WO2003085716A1

WO2003085716A1 - Plasma etching method and plasma etching device

Info

Publication number: WO2003085716A1
Application number: PCT/JP2003/004410
Authority: WO
Inventors: Shoichiro Matsuyama; Masanobu Honda; Kazuya Nagaseki; Hisataka Hayashi
Original assignee: Tokyo Electron Limited; Kabushiki Kaisha Toshiba
Priority date: 2002-04-08
Filing date: 2003-04-07
Publication date: 2003-10-16
Also published as: US20050039854A1; TWI233644B; JP4377698B2; AU2003236307A8; TW200402792A; JPWO2003085716A1; AU2003236307A1

Abstract

A plasma etching method characterized in that it comprises an arrangement step of arranging a pair of electrodes in a chamber, placing a substrate to be processed and having a silicon film and an inorganic material film adjacently between the electrodes, and allowing one of the electrodes to support the substrate and an etching step of applying a high-frequency power to at least one of the electrodes to produce a high-frequency electric field between the pair of electrodes, supplying a process gas into the chamber to produce a plasma of the process gas by the electric field, and plasma-etching the silicon film of the substrate by the plasma, and that in the etching step, the frequency of the high-frequency power applied to at least one of the electrodes is in the range from 50 to 150 MHz.

Description

Description Plasma etching method and plasma etching equipment

The present invention relates to a plasma etching method and apparatus for plasma etching a silicon film on a substrate to be processed such as a semiconductor wafer having a silicon film and an inorganic material film adjacent thereto. Background technology

In a semiconductor device manufacturing process, after a silicon film such as a polysilicon film or a multilayer film such as an insulating film is formed on a semiconductor wafer, a plasma etching is performed to form a predetermined wiring pattern. Done.

Various apparatuses have been used to perform such plasma etching. Among them, a capacitively coupled parallel plate plasma etching apparatus is mainly used. In a capacitively coupled parallel plate plasma processing apparatus, a pair of parallel plate electrodes (upper and lower electrodes) are arranged in one chamber, a processing gas is introduced into the chamber, and high-frequency power is applied to at least one of the electrodes. When applied, a high-frequency electric field is formed between the electrodes. The high-frequency electric field forms a plasma of a processing gas, and a plasma etching process is performed on the substrate to be processed.

In such a plasma processing apparatus, etching is performed by supplying a high frequency power of about 13.5.6-4 OMHz to the lower electrode.

In such conditions, for example in the case of etching a silicon film such as port Rishirikon film using an inorganic material film such as S i 0 ₂ as a mask, in order to improve the E Dzuchingu selectivity to inorganic material film, Etching is performed under relatively high pressure conditions.

However, when etching is performed under relatively high pressure conditions as in the past, there is a problem that the etching selectivity of the silicon film to the inorganic material film is improved, but the etching shape controllability is poor. Such problems are caused by inorganic material films This occurs not only when using as a mask, but also when an inorganic material film is formed under the silicon film. Summary of the invention

The present invention has been made in view of such circumstances, and when etching a silicon film adjacent to an inorganic material film, it is possible to improve shape controllability while maintaining a high etching selectivity. An object of the present invention is to provide a plasma etching method and apparatus.

According to the study results of the present inventors, the etching of the silicon film such as a polysilicon film, a plasma density is dominant, and pair to the contribution of the ion energy is small, S i 0 ₂ and S i N Etching of inorganic material films such as films requires both plasma density and ion energy. Therefore, if the plasma density is high and the ion energy is low to some extent, the etching selectivity of the silicon film to the inorganic material film can be increased. In this case, the ion energy of the plasma indirectly corresponds to the self-bias voltage of the electrode during etching. Therefore, in order to increase the etching selectivity of the silicon film with respect to the inorganic material film, it is necessary to perform etching under conditions of high plasma density and low bias. On the other hand, in order to improve the shape controllability of etching, it is necessary that the process be performed at a low pressure. However, under the above conditions, a high etching selectivity can be realized with a lower pressure process. That is, if a high plasma density and a low self-bias voltage are realized, the etching selectivity of the silicon film with respect to the inorganic material film can be increased under lower pressure conditions, and a high etching selection ratio and good etching shape control can be achieved. Sex can be compatible.

According to the results of further studies by the present inventors, it has been found that when the frequency of the high-frequency power applied to the electrode is high, a state where the plasma density is high and the self-bias voltage is low can be realized.

The present invention provides a method in which a pair of electrodes are arranged in a chamber so as to face each other, and one of the electrodes is disposed between the two electrodes so that a substrate to be processed having a silicon film and an inorganic material film adjacent to each other is arranged. And an arrangement step of supporting the substrate to be processed by at least one of the electrodes. A high-frequency electric field is applied between the pair of electrodes to form a high-frequency electric field, a processing gas is supplied into the chamber, and a plasma of the processing gas is formed by the electric field. An etching step of plasma etching the silicon film, wherein the frequency of the high-frequency power applied to the at least one electrode in the etching step is 50 to 150 MHz.

According to the present invention, since the frequency of the high-frequency power applied to the electrode is 50 to 150 MHz, which is higher than the conventional frequency, a high plasma density and a low self-bias voltage can be realized even under a lower pressure condition. Thus, the silicon film can be etched with a high etching selectivity with respect to the inorganic material film and with good shape controllability.

The frequency of the high-frequency power applied to the electrode is more preferably 70 to 100 MHz, particularly preferably 100 MHz.

Further, in the etching step, the power density of the high frequency power is preferably 0.15 to 5 W / cm ² .

Further, in the etching step, the plasma density in the chamber is preferably 5 × 10 ⁹ to 2 × 10 ^{1 Q} cm− ³ .

Further, in the etching step, the pressure in the chamber is preferably 13.3 Pa or less.

Further, the present invention provides a method in which a pair of electrodes are arranged in a chamber so as to face each other, and a substrate to be processed having a silicon film and an inorganic material film adjacent to each other is arranged between the two electrodes. An arranging step of supporting the substrate to be processed by the electrodes, applying a high-frequency power to at least one of the electrodes to form a high-frequency electric field between the pair of electrodes, and supplying a processing gas into one chamber; Forming a plasma of a processing gas by plasma processing; and performing an etching step of plasma etching the silicon film of the substrate to be processed by the plasma. In the etching step, the processing gas is one of HBr gas and Cl ₂ gas. One anda wherein a chamber plasma density in one is ^{^{5 X 10 9 ~2 X 10 1}} (1 cm- 3, and self Baiasu voltage electrode is 200 V or less Is that plasma Etsu quenching method. According to the present invention, the HBr gas and C 1 gas are supplied under the condition that the plasma density in the chamber 1 is 5 × 10 ^{9 to 2} × 10 1 ^Q cm− ³ and the self-bias voltage of the electrode is 200 V or less. Since a gas plasma containing any one of the gases is formed, the silicon film can be etched with a high machining selectivity and good shape controllability with respect to the inorganic material film.

