JPH11102894A - Method and device for dry etching - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high selectivity ratio on a film of high aspect ratio by a method wherein two or more plasma regions, having different electron temperatures are formed, and the quantity of formed ions and the F with respect to CF2 are controlled independently. SOLUTION: Quantity of ions formed is determined by the electron density in plasma, and the electron density is substantially proportional to the high frequency power to be inputted. Since the dissociation of F/CF2 is generated by the collision of gas molecules and electrons and the electron density depends on high frequency power, the ratio of formation of F/CF2 can be controlled independently of the quantity of ions formed. In a device using an electron cyclotron resonance ECR, a high electron temperature region 103 is formed in an ECR region and a low electron temperature region 102 is formed on the part other than the region. Since the high electron temperature region widens when the gradient of magnetic field is small, the ratio of formation of F/CF2 becomes small, and when the gradient of magnetic field is made larger, the high electron temperature region becomes narrow. As a result, the ratio of formation of F/CF2 can be made larger, and the processing of a microscopic and deep oxide film becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dry etching apparatus and a dry etching method used for fine processing of a semiconductor device, and more particularly to a dry etching apparatus and a dry etching method for realizing a high-precision dry etching processing of a silicon oxide film.

[0002]

In a semiconductor device, between between transistors and metal interconnections formed on the wafer and metal wiring to electrically connect the insulating film formed between the transistor structure and wiring (SiO ₂ A contact hole is formed in a thin film containing a main component (hereinafter, referred to as an oxide film) by a dry etching method, and an electric conductor is filled in the contact hole. In dry etching, an etching gas is introduced into a vacuum vessel, a high-frequency bias or microwave is applied to the gas to generate plasma, and the oxide film is selectively etched by active species and ions generated in the plasma to form a contact hole. Form. During this etching, a resist thin film to which the hole pattern has been transferred is formed on the oxide film. In this contact hole processing, it is necessary to selectively etch an oxide film with respect to a resist film, a wiring layer below the contact hole, and silicon forming a transistor. In addition, in a dry etching method in which a gate electrode of a field-effect transistor formed on a wafer is covered with a second insulating film made of a material different from that of a wiring layer and a source / drain region is connected to a wiring layer, the etching is performed during etching. Since the second insulating film appears in the hole, selectivity to the second insulating film is also required. This contact processing is called self-aligned contact (SAC) processing, and a silicon nitride film is used as the second insulating film.

The above contact hole is processed by introducing a fluorocarbon gas such as CF ₄ , CHF ₃ , C ₄ F ₈ and an Ar gas into an etching apparatus, performing a high-frequency plasma discharge under a gas pressure condition of 4 Pa to 10 Pa, and performing wafer discharge. 1.5
Etching is performed under the condition that a Vpp voltage of 2.0 kV to 2.0 kV is applied. If the oxide film between the wiring layers is thick and the aspect ratio (depth / diameter) of the contact hole is high, oxygen gas is added to enhance the hole opening property, and SAC is added.
In the processing, C is used to increase the selectivity to the nitride film.
O gas has been added.

[0004]

However, in the conventional etching apparatus, when the etching conditions such as the gas pressure and the high frequency power required for generating the plasma are determined, the plasma density and the electron temperature are determined. The production amounts of F, CF ₂ and ions are fixed. In plasma, CF, CF ₃ , C _2, etc. exist in addition to CF _{2. In} this specification, C, CF, CF _2, etc.
It was represented by F ₂ radical, a CF ₂ radical in CF _2, denoted the F radicals F. Thus while a constant production of F and CF _2, changing the ion generation amount, an ion generation amount certain conditions, it is difficult to change the amount of incident F and CF _2. For example, in the case of a parallel plate type etching apparatus, the higher the high frequency bias power for plasma generation, increased ion generation amount for the plasma density is increased, at the same time, the generation of F with respect to CF ₂ for dissociation by a plasma progresses The amount will also change.

[0005] Such a conventional etching apparatus has the following problems. When processing a contact with a high aspect ratio, the fluorine radical F at the bottom of the contact hole decreases under the condition of a high resist selectivity.
A polymer is formed by CF-based radicals, and etching stops in the middle of the hole. On the other hand, under the condition that the etching is not stopped, addition of oxygen gas or excessive fluorine causes etching of the resist mask by oxygen or fluorine, so that a sufficient selectivity with respect to the resist cannot be obtained. In the related art, gas dissociation in plasma is fixed, and this problem cannot be solved.

