JPH08250479A - Method and device for surface treatment - Google Patents

Abstract

PURPOSE: To improve the etching yield of a sample and perform high-selectivity etching on the sample by periodically providing a first period in which a reactive species is adsorbed to the surface of the sample, second period in which accelerated particles are projected upon the surface of the sample, and third period in which resulting products of reaction are separated from the surface of the sample and discharged to the outside. CONSTITUTION: The processing course of a surface-treating method using plasma is mainly composed of a first period A in which a reactive species is adsorbed to the surface of a sample, second period B in which accelerated particles are projected upon the surface of the sample, and third period C in which resulting products of reaction are separated from the surface of the sample and discharged to the outside and the processing course composed of the periods A, B, and C is periodically performed in a period of 1 msec to 1sec. When ions are projected upon the surface of the sample as the accelerated particles, plasma discharge is performed with an arbitrary modulated power in the periods A and B and a bias is applied across a sample stage by using the arbitrary modulated power in the period B. In addition, the material is treated by stopping the plasma discharge and application of the bias power in the period C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment method and a surface treatment apparatus for surface-treating a material in a manufacturing process of a semiconductor integrated circuit, and more particularly to a dry etching method and a dry etching apparatus for fine processing.

[0002]

2. Description of the Related Art A conventional dry etching method and apparatus will be described.

In dry etching, a wafer is placed on a sample table in a processing chamber, the processing chamber is evacuated to a desired degree of vacuum, and then a gas for material processing is introduced. It is performed by irradiating the material surface formed into a plasma on the wafer.

The conventional apparatus for performing this dry etching includes the following.

First, a wafer is placed on one of a pair of opposing electrodes, and a high frequency is applied to this electrode or the other electrode to generate plasma to process the wafer, so-called high frequency discharge parallel plate type reactivity. Dry etching (RIE; Reactiv)
e Ion Etching) equipment. There is also a so-called magnetron RIE method in which a magnetic field is further combined.

In recent years, dry etching apparatuses have been moving toward low pressure and high density plasma, and there are the following new type apparatuses. First, a microwave plasma (E) that introduces microwaves (frequency is mainly 2.45 [GHz]) generated by a magnetron into the processing chamber to turn the gas into plasma
CR: Electron Cyclotron Resonance plasma (also called plasma). In this device, a bias can be applied to the sample table independently of the plasma discharge. In addition, there is a dry etching device using a helicon wave method or a high frequency induction method, as described in Electronic Materials, 1992, Supplement, page 121. There are two types of high-frequency induction methods, a helical resonance type and a TCP (transformer coupled plasma) type, depending on the winding type of a coil for applying a high frequency. Also in this device, a bias can be applied to the sample table independently of the plasma discharge.

In dry etching performed using the above-mentioned apparatus, there is a method of performing time modulation of plasma discharge and bias application. Examples are given below.

Japanese Unexamined Patent Publication (Kokai) No. 58-186937 describes a method of controlling the ratio and energy between species of ions incident on a wafer by temporally changing the frequency of high-frequency power for generating a discharge. .

Japanese Unexamined Patent Publication (Kokai) No. 59-47733 describes a method for controlling the ratio and composition of ions and radicals generated in plasma by changing the energy of microwaves in microwave discharge plasma with time. ing. This is based on controlling the electron temperature and electron density in plasma by modulating the discharge.

Japanese Unexamined Patent Publication No. 60-62125 discloses a method of intermittently supplying high-frequency power to eliminate spatial nonuniformity of active species and prevent contamination of a processing chamber due to re-decomposition of reaction products. Has been done.

Japanese Unexamined Patent Publication No. 60-86831 discloses a method of periodically modulating a high frequency voltage to generate a discharge.

Japanese Unexamined Patent Publication No. 56-13480 describes a method of preventing charge-up of a wafer by applying an AC voltage of 100 kHz to 10 MHz to a sample stage in a microwave plasma etching apparatus.

In Japanese Patent Laid-Open No. 62-111429, a DC voltage on a pulse is superposed on a discharge electrode to make it possible to modulate an ion acceleration voltage between a plasma and a sample, thereby preventing damage to the sample due to etching, etching rate and A method for improving the selectivity is described.

Japanese Unexamined Patent Publication (Kokai) No. 61-13625 describes a method of periodically modulating microwave power and a method of periodically changing the accelerating voltage of ions in a microwave plasma processing apparatus.

In Japanese Patent Laid-Open No. 1-236629, the generation of pulsed microwaves and the generation timing of high frequency bias are synchronized to avoid high frequency mismatch when discharge is turned off and to prevent high frequency discharge due to generation of high voltage on the substrate. The method is described.

According to Japanese Patent Laid-Open No. 3-155620, an AC bias voltage is supplied to the sample stage in synchronism with the timing at which microwaves are intermittently supplied, so that a bias is applied only when plasma is generated to achieve impedance matching. A method for improving the effect of AC bias is described.

In Japanese Patent Laid-Open No. 4-174514, the generation of the pulsed microwave and the generation time of the high frequency bias are synchronized, the rising time of the high frequency bias voltage is delayed from the generation time of the pulsed microwave, or the high frequency bias voltage is changed. By making the fall time earlier than the stop time of the pulsed microwave, when applying a high frequency bias voltage in synchronization with the microwave pulse, it is possible to prevent an abnormal voltage from being generated on the substrate grounding part in the substrate. How to do is described.

Japanese Patent Laid-Open No. 60-50923 discloses a method of changing the amount of gas introduced, a method of changing the application of an external voltage to the sample depending on the amount of gas introduced, and a method of changing the amount of gas introduced to the sample depending on the amount of gas introduced. The method of intermittently changing the irradiation of the plasma is described.

In Japanese Patent Laid-Open No. 2-105413, an etching gas and a deposition gas for forming a side wall protective film are alternately introduced periodically at a cycle of a few tens of seconds, and a plasma generation power is periodically supplied in association with a gas switching cycle. It is described that the micro-ding effect is eliminated by periodically turning on and off and periodically applying high frequency bias power in conjunction with the etching gas cycle.

Japanese Unexamined Patent Publication (Kokai) No. 3-12921 describes a method of intermittently performing at least one of the step of attaching a reactive gas to a sample and the step of irradiating a particle beam.

Japanese Unexamined Patent Publication (Kokai) No. 3-263827 describes an apparatus for discharging a plasma for generating an etchant and a plasma for irradiating a substrate with ions in a pulse shape at alternately controlled time intervals.

In Japanese Patent Laid-Open No. 5-267226, the effective total pumping speed of the processing chamber is 1300 [liter / sec] or more, the residence time of the gas in the processing chamber is 100 [msec] or less, and the gas flow rate adjusting means maintains a constant flow rate. The shortest possible time is set to 50 [msec] or less, and the operations of the gas flow rate adjusting means, the means for changing the exhaust speed, and the discharging means are controlled,
A method is described in which a gas is caused to flow periodically and intermittently at predetermined time intervals, and an etching step and a film forming step are repeated.

The surface reaction in the dry etching described above will be described. Dry etching is performed by irradiating the wafer with reactive gas plasma in a processing chamber evacuated to a desired degree of vacuum. At this time, a high-frequency bias is usually applied to the sample stage on which the wafer is placed, and thus negative etching is performed. It is at electric potential. In the plasma, radicals dissociated from gas molecules and positive and negative ions are present. This reactive species (radical or molecule) is adsorbed on the material surface, and when positive ions are incident on it, the reaction is activated by ion bombardment energy, so-called ion-assisted reaction, whereby the combination of bonds between the adsorbed reactive species and the material atom is changed. Occurrence occurs, the generated volatile reaction product is desorbed, and etching proceeds. The region where the surface is excited by the translational kinetic energy of the ions and the ion-assisted reaction occurs is hereinafter referred to as a reactive spot. As described above, the dry etching is composed of three elementary processes, that is, a process of adsorbing reactive species on the surface of the material to be etched, an ion assisted reaction process in which the reaction is activated by incident ions, and a process of desorbing and exhausting reaction products. However, in conventional dry etching, these three elementary processes coexist.

[0024]

The mixture of etching elementary processes causes a decrease in etching selectivity.
This will be described by taking an example of etching silicon (Si) with chlorine gas (Cl ₂ ) using a microwave plasma etching apparatus.

First, let us consider a time interval in which an ion assist reaction occurs at a certain reactive spot. It is considered that the size of the reactive spot depends on the incident energy of the ions regardless of the discharge means, if the material and etching gas are determined. journal·
Of Vacuum Science and Technology, Series B, Volume 4, 459 (1986) (Journal of
Vacuum Science And Technology, B volume 4, p459
(1986)), the ion assist reaction in RIE is described in detail, and the size of the reactive spot is about 50 [Å ² ]. Therefore, again, the size of the reactive spot is set to 50 [Å ² ].

The average incident time of Cl ions to the reactive spot is estimated. In the microwave plasma etching apparatus according to the present invention, the ion current density is set to Cl.
As a result of measurement with _two gas plasmas, the ion current density changes depending on the microwave power and the gas pressure. For example, when the gas pressure is 0.5 [mTorr] and the microwave power is 2000 [W], the ion current density; I (ion ) Was 6 [mA / cm ² ]. The estimation will be performed using this condition as an example. Unit area (1
[Cm ² ]) ion flux; Γ (ion) has a charge elementary amount of 1.6 × 10 ^-19 [C], so the following equation (1); Γ (ion) = I (ion) /1.6×10 ^{From -19} [C] (1), Γ (ion) = 3.8 × 10 ¹⁶ [ions / sec · cm ² ]. At this time, the number of ions incident on the reactive spot with an area of 50 [Å ² ] (= 50 × 10 ^-16 [cm ² ]); Γ _spot (ion) is
Equation (2); Γ _spot (ion) = Γ (ion) × 50 × 10 ^-16 [cm ² ] (2) From Γ _spot (ion) = 1.9 × 10 ² [ions / sec], Average interval of incidence of ions on the spot; T
_spot (ion) is expressed by the following expression (3); T _spot (ion) = 1 / Γ _spot (ion) (3), and T _spot (ion) = 5.3 [msec]. Therefore, in a part of a certain area 50 [Å ² ], the ion-assisted reaction occurs about every 5.3 [msec].

Next, the time for which the reactive spot is covered with Cl atoms is estimated. Temperature T [K],
Incident flux per unit surface area of gas having pressure P [mTorr] and mass m [g]; Γ is expressed by the following equation.

Γ = 1.333 · P / √ (2 · k _B · π · m · T) (4) where k _B is the Boltzmann constant (1.38 × 10 ⁻¹⁶ [erg / K]),
π is the pi. Since the dissociation rate of Cl ₂ in the plasma depends discharge conditions, unit area of the ^{_{Cl 2 (1 [cm 2]}} ) incident flux per the approximate calculation; estimate gamma (Cl _2). The mass of Cl ₂ is 1.18 × 10 ⁻²² [g] from the atomic weight of Cl of 35.45 and the Avogadro number of 6.02 × 10 ²³ . When gas temperature is approximated to room temperature (298 [K]), Γ (Cl ₂ ) is Γ (Cl ₂ ) ＝ 1.2 × 10 ¹⁷ [molec / sec ・ cm when the gas pressure is 0.5 [mTorr] according to Eq. (4). ² ] At this time, Cl ₂ is incident on the reactive spot.
Number of molecules; Γ _spot (Cl ₂ ) is the following equation (5); Γ _spot (Cl ₂ ) ＝ Γ (Cl ₂ ) × 50 × 10 ^-16 [cm ² ] (5) From Γ _spot (Cl ₂ ) = 6.0 × 10 ² [molec / sec], the average interval of Cl ₂ incidence on the reactive spot; T
_spot (Cl ₂ ) is expressed by the following equation (6); T _spot (Cl ₂ ) = 1 / Γ _spot (Cl ₂ ) (6), and T _spot (Cl ₂ ) = 1.7 [msec]. Since the van der Waals radius of Cl atoms is 1.8 [Å] (from the science chronology), there are about 5 reactive spots of Cl.
Covered by atoms. Therefore, even if the adsorption probability of Cl atoms is 1, the time until the entire surface of the reactive spot is covered with Cl atoms; T _spot (Cl) is the following (7)
Formula; T _spot (Cl) = T _spot (Cl ₂ ) × 5 (7), so T _spot (Cl) = 4.2 [msec] is required, which is about the same as the average ion injection interval of 5.3 [msec]. It can be seen that it is.

The above is a discussion based on the Cl ₂ surface incident flux, but since the dissociation efficiency of Cl _{2 in} plasma is usually 1 or less, the time until the entire surface of the reactive spot is covered with Cl atoms. Is considered to be 4.2 [msec] or more.