In the above, the inorganic material film is made of, for example, at least one of silicon oxide, silicon nitride, silicon oxynitride, and silicon carbide.

Further, it is preferable that the high-frequency power is applied to an electrode supporting the substrate to be processed. In this case, a second high-frequency power of 3.2 to 13.56 MHz may be applied to the electrode supporting the substrate to be processed, superimposed on the high-frequency power. As described above, by superimposing the second high-frequency power having a lower frequency, the plasma density and the ion attraction effect can be adjusted, and the etching of the silicon film can be performed while securing the etching selectivity to the inorganic material film. Rate can be further increased.

The second high frequency power to be superimposed is preferably 13.56 MHz. When the frequency of the high frequency power to be superimposed is 13.56 MHz, the power density is preferably 0.64 W / cm ² or less. When a second high-frequency power of 3.2 to 13.56 MHz is applied, the self-bias voltage of the electrode supporting the substrate to be processed is preferably 200 V or less.

The present invention also provides a chamber for accommodating a substrate to be processed having a silicon film and an inorganic material film adjacent to each other, and a pair of chambers provided in the chamber, one of which supports the substrate to be processed. An electrode; a processing gas supply system for supplying a processing gas into the chamber; an exhaust system for exhausting the interior of the chamber; and a high-frequency power supply for supplying high-frequency power for plasma formation to at least one of the electrodes. And a frequency of the high frequency power generated from the high frequency power is 50 to 150 MHz.

The frequency of the high-frequency power generated from the high-frequency power source is preferably 70 to 100 MHz, particularly 100 MHz.

Preferably, the power density of the high frequency power is a 0. 15 ~ 5W / cm ² Further, the pressure in the chamber is preferably 13.3 Pa or less. Preferably, the high-frequency power is applied to an electrode supporting the substrate to be processed.

Preferably, the plasma etching apparatus further includes a second high-frequency power supply that applies a second high-frequency power of 3.2 to 13.56 MHz superimposed on the high-frequency power on an electrode supporting the substrate to be processed. Prepare. In this case, preferably, the frequency of the second high frequency power is 13.56 MHz. Preferably, the power density of the second high-frequency power is 0.64 W / cm ² or less.

By the way, according to Paschen's law, the firing voltage Vs takes the minimum value (the minimum value of Paschen) when the product pd of the gas pressure P and the distance d between the electrodes is a certain value, and the product pd that takes the minimum value of Paschen The value becomes smaller as the frequency of the high-frequency power increases. Therefore, when the frequency of the high-frequency power is large, in order to reduce the firing voltage Vs to facilitate and stabilize the discharge, it is necessary to reduce the distance d between the electrodes when the gas pressure p is constant. Therefore, in the present invention, the distance between the electrodes is preferably less than 50 mm. By setting the distance between the electrodes to less than 50 mm, the residence time of the gas in the chamber can be shortened. As a result, the effect of efficiently discharging the reaction product and reducing the number of etching stops can be obtained.

Preferably, the apparatus further comprises a magnetic field forming means for forming a magnetic field around the plasma region between the pair of electrodes.

When the frequency of the applied high-frequency power is high, a phenomenon may occur in which the etching rate is higher in the central portion, which is the power supply position, than in the peripheral portion, but a magnetic field is generated around the plasma region between the pair of electrodes. By forming, the plasma confinement effect is exhibited, and even when the frequency of the applied high-frequency power is high, the etching rate of the substrate to be processed in the processing space is determined by the edge portion (peripheral portion) and the center of the substrate to be processed. It can be made substantially the same for each part. That is, the etching rate can be made uniform.

The intensity of the magnetic field formed around the plasma region between the pair of electrodes by the magnetic field forming means is preferably in the range of 0.03 to 0.045T (300 to 450 Gauss). Good.

In addition, a focus ring is provided around the electrode supporting the substrate to be processed, and when a magnetic field is formed around the plasma region, the magnetic field intensity on the focus ring is reduced.

It is preferable that the intensity of the magnetic field on the substrate to be processed is not more than 0.001 T (1 OGauss) and not more than 0.001 T.

By setting the magnetic field strength on the focus ring to 0.001 T or more, drift motion of electrons occurs on the focus ring, and the plasma density in the peripheral region increases, and the plasma density becomes uniform. On the other hand, by setting the magnetic field intensity on the substrate to be processed to 0.001 T or less, which does not substantially affect the substrate to be processed, charge damage can be prevented. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic sectional view showing a plasma etching apparatus according to one embodiment of the present invention.

FIG. 2 is a horizontal cross-sectional view schematically showing a ring magnet arranged around one chamber of the plasma etching apparatus of FIG.

FIG. 3 is a cross-sectional view showing an example of the structure of a semiconductor wafer to which the plasma etching of the present invention is applied.

FIG. 4 is a cross-sectional view showing another example of the structure of a semiconductor wafer to which the plasma etching of the present invention is applied.

FIG. 5 is a schematic sectional view partially showing a plasma processing apparatus provided with a high-frequency power supply for generating plasma and a high-frequency power supply for drawing ions.

FIG. 6 is a diagram showing the relationship between the absolute value I Vdc of the self-bias voltage and the plasma density Ne when the frequency of the high-frequency power is 4 OMHz and 10 OMHz in the argon gas plasma. .

FIG. 7A is a diagram showing the values of the etching rate of the polysilicon film with respect to the position of the wafer when the high-frequency power is 100 MHz for the high-frequency power of 500 W, 1000 W, and 1500 W.

Figure 7B shows the poly against the wafer position when the high frequency power is 4 OMHz. FIG. 7 is a diagram showing values of an etching rate of a silicon film in cases where high-frequency power is 500 W, 1000 W, and 1500 W;

FIG. 8 is a diagram showing the relationship between the high-frequency power level and the etching rate of the polysilicon film when the high-frequency power is 4 OMHz and 10 OMHz.

FIG. 9 is a diagram showing the relationship between the high frequency power and the etching rate of the SiO ₂ film when the high frequency power is 40 MHz and 100 MHz.

FIG. 10 shows the relationship between the high-frequency power and the etching rate of the polysilicon film, and the relationship between the high-frequency power and the ratio of the etching rate of the polysilicon film / the etching rate of the SiO ₂ film corresponding to the etching selectivity. FIG. 3 is a diagram showing the case where the high-frequency power is 40 MHz and 100 MHz.

11, the relationship between the etching rate ZS i 0 ₂ film etching rate ratio of the polysilicon film corresponding to the etching rate and etching selection ratio of the polysilicon film, when high-frequency power of 40 MHz and 100 MHz FIG. FIG. 12A is a diagram showing a relationship between the pressure inside the chamber at the time of etching and the etching rate of the polysilicon film when the high-frequency power is 100 MHz and 40 MHz.

