the period of the pulse bias voltage is 0.1 μs to 10 μs.
and a plasma processing apparatus. 14. The plasma processing apparatus according to claim 13, wherein the pulse bias voltage has a duty ratio of 40% or less. 15. The plasma processing apparatus according to claim 6, wherein the voltage of the electrostatic adsorption means is 1 of the pulse bias voltage.
The plasma processing apparatus, wherein the film pressure of the electrostatic adsorption film formed on the surface of the sample table is set to 10 µm to 400 µm such that the film thickness becomes 1/2 or less. 16. The plasma processing apparatus according to claim 6, wherein the voltage of the electrostatic attraction means is 1 of the pulse bias voltage.
The plasma processing apparatus characterized in that the dielectric constant of the electrostatic adsorption film formed on the surface of the sample table is set to 10 to 100 so that the ratio becomes 1/2 or less. 17. The plasma processing apparatus according to claim 6, wherein the film pressure, the dielectric constant, or the period of the pulse bias voltage of the electrostatic adsorption film formed on the surface of the sample table is at least 2. The plasma processing apparatus is characterized in that the electrostatic attraction voltage is set to ½ or less of the pulse bias voltage by two combinations. 18. The plasma processing apparatus according to claim 6, wherein the electrostatic attraction power supply and the pulse bias power supply are configured as a common power supply. 19. The plasma processing apparatus according to claim 6, wherein the plasma generating means includes a high frequency power source, and the high frequency power source has a frequency of 30 MHz to 100 MHz. . 20. The plasma processing apparatus according to claim 8 or 9, wherein a gap between the pair of opposed electrodes is 10 mm to 50 mm. 21. A step of placing a sample on one of electrodes provided in a vacuum processing chamber, a step of holding an outer sample on the sample by electrostatic attraction, and an atmosphere in which the sample is placed and held, Supplying a desired amount of radicals by plasmaizing a radical generating gas in advance; supplying an ion generating gas to the atmosphere; depressurizing the atmosphere to a processing pressure of the sample; Plasmaizing the ion generating gas under pressure, treating the sample with the plasma, applying a pulse bias voltage to the sample,
A plasma processing method comprising: 22. A step of placing a sample on one of the electrodes facing each other, a step of holding the placed sample on the electrode by electrostatic adsorption force, and a radical generation in an atmosphere in which the sample is placed and held. Supplying a desired amount of radicals to a gas for plasma in advance, supplying an ion generating gas to the atmosphere, converting the supplied ion generating gas into plasma, and the sample using the plasma. And a step of applying a pulse bias voltage to the one electrode during the etching treatment, wherein SiO ₂ is used as the sample. 23. A step of placing a sample on one of the electrodes facing each other, a step of holding the placed sample on the electrode by electrostatic attraction, and a radical generation in an atmosphere in which the sample is placed and held. Supplying a desired amount of radicals to a gas for plasma in advance, supplying an ion generating gas to the atmosphere, exhausting the atmosphere under reduced pressure to 5 mTorr to 40 mTorr, and applying 10 MHz to the opposing electrode. Applying a high frequency voltage of up to 500 MHz and converting the ion generating gas supplied under the pressure into plasma; etching the sample with the plasma; and applying a pulse to the one electrode during the etching. It consists applying a bias voltage, characterized by using SiO ₂ as the sample plasma Management method. 24. A step of disposing a sample on one of the electrodes provided in the vacuum processing chamber, a step of holding the sample on the electrode by electrostatic attraction force, and an atmosphere in which the sample is arranged / held, Supplying a desired amount of radicals to a radical-generating gas in advance into plasma, supplying an ion-generating gas to the atmosphere, applying a high-frequency voltage of 30 MHz to 100 MHz to the atmosphere, and supplying under the pressure A plasma characterized in that the ion-generating gas is made into plasma, the sample is treated with the plasma, and a pulse bias voltage is applied to the sample, and SiO ₂ is used as the sample. Processing method. 25. A step of placing a sample on one of the electrodes provided in the vacuum processing chamber, a step of holding the sample on the electrode by electrostatic attraction force, and an atmosphere in which the sample is placed and held, Supplying a desired amount of radicals to a plasma of a radical generating gas in advance; supplying an ion generating gas to the atmosphere; depressurizing the atmosphere to a processing pressure of the sample; The ion-generating gas supplied below is converted into plasma, the sample is treated with the plasma, and a pulse bias voltage is applied to the sample. A plasma processing method, characterized in that the pulse bias voltage is ½ or less. 26. A step of placing a sample on one of opposing electrodes provided in a vacuum processing chamber, a step of holding the sample on the electrode by electrostatic attraction, and an atmosphere in which the sample is placed and held. To supply a desired amount of radicals to a radical generating gas in advance into plasma, supplying an ion generating gas to the atmosphere, exhausting the atmosphere under reduced pressure to 5 mTorr to 40 mTorr, Applying a high-frequency voltage of 30 MHz to 100 MHz between the electrodes, plasmaizing the ion-generating gas supplied under the pressure, treating the sample with the plasma, and applying a pulse bias voltage to the sample. A plasma processing method comprising a step of applying. 27. The plasma processing method according to claim 21, wherein the one electrode is applied to the one electrode when the pulse bias voltage is applied.
A plasma processing method, characterized in that a pulse bias voltage having a period of 0.1 µs to 10 µs is applied.