In the above discussion, the average incidence interval of ions on the reactive spot and the time during which the entire surface of the reactive spot is covered with adsorbed particles are statistical average values. If there are mixed elementary processes,
When a certain ion is incident on the surface and a reactive spot is generated, there are cases where almost no reactive species are adsorbed to the area, or the reaction product is not completely desorbed. Alternatively, it is possible that reactive species are adsorbed on the surface in multiple layers. That is, when an ion is incident and one reactive spot is generated, there is a variation in the number of reactive species adsorbed in the spot area.

When an ion is incident and one reactive spot is generated, if the number of adsorption reaction species of the reactive spot varies, the etching yield (the number of material atoms etched per incident ion) will be decreased. Bring about a decline. This will be described with reference to FIG. The etching yield (Y) increases as the number of adsorbed reaction species (N) increases, but there is an upper limit to the etching yield that is activated by ion incidence of a certain energy, and many reaction species are adsorbed. If so, the etching yield does not increase that much. Therefore, the etching yield Y and the number of adsorption reaction species N
It is considered that the relationship of is as shown in FIG. It can be considered that the increase in N on the horizontal axis in FIG. 1 corresponds to the passage of time after the ions are incident on a certain reactive spot and the ion assist reaction occurs. That is, it is shown that N and Y increase with the elapse of this time, but the etching yield reaches the maximum value Y _{max when the} number of adsorption reaction species N ₀ or more. By the way, although the ion incidence interval on a certain reactive spot can be statistically calculated as described above, this is only an average value, and the ion incidence time interval actually varies. In addition, it is considered that the increase in the number of adsorbed reaction species due to the passage of time also varies. Therefore, when a certain ion is incident, there may be a situation where almost no reactive species are adsorbed on the reactive spot (FIG. 1-), and the etching yield becomes low. It is also possible that reactive species are adsorbed in multiple layers on the surface, but an etching yield above a certain upper limit (Y _max ) cannot be obtained (Fig. 1-). That is, the occurrence of etching in such a situation causes a decrease in yield.

Further, as a second cause for lowering the etching yield, there is an influence of reaction products. That is, even if ions are incident on the surface where the reaction products have not been desorbed, high-yield etching is not performed. Further, the reaction products may be redeposited on the surface of the material to be etched. The volatile reaction product generated on the surface of the material by the ion assist reaction is desorbed from the surface, then dissociated in the plasma and reattached when incident on the surface. When the reaction product is redeposited on the surface of the material, the reactive species cannot be adsorbed to that extent, which causes a decrease in etching yield.

As described above, since the etching is conventionally performed in a state where the etching yield is lowered, it is necessary to extend the etching time in order to obtain a predetermined etching amount. That is, excessive ion injection was required. This excessive incidence of ions accelerates the etching of the mask material and the underlying material during overetching. The problem of the etching rate selectivity between the material to be etched, the mask material, and the underlying material becomes extremely difficult as the integration of LSI becomes higher and the miniaturization of etching progresses, and the improvement of selectivity becomes an important technical issue. -ing

In view of the above situation, the object of the present invention is to
An object of the present invention is to provide a method and an apparatus for increasing etching yield due to incidence of accelerated particles and performing highly selective etching.

[0035]

The means of the present invention for increasing the selectivity will be described below.

The first means is to place a wafer on a sample table in the processing chamber, evacuate the processing chamber to a desired degree of vacuum by an evacuation means, and introduce a material processing gas into the processing chamber by a gas introduction means. A surface treatment method of converting the introduced gas into plasma by a plasma discharge means and treating a material formed on a wafer by the plasma, wherein the treatment step mainly includes an elementary step in which reactive species are adsorbed on the surface; Period A, and then a second period B including the elementary process in which the surface is irradiated with accelerated particles to promote the reaction between the adsorbed reaction species and the material, and then the elementary process in which the reaction product is desorbed from the surface and exhausted. And a third period C including, and a processing process including the periods A, B, and C is 1 [msec] or more and 1 [se
c] The surface treatment method is characterized in that it is carried out periodically in the following cycles.

The second means is to place a wafer on a sample table in the processing chamber, evacuate the processing chamber to a desired degree of vacuum by an evacuation means, and introduce a material processing gas into the processing chamber by a gas introduction means. A surface treatment method in which the introduced gas is made into plasma by a plasma discharge means and a material formed on a wafer is treated by the plasma, in the treatment process, a process in which a reactive species is adsorbed on a surface and an adsorbed reactive species and a material A first period D including the step of irradiating the surface with accelerated particles to accelerate the reaction of the second step E, and then a second period E including the step of desorbing the reaction product from the surface and evacuating, and The processing process consisting of the periods D and E is 1 [mse
The surface treatment method is characterized in that it is carried out periodically with a period of c] or more and 1 [sec] or less.

A third means places a wafer on a sample table in the processing chamber, evacuates the processing chamber to a desired degree of vacuum by an exhausting means, and introduces a material processing gas into the processing chamber by a gas introducing means. A surface treatment method of converting the introduced gas into plasma by a plasma discharge means and treating a material formed on a wafer with the plasma, the treatment process includes a process of adsorbing a reactive species on the surface and a reaction generated on the surface. A first period F, which includes the process of desorbing the product from the surface and evacuating, and then a second process, which includes the process of irradiating the surface with accelerated particles to promote the reaction of the adsorbed species with the material.
The surface treatment method is characterized in that the treatment process consisting of the period G and the period F and G is periodically performed at a period of 1 [msec] or more and 1 [sec] or less.

In the fourth means, particles which are accelerated and irradiated on the surface to accelerate the reaction between the adsorbing reaction species and the material described in any of the first, second and third means are radiated to the sample stage. The surface treatment method according to the first, second, or third means is characterized in that the ions are accelerated by the applied bias power.

A fifth means is the same as the first means, wherein the effective total exhaust speed of the exhaust means is 500 [liter / sec] or more,
It is said that plasma discharge is performed with arbitrary modulation power in the periods A and B, bias power is applied to the sample stage with arbitrary modulation power in the period B, and plasma discharge and application of bias power are stopped in the period C. The surface according to the first means, characterized in that the material formed on the wafer is processed by periodically performing the processing consisting of the periods A, B, and C at a cycle of 1 [msec] or more and 1 [sec] or less. It is a processing method.

A sixth means is a sample stage for holding a wafer in the processing chamber, an exhaust means for exhausting the processing chamber, a gas introducing means for introducing a material processing gas into the processing chamber, and the supply means. In a surface treatment apparatus having plasma discharge means for converting the gas into plasma and bias power application means for applying bias power to the sample stage, the exhaust means has an effective total exhaust speed of 500 [liter / sec] or more. The plasma discharge means has a function of generating a plasma discharge periodically with an arbitrary modulation power and at a period of 1 [sec] or less, and the bias power applying means applies a bias power to the sample stage with an arbitrary modulation power. And having a function of periodically applying a cycle of 1 [sec] or less, and a function of periodically applying the plasma discharge and the application of the bias power in an arbitrary phase. Do A surface treatment apparatus is to process the material using the same.

In a seventh means, in any one of the second and third means, the effective total exhaust speed of the exhaust means is 500 [liter / se.
c] or more, at least one of plasma discharge and application of bias power to the sample table is an arbitrary modulation power, and 1
The surface treatment described in the second and third means, characterized in that the material formed on the wafer placed on the sample stage is processed periodically by a cycle of [msec] or more and 1 [sec] or less. Is the way.

The eighth means is a sample stage for holding a wafer in the processing chamber, an exhaust means for exhausting the processing chamber, a gas introducing means for introducing a wafer processing gas into the processing chamber, and the gas supply means. In a surface treatment apparatus having plasma discharge means for converting the gas into plasma and bias power application means for applying bias power to the sample stage, the exhaust means has an effective total exhaust speed of 500 [liter / sec] or more. A surface treatment apparatus characterized in that any one of the plasma discharge means or the bias power application means has an arbitrary modulation power, and has a function of operating periodically at a cycle of 1 [sec] or less, It is used to process the material.

The ninth means irradiates the surface of the wafer mounted on the sample table with acceleration so as to accelerate the reaction between the adsorbing reaction species and the material according to any one of the first, second and third means. The first, second, and third means characterized in that the particles to be generated are neutral particle beams generated by accelerating ions generated in plasma and imparting charges to the ions to neutralize them. The surface treatment method described in 1.

A tenth means is a sample stage for holding a wafer in the processing chamber, an exhaust means for exhausting the processing chamber, and at least one gas introduction for introducing a wafer processing gas into the processing chamber. Means, plasma discharge means for converting the supplied gas into plasma, ion accelerating means for accelerating ions generated in the plasma toward a wafer surface mounted on the sample stage, and mounted on the sample stage In the surface treatment apparatus provided on the front surface of the wafer, which has an ion incidence blocking means for electrically eliminating ions incident toward the wafer surface and allowing only neutral particles to enter the wafer surface, the exhaust means Is the effective total pumping speed 500 [liter /
sec] or more, the plasma discharge means has a function of periodically generating a plasma discharge with an arbitrary modulation voltage and a cycle of 1 [sec] or less, and the ion acceleration means has an arbitrary ion acceleration voltage. Modulation power and a function of being periodically applied at a period of 1 [sec] or less, and a function of periodically applying the plasma discharge and the application of the ion acceleration voltage in an arbitrary phase. The surface treatment apparatus is characterized in that it is used to treat a material.

The eleventh means is the exhaust means according to any one of the first, second and third means, and the effective total exhaust speed is 500 [liter / se.
c] The surface treatment method according to any one of the first, second and third means, characterized by having the above.

The twelfth means is the first, second, third, fifth,
1st, 2nd, 3rd, 3rd, characterized in that the exhaust means according to any one of the 6th, 7th, 8th, and 10th means has an effective total exhaust speed of 800 [liter / sec] or more. The surface treatment method described in the fifth and seventh means, and the surface treatment apparatus described in the sixth, eighth, and tenth means, and the material is treated by using the surface treatment apparatus.

The thirteenth means is the first, second, third, fifth,
The first, the second, the third, the second, the third, the second, the sixth, the seventh, the eighth, and the tenth means, wherein the exhaust means has an effective total exhaust speed of 1300 [liter / sec] or more. The surface treatment method described in the fifth and seventh means, and the surface treatment apparatus described in the sixth, eighth, and tenth means, and the material is treated by using the surface treatment apparatus.

The fourteenth means is the first, second, third, fifth,
1st, 2nd, 3rd, 5th characterized in that the cycle described in any of the 6th, 7th, 8th, and 10th means is 1 [msec] or more and 500 [msec] or less. The surface treatment method according to the seventh means, and the surface treatment apparatus according to the sixth, eighth, and tenth means, wherein the material is treated.

The fifteenth means is the first, second, third, fifth,
1st, 2nd, 3rd, 5th characterized in that the cycle described in any of the 6th, 7th, 8th, and 10th means is 1 [msec] or more and 350 [msec] or less. The surface treatment method according to the seventh means, and the surface treatment apparatus according to the sixth, eighth, and tenth means, wherein the material is treated.

The sixteenth means is the first, second, third, fifth,
1st, 2nd, 3rd, 5th characterized in that the cycle described in any of the 6th, 7th, 8th, and 10th means is 1 [msec] or more and 250 [msec] or less. The surface treatment method according to the seventh means, and the surface treatment apparatus according to the sixth, eighth, and tenth means, wherein the material is treated.

The seventeenth means is the first, second, third, fifth,
The exhaust means and the cycle according to any of the sixth, seventh, eighth, and tenth means are exhaust means having an effective total exhaust speed of 500 [liter / sec] or more, and a cycle of 1 [msec] or more. 500 [mse
c] The surface treatment method according to any one of the first, second, third, fifth and seventh means characterized by being the following, and the surface according to the sixth, eighth and tenth means: A processing device, which is used to process a material.

The eighteenth means is the first, second, third, fifth,
The exhaust means and the cycle according to any of the sixth, seventh, eighth, and tenth means are exhaust means having an effective total exhaust speed of 800 [liter / sec] or more, and a cycle of 1 [msec] or more. 350 [mse
c] The surface treatment method according to any one of the first, second, third, fifth and seventh means characterized by being the following, and the surface according to the sixth, eighth and tenth means: A processing device, which is used to process a material.

The nineteenth means is the first, second, third, fifth,
The exhaust means and the cycle according to any one of the sixth, seventh, eighth, and tenth means are exhaust means having an effective total exhaust speed of 1300 [liter / sec] or more, and a cycle of 1 [msec] or more. 250 [m
sec] or less, the surface treatment method according to the first, second, third, fifth and seventh means, and the surface according to the sixth, eighth and tenth means A processing device, which is used to process a material.