Figure 12B is a diagram showing the relationship between the etching rate of the S I_〇 ₂ film in case one internal pressure and the high frequency power chamber in the case of 100MHz and 40 MHz during etching.

Fig. 13 shows the relationship between the chamber internal pressure and the ratio of the etching rate of the polysilicon film to the etching rate of the SiO ₂ film, which corresponds to the etching selectivity, for the case where the high-frequency power is 4 OMHz and 10 OMHz. FIG.

FIG. 14 shows the relationship between the pressure in the chamber and the etching rate of the polysilicon film, and the ratio of the etching rate of the polysilicon film / the etching rate of the SiO ₂ film corresponding to the high-frequency power and the etching selectivity. FIG. 4 is a diagram showing the relationship between the high-frequency powers of 40 MHz and 100 MHz.

FIG. 15 shows the relationship between the etching rate of the polysilicon film and the ratio of the etching rate of the polysilicon film / the etching rate of the SiO ₂ film, which corresponds to the etching selectivity, when the high-frequency power is 40 MHz and 100 MHz. FIG. Fig. 16 shows the case where the frequency of the high frequency power is 100 MHz, the second high frequency power is 13 MHz, and each high frequency power is changed in the HBr gas plasma (high frequency power: 500 W, 1000 W , 1500 W, 2000 W, the second high frequency power: 0 W, 20 OWs 600 W), and the relationship between the absolute value I Vdc of the self-bias voltage and the plasma density Ne.

Figure 17 is a high frequency power relationship between the etching rate of the high-frequency power power and polysilicon film, and the etching rate / S i 0 ₂ film of the polysilicon film corresponding to a high frequency power power and the etching selectivity of the high-frequency power FIG. 4 is a diagram showing a relationship between an etching rate ratio and

Figure 18 shows the relationship between the high-frequency power of the second high-frequency power and the etching rate of the polysilicon film, and the high-frequency power of the second high-frequency power and the etching rate / Si of the polysilicon film corresponding to the etching selectivity. 0 is a diagram showing a relationship between ₂ film etching rate one bets ratio.

Figure 19 shows the relationship between the Ar gas flow rate and the pressure difference ΔΡ between the center and periphery of the wafer when Ar gas was used as the plasma gas for the case of a gap between electrodes of 25 mm and 40 mm. It is a figure shown in comparison. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a sectional view showing a plasma etching apparatus used for carrying out the present invention. This etching apparatus is airtightly provided and has a stepped cylindrical chamber 11 composed of a small-diameter upper portion 1a and a large-diameter lower portion 1b. The wall of the chamber 11 is made of, for example, aluminum.

In the chamber 11, a support table 2 for horizontally supporting a wafer W as a substrate to be processed is provided. The support table 2 is made of, for example, aluminum, and is supported on a conductor support 4 via an insulating plate 3. A focus ring 5 made of a conductive material or an insulating material is provided on an outer periphery above the support table 2. When the diameter of the wafer W is 200 mm ø, the focus ring 5 is preferably 240 to 280 mm (^. Support table 2, insulating plate 3, support table The focus ring 4 and the focus ring 5 can be moved up and down by a ball screw mechanism including a ball screw 7. The lifting drive section below the support 4 is covered with a stainless steel (SUS) rose 8. Chamber 11 is grounded. In addition, a support channel (not shown) is provided in the support table 2 so that the support table 2 can be cooled. A bellows cover 9 is provided outside the bellows 8. At approximately the center of the support table 2, a power supply line 12 for supplying high-frequency power is connected. A high-frequency power supply 10 is connected to the power supply line 12 via a matching box 11. From the high-frequency power source 10, high-frequency power of a predetermined frequency is supplied to the support table 2. On the other hand, above the support table 2, shower heads 16 to be described later are provided so as to face each other in parallel. Shower head 16 is grounded. Therefore, the support table 2 functions as a lower electrode, and the shower head 16 functions as an upper electrode. That is, the support table 2 and the shower head 16 constitute a pair of flat electrodes.

The distance between these electrodes is preferably set to less than 50 mm. The reason is as follows.

According to Paschen's law, the discharge starting voltage V s takes the minimum value (the minimum value of Passion) when the product pd of the gas pressure P and the distance d between the electrodes is a certain value, and the product that takes the minimum value of Paschen. The value of pd decreases as the frequency of the high-frequency power increases. Therefore, when the frequency of the high-frequency power is large as in the present embodiment, in order to reduce the discharge starting voltage V s and facilitate and stabilize the discharge, the distance between the electrodes is constant if the gas pressure p is constant. It is necessary to reduce d. Therefore, it is preferable that the distance between the electrodes is less than 50 mm. In addition, when the distance between the electrodes is less than 50 mm, the residence time of the gas in the chamber can be shortened. As a result, there is also obtained an effect that the reaction product is efficiently discharged and the etching stop can be reduced.

However, if the distance between the electrodes is too small, the pressure distribution (the pressure difference between the central part and the peripheral part) on the surface of the wafer W to be processed increases. In this case, problems such as a decrease in etching uniformity may occur. In order to make the pressure difference smaller than 0.27 Pa (2 mTorr) regardless of the gas flow rate, the distance between the electrodes is preferably 35 mm or more. Good.

An electrostatic chuck 6 for electrostatically attracting the wafer W is provided on the surface of the support tape 2. The electrostatic chuck 6 has an electrode 6a interposed between insulators 6b. A DC power supply 13 is connected to the electrode 6a. When a voltage is applied from the DC power supply 13 to the electrode 6a, the semiconductor wafer W is attracted by, for example, Coulomb force.

Inside the support table 2, a refrigerant flow path (not shown) is formed. By circulating an appropriate coolant therein, the wafer W can be controlled to a predetermined temperature. Further, in order to efficiently transmit the cold heat from the refrigerant to the wafer W, a gas introduction mechanism (not shown) for supplying He gas to the back surface of the wafer W is provided. Further, a baffle plate 14 is provided outside the focus ring 5. The nuffle plate 14 communicates with the chamber 11 through the support 4 and the bellows 8. A shower head 16 is provided on the ceiling wall of the chamber 11 so as to face the support table 2. The shower head 16 is provided with a number of gas discharge holes 18 on the lower surface, and has a gas inlet 16a on the upper portion. Further, a space 17 is formed therein. A gas supply pipe 15a is connected to the gas introduction section 16a, and the other end of the gas supply pipe 15a is supplied with a processing gas for supplying a processing gas comprising a reactive gas for etching and a diluting gas. Gas supply system 15 is connected.

As a reaction gas, a halogen-based gas is used, and as a diluting gas, a gas usually used in this field, such as an Ar gas or a He gas, can be used.

Such processing gas flows from the processing gas supply system 15 to the space 17 of the shower head 16 via the gas supply pipe 15a and the gas inlet 16a, and from the gas discharge hole 18 The discharged film formed on the wafer W is etched.