In addition, when etching a contact hole having a high aspect ratio under a condition of a high gas pressure (4 Pa or more), ions that enter the wafer from an inclined direction due to collision with gas molecules cause an oxide film to be formed. Is partially etched in the horizontal direction, making it difficult to perform vertical processing. The collision with gas molecules can be reduced by lowering the gas pressure. However, in the conventional apparatus, when the gas pressure is lowered, the plasma density and the electron temperature change, so that the ratio of F increases, and the resist and nitride film are increased. Sufficient selectivity was not obtained, and this was an obstacle to lowering gas pressure.

In the etching of the oxide film, with the miniaturization of the semiconductor device, the processing accuracy, the selectivity to the nitride film (selectivity to the nitride film), the selectivity to the resist, and the like are improved, and the semiconductor device is planarized. With the increase in wiring and wiring, it has become necessary to process contact holes having a high depth / hole diameter ratio (aspect ratio).

The problem to be solved by the present invention is to control independently the generation amount of F and ions with respect to CF _{2 in} plasma, and to require a high selectivity for contact holes and silicon nitride films having a high aspect ratio. The processing of the oxide film to be performed is realized.

[0009]

The above object is achieved by forming two or more plasma regions having different electron temperatures.

In oxide film etching using a fluorocarbon gas, the amount of F generated for CF ₂ depends on the plasma temperature, and the amount of ions generated is determined in proportion to the power introduced for plasma generation. For C ₄ F _8, with respect to the C ₄ F ₈ in the range of about threshold energy 6eV the production of F, C
The generation of F ₂ is about 12 eV. Therefore, when the electron temperature is low (1 to 4 eV), F is easily generated and F / CF
_{2 The} production ratio increases. At an electron temperature of 5-20 eV,
Since the generation of CF ₂ is promoted, the F / CF ₂ generation ratio is smaller than that at a low electron temperature. Therefore, when two types of electron temperatures are used, it is possible to generate F and CF ₂ in a high electron temperature region and to generate F in a low temperature region. By varying the size of the two electron temperature regions, the F / CF ₂ ratio is controlled. The difference between these electron temperatures is 1 eV or more, preferably 5 eV or more.

The fact that the amounts of F and ions generated for CF ₂ in the plasma should be controlled independently is as follows. The introduced fluorocarbon gas is dissociated into CF ₂ radicals, F radicals and ions in the plasma and enters the wafer. The etching of the oxide film proceeds when ions enter the surface to which CF ₂ and F are attached. On the other hand, the resist and the silicon nitride film are mainly etched by F and ions, and CF ₂ forms a polymer on the surface, and thus acts as an anti-etching film on the resist and the silicon nitride film. Therefore, C
When etching is performed under the condition that the incident amount of ions or F is smaller than that of F ₂ , a high selectivity with respect to a resist or a silicon nitride film can be obtained. However, when the amount of incident ions is reduced, the etching rate of the oxide film is reduced, and when the amount of incident F is reduced, there occurs a problem that etching is stopped in holes having a high aspect ratio. Thus, the etching process of the oxide film is substantially C
It is determined by F ₂ , F, and the incidence of ions, and particularly depends on the amount of F ₂ and F incident on CF ₂ .
Therefore, if the amount of generation of F and ions with respect to CF _{2 in} plasma can be controlled independently, the process conditions are widened, and as a result, a finer and deeper oxide film can be processed.

However, since F is generated in both of the two electron temperature regions, F is generated under an excessively large condition.
/ CF ₂ will be controlled. To selectively exclude F, a gas containing a hydrogen atom (H ₂ , CH ₂ F ₂ , CH _4, etc.)
Can be added to react F with H radicals and be excluded. In addition, F can be consumed by the reaction with the inner wall material. Specifically, an Si plate, S
A material that reacts with F, such as an iC plate, is installed, and a high frequency bias is applied to the plate to promote F consumption.
Exclude In addition, F can be removed by reacting F with a polymer formed by adhering CF ₂ to the wall.
When the distance between the wafer and the inner wall portion is reduced, the area of the inner wall surface with respect to the volume of plasma increases, so that the ratio of F generated by the plasma in the etching apparatus to the inner wall portion increases. That is, by bringing the wafer and the inner wall portion close to each other, F efficiently reacts with the polymer and is eliminated. Specifically, shortening the distance between the wafer and the wafer-facing surface of the etching apparatus can be mentioned. By using these methods and plasma having two kinds of electron temperatures, F / CF
_The ratio can be controlled in a wide range.

