JPWO2003085716A1 - Plasma etching method and plasma etching apparatus - Google Patents

Abstract

In the present invention, a pair of electrodes are disposed opposite to each other in a chamber, and a substrate to be processed having a silicon film and an inorganic material film adjacent to each other is disposed between the electrodes. An arrangement step for supporting the processing substrate, and applying a high frequency power to at least one of the electrodes to form a high frequency electric field between the pair of electrodes, supplying a processing gas into the chamber, and generating plasma of the processing gas by the electric field And an etching step of plasma-etching the silicon film of the substrate to be processed with the plasma, and the frequency of the high-frequency power applied to the at least one electrode in the etching step is 50 to 150 MHz. A plasma etching method characterized by the above.

Description

Technical field
The present invention relates to a plasma etching method and apparatus for plasma etching a silicon film of a substrate to be processed such as a semiconductor wafer having a silicon film and an inorganic material film adjacent thereto.
Background art
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, plasma etching is performed in order to form a predetermined wiring pattern.
Various apparatuses are used to perform such plasma etching. Among them, the capacitively coupled parallel plate plasma etching apparatus is the mainstream. In a capacitively coupled parallel plate plasma processing apparatus, a pair of parallel plate electrodes (upper and lower electrodes) are disposed in a chamber, a processing gas is introduced into the chamber, and high frequency power is applied to at least one of the electrodes. A high frequency electric field is formed between the electrodes. By this high frequency electric field, plasma of a processing gas is formed, and a plasma etching process is performed on the target substrate.
In such a plasma processing apparatus, etching is performed by supplying high frequency power of about 13.56 to 40 MHz to the lower electrode.
Under such conditions, for example, SiO ₂ In the case of etching a silicon film such as a polysilicon film using an inorganic material film as a mask, etching is performed under a relatively high pressure condition in order to improve the etching selectivity with respect to the inorganic material film. Yes.
However, when etching is performed under a relatively high pressure condition as in the prior art, the etching selectivity of the silicon film to the inorganic material film is improved, but there is a problem that the etching shape controllability is poor. Such a problem occurs not only when the inorganic material film is used as a mask but also when the inorganic material film is formed on the base of 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, plasma capable of improving shape controllability while maintaining a high etching selectivity. An object is to provide an etching method and apparatus.
According to the examination results of the present inventors, in the etching of a silicon film such as a polysilicon film, the plasma density is dominant and the contribution of ion energy is small. ₂ In etching an inorganic material film such as SiN film, both plasma density and ion energy are required. Therefore, if the plasma density is high and the ion energy is somewhat low, 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 to the inorganic material film, it is necessary to etch under conditions of high plasma density and low bias.
On the other hand, in order to improve the etching shape controllability, the process needs to be performed at a low pressure. However, under the above conditions, a high etching selectivity can be realized by 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 to the inorganic material film can be increased under a lower pressure condition, and the high etching selectivity and good etching shape controllability can be achieved. Can be made compatible.
According to further examination results by the present inventors, it has been found that if the frequency of the high-frequency power applied to the electrode is high, a state in which the plasma density is high and the self-bias voltage is low can be realized.
In the present invention, a pair of electrodes are disposed 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 disposed between the electrodes. An arrangement step for supporting the processing substrate, and applying a high frequency power to at least one of the electrodes to form a high frequency electric field between the pair of electrodes, supplying a processing gas into the chamber, and generating plasma of the processing gas by the electric field And an etching step of plasma-etching the silicon film of the substrate to be processed with the plasma, and the frequency of the high-frequency power applied to the at least one electrode in the etching step is 50 to 150 MHz. A plasma etching method characterized by the above.
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 before, it is possible to realize a high plasma density and a low self-bias voltage even under a lower pressure condition. 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 100 MHz.
In the etching step, the power density of the high frequency power is 0.15 to 5 W / cm. ² It is preferable that
In the etching step, the plasma density in the chamber is 5 × 10 5. ⁹ ~ 2x10 ¹⁰ cm ^-3 It is preferable that
Moreover, in the said etching process, it is preferable that the pressure in the said chamber is 13.3 Pa or less.
In addition, the present invention provides a substrate having a pair of electrodes opposed to each other and a substrate to be processed having a silicon film and an inorganic material film adjacent to each other. An arrangement step for supporting the substrate to be processed, and a high frequency electric field is applied between at least one of the electrodes to form a high frequency electric field between the pair of electrodes, and a processing gas is supplied into the chamber. And 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 HBr gas and Cl ₂ Including any one of the gases, and the plasma density in the chamber is 5 × 10 ⁹ ~ 2x10 ¹⁰ cm ^-3 The plasma etching method is characterized in that the self-bias voltage of the electrode is 200 V or less.
According to the present invention, the plasma density in the chamber is 5 × 10 5. ⁹ ~ 2x10 ¹⁰ cm ^-3 And the condition that the self-bias voltage of the electrode is 200 V or less, HBr gas and Cl ₂ Since the plasma of the gas containing any one of the gases is formed, the silicon film can be etched with a high etching selectivity and good shape controllability with respect to the inorganic material film.
In the above, the inorganic material film is made of at least one of silicon oxide, silicon nitride, silicon oxynitride, and silicon carbide, for example.
The high frequency power is preferably applied to an electrode that supports the substrate to be processed. In this case, the second high frequency power of 3.2 to 13.56 MHz may be applied to the electrode supporting the substrate to be processed so as to be superimposed on the high frequency power. Thus, by superimposing the second high frequency power of a lower frequency, it is possible to adjust the plasma density and the ion pulling action, and to secure the etching selectivity with respect to the inorganic material film, and to adjust the etching rate of the silicon film. It is possible to raise it further.