An exhaust port 19 is formed on the side wall of the lower part lb of the chamber 11, and an exhaust system 20 having a vacuum pump is connected to the exhaust port 19. By operating the vacuum pump, the pressure inside the chamber 11 can be reduced to a predetermined degree of vacuum. On the other hand, a loading / unloading port for the wafer W and a gate valve 24 for opening and closing the loading / unloading port are provided above the side wall of the lower portion 1 b of the processing chamber 1. On the other hand, a ring magnet 21 is arranged concentrically around the upper part 1 a of the chamber 11, and a magnetic field is formed around the processing space between the support table 2 and the shower head 16. Is formed. The ring magnet 21 is rotatable (in the circumferential direction) around the center axis of the arrangement by the rotating mechanism 25.

As shown in the horizontal sectional view of FIG. 2, the ring magnet 21 is configured such that a plurality of segment magnets 22 made of permanent magnets are arranged in a ring shape while being supported by a support member (not shown). In this example, 16 segment magnets 22 are arranged in a multipole state in a ring shape (concentric shape). That is, the ring magnets 21 are arranged such that the magnetic poles of the adjacent segment magnets 22 are opposite to each other. Therefore, the magnetic field lines are formed between the adjacent segment magnets 22 as shown in the figure, and are provided only in the peripheral portion of the processing space, for example, in the range of 0.02 to 0.2 T (200 to 2000 Gauss), preferably in the range of 0.03 to 0.2. A magnetic field of 045 T (300 to 450 Gauss) is formed. On the other hand, the wafer arrangement region is substantially in a state of no magnetic field. The reason why the magnetic field strength as described above is defined is that if the magnetic field is too strong, it may cause a leakage magnetic field, and if the magnetic field is too weak, the plasma confinement effect cannot be obtained. However, the appropriate magnetic field strength also depends on the device structure. That is, the appropriate range of the magnetic field strength may vary from device to device.

Further, when the above-described magnetic field is formed in the peripheral portion of the processing space, it is desirable that the magnetic field strength on the focusing 5 be equal to or more than 0.001 T (10 Gauss). In this case, drift motion of electrons (EXB drift) occurs on the focus ring, and the plasma density at the peripheral portion of the wafer increases, and the plasma density becomes uniform. On the other hand, from the viewpoint of preventing the charge-up damage of the wafer W, it is desirable that the magnetic field strength in the portion where the wafer W exists is 0.001 T (1 OGauss) or less. Here, “substantially no magnetic field in the wafer arrangement region” means that a magnetic field that affects the etching process in the wafer arrangement region is not formed. That is, this includes the case where a magnetic field that does not substantially affect the wafer processing exists.

In the state shown in FIG. 2, a magnetic field having a magnetic flux density of, for example, 0.42 mT (4.2 Gauss) or less is applied to the periphery of the wafer. As a result, the function of confining the plasma is exhibited. When a magnetic field is formed by such a ring magnet in a multipole state, there is a possibility that a portion corresponding to the magnetic pole on the wall of the chamber 1 (for example, a portion indicated by P in FIG. 2) may be locally shaved. There is. Therefore, the ring magnet 21 is rotated along the circumferential direction of the chamber 1 by the rotation mechanism 25. This prevents the magnetic pole from abutting (positioning) locally on the chamber-wall, and prevents the chamber wall from being locally scraped.

Each of the segment magnets 22 is rotatable about a vertical axis by a segment magnet rotating mechanism (not shown). In this way, by rotating the segment magnets 22, it is possible to switch between a state in which a multi-pole magnetic field is substantially formed and a state in which a multi-pole magnetic field is not formed. Depending on the conditions, the multipole field may or may not work effectively. Accordingly, by making it possible to switch between a state in which a multipole magnetic field is formed and a state in which a multipole magnetic field is not formed, an appropriate state can be selected according to conditions. Since the state of the magnetic field changes according to the arrangement of the segment magnets, various magnetic field intensity profiles can be formed by variously changing the arrangement of the segment magnets. Therefore, it is preferable to arrange the segment magnets so as to obtain a necessary magnetic field strength profile.

The number of segment magnets is not limited to this example. Also, the cross-sectional shape is not limited to a rectangle as in this example, and an arbitrary shape such as a circle, a square, a trapezoid and the like can be adopted. The magnet material constituting the segment magnets 22 is not particularly limited, either. For example, known magnet materials such as rare earth magnets, ferrite magnets, and alnico magnets can be applied.

The plasma etching apparatus having the above configuration can be applied to a case where polysilicon adjacent to an inorganic material film such as SiO 2 or SiO ₂ is etched. Hereinafter, a processing operation when such etching is performed using the plasma etching apparatus having the above configuration will be described.

As shown in FIG. 3, for example, a wafer W to be etched has a polysilicon film 32 formed on a silicon substrate 31 and an inorganic-based material having a predetermined pattern as a hard mask on the silicon film 32. It has a configuration in which a material film 33 is formed. There As shown in FIG. 4, an inorganic material film 42 made of SiO ₂ is formed on a silicon substrate 41 as a gate oxide film, and a gate is formed on the inorganic material film 42, as shown in FIG. A polysilicon film 43 is formed, and a resist film 44 having a predetermined pattern serving as a mask is formed on the polysilicon film 43. The inorganic material film 33 is made of a material generally used as a hard mask. Suitable examples include silicon oxide, silicon nitride, silicon oxynitride, silicon carbide and the like. That is, the inorganic material film 33 is preferably made of at least one of these.

For the wafer W having these structures, the polysilicon film 32 or 43 is etched. First, the gate valve 24 is opened, and the wafer W is carried into the chamber 1 by the transfer arm and placed on the support table 2. Thereafter, the transfer arm is retracted, the gate valve 24 is closed, and the support tape 2 is raised to the position shown in FIG. Further, the inside of the chamber 11 is set to a predetermined degree of vacuum through the exhaust port 19 by the vacuum pump of the exhaust system 20.

Thereafter, a predetermined processing gas, for example, HBr gas, is introduced into the chamber 11 from the processing gas supply system 15 at, for example, 0.02 to 0.4 L / min (20 to 400 sccm), and The inside of 1 is maintained at a predetermined pressure. In this state, high frequency power having a frequency of 50 to 150 MHz, preferably 70 to 100 MHz, is supplied from the high frequency power supply 10 to the support table 2. At this time, the power per unit area, that is, the power density is preferably in the range of about 0.15 to about 5. OW / cm ² _c. A predetermined voltage is applied to a, and the wafer W is attracted to the electrostatic chuck 6 by, for example, Coulomb force.

By applying the high-frequency power to the supporting table 2 serving as the lower electrode, a high-frequency electric field is formed in the processing space between the shower head 16 serving as the upper electrode and the supporting table 2 serving as the lower electrode. Is done. As a result, the processing gas supplied to the processing space is turned into plasma, and the polysilicon film on the wafer W is etched by the plasma.