In a twentieth means, the periodic plasma discharge and bias power application according to any one of the fifth and sixth means causes an output signal of a time modulation controller having a plurality of output channels to be output. It is carried out by inputting to the plasma discharge means and the bias power application means, periodically modulating the output power of the power supply of the plasma discharge means and the power supply of the bias power application means, and each output of the time modulation controller. The signal of a channel can be set independently for each channel by setting an arbitrary waveform and synchronizing with an arbitrary phase, which allows discharge modulation with arbitrary power, and bias modulation with arbitrary power, and The surface treatment method according to the fifth means is characterized in that the discharge modulation and the bias modulation are performed in synchronization with each other at arbitrary phases, and the sixth means is also described. A surface treatment apparatus is to process the material using the same.

In a twenty-first means, the periodic plasma discharge described in any one of the seventh and eighth means inputs the output signal of the time modulation controller to the plasma discharge means,
This is performed by periodically modulating the output power of the power source of the plasma discharge means, and the signal of the output channel of the time modulation controller can be set with an arbitrary waveform, which allows discharge modulation with an arbitrary power. The method is the surface treatment method described in the seventh means, and the surface treatment apparatus described in the eighth means, which is to treat the material.

The twenty-second means is characterized in that the application of the bias power which is periodically performed according to the seventh or eighth means,
The output signal of the time modulation controller is input to the bias power applying means, and the output power of the power source of the bias power applying means is periodically modulated, and the signal of the output channel of the time modulation controller is The surface treatment method according to the seventh means is characterized in that it can be set with an arbitrary waveform, and thereby bias modulation is performed with arbitrary power, and the surface treatment apparatus according to the eighth means. , To process the material with it.

The twenty-third means is characterized in that the periodical plasma discharge and the application of the ion acceleration voltage described in the tenth means are performed.
The output signal of the time modulation controller having a plurality of output channels is input to the plasma discharge means and the ion acceleration voltage application means, and the output power of the power supply of the plasma discharge means and the output voltage of the power supply of the ion acceleration voltage application means are set. The signal of each output channel of the time modulation controller can be set by synchronizing with an arbitrary waveform and an arbitrary phase independently for each channel. In the tenth means characterized in that the discharge modulation is performed with the electric power of, and the ion acceleration voltage is modulated with the arbitrary power, and the discharge modulation and the ion acceleration voltage are synchronized with the arbitrary phase. The surface treatment apparatus described is to treat a material using the surface treatment apparatus.

A twenty-fourth means is characterized in that the signal waveform from the output channel of the time modulation controller according to any one of the twentieth, twenty-first, twenty-second and twenty-third means is a rectangular wave. 2
The surface treatment method and the surface treatment apparatus according to the 0th, 21st, 22nd, and 23rd means are used to treat a material.

The twenty-fifth means is for the first, second, third, fourth,
The sample stage according to any one of the fifth, sixth, seventh, eighth, ninth and tenth means has a temperature adjusting means for holding the wafer temperature at a desired temperature. The surface treatment method according to any one of the first, second, third, fourth, fifth, seventh and ninth means, and the surface treatment apparatus according to the sixth, eighth and tenth means, It is used to process the material.

The twenty-sixth means is for the first, second, third, fourth,
The bias according to any one of the fifth, sixth, seventh, and eighth means is a high-frequency bias,
The surface treatment method described in the second, third, fourth, fifth, and seventh means, and the surface treatment apparatus described in the sixth and eighth means, are used to treat the material. That is.

The twenty-seventh means is the first, second, third, fourth,
The bias according to any one of the fifth, sixth, seventh, and eighth means is obtained by modulating the output of a DC power supply, and the first, second, third, fourth, and fourth are provided. The surface treatment method described in 5th and 7th means, and the surface treatment apparatus described in 6th and 8th means, in which the material is treated.

In the twenty-eighth means, the plasma discharge means according to any one of the first, second, third, fifth, sixth, seventh, eighth, and tenth means discharges plasma by microwaves. The surface treatment method according to the first, second, third, fifth, and seventh means characterized in that the surface is generated, and the surface according to the sixth, eighth, and tenth means. A processing device, which is used to process a material.

In a twenty-ninth means, the plasma discharge means according to any one of the first, second, third, fifth, sixth, seventh, eighth and tenth means is a helicon wave type or a high frequency wave. A surface treatment method according to any one of the first, second, third, fifth and seventh aspects, characterized in that plasma discharge is generated by an induction method, and the sixth, eighth and tenth aspects are also provided. It is the surface treatment apparatus described in the means, which is to treat the material.

[0065]

The function of the present invention will be described below.

First, the first means, that is, the wafer is placed on the sample stage in the processing chamber, the processing chamber is evacuated to a desired vacuum degree by the evacuation means, and the material processing gas is introduced into the processing chamber by the gas introduction means. In the surface treatment method, the introduced gas is turned into plasma by the plasma discharge means, and the material formed on the wafer by the plasma is treated,
The treatment process comprises a first period A during which the reactive species are adsorbed on the surface, followed by a second period B during which particles are accelerated to accelerate the reaction of the adsorbed reactive species with the material, and then the reaction product. And a third period C during which the gas is desorbed from the surface and exhausted, and the processing process consisting of the periods A, B, and C is periodically performed at a cycle of 1 [msec] or more and 1 [sec] or less. The operation of the characteristic surface treatment method will be described.

Here, when the particles that are accelerated to irradiate the surface to promote the reaction between the adsorbing reaction species and the material are ions, the present method is such that, as shown in FIG. Plasma discharge in period B
At, applying a bias to the sample table with arbitrary modulation power,
In period C, the plasma discharge and the application of bias power are stopped to process the material.

First, the first period A in which the reactive species are adsorbed on the surface will be described. The gas is made into reactive plasma by electric discharge and the reactive species are adsorbed on the surface.However, as described in "Problems to be solved by the invention", the reaction is performed by one ion at the reactive spot formed by ion bombardment. Number of adsorbed reactive species that activate
(See FIG. 1) there is an upper limit (N ₀ ). The larger the ion energy, the wider the reactive spot region that becomes reactive due to the energy, and the larger the number of reactive species to be activated. Therefore, N ₀ is an amount that depends on the ion energy (ie, bias power). Letting a be the time required for the N ₀ reactive species to be adsorbed to the reactive spot, a is an amount that depends on the incident flux of the reactive species on the surface. If the time of the period A is set to a, N ₀ reactive species should be adsorbed to a certain reactive spot as shown in FIG. 3- (1). At this time, statistically, N ₀ reactive species are uniformly adsorbed on the material surface.

After this period A, as shown in FIG. 3- (2), in period B, bias power is applied to accelerate the reaction between the adsorbed reaction species and the material to be etched, and accelerated ions are incident on the surface. If so, the ion-assisted reaction can occur at the maximum yield per ion (see FIG. 1). Therefore, it is possible to suppress excessive ion incidence, and it is possible to improve the selectivity with respect to the mask material and the base material. The optimum time b for the period B corresponds to the time from the injection of one ion to the reactive spot until the ion is incident again, and is determined by the ion current density and the area of the reactive spot region. By setting the time of the period B to b, when the material surface is divided by the area of the reactive spot, the ions are statistically incident on all the divided regions, and the ions are uniformly distributed on the material surface. An assist reaction will occur.

Next, as shown in FIG. 3- (3), a third period C in which the reaction product is desorbed from the surface and exhausted is provided. At this time, as shown in FIG. 2, since the discharge is stopped, it is possible to suppress the reaction products from being dissociated in the plasma and redeposited on the material surface. This improves the adsorption efficiency of the reactive species during the period A of the next cycle. As a result, the etching yield can be further increased, and excess ion incidence can be suppressed, so that the selectivity with respect to the mask material and the base material can be further improved. Optimal time c for this period C
Will be described.

The time change of the pressure P in the processing chamber from the stop of the gas supply to the discharge of the gas is expressed by equation (8).

DP / dt = −S · P / V (8) Here, t is the exhaust time, S is the effective exhaust speed, and V is the volume of the processing chamber. From the integration of the equation (8), the pressure before discharge; the time t required to exhaust from P ₁ to the pressure P ₂ is expressed by the following equation.

T = (V / S) ln (P ₁ / P ₂ ) (9) Here, when the gas flow rate is Q and the staying time in the processing chamber is τ, τ = P · V / Q (10) = V / S (11), equation (9) can be rewritten as follows.

T = τln (P ₁ / P ₂ ) (12) Further, from the equation (12), P ₂ = P ₁ · exp (-t / τ) (13) is obtained. Here, assuming that the gas flow rate Q is the amount of the reaction product flowing out from the wafer surface and τ is the staying time of the reaction product in the processing chamber, no reaction product is generated in the period C, only desorption and exhaust. because it is, given the beginning of the period C the time of stopping the gas supply, the partial pressure of the reaction product in the period C from (13); change due P _C of the time c, the partial reaction product in the period B The pressure is represented by the equation (14) using P _B.

P _C = P _B · exp (−c / τ) (14) That is, the partial pressure of the reaction product changes as shown in FIG.
Therefore, for example, when the staying time elapses from the start of the period C, since C = τ in the equation (14), P _C decreases to 37% of P _B. When c is further set to 2τ and 3τ, P _C is reduced to 14% and 5% of P _B , respectively. Therefore, the longer c is, the more the adsorption efficiency of the reactive species that contribute to the etching in the period A in the next cycle is increased, and the etching yield is increased. Thus, c that gives an appropriate P _C is related to the residence time of the gas in the processing chamber, that is, the volume of the processing chamber and the exhaust speed.
Therefore, the smaller the volume of the processing chamber, the shorter the staying time and the shorter the required c. Further, the higher the exhaust speed, the shorter the staying time and the shorter the required c. Even if the time c is 3 times or more of the residence time, the partial pressure of the reaction product is slightly decreased. Considering the decrease of the etching rate due to the increase of the time c, the time c is set to 3 times or less of the residence time. Is appropriate.

Next, the times a, b, and c in the periods A, B, and C
And the cycle (a + b + c) will be described. Again, Cl ₂
Taking silicon etching by gas as an example, let us consider the area of the reactive spot as 50 Å and consider the range of etching conditions using the current etching equipment.

The reaction species incident on the surface are Cl ₂ molecules, and it is assumed that they are all dissociatively adsorbed, and the time a of the period A is estimated. It is approximated that a is determined by the surface incident Cl ₂ gas flux, that is, Cl ₂ gas pressure. Using equations (4)-(7), a is about 21 [mse at 0.1 [mTorr], which is considered to be the lower limit of low gas pressure.
c], and a is about 0.04 [msec] at 50 [mTorr], which is considered to be the upper limit of the gas pressure in the microwave plasma etching apparatus. If the adsorption efficiency is 1 or less, a will be longer than this estimate.

Next, the time b of the period B is estimated. Although b also depends on the ion energy, that is, the bias power, assuming that it is almost determined by the ion current density, from equations (1)-(3), b is about 64 at a relatively low density of 0.5 [mA / cm ² ]. [msec]
And b is about 0.8 [msec] at 40 [mA / cm ² ] which is a fairly high density when discharged with a large amount of electric power.

The time c of the period C is related to the residence time of the reaction product in the processing chamber. For example, a low effective total pumping speed of 100
If a processing chamber with a relatively large capacity of 100 [liter] is exhausted at [liter / sec], the residence time is about 285 [msec] from Eq. (11), and the effective total exhaust speed is 1300 [liter / sec] for comparison. If a processing chamber with a relatively small capacity of 50 [liter] is evacuated, the stay time is approximately 39
It is [msec].

Consider the maximum value of the cycle from the above estimation. In the above estimation, a is up to 21 [msec] and b is up to 64 [mse].
c], c is about 855 [msec] at maximum, assuming that 3τ is exhausted. One cycle from the total is less than 1 [sec] at maximum. This is considered to be the maximum period for practical etching obtained from the conditions of the current etching apparatus, which will be described later in Examples. The reason is that if c is further lengthened, the effect of the reaction product decreases and the selectivity improves, but the decrease in the amount of the reaction product is an exponential decrease with respect to c, as shown in FIG. This is because, even if c is increased, the rate of decrease in the amount of reaction products becomes small, that is, the rate of increase in the selection ratio saturates, and conversely, the decrease in etching rate due to the extreme increase in desorption / exhaust time is considered to be a problem. .

Next, consider the minimum value of the period. According to the above estimation, a is about 0.04 [msec] minimum and b is about 0.8 [msec] minimum. Here, assuming that c = 3τ, even if the processing chamber having a volume of 50 [liter] is exhausted by an exhaust means having an effective total exhaust speed of 10,000 [liter / sec], c is 15 [msec], and a The ratio of the desorption / exhaust time c to b is too large, resulting in an extremely low etching rate. In this case,
In order to obtain a practical etching rate, it is necessary to sacrifice the improvement of the selection ratio to some extent by setting c << 3τ. Therefore, the minimum period is about 1 [msec].