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 0.64 W / cm. ² The following is preferable. When a second high frequency power of 3.2 to 13.56 MHz is applied, the self-bias voltage of the electrode that supports the substrate to be processed is preferably 200 V or less.
Further, the present invention provides 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 chamber; and a high-frequency power source for supplying high-frequency power for plasma formation to at least one of the electrodes. The plasma etching apparatus is characterized in that the frequency of the high-frequency power generated from the power source 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 0.15 to 5 W / cm. ² It is.
The pressure in the chamber is preferably 13.3 Pa or less.
Preferably, the high frequency power is applied to an electrode that supports the substrate to be processed.
Preferably, the plasma etching apparatus further includes a second high-frequency power source that applies a second high-frequency power of 3.2 to 13.56 MHz so as to be superimposed on the high-frequency power on an electrode that supports the substrate to be processed. 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 It is as follows.
By the way, according to Paschen's law, the discharge start voltage Vs takes a minimum value (Paschen minimum value) and takes a Paschen minimum value when the product pd of the gas pressure p and the inter-electrode distance d is a certain value. The value of the product pd decreases 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 discharge start voltage Vs to facilitate and stabilize the discharge, it is necessary to reduce the inter-electrode distance d if the gas pressure p is constant. Therefore, in the present invention, the distance between the electrodes is preferably less than 50 mm. Moreover, the residence time of the gas in a chamber can be shortened because the distance between electrodes is less than 50 mm. Thereby, the reaction product can be efficiently discharged, and the effect that the etching stop can be reduced is also obtained.
Moreover, it is preferable to further comprise 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 that is the feeding position than in the peripheral portion, but a magnetic field is formed around the plasma region between the pair of electrodes. Thus, even when the plasma confinement effect is exhibited and the frequency of the applied high frequency power is high, the etching rate of the substrate to be processed in the processing space is changed between the edge portion (peripheral portion) and the central portion of the substrate to be processed. It can be almost equivalent. That is, the etching rate can be made uniform.
The intensity of the magnetic field formed by the magnetic field forming unit around the plasma region between the pair of electrodes is preferably 0.03 to 0.045 T (300 to 450 Gauss).
In addition, when a focus ring is provided around the electrode that supports the substrate to be processed and a magnetic field is formed around the plasma region, the magnetic field strength on the focus ring is 0.001 T (10 Gauss) or more, and It is preferable that the magnetic field intensity on the treatment substrate is 0.001 T or less.
By setting the magnetic field intensity on the focus ring to 0.001 T or more, electron drift motion occurs on the focus ring, the plasma density in the peripheral portion 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 that does not substantially affect the substrate to be processed, charge-up damage can be prevented.
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 cross-sectional view showing a plasma etching apparatus used for carrying out the present invention. This etching apparatus is airtightly configured and includes a stepped cylindrical chamber 1 having a small-diameter upper portion 1a and a large-diameter lower portion 1b. The wall portion of the chamber 1 is made of, for example, aluminum.
In the chamber 1, a support table 2 that horizontally supports a wafer W that is a substrate to be processed is provided. The support table 2 is made of aluminum, for example, 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 the outer periphery above the support table 2. When the diameter of the wafer W is 200 mmφ, the focus ring 5 is preferably 240 to 280 mmφ. The support table 2, the insulating plate 3, the support base 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 portion below the support 4 is covered with a bellows 8 made of stainless steel (SUS). The chamber 1 is grounded. In addition, a coolant 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.
A power supply line 12 for supplying high frequency power is connected to substantially the center of the support table 2. A high frequency power source 10 is connected to the feeder line 12 via a matching box 11. A high frequency power having a predetermined frequency is supplied from the high frequency power supply 10 to the support table 2. On the other hand, a shower head 16 described later is provided above the support table 2 so as to face each other in parallel. The 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 plate electrodes.
In addition, it is preferable that the distance between these electrodes is set to less than 50 mm. The reason is as follows.
According to Paschen's law, the discharge start voltage Vs takes a minimum value (Paschen minimum value) and a Paschen minimum value pd when the product pd of the gas pressure p and the interelectrode distance d is a certain value. The value of becomes smaller as the frequency of the high-frequency power increases. Accordingly, when the frequency of the high frequency power is large as in the present embodiment, in order to make the discharge start voltage Vs small and facilitate discharge and stabilize, the inter-electrode distance d is made small if the gas pressure p is constant. There is a need to. For this reason, the distance between the electrodes is preferably less than 50 mm. Moreover, the residence time of the gas in a chamber can be shortened because the distance between electrodes is less than 50 mm. Thereby, the reaction product can be efficiently discharged, and the effect that the etching stop can be reduced is also obtained.
However, if the distance between the electrodes is too small, the pressure distribution (pressure difference between the central portion and the peripheral portion) on the surface of the wafer W that is the substrate to be processed increases. In this case, problems such as a decrease in etching uniformity may occur. Regardless of the gas flow rate, in order to make the pressure difference smaller than 0.27 Pa (2 mTorr), the distance between the electrodes is preferably 35 mm or more.
An electrostatic chuck 6 for electrostatically attracting the wafer W is provided on the surface of the support table 2. The electrostatic chuck 6 is configured by interposing an electrode 6a between insulators 6b. A DC power supply 13 is connected to the electrode 6a. Then, when a voltage is applied to the electrode 6a from the DC power supply 13, the semiconductor wafer W is attracted by, for example, Coulomb force.
A coolant channel (not shown) is formed inside the support table 2. The wafer W can be controlled to a predetermined temperature by circulating an appropriate refrigerant therein. In addition, 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 baffle plate 14 is electrically connected to the chamber 1 through the support 4 and the bellows 8.