At the time of this etching step, a magnetic field as shown in FIG. 2 can be formed around the processing space by the ring magnet 21 in the multipole state. In this case, plasma confinement Therefore, the etching rate of the wafer W can be made uniform even in the case of a high frequency where plasma non-uniformity is likely to occur as in the present embodiment. Depending on the conditions, it may be better not to form such a magnetic field. In that case, the segment magnet 22 may be rotated so that the magnetic field is not substantially formed around the processing space to perform the processing.

When the magnetic field is formed, the effect of uniformizing the plasma processing can be further enhanced by the conductive or insulating focus ring 5 provided around the wafer W on the support table 2. In other words, if the plasma density at the wafer periphery is high and the etching rate at the wafer periphery is higher than the etching rate at the wafer center, use a focus ring made of a conductive material such as silicon or SiC. Accordingly, the region up to the focus ring region functions as a lower electrode, so that the plasma formation region extends to above the focus ring 5, plasma processing in the peripheral portion of the wafer W is promoted, and the uniformity of the etching rate is improved. On the other hand, when the plasma density around the wafer is low and the etching rate around the wafer is lower than the etching rate around the center of the wafer, the focus ring made of an insulating material such as quartz can be used. Since charges cannot be transferred between the focus ring 5 and electrons or ions in the plasma, the action of confining the plasma can be increased, and the uniformity of the etching rate can be improved.

In order to adjust the plasma density and the ion attracting action, the high frequency for generating plasma and the second high frequency for attracting ions in the plasma may be superimposed. Specifically, as shown in FIG. 5, in addition to the high-frequency power supply 10 for plasma generation, a second high-frequency power supply 26 for ion attraction is connected to the matching box 11, and these are superimposed. In this case, the frequency of the second high-frequency power supply 26 for attracting ions is preferably from 3.2 to 13.56 MHz, and in this range, 13.56 MHz is particularly preferable. As a result, the parameter for controlling the ion energy increases, so that the etching rate of the polysilicon film can be further increased while securing the etching selectivity to the necessary and sufficient inorganic material film. Processing conditions can be easily set.

By the way, according to the study results of the present inventors, in etching a polysilicon film, Ten

15 While the plasma density is dominant and the ion energy contribution is small, the etching of inorganic materials requires both the plasma density and the ion energy. Therefore, as shown in FIGS. 3 and 4, when etching the polysilicon film adjacent to the inorganic material film, the plasma density is high in order to perform etching with a high etching selectivity to the inorganic material film. In addition, the ion energy must be low. In other words, if the ion energy required for etching an inorganic material is reduced and the plasma density which is dominant for polysilicon etching is increased, the polysilicon film is selectively etched. Here, the ion energy of the plasma indirectly corresponds to the self-bias voltage of the electrode at the time of etching. Therefore, in order to etch the polysilicon film with a high etching selectivity, after all, a high plasma density and a low It is necessary to perform etching under the condition of self-bias voltage. On the other hand, in order to improve the shape controllability of the etching, it is necessary to perform etching at a low pressure. However, if the above conditions are satisfied, a high etching selectivity can be achieved with a lower pressure process. Can be realized. That is, if a high plasma density and a low self-bias voltage are realized, the etching selectivity of the polysilicon film relative to the inorganic material film can be increased even under a lower pressure condition, and the high etching selectivity can be achieved. And good etching shape controllability can be achieved at the same time. Then, it was found that the frequency of the high-frequency power applied to the electrode should be set to 50 to 15 OMHz higher than the conventional frequency.

Hereinafter, this will be described with reference to FIG. FIG. 6 is a graph showing the relationship between the absolute value | V dc | of the self-bias voltage and the plasma density when the frequency of the high frequency power is 40 MHz and 10 MHz. The horizontal axis is the absolute value of the self-bias voltage, IV dc I, and the vertical axis is the plasma density. Here, Ar was used for the evaluation instead of the actual etching gas as the plasma gas. At each frequency, the value of the plasma density Ne and the absolute value IVdcI of the self-bias voltage were changed by changing the applied high-frequency power. In other words, for each frequency, as the applied high-frequency power increases, both the plasma density Ne and the absolute value IVdcI of the self-bias voltage increase. Plasma density was measured with a microwave interferometer. As shown in Fig. 6, when the frequency of the high-frequency power was 4 OMz, the plasma density increased to increase the etching rate of the polysilicon film, and the IV dc I also increased significantly. On the other hand, when the frequency of the high-frequency power was 100 MHz, which was higher than before, I Vdc I did not increase much even when the plasma density was increased, and was suppressed to almost 100 V or less. That is, it has been found that a high plasma density and a low self-bias voltage can be realized. In other words, when the frequency is relatively low as in the past, under a low pressure, if the etching rate of the polysilicon film is increased in the actual etching, the inorganic material film is also etched to the same extent, and good selective etching is performed. On the other hand, it has been found that the polysilicon film can be etched at a high etching selectivity with respect to the inorganic material film at a high frequency of 10 OMHz while the property cannot be obtained.

As can be understood from FIG. 6, in order to etch the polysilicon film with a higher selectivity under a low pressure and a higher plasma density and a lower self-bias voltage than before, the plasma of the argon gas is required. when forming, plasma density IX 10 ^1Q cm_ ³ or more and the self-bias voltage of the electrode is 100 V or less, or self-bias voltage of the bra Zuma density 5 X 10 ^1Q cm- ³ or more and electrodes 200 V or less, and It is considered preferable to form the plasma under such conditions. In order to satisfy such plasma conditions, it is assumed that high frequency power of 5 OMHz or more is required.

Therefore, the frequency of the high frequency power for plasma formation is set to 5 OMHz or more as described above. However, if the frequency of the high frequency power for plasma formation exceeds 15 OMHz, the uniformity of the plasma may be impaired. For this reason, the frequency of the high frequency power for plasma formation is preferably set to 15 OMHz or less. In particular, in order to exhibit the above effects effectively, the frequency of the high frequency power for plasma formation is preferably 70 to 100 MHz.

The pressure in the chamber during etching is preferably set to 13.3 Pa (10 OmT) or less. From the viewpoint of achieving both the etching selectivity of the polysilicon film with respect to the inorganic material film and the controllability of the etching shape, the pressure within the chamber is more preferably 4 Pa (3 OmT) or less. If more importance is placed on the control of the etching shape, More preferably, the Yamba internal pressure is 1.33 pa (1 OmT) or less.

Next, in order to grasp the etching selection ratio to the actual Edzuchingureto and inorganic material film of the polysilicon film, the experimental result of etching of the S I_〇 ₂ the entire surface of the formed film is a polysilicon film and an inorganic material film Will be described.

Here, a 20 Omm wafer is used as the wafer W, HBr gas: 0.2 L / min (0.02 L / min only when the pressure is 0.133 Pa) is supplied as an etching gas, and the gap between the electrodes is 27 mm. The etching treatment was performed with the pressure in the chamber being 4 Pa.