Next, the cycle when the effective total evacuation speed is changed and the processing chamber having a standard capacity of 70 [liter] is evacuated will be described. When the effective total pumping speed is set to 500 [liter / sec], τ = 140 [msec] and 3τ = 420 [msec] from Eq. (11). The maximum value of a + b is about 85 [msec], so a + b
+ C is 505 [msec]. As mentioned above, it is considered that c ≦ 3τ is appropriate, so in this case the cycle is 1 [msec].
Above 500 [msec] is appropriate. 800 effective total pumping speed
When [liter / sec] is set, τ = 87.5 [mse from Eq. (11)
c], 3τ = 263 [msec]. The maximum value of a + b is 85 [msec]
Since it is approximately, a + b + c = 348 [msec]. Therefore, in this case, the cycle is appropriately 1 [msec] or more and 350 [msec] or less. When the effective pumping speed is 1300 [liter / sec],
From equation (11), τ = 53.8 [msec] and 3τ = 162 [msec]. a
The maximum value of + b is about 85 [msec], so a + b + c =
It becomes 247 [msec]. Therefore, in this case, the cycle is 1 [msec] or more.
250 [msec] or less is suitable.

In the above description, the particles that are accelerated to irradiate the surface of the material to accelerate the reaction between the adsorbing reactive species and the material are referred to as ions. However, this can be obtained by giving a charge to the accelerated ions. The above-described operation of the present invention is essentially the same even for a sexual particle beam.

By the above-mentioned action, the etching process including the adsorption process of the reactive species, the reaction process of the adsorbed reactive species and the material promoted by the accelerated particles, and the desorption and exhaust process of the reaction products is performed for 1 [msec] or more. The method of the present invention in which high-speed separation is performed at a cycle of 1 [sec] or less and this processing process is performed cyclically increases the etching yield and minimizes the amount of incident ions. Can be suppressed and the selectivity can be increased.

Next, the second means, that is, the wafer is placed on the sample stage in the processing chamber, the processing chamber is evacuated to a desired vacuum degree by the evacuation means, and the material processing gas is introduced into the processing chamber by the gas introduction means. Introducing, plasmaizing the introduced gas by plasma discharge means, in the surface treatment method of treating the material formed on the wafer by the plasma,
The treatment step includes a step of adsorbing the reactive species on the surface and a step of irradiating the surface with particles accelerated to promote the reaction between the adsorbed reactive species and the material, and then the reaction product is removed from the surface during the first period D. It is composed of the second period E which is desorbed and exhausted, and the processing process consisting of the periods D and E is 1 [msec].
The operation of the surface treatment method, which is characterized by being performed periodically at a period of 1 [sec] or less, will be described.

In the present method, when the particles that are accelerated to accelerate the reaction between the adsorbing reaction species and the material and are irradiated on the surface are ions, the bias application power is constant as shown in FIG. Is turned on and the discharge is stopped in the period E. This method also uses a neutral particle beam as the particles that are accelerated to accelerate the reaction between the adsorbing reaction species and the material and irradiate the surface with a neutral particle beam. Figure 5
This is a method that is performed periodically as shown in.

The present method is a method in which the reactive species adsorption process (1) and the accelerated particle injection process (2) coexist in the period D of the etching element process shown in FIG. Therefore, since the ion or neutral particle beam is not always incident on the region where the reactive species are sufficiently adsorbed, the etching yield is lower than that of the first means and the mask material and the base material are not removed. Is less selective. However, since the discharge is stopped and the reaction products are desorbed and exhausted in the period E, reattachment of the reaction products can be reduced. Therefore, the radical adsorption efficiency in the period D increases, and the selectivity with respect to the mask material or the base material can be improved as compared with the case where etching is continuously performed without time modulation.

Next, the third means, that is, the wafer is placed on the sample table in the processing chamber, the processing chamber is evacuated to a desired vacuum degree by the evacuation means, and the material processing gas is introduced into the processing chamber by the gas introduction means. Introducing, plasmaizing the introduced gas by plasma discharge means, in the surface treatment method of treating the material formed on the wafer by the plasma,
The treatment process includes a process of adsorbing the reactive species on the surface and a process of desorbing and exhausting the reaction product generated on the surface from the surface for the first period F, and then accelerating to promote the reaction between the adsorbed reactive species and the material. Characterized in that the treatment process consisting of the second period G in which the irradiated particles are irradiated to the surface and the period of F and G is periodically performed at a period of 1 [msec] or more and 1 [sec] or less. The operation of the surface treatment method will be described.

In this method, when the particles that are accelerated to accelerate the reaction between the adsorbing reaction species and the material and are irradiated on the surface are ions, the discharge power is constant as shown in FIG. In this method, the bias power is applied in the period G without applying the bias power. This method also accelerates the ions that are extracted to neutralize by giving an electric charge when the particles that are accelerated to accelerate the reaction between the adsorbed reactive species and the material and irradiate the surface are neutral particle beams. In this method, a voltage is applied only in the period G, and ions are extracted from the plasma to be accelerated periodically.

In this method, the reaction species adsorption process (1) in the period F of the etching element process shown in FIG. 3 and the desorption and exhaust process (3) of the reaction product generated in the period G of the previous cycle.
Is a mixed method. Therefore, in the period F, the reaction products are dissociated in the plasma and redeposited on the material surface, so that the radical adsorption efficiency in the period F decreases.
As a result, the etching yield is lower than that of the first means, and the selectivity with respect to the mask material and the base material is reduced. But,
Reactive species adsorption process (1) and accelerated particle injection process (2) shown in Fig. 3
Are separated, the etching yield is improved as compared with the case where etching is continuously performed without time modulation, and the selectivity with respect to the mask material and the base material can be improved.

In the present invention described above, the etching treatment process is mainly a process in which the reactive species are adsorbed on the surface, and then a process in which the surface is irradiated with particles accelerated to promote the reaction between the adsorbed reactive species and the material. Either the reaction product is separated from the surface and is exhausted, or the time is separated.
At least one of the two processes is time-separated, and the process consisting of these processes is periodically performed at a cycle of 1 [msec] or more and 1 [sec] or less to improve etching selectivity. is there. In this method, in the same gas plasma, the incidence interval of ions to a reactive spot where an ion-assisted reaction occurs, the time for which the surface incident reactive species are adsorbed and the reactive spot is covered, and the reaction product is exhausted. The cycle is adjusted to follow the time scale related to the movement of atomic molecules or ions in the gas phase such as time, and the etching process is smoothly repeated without extra time consumption, thus improving the efficiency of the ion assist reaction. It is possible to increase the maximum value and prevent the etching rate from being extremely lowered. Further, in terms of performing time modulation in combination with the gas residence time in the processing chamber, plasma discharge, bias application, and gas introduction, as described in the section of the prior art, may be time-modulated individually, or simply combined. The method of the present invention is different from the synchronously time-modulated method.

[0092]

EXAMPLES The present invention will be described in detail below with reference to examples.

Example 1 FIG. 7 shows an example in which the surface treatment apparatus of the present invention was implemented in a microwave plasma etching apparatus.

This surface processing apparatus is equipped with a load lock mechanism, and the processing chamber 18 and the wafer exchange chamber 22 are provided with a gate valve 28.
Are separated by, and each is evacuated independently. The wafer processing chamber 18 is evacuated by a combination of the turbo molecular pump 4, the mechanical booster pump 5, and the rotary pump 27. Pumping speed is 3000 [liter / sec] at maximum by changing the conductance of valve 17.
The effective total pumping speed up to is obtained. The effective total exhaust speed of this exhaust means may be 500 [liter / sec] or more, or 800 [liter / sec] or more, or 1300 [liter / sec] or more, if necessary. Wafer 6 to be processed is wafer exchange chamber 2
It is transferred from 2 to the processing chamber 18 by the transfer system 21. When mounting the wafer 6 to be processed on the sample table 8, the sample table up-and-down mechanism 14 moves the sample table 8 up and down. The wafer 6 to be processed is mounted on a sample table by a wafer fixing pin (not shown) and an electrostatic chuck.
Fixed at 8.

The plasma discharge means will be described. The discharge generating power supply 30 is controlled by the time modulation controller 1, and in accordance with the output signal of the time modulation controller 1, time-modulated output power is applied to the magnetron intermittently and periodically at a period of 1 [sec] or less. . The microwaves excited by the magnetron 20 by the time-modulated power supplied from the discharge-generating power supply 30 are guided to the waveguide 19 to generate the time-modulated plasma 7 in the discharge tube 23 in the processing chamber 18. The solenoid coil 29 functions to increase the excitation efficiency by electron cyclotron resonance.

The bias applying means will be described. The bias power supply 16 is controlled by the time modulation controller 1, and according to the output signal of the time modulation controller 1, the output bias power time-modulated at a period of 1 [sec] or less is intermittently and periodically sampled through the matching device 35. Apply to platform 8. The bias power supply 16 is an AC power supply, and in this embodiment, a bias power supply having a frequency of 400 kHz is used. However, the frequency is not particularly limited to 400 kHz, and may be, for example, 13.56 MHz, 2 MHz, or another frequency. Further, the bias power supply 16 may be a DC power supply capable of output voltage modulation by an external input. It suffices to select a power supply having an optimum frequency according to the etching specifications.

The time modulation controller 1 has a plurality of output channels, and the signal of each output channel can be set independently for each channel in synchronization with an arbitrary waveform and an arbitrary phase. The time modulation controller 1 can perform discharge modulation with arbitrary power, bias modulation with arbitrary power, and discharge modulation and bias modulation can be performed in synchronization with arbitrary phases. As the time modulation controller 1, an arbitrary waveform generator, a pulse generator, or the like may be used, or a combination of these and a computer may be used.

The gas introduction means will be described. The discharge gas in the gas cylinder 2 passes through the regulator-12, is adjusted to a desired flow rate by the gas flow rate adjusting means 3, and is introduced into the processing chamber 18 through the gas introduction valve 11. The gas introducing means may be changed in the number of systems as necessary.

The sample stage 8 is provided with a tank for the coolant 10 in the lower part thereof, and is connected to the wafer processing chamber 18 via an insulator 15. The temperature of the wafer 6 to be processed placed on the sample table 8 is adjusted by a heater 9 built in the sample table 8 and a coolant 10 introduced below the sample table 8. The refrigerant is supplied to the lower part of the sample table 8 by the refrigerant supplier 24. The temperature of the wafer 6 to be processed is measured by the temperature sensor 13 to measure the back surface temperature and monitored by the temperature controller 25. The temperature controller 25 controls the amount of the coolant supplied from the coolant supplier 24 and the power supplied from the heater power source 26 while monitoring the temperature to adjust the temperature of the wafer 6 to be processed. Freon gas-based refrigerant, liquid nitrogen, or cooling water is used as the refrigerant. A small amount of helium gas is flown between the back surface of the wafer 6 to be processed and the sample stage 8 in order to increase the efficiency of heat exchange.

An example in which the surface treatment is performed by using the above-described surface treatment apparatus will be described below. The present embodiment is an example of etching polycrystalline silicon using Cl ₂ gas.
As a sample, a thermal oxide film was formed on a silicon substrate, a polycrystalline silicon layer was formed thereon, and a photoresist mask was patterned. The processing conditions were set such that the flow rate of Cl ₂ gas was 100 [sccm] and the pressure was 0.5 [mTorr].
The effective total pumping speed at this time is 2530 [liter / sec]. The discharge power was 400 [W], the bias power was 20 [W], and the sample temperature during the treatment time was adjusted to 20 ° C.

The discharge power and the bias power were modulated in synchronization as shown in FIG. A method of setting the times a, b, and c of the periods A, B, and C in this modulation method will be described. First, from the set gas pressure, the average incidence interval of gas to the reactive spot is calculated by the estimation method as described in the section of the prior art to determine an approximate value of a. According to the above estimation, when Cl ₂ is 0.5 [mTorr], the time until the entire surface of the reactive spot is covered with Cl atoms is 4.2 [msec] or more. Next, the ion current density is measured, and the average interval of incidence of ions on the reactive spot is calculated by the estimation method as described in the section of the prior art to determine an approximate value of b. The ion current density measured under the conditions of this example was 3.2 [mA / cm ² ].
At this time, the average incidence interval of the ions on the reactive spot is 10.8 [msec]. A obtained in this way
The values of a and b may be referred to, and the optimum values of a and b may be experimentally determined in consideration of the etching rate and selectivity. Regarding the period C, the longer c is, the larger the amount of reaction products exhausted is. However, if the period is too long, one cycle becomes longer, the etching time becomes longer, and the etching rate is lowered. Therefore, the optimum value of c may be determined by an experiment in consideration of the etching rate and the selectivity. In this embodiment, the processing chamber has a volume of 70 [liter], a flow rate of 100 [sccm], and a pressure of 0.5 [mTorr].
In case of, the stay time τ is 28 [msec].