On the other hand, the amount of generated ions is determined by the electron density in the plasma, and the electron density is almost proportional to the input high frequency power. Since the dissociation of F / CF ₂ is generated by gas molecules and electron collisions, it depends on the power of the high frequency. However, by varying the two electron temperature regions, the F / CF ₂ generation is independent of the ion generation amount. The ratio can be controlled.

As a specific method for generating two kinds of electron temperature regions, as shown in FIG. 1, in the case of an etching apparatus using electron cyclotron resonance (ECR),
The electron temperature is high in the CR region (high electron temperature region 103),
In other portions, the low electron temperature region 102 is formed. The ECR region becomes narrower when the magnetic field gradient of the magnetic field applied from the outside is increased. Therefore, EC
By controlling the magnetic field gradient in the R region, the F / CF ₂ generation ratio can be made variable. As shown in FIG. 2, under the condition where the magnetic field gradient is small, the high electron temperature region is widened.
As the / CF ₂ generation ratio decreases and the magnetic field gradient increases, the high electron temperature region narrows, so that the F / CF ₂ generation ratio can be increased. In addition, the ECR region is roughly inversely proportional to the frequency of the introduced high frequency. For example, if the frequency is changed from 2.45 GHz to 450 MHz, the ECR
The area extends about five times. Therefore, by lowering the frequency of the introduced high frequency, the high electron temperature region can be widened and the F / CF ₂ generation ratio can be reduced.

When the ECR region 101 is fixed, the size of the low electron temperature region 102 can be changed by changing the distance between the wafer 6 and the wafer facing surface 103. As shown in FIG. 2, when the distance between the wafer 6 and the wafer facing surface 103 is reduced, the low electron temperature region 102 becomes narrower, so that the F / CF ₂ generation ratio can be reduced.

As described above, in the case of the ECR etching apparatus, the F / CF ₂ generation ratio can be controlled independently of the ion generation amount by controlling the magnetic field gradient, the frequency of the introduced high frequency, and the distance between the wafer and the wafer facing surface. Can be controlled.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. 4 shows a dry etching apparatus used in the present invention. In this apparatus, an etching gas is introduced into an etching processing chamber 1 and 900 M
A high frequency of between 2.45 GHz and 2.45 GHz is generated, and the high frequency is transmitted through the waveguide 3 to the etching chamber 1 to generate gas plasma. Four solenoid coils for generating a magnetic field are installed around the etching chamber so that the vertical magnetic field gradient in the ECR region can be controlled in a wide range with respect to the magnetic field intensity in the ECR region. These solenoid coils 4 control the four coil currents so that a magnetic field between 0 and 875 Gauss is almost directly above the processing table,
A high-density plasma having an electron density of 10 ¹¹ / cm ³ or more is generated by using electron cyclotron resonance (ECR). The magnetic field gradient in the ECR region is controlled so that the value of the magnetic field gradient / magnetic field strength is in the range of 0.1 cm ⁻¹ to 0.01 cm ⁻¹ . A processing table 5 is provided in the etching processing chamber 1, and a processing object 6 is set on the processing table 5, and an etching process is performed by gas plasma. The etching gas is introduced into the etching chamber 1 through a gas flow controller, and is exhausted out of the etching chamber 1 by an exhaust pump 7. The processing table 5 on which the object to be processed is installed is provided with a high-frequency power supply 12 and has a frequency of 400 kHz.
To 13.56 MHz. The position of the processing table is the opposite side of the processing table (gas inlet 1
The distance from 1) can be fixed in the range of 20 mm to 150 mm.

An 8-inch silicon wafer is transported to this apparatus as an object to be processed. An oxide film having a thickness of 2 mm is formed on the silicon wafer, and a resist mask on which a mask pattern is transferred is formed thereon. Holes having a diameter of 200 nm are formed in the resist mask.