Figure 7 A is in the case the high-frequency power is 10 OMHz, the value of Edzuchingureto polysilicon film with respect to the position of the wafer, the high frequency power power ^{500W (1. 59 W / cm 2} ), 1000W (3. 18W / cm z ) And 150 OW (4.77 W / cm ² ). 7B is when high-frequency power of 40MH z, the value of the etching rate of the polysilicon film with respect to the position of the wafer, the high frequency power power 50 OW (1 · 59 W / cm 2) 100 OW (3. 18 W / cm ²⁾ is a diagram showing a case each of the 150 OW (4. 77 W / cm 2). FIG. 8 is a diagram showing the relationship between the high-frequency power and the etching rate of the polysilicon film for each of 4 OMHz and 10 OMHz. 9, the relationship between Edzuchingureto high frequency power power and S i0 ₂ film, a diagram illustrating a case each of 40MH z and 10 OMH z. FIG. 10 shows the relationship between the high-frequency power power and the etching rate of the polysilicon film, and the high-frequency power power and the etching rate ratio of the polysilicon film / etching rate of the SiO ₂ film corresponding to the etching selectivity (FIG. 10). FIG. 4 is a diagram showing the relationship between the etching selectivity and the description in each of 4 OMHz and 10 OMHz. FIG. 11 shows the relationship between the etching rate of the polysilicon film and the etching rate ratio of the polysilicon film / etching rate of the SiO ₂ film corresponding to the etching selectivity (also described in FIG. 11 as the etch selectivity). It is a figure shown about each case of 4 OMHz and 10 OMHz.

From these figures, it can be seen that the etching rate of the polysilicon film tends to increase as the RF power increases, but the etching rate at 4 There is no large difference between the etching rate at MHz. Further, the same gas pressure and the same power, the etching rate of the etching rate and 100M H z at 4 OMH z polysilicon film is a comparable, the etching rate of the S i0 ₂ film than in the case of 10 OMHz Is also higher at 4 OMH z. Therefore, the etching selectivity of the polysilicon film with respect to the SiO ₂ film is higher at 10 OMHz than at 40 MHz, which means that the etching rate ratio of the polysilicon film / SiO ₂ film is higher. confirmed. In other words, from the experimental results of the evaluation samples, it was confirmed that using a high-frequency power of 10 OMHz rather than 4 OMHz at 4 Pa has a higher possibility of etching the polysilicon film with a high etching selectivity. Since the etching rate of the polysilicon film and the etching selection ratio are in a trade-off relationship, if the high-frequency power is too large, the etching rate of the polysilicon film increases but the etching selection ratio decreases. Therefore, the power density of the high frequency power of 10 OMHz is preferably 5 W / cm ² (about 1500 W) or less.

On the other hand, at 10 OMHz, the etching rate of the polysilicon film decreases in the direction of lower power density, and the etching selectivity with respect to the SiO ₂ film increases. If the underlying etch ring target film is a gate oxide film, such as S i 0 _2, since the thickness is usually about the number nm, lowers the etching rate of the S i 0 ₂ to 0. lnm / min order one There is a need. For example, under a pressure condition of 1.33 Pa (1 OmTorr), at a power density of 1.5 W / cm ² (about 500 W), the etching rate of the polysilicon film is 100 nm / min, and the etching selectivity is 70. And the etching rate of SiO ₂ is 1.3 nm / min. Therefore, in order to lower the Etsu Chin Great S i 0 ₂ to 0. 1 nmZmi n order one, the power density 0. 15-0 3W / cm ² (about 50~: I 00 W). Necessary to reduce to the extent It is expected that there will be. In consideration of the above points, the minimum high frequency power is preferably 0.3 W / cm ² or more, and more preferably 0.15 W / cm ² (about 50 W). From the viewpoint of etching selectivity alone, the high-frequency power is preferably 1.5 W / cm ² (about 500 W) or less.

Next, the flow rate of HBr gas is changed between 0.02 and 0.2 L / min, and The pressure in the Yanbar was changed between 0.133 and 13.3 Pa, the high frequency power was fixed at 500 W, and the other conditions were etched under the above conditions.

FIG. 12A is a diagram showing the relationship between the pressure inside the chamber at the time of etching and the etching rate of the polysilicon film when the high-frequency power is 10 OMHz and 4 OMHz, and FIG. 12B is a diagram showing the chamber at the time of etching. FIG. 6 is a diagram showing the relationship between the internal pressure and the etching rate of the SiO ₂ film when the high-frequency power is 10 OMHz and when it is 4 OMHz. FIG. 13 shows the relationship between the pressure inside the chamber and the ratio of the etching rate of the polysilicon film corresponding to the etching selectivity / the etch rate of the SiO ₂ film (described as the etching selectivity in FIG. 13) at 40 MHz and 10 MHz. It is a figure shown about each case of OMHz. Figure 14 shows the relationship between the internal pressure of the chamber and the etching rate of the polysilicon film, and the ratio of the etching rate of the polysilicon film to the etching rate of the SiO ₂ film corresponding to the high-frequency power and the etching selectivity. FIG. 15 is a diagram showing the relationship between (4) and 10 (10) MHz in FIG. FIG. 15 shows the relationship between the etching rate of the polysilicon film and the ratio of the etching rate of the polysilicon film to the etching rate of the SiO ₂ film, which corresponds to the etching selectivity (also described in FIG. 15 as the etch selectivity). It is a figure shown about each case of 4 OMHz and 10 OMHz.

From these figures, it was confirmed that the etching rate of the polysilicon film was slightly higher and the etching selectivity was higher at 10 OMHz than at 4 OMHz at the same high frequency power and the same pressure in the chamber. . In addition, it was confirmed that with the same high-frequency power, a higher etching selectivity can be obtained at a lower pressure at 10 OMHz than at 4 OMHz. Furthermore, as shown in Fig. 15, it was confirmed that at the same high frequency power and etching rate, the etching selectivity was higher at 10 OMHz than at 4 OMHz. From these facts, at 10 OMHz, it is possible to obtain a high etching selectivity under low-pressure conditions, which is advantageous for etching shape control, and to achieve both high etching selectivity and good etching shape control. Was confirmed.

Regarding the effect of pressure, both at 4 OMHz and at 10 OMHz, However, it was confirmed that the etching rate and the etching selectivity of the polysilicon film were good. However, from the viewpoint of the controllability of the etching shape of the polysilicon film, it was confirmed that the lower pressure, specifically 13.3 Pa or less, was preferable.

Next, the results of measuring (measuring) the absolute value I Vdc I of the self-bias voltage and the plasma density when a high-frequency power of 100 MHz is applied using an actual etching gas (HBr) will be described.