The time b of the period B is fixed at 12 [msec], the time c of the period C is fixed at 28 [msec], and the time a of the period A is changed to etch the polycrystalline silicon. The selectivity for the oxide film is shown in FIG. The selection ratio between resist and oxide film increases with the increase of a, and a = 16 [m
It became saturated for more than sec]. Even if a is made longer than necessary, only reactive species are adsorbed, the ion assist reaction does not occur, and the etching rate decreases. So next time a is 16
[msec], the time c was fixed at 28 [msec], the time b of the period B was changed, and the polycrystalline silicon was etched. FIG. 9 shows the selectivity with respect to the resist mask and the underlying oxide film at this time. The selection ratio between the resist and the oxide film increased with the increase of b, reached the maximum at b = 20 [msec], and decreased above that. Increasing the time b is closer to the case where the discharge and the application of the bias power are continuously performed without time modulation, and making the b longer than necessary again causes a decrease in selectivity. Discharge power is 400 [W], bias power is
At 20 [W], the other conditions were the same, and the selection ratio when discharge and bias application were continuously performed was 4 for resist and 20 for oxide film.

Next, the time a of the period A is 16 [msec], and the period B is
The time b was fixed at 20 [msec], and the time c during the period C was changed to etch the polycrystalline silicon. FIG. 10 shows the selectivity with respect to the resist mask and the underlying oxide film at this time. Although the selection ratio increases with the increase of c, it gradually saturates. Here, the time c was changed to three times the staying time. As stated in the "Action" section above, time c
Is 3 times the residence time, the reaction product is reduced to 5%. After that, the way of decreasing is exponential, and even if the value of c is long, the way of decreasing the reaction product becomes gradual. The result appears in the saturation of the selection ratio due to the increase of c in FIG. As described above, even if the time c is set to be three times as long as the residence time or more, the increase in the selection ratio is slight, and considering the decrease in the etching rate due to the increase in the time c, the time c is set to be three times or less than the residence time. Is appropriate.

The case where the effective total pumping speed is 500 [liter / sec] will be described. Since the volume of the processing chamber is 70 [liter], the gas residence time is 140 [msec] according to the equation (11),
Three times that is 420 [msec]. The pressure of Cl ₂ gas is 0.1 [mTor
r], discharge power is 100 [W], bias power is 50 [W]
As a result, polycrystalline silicon was etched. The sample used was the same as that described above. As a result, a is 30 [m
sec], b is set to 70 [msec], and c is set to 400 [msec], the etching rate does not extremely decrease. The selection ratio between the resist mask and the underlying oxide film was maximized.
The cycle at this time is 500 [msec].

A case where the effective total pumping speed is 800 [liter / sec] will be described. Since the volume of the processing chamber is 70 [liter], the gas residence time is 87.5 [msec] according to the equation (11),
Three times that is 263 [msec]. The pressure of Cl ₂ gas is 0.1 [mTor
r], discharge power is 100 [W], bias power is 50 [W]
As a result, polycrystalline silicon was etched. The sample used was the same as that described above. As a result, a is 26 [m
sec], b is 70 [msec], and c is 254 [msec], the etching rate does not drop extremely. The selection ratio between the resist mask and the underlying oxide film was maximized.
The cycle at this time is 350 [msec].

The case where the effective total pumping speed is 1300 [liter / sec] will be described. Since the volume of the processing chamber is 70 [liter], the gas residence time is 54 [msec] according to equation (11),
Three times that is 162 [msec]. The pressure of Cl ₂ gas is 0.1 [mTor
r], discharge power is 100 [W], applied bias power is 50
Polycrystalline silicon was etched as [W]. The sample used was the same as that described above. As a result,
When the etching rate is set to 22 [msec], b is 70 [msec], and c is 158 [msec], the etching rate does not drop extremely. The selection ratio between the resist mask and the underlying oxide film was maximized. The cycle at this time is 250 [msec].

In the above example, a is related to the gas pressure, and becomes shorter as the gas pressure increases. In addition, b depends on the discharge power, and as the discharge power increases, the incident ion flux increases, so the time b decreases.

Next, an example in which the method of the present invention is carried out by using the apparatus according to the present invention having the same configuration as the apparatus shown in FIG. 7 and having a processing chamber volume of 100 [liter] will be described. As the exhaust means, one having an effective total exhaust speed of 350 [liter / sec] was used. The residence time of the gas is 286 [msec] from Eq. (11), and three times that is 857 [msec]. Cl ₂ gas pressure 0.1
Etching of polycrystalline silicon was performed by setting the discharge power to 100 [W] and the applied bias power to 50 [W] by setting to [mTorr]. The sample used was the same as that described above. As a result, when a is set to 70 [msec], b is set to 80 [msec], and c is set to 850 [msec], the etching rate does not extremely decrease. The selection ratio between the resist mask and the underlying oxide film was maximized. The cycle at this time is 1 [sec]. a is related to the gas pressure, and becomes shorter as the gas pressure increases. Also,
b depends on the discharge power, and as the discharge power increases, the incident ion flux increases, so the time b decreases.

Next, an embodiment of the present invention when discharging a large amount of electric power by using the apparatus shown in FIG. 7 will be described. Polycrystalline silicon was etched at a discharge power of 5 [kW], a bias power of 50 [W], a Cl ₂ gas flow rate of 200 [sccm], and a pressure of 50 [mTorr]. At this time, the effective total pumping speed is about 127 [liter / sec] and the gas residence time is about 553 [msec] from the equations (10) and (11). The sample used was the same as that described above. As a result, a is 0.1 [msec] and b is 0.8 [msec]
The longer c is, the larger the selection ratio between the resist mask and the underlying oxide film is. However, in this case, since the stay time is extremely longer than a and b, the time c
If τ is set to 3τ, the ratio of the exhaust time to the etching time becomes too large, and the etching rate is extremely reduced. In the case of this example, since a + b is 0.9 [msec], even if c = τ, a + b << c. To obtain a practical etching rate, 0.1 [msec] to 5 [mse
It was necessary to set c between [c]. Things like this example occur when the gas pressure and the discharge power are high. When the volume of the processing chamber is 70 [liter], an effective total pumping speed of 14000 [liter / sec] is required to make the residence time 5 [msec]. Therefore, in the case of this example, it is necessary to sacrifice the increase in the selection ratio due to the provision of the period C in order to obtain a practical etching rate. Therefore, the effective total pumping speed is 500 [liter / sec], 800 [liter / sec], 1300 [liter / s
In each case of [ec], the cycle is 1 [msec] or more.

As described above, the time a and the time b mainly change depending on the etching conditions such as gas pressure and discharge power, but the effective total pumping speed is 500 [liter / sec] or more and 800 [lite].
When r / sec] or more and 1300 [liter / sec] or more, the time modulation cycle is 1 [msec] or more and 500 [msec] or less, 1 [mse
c] or more and 350 [msec] or less, 1 [msec] or more and 250 [msec] or less were appropriate.

In the present embodiment, an example of performing etching of polycrystalline silicon using Cl ₂ gas has been described, but the method of this embodiment is used when etching of polycrystalline silicon is performed using another gas, or when another method is used. It is also effective when etching the material.

For example, even in the etching of single crystal silicon using Cl ₂ gas, the selectivity with the resist mask is improved by the method of this embodiment.

[0113] Also, the silicon oxide film using C ₄ F ₈ gas (S
Also in the etching of iO ₂ or BPSG, the selectivity of the resist mask and the underlying polycrystalline silicon or the silicon nitride film (Si ₃ N ₄ ) was improved by the method of this example.

[0114] Further, a silicon nitride film using CH ₃ F gas (S
Also in the etching of i ₃ N ₄ ), the selectivity with respect to the resist mask and the underlying SiO ₂ was improved by the method of this example.

[0115] Furthermore, the aluminum using BCl ₃ gas (A
Also in the etching of l), the selectivity with respect to the resist mask and the underlying SiO ₂ was improved by the method of this example.

In etching these various materials, the optimum set values of the times a, b, and c are different depending on the combination of the etching gas and the material and the etching conditions. The optimum value should be found accordingly.

The sample stage of the apparatus of this embodiment shown in FIG. 7 is provided with a sample temperature control mechanism. By using this to adjust the sample temperature, the time a during which the reactive species adsorb onto the surface can be adjusted. That is, since the physical adsorption is promoted at a lower temperature, the time a can be shortened as the sample temperature is lowered.

This embodiment has the effect of improving the selection ratio between the mask material and the base material.

Embodiment 2 FIG. 11 shows another example in which the surface treatment apparatus of the present invention is implemented in a microwave plasma etching apparatus. This apparatus is the same as the apparatus described in Embodiment 1 and shown in FIG. 7 except for the time modulation control method of the discharging means and the bias applying means.

The plasma discharge means of this apparatus will be described. The discharge generating power supply 30 is controlled by the time modulation controller 1, and in accordance with the output signal of the time modulation controller 1, time-modulated output power is applied to the magnetron intermittently and periodically at a period of 1 [sec] or less. . The microwaves excited by the magnetron 20 by the time-modulated power supplied from the discharge-generating power supply 30 are guided to the waveguide 19 to generate the time-modulated plasma 7 in the discharge tube portion 23 in the surface treatment chamber 18. . The other parts are the same as those of the device shown in FIG. 7 described in the first embodiment, and the description thereof will be omitted. However, the bias power supply 16
Is not controlled by the time modulation controller and the bias is always applied continuously with constant power.

Using the surface treatment apparatus described above, Cl ₂
An example in which polycrystalline silicon is etched using gas will be described below. As a sample, a thermal oxide film was formed on a silicon substrate, a polycrystalline silicon layer was formed thereon, and a photoresist mask was patterned. The sample temperature was adjusted to 20 ° C during the processing time. In the method of time modulation of discharge, as shown in FIG. 5, discharge is performed in the period D having the time d and then stopped in the period E having the time e. In this case, the power is time-modulated in a rectangular wave. A method of setting the time d and the time e will be described. As for the time e for exhausting the reaction product, as described in Example 1, it is appropriate to be 3 times or less than the residence time. When the etching time d is set longer than necessary, the effect of the present method of providing the period E and frequently exhausting the reaction products becomes small. It is considered that the time required for the ion-assisted reaction to occur uniformly on the surface to be treated should be set to d. This is the time b in the period B described in FIG. 2 described in the first embodiment.
However, this method does not adopt the method of causing the ion-assisted reaction after the reactive species are sufficiently adsorbed by dividing into the period A and the period B as in Example 1, so that the etching yield Is smaller than the method of the first embodiment. Therefore, it is appropriate that the time d is longer than the time b, and the etching process was performed under the following conditions.

An exhaust means having an effective total exhaust speed of 500 [liter / sec] was used, the gas pressure was set to 0.1 [mTorr], and the discharge power was 10
The applied bias power was 0 [W] and 50 [W]. As a result, when the time d is set to 100 [msec] and the time e is set to 400 [msec] and the polycrystalline silicon is etched, the etching rate does not extremely decrease. The selection ratio between the resist mask and the underlying oxide film was maximized. The cycle at this time is 500 [msec]
Is.

Next, using an exhaust means having an effective total exhaust speed of 800 [liter / sec], the gas pressure was set to 0.1 [mTorr], the discharge power was 100 [W], and the applied bias power was 50 [W]. And As a result, when the time d is set to 95 [msec] and the time e is set to 255 [msec] and the polycrystalline silicon is etched, the etching rate does not extremely decrease. The selection ratio between the resist mask and the underlying oxide film was maximized. The cycle at this time is 350
It is [msec].

Also, the effective total pumping speed is 1300 [liter / sec]
The gas pressure was set to 0.1 [mTorr], the discharge power was 100 [W], and the applied bias power was 50 [W]. As a result, when the time d is set to 90 [msec] and the time e is set to 160 [msec] and the polycrystalline silicon is etched, the etching rate does not extremely decrease. The selection ratio between the resist mask and the underlying oxide film was maximized. The cycle at this time is 25
It is 0 [msec].

Here, the time d required for the period D becomes shorter as the gas pressure is higher, the discharge power is larger, and the incident flux of ions is larger. At this time, if the time e is extremely longer than the time d, the etching rate is lowered as described in the first embodiment. In that case, e may be set in the same time region as d. When the discharge power is high, the role of the period E is not only the exhaust of the reaction products but also the heating of the processing chamber and the sample by the high power plasma. That is, it is possible to prevent the sample from being heated and the selectivity from being lowered by the intermittent discharge. Actually, the pressure of Cl ₂ gas is set to 2
0 [mTorr], discharge power 3000 [W], applied bias power 1
As a result of etching polycrystalline silicon with 00 [W], d set to 0.5 [msec] and e set to 0.5 [msec], the selection ratio between the resist mask and the underlying oxide film increased as compared with the case of continuous discharge. .