In this apparatus, 400 sccm of Ar, C ₄ F ₈
Is introduced into the processing chamber through a gas inlet of 10 sccm and 5 sccm of CH ₂ F ₂ to make the gas pressure 2 Pa. 2.45GH
z, a high frequency of 1 kW is generated from a microwave generator,
A bias of 800 kHz and 1000 W is applied to the processing table to etch the oxide film. Assuming that the position of the processing table is 100 mm from the microwave introduction window, the coil current is adjusted so that the magnetic field intensity is 875 Gauss at a position 6 cm directly above the wafer and the magnetic field gradient at that position is 50 Gauss / cm. Under these conditions, the thickness of the ECR region is about 10 mm, and the electron temperature is about 10 eV. The electron temperature outside the ECR region is about 3 eV. That is, a high electron region having a thickness of about 10 mm and a low electron region having a thickness of about 90 mm are formed. A part of F reacts with H generated from CH ₂ F ₂ and is excluded. For this reason, the amount of F generated from C ₄ F ₈ is about twice as large as CF ₂ , but F
The ratio of / CF ₂ can be estimated to be about 0.6. The electron density is about 3 × 10 ¹¹ / cm ³ and the ion current density is about 5 mA / cm ² . Under these conditions, the etching rate of the oxide film is about 700 nm / min, and the selectivity with respect to the resist is 5. Although a substantially vertical shape can be obtained as the processed shape, when the gas pressure is increased to 5 Pa under the same conditions, a shaving of about 20 nm is observed in the hole due to obliquely incident ions in the hole. At a gas pressure of 4 Pa or less, the processed shape becomes almost vertical.

When the magnetic field gradient is 15 G / cm, the ECR
The thickness of the region extends to about 20 mm, and as a result, the F / CF ₂ ratio incident on the wafer is reduced to about 0.3.
On the other hand, the plasma density hardly changes even when the magnetic field gradient is changed, and in both cases, the ion current density is about 5 mA / cm ² . For this reason, the etching rate of the oxide film hardly changes and is about 700 nm / min in the plane portion. In contrast, resist selectivity for the ratio of F decreases is better and 30, since the CF ₂ is excessive, oxide film is stopped is etched to a depth of about 1 mm.

A magnetic field gradient of 15 Gauss /
When the rate is changed from 10 cm / cm to 50 G / cm at 12 G / cm / min, the etching rate is changed to about 700 nm / min, and the etching is completed in about 3 minutes without stopping. The selectivity with respect to the resist becomes about 20, and the resist selectivity is greatly improved as compared with etching with a magnetic field gradient of 50 G / cm.

By controlling the magnetic field gradient in this way, the F / CF ₂ ratio can be changed while keeping the ion current constant. By reducing the magnetic field gradient, the selectivity to resist is increased. However, making the magnetic field gradient smaller means forming a uniform magnetic field in the etching apparatus, and in order to achieve this with the same magnetic field strength, it is necessary to install many coils around the etching apparatus. There is. On the other hand, when the magnetic field strength is reduced, the magnetic field gradient is also reduced in proportion thereto, so that the magnetic field gradient can be easily reduced. Since the magnetic field strength that forms ECR is determined by the frequency of the microwave,
In order to reduce the magnetic field strength and the magnetic field gradient, it is advantageous to reduce the frequency of the microwave.

(Embodiment 2) Next, the case where the frequency of a microwave is set to 900 MHz using the same apparatus will be described. The coil current is adjusted so that the magnetic field strength is 320 Gauss at a position 60 mm directly above the wafer and the magnetic field gradient at that position is 20 Gauss / cm. In this condition, EC
Under the condition that the thickness of the R region is about 20 mm and the magnetic field gradient / magnetic field intensity is almost constant, the E region is higher than the case of 2.45 GHz.
The CR region extends about twice. For this reason, when gas is introduced under the same conditions, the ion current density is about 5 mA / cm ² , which is almost the same as 2.45 GHz, but the ratio of F / CF ₂ incident on the wafer becomes about 0.7. Can be estimated. For this reason, the etching rate of the oxide film is about 700 nm.
/ Min, the selectivity to resist is 15.