A shower head 16 is provided on the ceiling wall portion of the chamber 1 so as to face the support table 2. The shower head 16 is provided with a large number of gas discharge holes 18 on the lower surface thereof, and has a gas introduction portion 16a on the upper portion thereof. And the space 17 is formed in the inside. A gas supply pipe 15a is connected to the gas introduction part 16a, and a processing gas supply system 15 for supplying a processing gas comprising an etching reaction gas and a dilution gas is connected to the other end of the gas supply pipe 15a. ing.
As the reaction gas, a halogen-based gas is used, and as the dilution gas, a gas usually used in this field, such as Ar gas or He gas, can be used.
Such a processing gas reaches the space 17 of the shower head 16 from the processing gas supply system 15 through the gas supply pipe 15a and the gas introduction portion 16a, and is discharged from the gas discharge holes 18 to form a film formed on the wafer W. Etched.
An exhaust port 19 is formed on the side wall of the lower portion 1 b of the chamber 1, and an exhaust system 20 having a vacuum pump is connected to the exhaust port 19. By operating the vacuum pump, the inside of the chamber 1 can be depressurized to a predetermined degree of vacuum. On the other hand, a wafer W loading / unloading port and a gate valve 24 for opening and closing the loading / unloading port are provided on the upper side wall of the lower portion 1 b of the processing chamber 1.
On the other hand, a ring magnet 21 is concentrically disposed around the upper portion 1 a of the chamber 1 so as to form a magnetic field around the processing space between the support table 2 and the shower head 16. . The ring magnet 21 can be rotated around the central axis of the arrangement (in the circumferential direction) by the rotation mechanism 25.
As shown in the horizontal sectional view of FIG. 2, the ring magnet 21 is configured by arranging a plurality of segment magnets 22 made of permanent magnets in a ring shape in a state of being supported by a support member (not shown). In this example, 16 segment magnets 22 are arranged in a ring shape (concentric shape) in a multipole state. That is, the ring magnet 21 is arranged so 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 only 0.02 to 0.2 T (200 to 2000 Gauss), preferably 0.03 to 0.045 T (300, for example) only in the periphery of the processing space. A magnetic field of ~ 450 Gauss) is formed. On the other hand, the wafer arrangement region is substantially in a no magnetic field state. The reason why the magnetic field intensity is defined as described above is that if the magnetic field is too strong, it can 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 and the like. That is, the proper range of magnetic field strength can vary from device to device.
Further, when the magnetic field as described above is formed in the periphery of the processing space, it is desirable that the magnetic field intensity on the focus ring 5 is 0.001T (10 Gauss) or more. In this case, an electron drift motion (E × B drift) occurs on the focus ring, and the plasma density around the wafer rises and the plasma density becomes uniform. On the other hand, from the viewpoint of preventing charge-up damage of the wafer W, it is desirable that the magnetic field strength of the existing portion of the wafer W be 0.001 T (10 Gauss) or less.
Here, “substantially no magnetic field in the wafer placement region” means that a magnetic field that affects the etching process in the wafer placement region is not formed. That is, the case where there is a magnetic field that does not substantially affect the wafer processing is included.
In the state shown in FIG. 2, a magnetic field having a magnetic flux density of 0.42 mT (4.2 Gauss) or less, for example, is applied to the periphery of the wafer. Thereby, the function of confining plasma is exhibited.
When a magnetic field is formed by such a multi-pole ring magnet, a portion corresponding to the magnetic pole of the wall portion of the chamber 1 (for example, a portion indicated by P in FIG. 2) may be locally scraped. . Therefore, the ring magnet 21 is rotated by the rotating mechanism 25 along the circumferential direction of the chamber. This prevents the magnetic pole from abutting (positioning) locally on the chamber wall and prevents the chamber wall from being locally cut.
Each of the segment magnets 22 is configured to be rotatable about a vertical axis by a segment magnet rotation mechanism (not shown). Thus, by rotating the segment magnet 22, it is possible to switch between a state in which a multipole magnetic field is substantially formed and a state in which no multipole magnetic field is formed. Depending on conditions, the multipole magnetic field may or may not work effectively. Therefore, by making it possible to switch between the state where the multipole magnetic field is formed and the state where it is not formed, an appropriate state can be selected according to the conditions.
Since the state of the magnetic field changes according to the arrangement of the segment magnets, various magnetic field strength profiles can be formed by changing the arrangement of the segment magnets in various ways. Therefore, it is preferable to arrange the segment magnets so that the required magnetic field strength profile can be obtained.
The number of segment magnets is not limited to this example. Further, the cross-sectional shape is not limited to a rectangle as in this example, and an arbitrary shape such as a circle, a square, or a trapezoid can be adopted. The magnet material constituting the segment magnet 22 is not particularly limited, and for example, a known magnet material such as a rare earth magnet, a ferrite magnet, or an alnico magnet can be applied.
The plasma etching apparatus having the above structure is made of SiO. ₂ It can be applied to the case of etching polysilicon adjacent to an inorganic material film such as SiN. Hereinafter, a processing operation in the case of performing such etching using the plasma etching apparatus having the above configuration will be described.
For example, as shown in FIG. 3, a wafer W to be etched has a polysilicon film 32 formed on a silicon substrate 31, and an inorganic material film 33 having a predetermined pattern is formed on the silicon film 32 as a hard mask. It has the structure which was made. Alternatively, as shown in FIG. 4, the wafer W may be formed on a silicon substrate 41 as a gate oxide film using SiO. ₂ An inorganic material film 42 is formed, a polysilicon film 43 serving as a gate is formed on the inorganic material film 42, and a resist film 44 having a predetermined pattern serving as a mask is formed on the polysilicon film 43. It has a formed configuration.