FIG. 16 is a diagram showing a comparison between the relationship between the absolute value of the self-bias voltage and the plasma density in the case where the frequency of the high-frequency power is set to 100 MHz and the plasma is formed using HBr gas. The horizontal axis is the absolute value of the self-bias voltage I Vd cI, and the vertical axis is the plasma density. Plasma density was measured with a microwave interferometer. At this time, the pressure inside the chamber was 2.7 Pa (2 OmT 0 rr). Also, by changing the power of the high frequency power of 10 OMHz between 500 and 2000 W, the plasma density and the absolute value of the self-bias voltage I Vdc I were changed. Further, when the power of the high frequency power of 10 MHz was 500 W, the second high frequency power of 13 MHz was superimposed at 0 W and 20 OWs 600 W.

As can be seen from FIG. 16, for each frequency, as the applied high-frequency power increases, both the plasma density Ne and the absolute value I Vd c I of the self-bias voltage increase.

As shown in FIG. 16, the plasma density of the actual etching gas plasma tends to be slightly lower than that of the Ar gas plasma (see FIG. 6). Also, when the second high frequency power (13 MHz) of lower frequency is superimposed and the power is increased, the self-bias voltage tends to increase.

Also, as can be seen from FIG. 16, when the second high-frequency power was not superimposed, I Vdc I did not increase so much even when the plasma density was increased, and was suppressed to almost 100 V or less. That is, it was found that high plasma density and low self-bias voltage were feasible.

FIG. 17 shows the relationship between the high frequency power of the high frequency power and the etching rate of the polysilicon film when the second high frequency power is not superimposed, and the high frequency power of the high frequency power and the etching selectivity. Etching of polysilicon film FIG. 4 is a diagram showing a relationship between a ratio of the etching rate of the Great / Si ₂ film. As the high frequency power increases, the etching rate of the polysilicon film increases, but the selectivity decreases. Therefore, about 1500 W (about 4.77 W / cm ² ) or less is preferable. On the other hand, as the power decreases, the etching rate decreases, but the selectivity increases. Therefore, the power is preferably about 500 W (about 1.5 W / cm ² ) or more.

From FIGS. 16 and 17, a high etching frequency of 10 OMHz can be used to obtain the required polysilicon etching rate, and the polysilicon film can be etched with a high etching selectivity with respect to the inorganic material film. It was confirmed that it was possible. In addition, as can be understood from FIGS. 16 and 17, at a low pressure, a higher plasma density and a lower self-bias voltage than in the prior art are required to etch the polysilicon film at a higher selectivity and a required etching rate. is a plasma density is ^{5 X 1 0 9 ~2 X 10} 1Q cm- 3, and, it may be preferable self-bias voltage of the electrode is below 200 V or less.

As a processing gas, a gas containing Cl ₂ gas may be used in addition to a gas containing HBr gas, but in the latter case, it is confirmed that the preferable range of the plasma density is the same as above. Was done.

On the other hand, Fig. 18 shows the RF power of the second RF power and the etching rate of the polysilicon film when the RF power of the RF power is fixed to 500 W and the RF power of the RF power is superimposed. FIG. 7 is a diagram showing the relationship between the ratio of the high-frequency power of the second high-frequency power and the ratio of the etching rate of the polysilicon film / the etching rate of the SiO ₂ film corresponding to the etching selectivity.

As can be seen from FIGS. 16 and 18, when the second high-frequency power of 13 MHz is superimposed and the power is increased, the etching rate increases and the self-bias voltage of the electrode also increases. As the self-bias voltage increases, the etching selection ratio tends to decrease.The etching selection ratio is within the allowable range up to the self-bias voltage of 200 V, that is, the second high-frequency power of about 200 W (about 0.64 W / cm ² ). It is possible to keep in the enclosure.

Therefore, the power (bias power) of the superimposed second high-frequency power is increased. As a result, the etching rate can be increased while maintaining the etching selectivity of 10 or more.

In the above test, the gap between the electrodes was 27 mm. However, as described above, if the distance between the electrodes is too small, the pressure distribution on the surface of the wafer W (the center and the periphery) If the pressure difference becomes large, problems such as a decrease in etching uniformity may occur. Therefore, the actual distance between the electrodes is more preferably 35 to 50 mm. This will be described with reference to FIG.

Figure 19 shows the relationship between the Ar gas flow rate and the pressure difference between the center of the wafer and the periphery of the wafer when Ar gas was used as the plasma gas, for the case where the electrode gap was 25 mm and 40 mm. FIG. As shown in FIG. 19, the pressure difference ΔΡ is smaller when the gap is 40 mm than when the gap is 25 mm. In the case of a gap of 25 mm, the pressure difference tends to increase sharply with the increase of the Ar gas flow rate, and when the gas flow rate is about 0.3 L / min or more, the etching uniformity may decrease. The allowable maximum pressure difference P, which does not cause any problems, exceeds 0.27 Pa (2 mTorr). On the other hand, when the gap is 40 mm, the pressure difference is smaller than 0.27 Pa (2 mTorr) regardless of the gas flow rate. Therefore, if the gap between the electrodes is about 35 mm or more, it is expected that the allowable maximum pressure difference that does not cause a problem such as a decrease in etching uniformity can be maintained regardless of the gas flow rate.

The present invention can be variously modified without being limited to the above embodiment. For example, in the above embodiment, the case where the polysilicon film is used as the silicon film has been described. However, the present invention is not limited to this, and other silicon films such as a single crystal silicon film and an amorphous silicon film may be used. Good.

Further, in the above-described embodiment, a ring magnet in a multipole state in which a plurality of segment magnets made of permanent magnets are arranged in a ring around the chamber as the magnetic field forming means is used. The present invention is not limited to this mode as long as a magnetic field can be formed in the plasma to confine the plasma. Also, such a peripheral magnetic field for confining the plasma is not always necessary. That is, etching may be performed in the absence of a magnetic field. In addition, the present invention is also applied to a plasma etching process in which a horizontal magnetic field is applied to a processing space to perform a plasma etching in an orthogonal electromagnetic field. 4410

23 It is possible.

Furthermore, in the above embodiment, high-frequency power for plasma formation is applied to the lower electrode, but is not limited to this, and may be applied to the upper electrode. Furthermore, the layer structure of the substrate to be processed is not limited to that shown in FIG. 3 or FIG. 4 of the above embodiment. Furthermore, although the case where a semiconductor wafer is used as a substrate to be processed has been described, the present invention is not limited to this and can be applied to etching of a polysilicon film on another substrate to be processed.

Claims

The scope of the claims

1. A pair of electrodes are arranged in the chamber so as to face each other, and one of the electrodes is arranged so that a substrate to be processed having a silicon film and an inorganic material film adjacent to each other is arranged between the two electrodes. An arrangement step of holding the processing substrate,

A high-frequency electric power is applied to at least one of the electrodes to form a high-frequency electric field between the pair of electrodes, a processing gas is supplied into the chamber, and a plasma of the processing gas is formed by the electric field. An etching step of plasma etching the silicon film of the substrate to be processed;

With

In the etching step, the frequency of the high-frequency power applied to the at least one electrode is 50 to 50 MHz.