(Embodiment 3) Next, another embodiment using the apparatus of FIG. 5 will be described. In this apparatus, an etching gas is introduced into the etching chamber 1, and a high frequency between 300 MHz and 900 MHz generated by the high frequency power supply 503 is introduced into the etching chamber 1 from the antenna 502 to generate gas plasma. Three solenoid coils 4 for generating a magnetic field are arranged around the etching chamber for high-efficiency discharge, and two coil currents are controlled so that a magnetic field between 0 and 320 Gauss is almost directly above the processing table. A high-density plasma having an electron density of 10 11 / cm 3 or more is generated by using electron cyclotron resonance (ECR). A processing table 5 is provided in the etching processing chamber 1, and a processing object 6 is set on the processing table 5, and an etching process is performed by gas plasma. The etching gas is introduced into the etching chamber 1 through a gas flow controller, and is exhausted out of the etching chamber 1 by an exhaust pump 7. The processing table 5 on which an object to be processed is installed is provided with a high-frequency power source 12 and has a frequency of 400 kHz.
A high frequency bias from z to 13.56 MHz can be applied. The position of the processing table is 2 mm away from the microwave introduction window.
It can be fixed in the range of 0 mm to 150 mm.

An 8-inch silicon wafer is transported to this apparatus as an object to be processed. A silicon nitride film having a thickness of 0.1 mm and an oxide film having a thickness of 1.5 mm are formed on the silicon wafer, and a resist mask on which a mask pattern is transferred is formed thereon. Holes having a diameter of 150 nm are formed in the resist mask.

In this apparatus, Ar 200 sccm, C ₄ F ₈
Is introduced into the processing chamber through the gas inlet and the gas pressure is adjusted to 1 Pa. A gas plasma is generated by a high frequency of 450 MHz and 1 kW.
A bias of 0 W is applied to etch the oxide film. Assuming that the position of the processing table is 60 mm from the antenna 502, the coil current is adjusted so that the magnetic field intensity is 160 gauss at a position 40 mm directly above the wafer and the magnetic field gradient at that position is 4 gauss / cm. Under these conditions, the thickness of the ECR region is about 50 mm, and the electron temperature is about 8 eV. EC
The electron temperature outside the R region is about 2 eV. Due to the dissociation of C ₄ F ₈ , the generation ratio of F / CF ₂ becomes about 1.0,
The amount of F incident on the wafer is reduced by the reaction between the polymer on the wafer-facing surface and F. For this reason, F /
The ratio of CF ₂ is estimated to be about 0.5. The ion current density becomes about 5 mA / cm ² . Under these conditions,
The etching rate of the oxide film is about 700 nm / min, the selectivity with respect to the resist is 20, and the selectivity with respect to the underlying nitrided film is 30.

Under this condition, if etching is performed with an oxide film having a thickness of 3 mm and a contact hole having a diameter of 150 nm, the etching stops at a depth of about 2 mm. In such a case, in the conventional technique, it is necessary to add oxygen gas to prevent the etching from being stopped. When oxygen gas is added, the selectivity of the resist is reduced to about 5 under the condition that the etching does not stop. On the other hand, the magnetic field gradient is changed from 4 Gauss / cm to 1
When it is increased to 0 gauss / cm and the generation amount of F is increased, the thickness of the oxide film becomes 3 mm and the diameter of the contact hole becomes 150 n.
In the etching of m, a substantially vertical processed shape can be obtained without stopping halfway. At this time, the selectivity with respect to the resist is reduced to about 10, but is increased as compared with the addition of oxygen.

As described above, by changing the magnetic field gradient and controlling the F / CF ₂ ratio even under the same gas condition, it becomes easy to cope with different etching conditions, and it becomes unnecessary to add oxygen gas or the like.

The frequency of the high frequency power supply for forming plasma is set to 3
Even if it is changed within the range of 00 MHz to 900 MHz, the same result as 450 MHz can be obtained by controlling the magnetic field gradient. When the frequency is lowered, the solenoid coil becomes smaller, and the condition of a low magnetic field gradient is easily realized. Therefore, a frequency of 300 MHz to 600 MHz is particularly desirable. Regarding the gas pressure, when the gas pressure is increased to about 5 Pa, the oxide film is seen to be scraped in the lateral direction, and at a low gas pressure of 0.1 Pa or less, the incident amount of CF ₂ decreases, so that the high selectivity is maintained. It is difficult to obtain a sufficient etching rate. Therefore, the gas pressure is particularly preferably 0.1 Pa to 4 Pa.