As described above, the time d and the time e vary depending on the etching conditions such as gas pressure, discharge power, exhaust speed, etc., but the effective total exhaust speed is 500 [liter / sec] or more, 800 [liter / sec] or more.
When [liter / sec] or more and 1300 [liter / sec] or more, the time modulation cycle (d + e) is 1 [msec] or more and 500 [msec] or more, respectively.
Below 1 [msec] and above 350 [msec], 1 [msec] and above 250 [mse
c] The following is appropriate.

In the present embodiment, an example of performing etching of polycrystalline silicon using Cl ₂ gas has been described, but the method of this embodiment is applied to the case of performing etching of polycrystalline silicon with another gas, or another method. It is also effective when etching the material.

For example, even in the etching of single crystal silicon using Cl ₂ gas, the selectivity of the resist mask is improved by the method of this embodiment.

[0129] Also, the silicon oxide film using C ₄ F ₈ gas (S
Also in the etching of iO ₂ or BPSG, the selectivity of the resist mask and the underlying polycrystalline silicon or the silicon nitride film (Si ₃ N ₄ ) was improved by the method of this example.

[0130] Further, a silicon nitride film using CH ₃ F gas (S
Also in the etching of i ₃ N ₄ ), the selectivity with respect to the resist mask and the underlying SiO ₂ was improved by the method of this example.

[0131] Furthermore, the aluminum using BCl ₃ gas (A
Also in the etching of l), the selectivity with respect to the resist mask and the underlying SiO ₂ was improved by the method of this example.

In the etching of these various materials, the optimum set values of the times d and e differ depending on the combination of the etching gas and the material and the etching conditions. Just find the optimum value.

The sample stage of the apparatus of this embodiment shown in FIG. 11 is provided with a sample temperature control mechanism. By using this, by adjusting the sample temperature, the time for which the reactive species are adsorbed on the surface can be adjusted. That is, since the physical adsorption is promoted at a lower temperature, the time d can be shortened as the sample temperature is lowered.

This embodiment has the effect of improving the selection ratio between the mask material and the base material.

Example 3 FIG. 12 shows an example in which the surface treatment apparatus of the present invention was implemented in a microwave plasma etching apparatus.

The bias applying means of this device will be described. The power supply 16 for bias application is controlled by the time modulation controller 1, and according to the output signal of the time modulation controller 1, 1 [msec]
The output power, which is time-modulated with a period of 1 [sec] or less, is applied to the sample stage 8 through the matching device 35 intermittently and periodically.
By this method, ions whose energy is time-modulated with a period of 1 [msec] or more and 1 [sec] or less are incident on the sample surface. The other parts are the same as those of the device shown in FIG. 7 described in the first embodiment, and the description thereof will be omitted. However, the discharge generating power supply 30 is not controlled by the time modulation controller, and the discharge is always continuously performed with a constant power. The volume of the processing chamber is 70 [liter].

Using the surface treatment apparatus described above, Cl ₂
An example in which polycrystalline silicon is etched using gas will be described below. As a sample, a thermal oxide film was formed on a silicon substrate, a polycrystalline silicon layer was formed thereon, and a photoresist mask was patterned. The sample temperature was adjusted to 20 ° C during the processing time. The method of time modulation of the bias power is as shown in FIG.
The bias application is stopped at and the period G after that has time g
Stop the discharge with. In this case, the power is time-modulated in a rectangular wave. That is, while exhausting the reaction product generated in the period G in the previous cycle in the period F, the reaction species are sufficiently adsorbed, and then the ion assist reaction occurs in the period G to increase the etching yield. The optimum method of setting the time f and the time g may be determined experimentally according to each etching condition.

The effective total pumping speed is set to 500 [liter / sec], and Cl
₂ Gas pressure was 0.1 [mTorr], discharge power was 100 [W], and applied bias power was 50 [W]. As a result, f was 420 [msec] and g was 80 [msec]. At that time, the etching rate did not extremely decrease, and the selectivity with respect to the resist mask and the underlying oxide film was improved. The cycle at this time is 500 [msec].

Next, the effective total pumping speed is set to 800 [liter / sec], the pressure of Cl ₂ gas is 0.1 [mTorr], the discharge power is 100 [W],
The applied bias power was 50 [W], and the polycrystalline silicon was etched. As a result, f was 270 [msec] and g was 80 [msec].
At that time, the etching rate did not extremely decrease, and the selectivity with respect to the resist mask and the underlying oxide film was improved.
The cycle at this time is 350 [msec].

Next, the effective total pumping speed is set to 1300 [liter / sec], the pressure of Cl ₂ gas is 0.1 [mTorr], and the discharge power is 100 [W],
The applied bias power was 50 [W], and the polycrystalline silicon was etched. As a result, f was 170 [msec] and g was 80 [msec].
At that time, the etching rate did not extremely decrease, and the selectivity with respect to the resist mask and the underlying oxide film was improved.
The cycle at this time is 250 [msec].

F becomes shorter as the gas pressure is higher and the incident flux of the reactive species is larger, and f becomes shorter as the residence time of the reaction product is shorter. Further, g becomes shorter as the discharge power is larger and the current density of incident ions is larger.

In this embodiment, unlike the first embodiment, the discharge is intermittently stopped and the reaction product is not exhausted. Therefore, it is not possible to prevent the reaction product from dissociating and adsorbing on the sample surface, which hinders the adsorption of the reactive species. Therefore, the etching yield is lower than that of the method of Example 1. However, since the amount of reaction products present decreases as the exhaust speed increases, the effect of adsorption of the reaction products can be suppressed by increasing the exhaust speed.

In the present embodiment, an example of performing etching of polycrystalline silicon using Cl ₂ gas has been described, but the method of the present embodiment is used when etching of polycrystalline silicon is performed using another gas, or when another method is used. It is also effective when etching the material.

For example, also in the etching of single crystal silicon using Cl ₂ gas, the selectivity with the resist mask is improved by the method of this embodiment.

[0145] Also, the silicon oxide film using C ₄ F ₈ gas (S
Also in the etching of iO ₂ or BPSG, the selectivity of the resist mask and the underlying polycrystalline silicon or the silicon nitride film (Si ₃ N ₄ ) was improved by the method of this example.

[0146] Further, a silicon nitride film using CH ₃ F gas (S
Also in the etching of i ₃ N ₄ ), the selectivity with respect to the resist mask and the underlying SiO ₂ was improved by the method of this example.

[0147] Furthermore, the aluminum using BCl ₃ gas (A
Also in the etching of l), the selectivity with respect to the resist mask and the underlying SiO ₂ was improved by the method of this example.

In the etching of these various materials, the optimum set values of the times f and g differ depending on the combination of the etching gas and the material and the etching conditions. Therefore, as already described in the present embodiment, depending on the purpose by experiments. Just find the optimum value.

The sample stage of the apparatus of this embodiment shown in FIG. 12 is equipped with a sample temperature control mechanism. By using this, by adjusting the sample temperature, the time for which the reactive species are adsorbed on the surface can be adjusted. That is, since the physical adsorption is promoted at a lower temperature, the time f can be shortened as the sample temperature is lowered.

This embodiment has the effect of improving the selection ratio between the mask material and the base material.

Embodiment 4 In this embodiment, a method will be described in which discharge power is applied intermittently and periodically, and power modulation is further performed during the intermittent power application period.

As shown in FIG. 13, the method of this embodiment in which discharge is performed in periods A and B and bias is applied in period B is basically the same as the method described in the first embodiment. However, in the present embodiment, the discharge power is further modulated as shown in FIG. 13 during the discharge in the periods A and B. Alternatively, in the time modulation of the discharge shown in FIG. 5 described in the second embodiment, the discharge power is further modulated within the period D. The period of this further modulation is h. h is shorter than a or d. When the period h is set to 1 [msec] or less, for example, about several tens [μsec], it is possible to change the types of ions and radicals generated in the plasma and the ratio of the generated amount between the generated species. The power modulation method in the period h is arbitrary modulation.

When the method of this embodiment is carried out by, for example, a microwave plasma etching apparatus, the time modulation resolution is higher when a cyclotron is used as the microwave source than a magnetron.

A case where the method of the present embodiment is applied to etching of a silicon oxide film with CHF ₃ gas will be described. Radicals generated in plasma from CHF ₃ include CF ₂ which contributes to both etching and deposition of a polymer film, and F which contributes only to etching. Therefore, by applying the method of the present embodiment, it is possible to improve the selectivity with respect to the mask material and the base material, and to change the type of ions and radicals to be generated and the ratio of the amount of generation between the generated species to achieve etching. The strength of the deposition can be controlled. The length of the cycle h, the method of modulating the discharge power within the cycle h, and the times a, b, and c may be determined according to processing conditions so that desired etching characteristics can be obtained.

The method of this embodiment is anisotropic by improving the effect of changing the kind of ions and radicals generated in plasma and the ratio of the amount of generated radicals, and the selectivity between the mask material and the base material. It also has the effect of improving the sex.

Sixth Embodiment In this embodiment, a method will be described in which bias power is applied intermittently and periodically, and power modulation is further performed during the intermittent bias power application period.

As shown in FIG. 14, the method of this embodiment in which discharge is performed in periods A and B and bias is applied in period B is basically the same as the method described in the first embodiment. However, in the present embodiment, the bias power is further modulated when the bias power is applied in the period B as shown in FIG. Alternatively, in the time modulation of bias application shown in FIG. 6 described in the third embodiment, the bias power is further modulated within the period G. The period of this further modulation is i. i is b
Alternatively, it is shorter than g. When the cycle i is set to 1 [msec] or less, it is possible to prevent the charge from being accumulated on the sample surface.

In the method of the present embodiment, the bias power source may be a high frequency power source or a direct current power source whose output power is modulated.

A case where the method of this embodiment is applied to etching of polycrystalline silicon with Cl ₂ gas will be described. As a sample, a thermal oxide film was formed on a silicon substrate, a polycrystalline silicon layer was formed thereon, and a photoresist mask was patterned. In the etching of polycrystalline silicon with Cl ₂ gas, it is known that when the underlying oxide film layer is exposed, abnormal etching shape side etching commonly called notching occurs near the interface with the oxide film during overetching. It is considered that this is a result of the trajectories of incident ions being laterally bent near the oxide film interface due to the accumulation of charges on the surface. By the method of this example, the selectivity with respect to the mask material and the underlying material was improved, and notching that occurred when the bias was continuously applied could be prevented. Here, the length of the cycle i, the method of modulating the bias power within the cycle i, and the times a, b, and c may be determined according to the processing conditions so that desired etching characteristics can be obtained.

The method of this embodiment has the effect of preventing the accumulation of charges on the material surface and the effect of improving the anisotropy by improving the selection ratio between the mask material and the base material.

Example 7 FIG. 15 shows an example in which the surface treatment apparatus of the present invention was carried out in a neutral particle beam assisted etching apparatus.

This surface processing apparatus is equipped with a load lock mechanism, and the processing chamber 18 and the wafer exchange chamber 22 are provided with a gate valve 28.
Are separated by, and each is evacuated independently. The evacuation means and the sample table are the same as those of the apparatus shown in FIG. 7 described in the first embodiment, and therefore the description thereof will be omitted here.

The plasma discharge means will be described. The discharge generating power supply 30 is controlled by the time modulation controller 1, and in accordance with the output signal of the time modulation controller 1, time-modulated output power is applied to the magnetron intermittently and periodically at a period of 1 [sec] or less. . The microwaves excited by the magnetron 20 by the time-modulated power supplied from the discharge-generating power supply 30 are guided to the waveguide 19 to generate the time-modulated plasma 7 in the discharge tube 23 in the processing chamber 18. The solenoid coil 29 functions to increase the excitation efficiency by electron cyclotron resonance.

The gas introduction means will be described. The reactive species supply gas in the gas cylinder 2 passes through the regulator 12 and is adjusted to a desired flow rate by the gas flow rate adjusting means 3, and is introduced into the surface treatment chamber 18 through the gas introduction valve 11. Also, the gas for supplying the neutral particle beam (rare gas such as Ar) in the gas cylinder 2'passes through the regulator 12 'and a gas flow rate adjusting means.
The flow rate is adjusted to a desired value by 3'and introduced into the discharge tube 23 through the gas introduction valve 11 '.