The inorganic material film 33 is made of a material generally used as a hard mask. Silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, etc. may be mentioned as suitable examples. 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 loaded 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 table 2 is raised to the position shown in FIG. Further, the inside of the chamber 1 is brought 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 such as HBr gas is introduced into the chamber 1 from the processing gas supply system 15 at, for example, 0.02 to 0.4 L / min (20 to 400 sccm), and the chamber 1 is maintained at a predetermined pressure. Is done. 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. In this case, the power per unit area, that is, the power density is about 0.15 to about 5.0 W / cm. ² It is preferable that it is the range of these. At this time, a predetermined voltage is applied from the DC power source 13 to the electrode 6a of the electrostatic chuck 6, and the wafer W is attracted to the electrostatic chuck 6 by, for example, Coulomb force.
Thus, by applying the high frequency power to the support table 2 that is the lower electrode, a high frequency electric field is formed in the processing space between the shower head 16 that is the upper electrode and the support table 2 that is the lower electrode. Thereby, 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.
During this etching step, a magnetic field as shown in FIG. 2 can be formed around the processing space by the ring magnet 21 in a multipole state. In this case, the plasma confinement effect is exhibited, and the etching rate of the wafer W can be made uniform even at 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 process may be performed by rotating the segment magnet 22 so that a magnetic field is not substantially formed around the processing space.
When the magnetic field is formed, the effect of uniformizing plasma processing can be further enhanced by the conductive or insulating focus ring 5 provided around the wafer W on the support table 2. That is, when the plasma density at the wafer peripheral part is high and the etching rate at the wafer peripheral part is larger than the etching rate at the wafer central part, by using a focus ring formed of a conductive material such as silicon or SiC, Since the region up to the focus ring region functions as the lower electrode, the plasma formation region extends onto 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 at the wafer peripheral portion is low and the etching rate at the wafer peripheral portion is smaller than the etching rate at the wafer central portion, a focus ring formed of an insulating material such as quartz is used. Since no charge can be transferred between the electrons 5 and the electrons or ions in the plasma, the action of confining the plasma can be increased, and the uniformity of the etching rate is improved.
In order to adjust the plasma density and the ion drawing action, the high frequency for plasma generation and the second high frequency for drawing ions in the plasma may be superimposed. Specifically, as shown in FIG. 5, in addition to the high-frequency power source 10 for plasma generation, a second high-frequency power source 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 ion attraction is preferably 3.2 to 13.56 MHz, and 13.56 MHz is particularly preferable in this range. As a result, the parameter for controlling the ion energy increases, so that an optimum processing condition that can further increase the etching rate of the polysilicon film while ensuring an etching selection ratio with respect to a necessary and sufficient inorganic material film is obtained. It can be set easily.
By the way, according to the examination results of the present inventors, in the etching of the polysilicon film, the plasma density is dominant and the contribution of the ion energy is small, whereas in the etching of the inorganic material, the plasma density and the ion energy are reduced. Both are necessary. Therefore, as shown in FIGS. 3 and 4, in the etching of the polysilicon film adjacent to the inorganic material film, in order to perform the etching with a high etching selectivity with respect to the inorganic material film, the plasma density is high, and The ion energy must be low. That is, if the ion energy required for etching the inorganic material is lowered and the plasma density dominant in the etching of polysilicon is increased, the polysilicon film is selectively etched. Here, since the ion energy of the plasma indirectly corresponds to the self-bias voltage of the electrode at the time of etching, in order to etch the polysilicon film with a high etching selectivity, after all, a high plasma density and a low self-bias are required. It is necessary to perform etching under voltage conditions. On the other hand, in order to improve the shape controllability of etching, it is necessary that etching is performed at a low pressure. However, if the above conditions are satisfied, a high etching selectivity can be realized by a lower pressure process. be able to. That is, if a high plasma density and a low self-bias voltage are realized, the etching selectivity of the polysilicon film to the inorganic material film can be increased even under a lower pressure condition, and the high etching selectivity and good etching can be achieved. It is possible to achieve both shape controllability. For this purpose, it has been found that the frequency of the high-frequency power applied to the electrode may be 50 to 150 MHz, which is higher than the conventional one.
This will be described below with reference to FIG. FIG. 6 is a diagram showing the relationship between the absolute value | Vdc | of the self-bias voltage and the plasma density when the frequency of the high-frequency power is 40 MHz and 100 MHz. The horizontal axis is the absolute value | Vdc | of the self-bias voltage, and the vertical axis is the plasma density. Here, as the plasma gas, Ar was used for evaluation, not an actual etching gas. At each frequency, the plasma density Ne and the absolute value | Vdc | of the self-bias voltage were changed by changing the applied high frequency power. That is, for each frequency, as the applied high frequency power increases, both the plasma density Ne and the absolute value | Vdc | of the self-bias voltage increase. The plasma density was measured with a microwave interferometer.
As shown in FIG. 6, when the frequency of the high frequency power is 40 MHz in the past, when the plasma density is increased to increase the etching rate of the polysilicon film, | Vdc | On the other hand, when the frequency of the high frequency power is 100 MHz, which is higher than the conventional frequency, | Vdc | does not increase so much even if the plasma density is increased, and is suppressed to about 100 V or less. That is, it has been found that high plasma density and low self-bias voltage are feasible. That is, when the frequency is relatively low as in the prior art, 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 achieved. 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 100 MHz.
Further, as understood from FIG. 6, in order to etch the polysilicon film at a higher selectivity with a lower plasma density and a lower self-bias voltage than in the past under low pressure, an argon gas plasma is formed. The plasma density is 1 × 10 ¹⁰ cm ^-3 The self-bias voltage of the electrode is 100 V or less, or the plasma density is 5 × 10 ¹⁰ cm ^-3 It is considered preferable to form plasma under the above conditions so that the electrode self-bias voltage is 200 V or less. In order to satisfy such plasma conditions, it is estimated that high frequency power of 50 MHz or more is required.