A plasma etching method characterized by the above-mentioned.

2. In the etching step, the frequency of the high-frequency power applied to the at least one electrode is 100 MHz.

2. The plasma etching method according to claim 1, wherein:

3. In the etching step, a power density of the high-frequency power is 0.15 to 5 W / cm ² .

2. The plasma etching method according to claim 1, wherein:

4. In the etching step, the plasma density in the chamber is 5 × 10 ⁹ -2 × 10 ¹⁰ cm— ³

2. The plasma etching method according to claim 1, wherein:

5. In the etching step, the pressure in the chamber is 13.3 Pa or less.

2. The plasma etching method according to claim 1, wherein:

6. The inorganic material film is made of at least one of silicon oxide, silicon nitride, silicon oxynitride, and silicon carbide.

The plasma etching method according to claim 1, wherein:

7. In the etching step, the high frequency power is applied to an electrode supporting the substrate to be processed.

The plasma etching method according to claim 1, wherein:

8. In the etching step, a second high frequency power of 3.2 to 13.56 MHz is applied so as to be superimposed on the high frequency power on an electrode supporting the substrate to be processed. 3. The plasma etching method according to item 1.

9. The frequency of the second high frequency power is 13.56 MHz

9. The plasma etching method according to claim 8, wherein:

10. The plasma etching method according to claim 9, wherein the power density of the second high frequency power is equal to or less than 0.1 GAWZcm ² .

11. In the etching step, a self-bias voltage of an electrode supporting the substrate to be processed is 200 V or less.

9. The plasma etching method according to claim 8, wherein:

12. The distance between the electrodes of the pair of electrodes is less than 50 mm

2. The plasma etching method according to claim 1, wherein:

13. In the etching step, a magnetic field is formed around a plasma region between the pair of electrodes.

2. The plasma etching method according to claim 1, wherein:

14. The strength of the magnetic field formed around the plasma region between the pair of electrodes is 0.03 to 0.045T (300 to 450 Gauss).

14. The plasma etching method according to claim 13, wherein:

15. When a magnetic field is formed around the plasma region between the pair of electrodes, the magnetic field strength on a focus ring provided around the substrate to be processed is 0.0001 T (1 OGauss) or more. And the magnetic field intensity on the substrate to be processed is 0.001 T or less.

15. The plasma etching method according to claim 14, wherein:

16. The silicon film is composed of polysilicon

The plasma etching method according to claim 1, wherein:

17. A pair of electrodes are arranged facing each other in one chamber, and one of the electrodes is processed so that a substrate having a silicon film and an inorganic material film adjacent to each other is arranged between the two electrodes. An arrangement step of supporting the substrate,

With

In the etching step, the process gas is an HB r gas and including any one of the C 1 ₂ gas, the plasma density of the chamber in one is ^{5 X 10 9 ~ 2 X 10} 10 cm one ^3, and, The self-bias voltage of the electrode is less than 200V

A plasma etching method characterized by the above-mentioned.

18. A pair of electrodes are arranged in one chamber so as to face each other, and one of the electrodes is arranged so that a substrate to be processed having a silicon film and an inorganic material film adjacent to each other is arranged between the two electrodes. An arrangement step of supporting the substrate to be processed by

Applying a high-frequency power to at least one of the electrodes to form a high-frequency electric field on the pair of electrodes, supplying an Ar gas into the chamber, and forming a plasma of the processing gas by the electric field;

With

In the plasma-forming step, a step of confirming that the plasma density in the chamber 1 is 1 × 10 1 ^Q cm− ³ or more and that the self-bias voltage of the electrode is 100 V or less is performed.

A method for confirming plasma etching conditions, characterized in that:

19. a chamber for accommodating a substrate to be processed having a silicon film and an inorganic material film adjacent to each other;

A pair of electrodes provided in the chamber, one of which supports the substrate to be processed;

A processing gas supply system for supplying a processing gas into the chamber;

An exhaust system for exhausting the inside of the chamber,

A high-frequency power supply for supplying high-frequency power for plasma formation to at least one of the electrodes;

With

The frequency of the high frequency power generated from the high frequency power supply is 50 to 15 OMHz.

A plasma etching apparatus characterized by the above-mentioned.

20. The frequency of the high frequency power generated from the high frequency power supply is 10 OMHz

20. The plasma etching apparatus according to claim 19, wherein:

21. The plasma etching apparatus according to claim 19, wherein a power density of the high frequency power is 0.15 to 5 W / cm ² .

22. The pressure in the chamber is 13.3 Pa or less

20. The plasma etching apparatus according to claim 19, wherein:

23. The plasma etching apparatus according to claim 19, wherein the high-frequency power is applied to an electrode supporting the substrate to be processed.

24. A second high frequency power supply for applying a second high frequency power of 56 MHz by superimposing the high frequency power on the electrode supporting the substrate to be processed.

24. The plasma etching apparatus according to claim 23, further comprising:

25. The frequency of the second high-frequency power is 13.56 MHz

25. The plasma etching apparatus according to claim 24, wherein:

26. The plasma etching apparatus according to claim 25, wherein the power density of the second high frequency power is 0.6 W / cm ² or less.

27. The distance between the electrodes of the pair of electrodes is less than 50 mm

20. The plasma etching apparatus according to claim 19, wherein:

28. Magnetic field forming means for forming a magnetic field around the plasma region between the pair of electrodes

20. The plasma etching apparatus according to claim 19, further comprising: 9. The strength of a magnetic field formed by the magnetic field forming means around a plasma region between the pair of electrodes is 0.03 to 0.045 T (300 to 450 Gauss). 29. The plasma etching apparatus according to 28.

30. A focus ring is provided around the substrate to be processed, When the magnetic field forming means forms a magnetic field around the plasma region between the pair of electrodes, the magnetic field strength on the focus ring is 0.001 T (10 Gauss) or more, and 30. The plasma etching apparatus according to claim 29, wherein a magnetic field intensity is 0.001 T or less.

31. A chamber for accommodating a substrate to be processed having a silicon film and an inorganic material film adjacent to each other;

A processing gas supply system for supplying a processing gas into the chamber,

An exhaust system for exhausting the inside of the chamber,

With the '

When a gas containing any one of HBr gas and C12 gas is used as a processing gas, the plasma density in the chamber becomes 5 × 10 ⁹ −2 × 10 1 ^Q cm− ³ , and The self-bias voltage of the electrode drops below 200 V

A plasma etching apparatus characterized by the above-mentioned.

32. A chamber for accommodating a substrate to be processed having a silicon film and an inorganic material film adjacent to each other;

A processing gas supply system for supplying a processing gas into the chamber;

An exhaust system for exhausting the inside of the chamber,

With

When Ar gas is used as the processing gas, the plasma density in the chamber 1 x 1 O ^ cm- ³ or more, and the self-bias voltage of the electrode is 10 OV or less

A plasma etching apparatus characterized by the above-mentioned.