A method of generating a neutral particle beam will be described by taking as an example the case where Ar gas is used as the gas for supplying the neutral particle beam. The Ar ions generated in the discharge tube 23 are extracted by the mesh-shaped ion accelerating electrode 33, then neutralized by the charge exchange reaction with the gas in the processing chamber, and enter the wafer 6 to be processed. The sample stage 8 is provided with an ion incidence blocking electrode 34, which prevents ions in the plasma from entering the wafer 6 to be processed by the voltage supplied from the ion incidence blocking voltage supply power source 32. The ion acceleration voltage supply power supply 31 for supplying a voltage to the ion acceleration electrode 33 is controlled by the time modulation controller 1, and according to the output signal of the time modulation controller 1, 1 [s
ec] The voltage is supplied to the ion accelerating electrode 33 intermittently and periodically with an accelerating voltage that is time-modulated with a cycle of the following.

Since the time modulation controller 1 is the same as that shown in FIG. 7 described in the first embodiment, the description thereof will be omitted here. In the device shown in FIG. 15, this time modulation controller 1 performs time modulation in synchronization with the discharge, that is, the generation of ions and the acceleration of ions, that is, the generation of a neutral beam, or at least one of the two is time modulated. Can be done.

An example in which the surface treatment is performed by the surface treatment apparatus described above will be described below. The silicon oxide film was etched using CHF ₃ gas as a reactant supply gas and Ar as a neutral particle beam supply gas. That is, the discharge is performed in the period A and the period B shown in FIG. 2, the accelerating voltage is supplied to the ion accelerating electrode instead of the bias application power in the period B, and the discharge and the ion accelerating electrode are performed in the period C. The process of stopping the supply of the accelerating voltage to was performed at a cycle of 1 [msec] or more and 1 [sec] or less.
Since the optimum values of the times a, b, and c are different depending on the etching conditions, the optimum values were determined experimentally under the respective conditions.
As a result, the selectivity with respect to the resist mask and the underlying polycrystalline silicon or the silicon nitride film (Si ₃ N ₄ ) was improved as compared with the case where the discharge and the ion acceleration voltage were continuously supplied. Here, in the method of the present embodiment, even when the accelerating voltage is supplied to the ion accelerating electrode not only in the period B but also in the period C, the selection ratio is similarly improved. Further, in the method shown in FIG. 5, instead of supplying the bias application power, the accelerating voltage is continuously supplied to the ion accelerating electrode, and only the discharge is intermittently and cyclically performed. There was an effect of improving the selection ratio for. Further, in the method shown in FIG. 6, a method of performing discharge continuously and intermittently and periodically supplying an accelerating voltage to the ion accelerating electrode instead of supplying bias application power is also used for the mask material and the base material. It had the effect of improving the selection ratio.

The method of this embodiment is also effective when etching a silicon oxide film with another gas or when etching another material.

For example, even in the etching of single crystal or other crystal silicon using Cl ₂ gas, the selectivity with the resist mask is improved by the method of this embodiment.

[0170] Further, a silicon nitride film using CH ₃ F gas (S
Also in the etching of i ₃ N ₄ ), the selectivity with respect to the resist mask and the underlying SiO ₂ was improved by the method of this example.

[0171] Furthermore, the aluminum using BCl ₃ gas (A
Also in the etching of l), the selectivity with respect to the resist mask and the underlying SiO ₂ was improved by the method of this example.

In etching these various materials, the optimum set values of the times a, b, c, d, e, f, and g differ depending on the combination of the etching gas and the material and the etching conditions. As described above, the optimum value may be found according to the purpose by experiments.

This embodiment has the effect of improving the selection ratio between the mask material and the base material.

Embodiment 8 FIG. 16 shows an example in which the surface treatment apparatus of the present invention is implemented by a helicon wave type plasma etching apparatus.

A loop antenna 37 for two turns in the radial direction is provided around the discharge tube 23 having a magnetic field formed perpendicularly to the axial direction by a solenoid coil provided around the discharge tube 23, and a matching device is provided from the high frequency power supply 36. The helicon wave plasma is excited by applying a high frequency wave through 35 '. The high frequency power supply 36 can apply to the antenna 37 high frequency power time-modulated in a cycle of 1 [sec] or less according to the output signal of the time modulation controller 1. Further, the bias power source 16 can also apply time-modulated bias power in a cycle of 1 [sec] or less in accordance with the output signal of the time modulation controller 1. As a result, the helicon wave plasma discharge and the bias power can be time-modulated in synchronization with each other, or one of the two can be time-modulated. Figure 7 except for the discharging means
Since it is equivalent to the device shown in FIG.

Using the surface treatment apparatus described above, discharge and bias power application are synchronized as shown in FIG.
Method to perform periodically with a cycle of 1 [msec] or more and 1 [sec] or less,
In addition, as shown in FIG. 5, the discharge is periodically performed at a period of 1 [msec] or more and 1 [sec] or less, and as shown in FIG. 6, the application of bias power is 1 [msec] or more 1 Etching of single crystal silicon, polycrystalline silicon, a silicon oxide film, a silicon nitride film, and aluminum was performed by a method periodically performed for a period of [sec] or less. As a result, the selection ratio between the mask material and the base material was improved by the method of this example for any of the materials.

This embodiment has the effect of improving the selection ratio between the mask material and the base material.

Embodiment 9 FIG. 17 shows an example in which the surface treatment apparatus of the present invention is implemented by a helical resonance type high frequency induction type plasma etching apparatus.

A spiral coil 39 is wound around the discharge tube 23, and a high frequency is applied from a high frequency power source 36 through a matching unit 35 'to excite plasma. The high frequency power supply 36 can apply to the spiral coil 39 high frequency power time-modulated in a cycle of 1 [sec] or less in accordance with the output signal of the time modulation controller 1. Further, the bias power source 16 can also apply time-modulated bias power in a cycle of 1 [sec] or less in accordance with the output signal of the time modulation controller 1. As a result, the discharge and the bias power can be time-modulated in synchronization with each other, or one of the two can be time-modulated. Except for the discharging means, it is the same as the device shown in FIG. 7, and therefore its explanation is omitted here.

Using the surface treatment apparatus described above, the discharge and the application of bias power are synchronized as shown in FIG.
Method to perform periodically with a cycle of 1 [msec] or more and 1 [sec] or less,
In addition, as shown in FIG. 5, the discharge is periodically performed at a period of 1 [msec] or more and 1 [sec] or less, and as shown in FIG. 6, the application of bias power is 1 [msec] or more 1 Etching of single crystal silicon, polycrystalline silicon, a silicon oxide film, a silicon nitride film, and aluminum was performed by a method periodically performed for a period of [sec] or less. As a result, the selection ratio between the mask material and the base material was improved by the method of this example for any of the materials.

This embodiment has the effect of improving the selection ratio between the mask material and the base material.

Embodiment 10 FIG. 18 shows an example in which the surface treatment apparatus of the present invention is implemented by a transformer coupled plasma (TCP) type high frequency induction type plasma etching apparatus.

Plasma is excited by applying a high frequency from a high frequency power source 36 to a coil 38, which is installed in a spiral shape facing the sample stage of the apparatus, through a matching device 35 '. The high frequency power supply 36 can apply high frequency power, which is time-modulated in a cycle of 1 [sec] or less, to the spiral coil 38 in accordance with the output signal of the time modulation controller 1. Further, the bias power supply 16 is also a time modulation controller 1
According to the output signal of, the bias power time-modulated with a period of 1 [sec] or less can be applied. As a result, the discharge and the bias power can be time-modulated in synchronization with each other, or one of the two can be time-modulated. Except for the discharging means, it is the same as the device shown in FIG. 7, and therefore its explanation is omitted here.

Using the surface treatment apparatus described above, discharge and bias power application are synchronized as shown in FIG.
Method to perform periodically with a cycle of 1 [msec] or more and 1 [sec] or less,
In addition, as shown in FIG. 5, the discharge is periodically performed at a period of 1 [msec] or more and 1 [sec] or less, and as shown in FIG. 6, the application of bias power is 1 [msec] or more 1 Etching of single crystal silicon, polycrystalline silicon, a silicon oxide film, a silicon nitride film, and aluminum was performed by a method periodically performed for a period of [sec] or less. As a result, the selection ratio between the mask material and the base material was improved by the method of this example for any of the materials.

This embodiment has the effect of improving the selection ratio between the mask material and the base material.

[0186]

The present invention has the effect of increasing the etching yield and improving the etching selection ratio between the mask material and the base material.

[0187]

[Brief description of drawings]

FIG. 1 is a diagram showing a change in etching yield per incident ion depending on the number of adsorption reaction species per reactive spot.

FIG. 2 is a diagram showing a method of time-modulating the discharge power and the bias application power in order to improve the etching yield in relation to the method of the present invention.

FIG. 3 shows a process in which a reactive species is adsorbed to a reactive spot formed on a material surface by the injection of accelerated particles by the method of the present invention, and a process in which the accelerated particles are incident on the reaction spot to cause a reaction. The conceptual diagram showing that the process in which the generated reaction product is desorbed from the reactive spot and exhausted is separated.

FIG. 4 is a graph showing a change in partial pressure of a reaction product with the elapse of evacuation time, which is related to the method of the present invention.

FIG. 5 is a diagram showing how discharge power is time-modulated in order to improve the etching yield in relation to the method of the present invention.

FIG. 6 is a diagram showing a method of time-modulating the bias applied power in order to improve the etching yield in relation to the method of the present invention.

FIG. 7 is a diagram showing an example in which the surface treatment apparatus according to the present invention is implemented in a microwave plasma etching apparatus.

FIG. 8 is a diagram showing an example relating to the present invention and showing that the etching selection ratio between a mask material and a base material changes due to the modulation of the discharge time.

FIG. 9 is a diagram showing an example relating to the present invention, showing that the etching selection ratio between a mask material and a base material changes due to the modulation of the bias application time.

FIG. 10 is a diagram showing an example relating to the present invention and showing that the etching selection ratio between a mask material and a base material changes due to the modulation of the discharge and the time during which the bias application is stopped.

FIG. 11 is a diagram showing an example in which the surface treatment apparatus according to the present invention is implemented in a microwave plasma etching apparatus.

FIG. 12 is a diagram showing an example in which the surface treatment apparatus according to the present invention is implemented in a microwave plasma etching apparatus.

FIG. 13 is a diagram showing an embodiment according to the present invention and is a diagram showing a method of further modulating discharge power in one cycle of time modulation of discharge power and bias applied power.

FIG. 14 is a diagram showing an embodiment according to the present invention and is a diagram showing a method of further modulating bias power in one cycle of time modulation of discharge power and bias applied power.

FIG. 15 is a diagram showing an example in which the surface treatment apparatus according to the present invention is implemented in a neutral particle beam assisted etching apparatus.

FIG. 16 is a diagram showing an example in which the surface treatment apparatus according to the present invention is implemented in a helicon wave type plasma etching apparatus.

FIG. 17 is a view showing an example in which the surface treatment apparatus according to the present invention is implemented in a helical resonance type high frequency induction type plasma etching apparatus.

FIG. 18 is a diagram showing an example in which the surface treatment apparatus according to the present invention is implemented in a transformer coupled plasma (TCP) type high frequency induction type plasma etching apparatus.

[Explanation of symbols]

 1. Time modulation controller 2. Gas cylinder 3. Gas flow rate adjusting means 4. Turbo molecular pump 5. Mechanical booster pump 6. Wafer to be processed 7. Plasma 8. Sample stand 9. Heater 10. Refrigerant 11. Gas introduction valve 12. Regulator 13. Temperature sensor 14. Sample table up / down mechanism 15． Insulator 16. Bias power supply 17. Valve 18. Processing room 19. Waveguide 20. Magnetron 21. Transport system 22. Wafer exchange room 23. Discharge tube 24. Refrigerant supply device 25. Temperature controller 26. Power supply for heater 27. Rotary pump 28. Gate valve 29. Solenoid coil 30. Discharge generation power supply 31. Ion acceleration voltage power supply 32. Ion injection blocking voltage power supply 33. Ion acceleration electrode 34. Ion incidence blocking electrode 35. Matching device 36. High frequency power supply 37. Antenna 38. Spiral coil 39. Spiral antenna

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsumi Mizutani 1-280, Higashi Koigokubo, Kokubunji, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd.