Therefore, the frequency of the high frequency power for plasma formation is 50 MHz or more as described above. However, if the frequency of the high frequency power for plasma formation exceeds 150 MHz, the uniformity of the plasma may be impaired. For this reason, it is preferable that the frequency of the high frequency electric power for plasma formation shall be 150 MHz or less. In particular, in order to effectively exhibit the above effects, the frequency of the high-frequency power for plasma formation is preferably 70 to 100 MHz.
The pressure in the chamber during the etching is preferably 13.3 Pa (100 mT) or less. From the viewpoint of achieving both the etching selectivity of the polysilicon film to the inorganic material film and the etching shape controllability, the pressure in the chamber is more preferably 4 Pa (30 mT) or less. If the etching shape controllability is more important, the pressure in the chamber is more preferably 1.33 pa (10 mT) or less.
Next, in order to grasp the actual etching rate of the polysilicon film and the etching selectivity with respect to the inorganic material film, the polysilicon film and the inorganic material film SiO ₂ The experimental results of etching the entire surface formed film will be described.
Here, a 200 mm 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 the etching gas, the gap between the electrodes is 27 mm, and the inside of the chamber Etching was performed at a pressure of 4 Pa.
FIG. 7A shows the value of the etching rate of the polysilicon film with respect to the wafer position when the high-frequency power is 100 MHz. The high-frequency power is 500 W (1.59 W / cm). ² ), 1000 W (3.18 W / cm ² ) 1500W (4.77W / cm) ² It is a figure shown about each case of (). FIG. 7B shows the value of the etching rate of the polysilicon film with respect to the wafer position when the high-frequency power is 40 MHz. The high-frequency power power is 500 W (1.59 W / cm). ² ), 1000 W (3.18 W / cm ² ) 1500W (4.77W / cm) ² It is a figure shown about each case of (). FIG. 8 is a diagram showing the relationship between the high-frequency power and the etching rate of the polysilicon film for each of 40 MHz and 100 MHz. FIG. 9 shows high frequency power and SiO ₂ It is a figure which shows the relationship with the etching rate of a film | membrane about each case of 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 etching rate of the polysilicon film corresponding to the high frequency power and the etching selectivity / SiO 2. ₂ It is a figure which shows the relationship with the etching rate ratio (it describes with an etching selection ratio in FIG. 10) about each case of 40 MHz and 100 MHz. FIG. 11 shows the etching rate of the polysilicon film corresponding to the etching rate of the polysilicon film and the etching selection ratio / SiO 2. ₂ It is a figure which shows the relationship with the etching rate ratio of a film | membrane (it describes also as an etching selectivity in FIG. 11) about each case of 40 MHz and 100 MHz.
From these figures, the etching rate of the polysilicon film tends to increase as the high-frequency power increases, but there is no significant difference between the etching rate at 40 MHz and the etching rate at 100 MHz. Further, at the same gas pressure and the same power, the etching rate of the polysilicon film at 40 MHz and the etching rate at 100 MHz are approximately the same. ₂ The etching rate of the film is higher at 40 MHz than at 100 MHz. Therefore, SiO is better at 100 MHz than at 40 MHz. ₂ The etching rate of the polysilicon film corresponding to the etching selectivity of the polysilicon film to the film / SiO 2 ₂ It was confirmed that the etching rate ratio of the film was high. That is, from the experimental results of the evaluation sample, it was confirmed that the use of high-frequency power of 100 MHz rather than 40 MHz at 4 Pa is more likely to etch the polysilicon film with a high etching selectivity. Since the etching rate of the polysilicon film and the etching selectivity are in a trade-off relationship, if the high-frequency power is excessively increased, the etching rate of the polysilicon film increases but the etching selectivity decreases. Therefore, the power density of high frequency power of 100 MHz is 5 W / cm. ² (About 1500 W) or less is preferable.
On the other hand, at 100 MHz, the etching rate of the polysilicon film decreases in the direction of lower power density, and SiO 2 ₂ The etching selectivity with respect to the film is improved. The base of the etching target film is SiO ₂ In the case of a gate oxide film such as, the thickness is usually about several nanometers. ₂ It is necessary to lower the etching rate to the order of 0.1 nm / min. For example, in the case of a pressure condition of 1.33 Pa (10 mTorr), 1.5 W / cm ² At a power density of (about 500 W), the etching rate of the polysilicon film is 100 nm / min, the etching selectivity is 70, and SiO 2 ₂ The etching rate is 1.43 nm / min. Therefore, SiO ₂ In order to lower the etching rate to the order of 0.1 nm / min, the power density is 0.15 to 0.3 W / cm. ² It is expected that it will need to be reduced to about (about 50 to 100 W). Considering the above points, the minimum high frequency power is 0.3 W / cm. ² More preferably 0.15 W / cm ² (About 50 W) or more is preferable. From the viewpoint of etching selectivity alone, the high frequency power is 1.5 W / cm. ² (About 500 W) or less is preferable.
Next, the flow rate of the HBr gas is changed between 0.02 to 0.2 L / min, and the pressure in the chamber is changed between 0.133 to 13.3 Pa to fix the high frequency power power to 500 W. Etching was performed under the above conditions for the others.
FIG. 12A is a diagram showing the relationship between the pressure in 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, and FIG. SiO when the high-frequency power is 100 MHz and 40 MHz ₂ It is a figure which shows the relationship with the etching rate of a film | membrane. FIG. 13 shows the etching rate of the polysilicon film corresponding to the pressure in the chamber and the etching selection ratio / SiO 2. ₂ It is a figure which shows the relationship with the ratio (it describes with an etching selectivity in FIG. 13) of the etching rate of a film | membrane about each case of 40 MHz and 100 MHz. FIG. 14 shows the relationship between the pressure in the chamber and the etching rate of the polysilicon film, and the etching rate of the polysilicon film corresponding to the high frequency power and the etching selection ratio / SiO 2. ₂ It is a figure which shows the relationship with the ratio of the etching rate of a film | membrane (it describes with an etching selection ratio also in FIG. 14) about each case of 40 MHz and 100 MHz. FIG. 15 shows the etching rate of the polysilicon film corresponding to the etching rate of the polysilicon film and the etching selection ratio / SiO 2. ₂ It is a figure which shows the relationship with the ratio of the etching rate of a film | membrane (it describes with an etching selection ratio also in FIG. 15) in each case of 40 MHz and 100 MHz.
From these figures, it was confirmed that the etching rate of the polysilicon film was slightly higher and the etching selectivity was higher in the case of 100 MHz than in the case of 40 MHz for the same high-frequency power and chamber pressure. In addition, it was confirmed that a high etching selectivity can be obtained at a lower pressure at 100 MHz than at 40 MHz with the same high-frequency power. Furthermore, as shown in FIG. 15, it was also confirmed that the etching selectivity was higher in the case of 100 MHz than in the case of 40 MHz with the same high frequency power and etching rate. From these facts, in the case of 100 MHz, it is possible to obtain a high etching selectivity under a low pressure condition advantageous for etching shape controllability, and to realize both high etching selectivity and good etching shape controllability. confirmed.
Regarding the influence of pressure, it was confirmed that the etching rate and the etching selectivity of the polysilicon film were better at higher pressures at both 40 MHz and 100 MHz. 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, is preferable.
Next, the result of grasping (measuring) the absolute value | Vdc | 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 comparing 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 100 MHz and plasma is formed with HBr gas. The horizontal axis is the absolute value | Vdc | of the self-bias voltage, and the vertical axis is the plasma density. The plasma density was measured with a microwave interferometer.
The pressure in the chamber at this time was 2.7 Pa (20 mTorr). Moreover, the absolute value | Vdc | of the plasma density and the self-bias voltage was changed by changing the power of the high-frequency power of 100 MHz between 500 and 2000 W. Furthermore, in the case where the power of the 100 MHz high frequency power is 500 W, the second high frequency power of 13 MHz was superimposed at 0 W, 200 W, and 600 W.
As can be seen from FIG. 16, the plasma density Ne and the absolute value | Vdc | of the self-bias voltage both increase as the applied high frequency power increases at each frequency.
As shown in FIG. 16, in the actual etching gas plasma, the plasma density tends to be slightly lower than the Ar gas plasma (see FIG. 6). Further, when the second high frequency power (13 MHz) having a lower frequency is superimposed and the power is increased, the self-bias voltage tends to increase.
Further, as can be seen from FIG. 16, in the case where the second high-frequency power is not superimposed, | Vdc | does not increase so much even if the plasma density is increased, and is suppressed to approximately 100 V or less. That is, it has been found that high plasma density and low self-bias voltage are feasible.
FIG. 17 shows the relationship between the high-frequency power of the high-frequency power and the etching rate of the polysilicon film and the polysilicon film corresponding to the high-frequency power of the high-frequency power and the etching selectivity when the second high-frequency power is not superimposed. Etching rate / SiO ₂ It is a figure shown about the relationship with the ratio of the etching rate of a film | membrane.
When the high frequency power is increased, the etching rate of the polysilicon film is increased, but the selection ratio is decreased, so that about 1500 W (about 4.77 W / cm). ² The following are preferred. On the other hand, when the power is reduced, the etching rate is reduced but the selection ratio is increased. ² The above is preferable.
16 and 17, a necessary polysilicon etching rate can be obtained at a high frequency of 100 MHz, and the polysilicon film can be etched with a high etching selectivity with respect to the inorganic material film. Was confirmed.
Further, as understood from FIGS. 16 and 17, in order to etch a polysilicon film at a higher selectivity and a required etching rate under a low pressure with a higher plasma density and a lower self-bias voltage than conventional ones. , Plasma density is 5 × 10 ⁹ ~ 2x10 ¹⁰ cm ^-3 In addition, it is considered that the self-bias voltage of the electrode is preferably 200 V or less.
As the processing gas, in addition to the gas containing HBr gas, Cl ₂ Although a gas containing a gas can also be used, it has been confirmed that the preferable plasma density range is the same as the above in the latter case.
On the other hand, FIG. 18 shows the high-frequency power power of the second high-frequency power and the etching rate of the polysilicon film when the high-frequency power power of the high-frequency power is fixed at 500 W and the high-frequency power power of the second high-frequency power is superimposed. And the etching rate of the polysilicon film corresponding to the high-frequency power of the second high-frequency power and the etching selection ratio / SiO 2 ₂ It is a figure shown about the relationship with the ratio of the etching rate of a film | membrane.
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 is increased while the self-bias voltage of the electrode is also increased. As the self-bias voltage increases, the etching selectivity tends to decrease. The self-bias voltage is 200 V, that is, the second high-frequency power is about 200 W (about 0.64 W / cm). ² ) Until the etching selectivity can be maintained within an allowable range.
Therefore, the etching rate can be increased while maintaining the etching selection ratio of 10 or more by increasing the power (bias power) of the second high frequency power to be superimposed.
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 that is the substrate to be processed (the pressure difference between the central portion and the peripheral portion). ) May increase and cause problems such as a decrease in etching uniformity. Therefore, the actual distance between electrodes is more preferably 35 to 50 mm. This will be described with reference to FIG.
FIG. 19 shows a comparison between the Ar gas flow rate and the pressure difference ΔP between the wafer center and the wafer periphery when Ar gas is used as the plasma gas in the case of the gap between electrodes of 25 mm and 40 mm. FIG. As shown in FIG. 19, the pressure difference ΔP 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 ΔP tends to increase rapidly as the Ar gas flow rate increases, and problems such as a decrease in etching uniformity occur when the gas flow rate is about 0.3 L / min or more. The allowable maximum pressure difference ΔP that does not occur 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 can be maintained without causing problems such as a decrease in etching uniformity regardless of the gas flow rate.