Claims (32)

[Claims] 1. A wafer is placed on a sample stage in a processing chamber, the processing chamber is evacuated to a desired degree of vacuum by an evacuation unit, and a material processing gas is introduced into the processing chamber by a gas introduction unit,
In the surface treatment method of converting the introduced gas into plasma by the plasma discharge means and treating the material formed on the wafer by the plasma, the treatment process mainly includes the elementary process in which the reactive species are adsorbed on the surface. A period A, and then a second period B including an elementary process in which accelerated particles are irradiated on the surface to promote the reaction between the adsorbed reaction species and the material, and then an elementary process in which reaction products are desorbed from the surface and exhausted A surface treatment method comprising: a third period C, which includes the process, and a process including the periods A, B, and C, periodically at a cycle of 1 [msec] or more and 1 [sec] or less. 2. A wafer is placed on a sample stage in a processing chamber, the processing chamber is evacuated to a desired vacuum degree by an exhausting means, and a material processing gas is introduced into the processing chamber by a gas introducing means.
In the surface treatment method of converting the introduced gas into plasma by the plasma discharge means and treating the material formed on the wafer with the plasma, the treatment step includes a step of adsorbing the reactive species on the surface and an adsorption of the reactive species and the material. A first period D including the step of irradiating the surface with accelerated particles to promote the reaction, and then a second period E including the step of desorbing the reaction products from the surface and evacuating; and A surface treatment method characterized in that a treatment process consisting of periods D and E is periodically performed at a period of 1 [msec] or more and 1 [sec] or less. 3. A wafer is placed on a sample stage in the processing chamber, the processing chamber is evacuated to a desired vacuum degree by an exhaust means, and a material processing gas is introduced into the processing chamber by a gas introduction means,
In the surface treatment method of converting the introduced gas into plasma by the plasma discharge means and treating the material formed on the wafer with the plasma, the treatment process includes a process of adsorbing reactive species on the surface and a reaction product generated on the surface. From a first period F including a process of desorbing substances from the surface and exhausting, and then a second period G including a process of irradiating the surface with particles accelerated to promote a reaction between the adsorbing reaction species and the material. And the processing process consisting of these F and G periods is 1 [mse
A surface treatment method characterized in that it is carried out periodically at a period of c] or more and 1 [sec] or less. 4. The particles, which are accelerated to accelerate the reaction between the adsorbing reaction species and the material according to claim 1, and are irradiated onto the surface, are accelerated by a bias power applied to the sample stage. 2. The ion as defined in claim 1,
The surface treatment method described in 2 or 3. 5. The plasma discharge according to claim 1, wherein the effective exhaust speed of the exhaust means is 500 [liter / sec] or more, and plasma discharge is performed with arbitrary modulation power in the period A and the period B.
In the period B, bias power is applied to the sample table with arbitrary modulation power, and in the period C, plasma discharge and the application of bias power are stopped. The surface treatment method according to claim 1, wherein the material formed on the wafer is treated by performing the treatment periodically at a period of [sec] or less. 6. A sample stage for holding a wafer, an exhaust means for exhausting the processing chamber, a gas introducing means for introducing a material processing gas into the processing chamber, and a plasma for the supplied gas. In the surface treatment apparatus having a plasma discharge means for changing the temperature of the sample and a bias power applying means for applying a bias power to the sample stage, the exhaust means has an effective total exhaust speed of 500 [liter / sec] or more, and the plasma discharge The means has a function of periodically generating a plasma discharge with an arbitrary modulation power and a cycle of 1 [sec] or less, and the bias power applying means applies a bias power to the sample stage with an arbitrary modulation power and 1 [sec]. sec] or less, and a function of periodically applying the plasma discharge and the application of the bias power in a synchronized manner at an arbitrary phase and periodically. . 7. The surface treatment method according to claim 2, wherein the effective total exhaust speed of the exhaust means is 500 [liter / sec] or more, and the plasma discharge and the application of bias power to the sample stage are performed. At least one of them has an arbitrary modulation power and 1 [mse
4. The surface treatment method according to claim 2, wherein the material formed on the wafer placed on the sample stage is processed by periodically performing the cycle of c] or more and 1 [sec] or less. 8. A sample stage for holding a wafer in the processing chamber, an exhaust means for exhausting the processing chamber, a gas introducing means for introducing a wafer processing gas into the processing chamber, and a plasma for supplying the supplied gas. In the surface treatment apparatus having a plasma discharge means for changing the temperature of the sample and a bias power applying means for applying a bias power to the sample stage, the exhaust means has an effective total exhaust speed of 500 [liter / sec] or more, and the plasma discharge One of the means and the bias power applying means has a function of operating periodically with an arbitrary modulation power and at a cycle of 1 [sec] or less. 9. Particles irradiated to the surface of a wafer placed on a sample stage, which are accelerated to promote the reaction between the adsorbing reactive species and the material according to claim 1, are in plasma. 4. The surface treatment method according to claim 1, wherein the ion beam is a neutral particle beam produced by accelerating the ions generated in step 1 and imparting a charge to the ions to neutralize them. 10. A sample stage for holding a wafer in a processing chamber, an exhaust means for exhausting the processing chamber, at least one gas introducing means for introducing a wafer processing gas into the processing chamber, and the supply. Plasma discharge means for converting the generated gas into plasma, ion accelerating means for accelerating ions generated in the plasma toward the surface of the wafer mounted on the sample stage, wafer mounted on the sample stage In a surface treatment apparatus provided on the front surface, which electrically excludes ions that are incident toward the wafer surface, and has an ion incidence blocking means for allowing only neutral particles to enter the wafer surface,
The evacuation means has an effective total evacuation speed of 500 [liter / sec] or more, and the plasma discharge means has a function of periodically generating plasma discharge with arbitrary modulation power and at a period of 1 [sec] or less. The ion accelerating means has a function in which an ion accelerating voltage is periodically applied at an arbitrary modulation voltage and a period of 1 [sec] or less, and the plasma discharge and the application of the ion accelerating voltage are performed at an arbitrary phase. A surface treatment apparatus having a function of performing synchronization in a periodic manner. 11. The surface according to claim 1, 2 or 3, wherein the exhaust means according to any one of claims 1, 2 and 3 has an effective total pumping speed of 500 [liter / sec] or more. Processing method. 12. A method according to claim 1, 2, 3, 5, 6, 7, 8, 10.
The exhaust means described in any one of the above is an effective total exhaust speed of 800 [lite
r / sec] or more.
The surface treatment method according to claim 3, 5 or 7, and claims 6 and 8,
10. The surface treatment device as described in 10. 13. A method according to claim 1, 2, 3, 5, 6, 7, 8, 10.
The exhaust means described in any one of
er / sec] or more.
The surface treatment method according to claim 3, 5 or 7, and claims 6 and 8,
10. The surface treatment device as described in 10. 14. Claims 1, 2, 3, 5, 6, 7, 8, 10
The surface treatment method according to any one of claims 1, 2, 3, 5 and 7, and the cycle according to any one of claims 6, 8 and 10, characterized in that the cycle described in any one of 1 to 4 is not less than 1 [msec] and not more than 500 [msec]. The surface treatment apparatus according to. 15. Claims 1, 2, 3, 5, 6, 7, 8, 10
The surface treatment method according to any one of claims 1, 2, 3, 5 and 7, and the cycle according to any one of claims 6, 8 and 10, characterized in that the cycle according to any one of claims 1 to 3 is 350 [msec] or more. The surface treatment apparatus according to. 16. The method according to claim 1, 2, 3, 5, 6, 7, 8, 10.
The surface treatment method according to any one of claims 1, 2, 3, 5 and 7, and the cycle according to any one of claims 6, 8 and 10 are characterized in that the cycle according to any one of 1 to 4 is not less than 1 [msec] and not more than 250 [msec]. The surface treatment apparatus according to. 17. The method according to claim 1, 2, 3, 5, 6, 7, 8, 10.
The exhaust means and cycle described in any one of 1 to 3 are exhaust means having an effective total exhaust speed of 500 [liter / sec] or more, and a cycle of 1 [msec] or more and 500 [msec] or less. The surface treatment method according to items 1, 2, 3, 5, and 7, and the surface treatment apparatus according to claims 6, 8, and 10. 18. Claims 1, 2, 3, 5, 6, 7, 8, 10
The exhaust means and cycle described in any one of the above are exhaust means having an effective total exhaust speed of 800 [liter / sec] or more and a cycle of 1 [msec] or more and 350 [msec] or less. The surface treatment method according to items 1, 2, 3, 5, and 7, and the surface treatment apparatus according to claims 6, 8, and 10. 19. Claims 1, 2, 3, 5, 6, 7, 8, 10
The exhaust means and cycle described in any one of the above are exhaust means having an effective total exhaust speed of 1300 [liter / sec] or more and a cycle of 1 [msec] or more and 250 [msec] or less. The surface treatment method according to items 1, 2, 3, 5, and 7, and the surface treatment apparatus according to claims 6, 8, and 10. 20. The periodic plasma discharge and bias power application according to claim 5, wherein the output signal of the time modulation controller having a plurality of output channels is supplied to the plasma discharge means and the bias. This is performed by periodically modulating the output power of the power supply of the plasma discharge means and the power supply of the bias power application means, and the signal of each output channel of the time modulation controller is input to each channel. Each waveform can be set independently and in synchronization with any waveform and any phase.This allows discharge modulation with arbitrary power, bias modulation with arbitrary power, and discharge modulation and bias modulation. 6. The method according to claim 5, wherein the steps are performed in synchronization with an arbitrary phase.
The surface treatment method according to claim 6 and the surface treatment device according to claim 6. 21. The periodic plasma discharge according to claim 7, wherein the output signal of the time modulation controller is input to the plasma discharge means, and the output power of the power source of the plasma discharge means is supplied. 7. The signal of the output channel of the time modulation controller can be set with an arbitrary waveform, whereby discharge modulation is performed with an arbitrary power. The surface treatment method according to claim 8 and the surface treatment device according to claim 8. 22. Periodically applied bias power according to any one of claims 7 and 8, wherein an output signal of a time modulation controller is inputted to the bias power application means, and the bias power application means outputs the bias power application means. It is performed by periodically modulating the output power of the power supply, and the signal of the output channel of the time modulation controller can be set with an arbitrary waveform, whereby bias modulation is performed with an arbitrary power. The surface treatment method according to claim 7 and the surface treatment device according to claim 8. 23. The periodic plasma discharge and the application of the ion acceleration voltage according to claim 10, wherein the output signal of the time modulation controller having a plurality of output channels is supplied to the plasma discharge means and the ion acceleration voltage applying means. By periodically modulating the output power of the power supply of the plasma discharge means and the output voltage of the power supply of the ion acceleration voltage applying means, and the signal of each output channel of the time modulation controller is It can be set independently for each channel in synchronization with any waveform and any phase, which allows discharge modulation with arbitrary power, ion acceleration voltage modulation with arbitrary power, and discharge modulation. 11. The surface treatment apparatus according to claim 10, wherein the modulation of the ion acceleration voltage is performed in synchronization with an arbitrary phase. 24. The signal waveform from the output channel of the time modulation controller according to any one of claims 20, 21, 22, and 23 is a rectangular wave. The surface treatment method and surface treatment apparatus described in 1. 25. Claims 1, 2, 3, 4, 5, 6, 7,
The sample stage according to any one of claims 8, 9, and 10 has a temperature adjusting means for maintaining the wafer temperature at a desired temperature. The surface treatment method according to claim 6 and the surface treatment device according to claim 6, 8, or 10. 26. Claims 1, 2, 3, 4, 5, 6, 7, 8
9. The surface treatment method according to claim 1, 2, 3, 4, 5, or 7, and the surface treatment apparatus according to claim 6, wherein the bias according to any one of claims 1 to 3 is a high frequency bias. 27. Claims 1, 2, 3, 4, 5, 6, 7, 8
The bias according to any one of claims 1 to 3, wherein the output of the DC power supply is modulated.
The surface treatment method according to any one of claims 4, 5, and 7, and the surface treatment apparatus according to claims 6 and 8. 28. Claims 1, 2, 3, 5, 6, 7, 8, 10
8. The surface treatment method according to claim 1, 2, 3, 5, and 7, and the plasma discharge means according to claim 6, wherein the plasma discharge means generates plasma discharge by microwaves. 10. The surface treatment apparatus according to item 10. 29. Claims 1, 2, 3, 5, 6, 7, 8, 10
The plasma discharge means according to any one of claims 1 to 3, wherein the plasma discharge is generated by a helicon wave method or a high frequency induction method.
The surface treatment method according to claim 5 or 7, and the surface treatment apparatus according to claim 6, 8, or 10. 30. The material according to any one of claims 1, 2, 3, 4, 5, 7, 9 is single crystal silicon or polycrystalline silicon. 4,
The surface treatment method according to 5, 7, or 9. 31. The material according to any one of claims 1, 2, 3, 4, 5, 7, 9 is a silicon oxide film or a silicon nitride film. 3,
The surface treatment method according to 4, 5, 7, or 9. 32. The material according to claim 1, 2, 3, 4, 5, 7, 9 is aluminum. The surface treatment method described in.