The present invention can be variously modified without being limited to the above embodiment. For example, although the case where a polysilicon film is used as the silicon film has been described in the above embodiment, 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.
In the above embodiment, a multi-pole ring magnet in which a plurality of segment magnets made of permanent magnets are arranged in a ring shape around the chamber is used as the magnetic field forming means. As long as it can be formed and confined with plasma, it is not limited to this mode. Further, such a peripheral magnetic field for confining plasma is not always necessary. That is, etching may be performed in the absence of a magnetic field. The present invention is also applicable to a plasma etching process in which a horizontal magnetic field is applied to a processing space and plasma etching is performed in an orthogonal electromagnetic field.
Furthermore, in the above-described embodiment, high-frequency power for plasma formation is applied to the lower electrode, but the present invention 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 the substrate to be processed has been described, the present invention is not limited to this, and the present invention can be applied to etching of a polysilicon film on another substrate to be processed.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing a plasma etching apparatus according to an embodiment of the present invention.
FIG. 2 is a horizontal sectional view schematically showing a ring magnet disposed around the chamber of the plasma etching apparatus of FIG.
FIG. 3 is a 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 source for plasma generation and a high-frequency power source for ion attraction.
FIG. 6 is a diagram showing the relationship between the absolute value | Vdc | of the self-bias voltage and the plasma density Ne when the frequency of the high-frequency power is 40 MHz and 100 MHz in the argon gas plasma.
FIG. 7A is a diagram showing the value of the etching rate of the polysilicon film with respect to the wafer position when the high-frequency power is 100 MHz for each of the cases where the high-frequency power is 500 W, 1000 W, and 1500 W.
FIG. 7B is a diagram showing the value of the etching rate of the polysilicon film with respect to the wafer position when the high-frequency power is 40 MHz for each of the high-frequency power powers of 500 W, 1000 W, and 1500 W.
FIG. 8 is a diagram showing the relationship between the high frequency power and the polysilicon film etching rate when the high frequency power is 40 MHz and 100 MHz.
FIG. 9 shows high frequency power and SiO ₂ It is a figure which shows the relationship with the etching rate of a film | membrane about the case where high frequency electric 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 etching rate / SiO 2 of the polysilicon film corresponding to the high-frequency power and the etching selectivity. ₂ It is a figure which shows the relationship with the ratio of the etching rate of a film | membrane about the case where high frequency electric power is 40 MHz and 100 MHz.
FIG. 11 shows the etching rate of the polysilicon film corresponding to the etching rate of the polysilicon film and the etching selection ratio / SiO 2. ₂ It is a figure which shows the relationship with the ratio of the etching rate of a film | membrane about the case where high frequency electric power is 40 MHz and 100 MHz.
FIG. 12A is a diagram showing the relationship between the pressure in the chamber during etching and the etching rate of the polysilicon film when the high-frequency power is 100 MHz and 40 MHz.
FIG. 12B shows SiO 2 when the pressure in the chamber and the high frequency power during the etching are 100 MHz and 40 MHz. ₂ It is a figure which shows the relationship with the etching rate of a film | membrane.
FIG. 13 shows the etching rate of the polysilicon film corresponding to the pressure in the chamber and the etching selection ratio / SiO 2. ₂ It is a figure which shows the relationship with the ratio of the etching rate of a film | membrane about the case where high frequency electric power is 40 MHz and 100 MHz.
FIG. 14 shows the relationship between the pressure in the chamber and the etching rate of the polysilicon film, and the etching rate of the polysilicon film corresponding to the high frequency power and the etching selection ratio / SiO 2. ₂ It is a figure which shows the relationship with the ratio of the etching rate of a film | membrane about the case where high frequency electric power is 40 MHz and 100 MHz.
FIG. 15 shows the etching rate of the polysilicon film corresponding to the etching rate of the polysilicon film and the etching selection ratio / SiO 2. ₂ It is a figure which shows the relationship with the ratio of the etching rate of a film | membrane about the case where high frequency electric power is 40 MHz and 100 MHz.
FIG. 16 shows the case where the frequency of the high-frequency power is 100 MHz and the second high-frequency power is 13 MHz in the HBr gas plasma, and each high-frequency power is changed (high-frequency power: 500 W, 1000 W, 1500 W, 2000 W, (2nd high frequency electric power: 0W, 200W, 600W), It is a figure which shows the relationship between absolute value | Vdc | of self-bias voltage, and plasma density Ne.
FIG. 17 shows the relationship between the high frequency power of the high frequency power and the etching rate of the polysilicon film, and the etching rate of the polysilicon film corresponding to the high frequency power of the high frequency power and the etching selection ratio / SiO 2. ₂ It is a figure shown about the relationship with the ratio of the etching rate of a film | membrane.
FIG. 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 etching rate / SiO2 of the polysilicon film corresponding to the high-frequency power of the second high-frequency power and the etching selectivity. ₂ It is a figure shown about the relationship with the ratio of the etching rate of a film | membrane.
FIG. 19 shows the relationship between the Ar gas flow rate and the pressure difference ΔP between the wafer central portion and the peripheral portion when Ar gas is used as the plasma gas, when the gap between the electrodes is 25 mm and when it is 40 mm. FIG.

Claims (32)

A pair of electrodes are placed opposite to each other in the chamber, and the substrate to be processed is supported by one electrode so that a substrate to be processed having a silicon film and an inorganic material film adjacent to each other is disposed between the electrodes. An arrangement step of
A high frequency electric field 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, a plasma of the processing gas is formed by the electric field, and the processing target is formed by the plasma. An etching step of plasma etching the silicon film of the substrate;
With
In the etching step, the frequency of the high frequency power applied to the at least one electrode is 50 to 150 MHz. 2. The plasma etching method according to claim 1, wherein in the etching step, a 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 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 in the etching step, a plasma density in the chamber is 5 × 10 ⁹ to 2 × 10 ¹⁰ cm ⁻³ . The plasma etching method according to claim 1, wherein, in the etching step, a pressure in the chamber is 13.3 Pa or less. 2. The plasma etching method according to claim 1, wherein the inorganic material film is made of at least one of silicon oxide, silicon nitride, silicon oxynitride, and silicon carbide. 2. The plasma etching method according to claim 1, wherein in the etching step, the high-frequency power is applied to an electrode that supports the substrate to be processed. 8. The plasma etching according to claim 7, wherein in the etching step, a second high frequency power of 3.2 to 13.56 MHz is applied to an electrode supporting the substrate to be processed so as to be superimposed on the high frequency power. Method. The plasma etching method according to claim 8, wherein the frequency of the second high-frequency power is 13.56 MHz. The plasma etching method according to claim 9, wherein a power density of the second high frequency power is 0.64 W / cm ² or less. 9. The plasma etching method according to claim 8, wherein in the etching step, a self-bias voltage of an electrode supporting the substrate to be processed is 200 V or less. The plasma etching method according to claim 1, wherein the distance between the pair of electrodes is less than 50 mm. The plasma etching method according to claim 1, wherein a magnetic field is formed around a plasma region between the pair of electrodes in the etching step. 14. The plasma etching method according to claim 13, wherein the strength of the magnetic field formed around the plasma region between the pair of electrodes is 0.03 to 0.045 T (300 to 450 Gauss). When a magnetic field is formed around the plasma region between the pair of electrodes, a magnetic field intensity on a focus ring provided around the substrate to be processed is 0.001 T (10 Gauss) or more, and the substrate to be processed The plasma etching method according to claim 14, wherein the upper magnetic field strength is 0.001 T or less. The plasma etching method according to claim 1, wherein the silicon film is made of polysilicon. A pair of electrodes are placed opposite to each other in the chamber, and the substrate to be processed is supported by one electrode so that a substrate to be processed having a silicon film and an inorganic material film adjacent to each other is disposed between the electrodes. An arrangement step of
A high frequency electric field 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, a plasma of the processing gas is formed by the electric field, and the processing target is formed by the plasma. An etching step of plasma etching the silicon film of the substrate;
With
In the etching step, the processing gas includes any one of HBr gas and Cl ₂ gas, the plasma density in the chamber is 5 × 10 ⁹ to 2 × 10 ¹⁰ cm ⁻³ , and the electrode self A plasma etching method, wherein a bias voltage is 200 V or less. A pair of electrodes are placed opposite to each other in the chamber, and the substrate to be processed is supported by one electrode so that a substrate to be processed having a silicon film and an inorganic material film adjacent to each other is disposed between the electrodes. An arrangement step of
Forming a high frequency electric field between the pair of electrodes by applying high frequency power to at least one of the electrodes, supplying Ar gas into the chamber, and forming a plasma of the processing gas by the electric field;
With
In the plasma forming step, the step of confirming that the plasma density in the chamber is 1 × 10 ¹⁰ cm ⁻³ or more and the self-bias voltage of the electrode is 100 V or less is performed. To confirm plasma etching conditions. 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 chamber;
A high frequency power source for supplying high frequency power for plasma formation to at least one of the electrodes,
The plasma etching apparatus characterized in that the frequency of the high-frequency power generated from the high-frequency power source is 50 to 150 MHz. 20. The plasma etching apparatus according to claim 19, wherein the frequency of the high frequency power generated from the high frequency power source is 100 MHz. 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 . The plasma etching apparatus according to claim 19, wherein the pressure in the chamber is 13.3 Pa or less. The plasma etching apparatus according to claim 19, wherein the high-frequency power is applied to an electrode that supports the substrate to be processed. 24. The apparatus according to claim 23, further comprising a second high-frequency power source that applies a second high-frequency power of 3.2 to 13.56 MHz so as to be superimposed on the high-frequency power on an electrode that supports the substrate to be processed. Plasma etching equipment. The plasma etching apparatus of claim 24, wherein the frequency of the second high frequency power is 13.56 MHz. The plasma etching apparatus according to claim 25, wherein a power density of the second high-frequency power is 0.64 W / cm ² or less. The plasma etching apparatus according to claim 19, wherein the distance between the pair of electrodes is less than 50 mm. The plasma etching apparatus according to claim 19, further comprising magnetic field forming means for forming a magnetic field around a plasma region between the pair of electrodes. 29. Plasma etching according to claim 28, wherein the magnetic field forming means forms a magnetic field intensity around the plasma region between the pair of electrodes of 0.03 to 0.045 T (300 to 450 Gauss). apparatus. A focus ring is provided around the substrate to be processed,
When the magnetic field forming unit forms a magnetic field around the plasma region between the pair of electrodes, the magnetic field intensity on the focus ring is 0.001 T (10 Gauss) or more, and the magnetic field intensity on the substrate to be processed is 30. The plasma etching apparatus according to claim 29, wherein the plasma etching apparatus is 0.001 T or less. 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 chamber;
A high frequency power source for supplying high frequency power for plasma formation to at least one of the electrodes,
When a gas containing any one of HBr gas and Cl ₂ gas is used as a processing gas, the plasma density in the chamber is 5 × 10 ⁹ to 2 × 10 ¹⁰ cm ⁻³ , and the electrode A plasma etching apparatus having a self-bias voltage of 200 V or less. 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 chamber;
A high frequency power source for supplying high frequency power for plasma formation to at least one of the electrodes,
When using Ar gas as a processing gas, the plasma density in the chamber is 1 × 10 ¹⁰ cm ⁻³ or more and the electrode self-bias voltage is 100 V or less. .

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