Under the same etching conditions that the frequency of the high frequency applied to the antenna described above is 450 MHz and the magnetic field gradient is 4 gauss / cm, the distance between the wafer and the antenna is changed from 60 mm to 100 mm, and a 1.5 mm silicon oxide film and a contact hole are formed. Of 150 nm in diameter. Increasing the distance increases the low electron temperature region and reduces the effect of F consumption on the wafer-facing surface.
Increase in relative incidence. For this reason, the selectivity to the resist and the nitrogen film becomes as small as 10 and 12, respectively. When the distance between the wafer and the antenna was 100 mm or more, no change in the selectivity was observed. When about 5 sccm of CH ₂ F ₂ gas is added to these conditions, the selectivity of the resist becomes 20,
Although the selectivity of the nitrogenated film is about 25, CH ₂ F ₂ has a high deposition property and adheres to the inner wall surface, so that the frequency of cleaning increases and the throughput decreases. That is, it is more advantageous in terms of throughput to shorten the distance between the wafer and the antenna to 60 mm and improve the selectivity. Conversely, if the distance between the wafer and the antenna is reduced to 40 mm, the amount of incident F decreases and the selectivity increases, but the etching stops at a depth of about 1.2 mm. As described above, by controlling the relative incident amount of F by controlling the distance between the wafer and the antenna and the magnetic field gradient, desired etching conditions can be achieved without adding a gas.

Next, another embodiment using the apparatus shown in FIG. 6 will be described. In this apparatus, an etching gas is introduced into the etching processing chamber 1, and a first high-frequency power supply 601 and a second high-frequency power supply 602 generate a high-frequency power of 10 to 100 MHz.
3, 604 are introduced into the etching chamber 1 to generate gas plasma. The electron density of the plasma is 10
High density plasma of ¹¹ / cm ³ or more. A processing table 5 is provided in the etching processing chamber 1, and a processing object 6 is set on the processing table 5, and an etching process is performed by gas plasma. The etching gas is introduced into the etching chamber 1 through a gas flow controller, and is exhausted out of the etching chamber 1 by an exhaust pump 7. The processing table 5 on which the object to be processed is installed is provided with a high-frequency power supply 12 and operates from 400 kHz to 13.56.
High frequency bias up to MHz can be applied.

An 8-inch silicon wafer is transferred to this apparatus as an object to be processed. An oxide film having a thickness of 2 mm is formed on the silicon wafer, and a resist mask on which a mask pattern is transferred is formed thereon. Holes having a diameter of 200 nm are formed in the resist mask.

In this apparatus, Ar 400 sccm, C ₄ F ₈
Is introduced into the processing chamber through the gas inlet and the gas pressure is adjusted to 3 Pa. A 1500 W high frequency of 13.56 MHz is applied to the first ring antenna 603, and 13.5
A high frequency of 1000 MHz of 6 MHz is applied to the second ring antenna 604 to generate gas plasma,
A bias of 00 kHz and 1200 W is applied to etch the oxide film. Under these conditions, the electron temperature near the height of the first ring antenna is about 10 eV and 4 near the wafer.
eV. The etching rate of the oxide film is about 700 nm /
In min, the selectivity to resist becomes about 25,
Etching stops in the middle of the contact hole.

When the high frequency power applied to the second ring antenna 604 is set to 500 W, the electron temperature near the wafer decreases to about 2 eV. Since the plasma density is substantially determined by the first ring antenna, the ion current density does not change, and the etching rate of the oxide film is 700 nm / min. However, the selectivity of the resist decreases to about 10 due to the decrease in the electron temperature. However, under this condition, the etching does not stop.

During the etching, the second ring antenna 6
04 to 1000 W to 500 W
When the etching time is changed over time, a contact hole is formed without stopping the etching. The average resist selectivity during etching is about 20.

[0036]

According to the present invention, since the generation ratio of F / CF ₂ can be arbitrarily controlled, the oxide film etching can be performed with a high selectivity to a resist or a nitrided film without largely depending on the gas pressure and the gas flow rate. Will be possible. According to the present invention, it is possible to process a contact hole having a high aspect ratio and to process an oxide film with a high selectivity to a resist and a silicon nitride film. The above-described etching can be performed even under low gas pressure conditions of 1 Pa to 4 Pa, so that a vertical processed shape can be obtained with a contact hole having a high aspect ratio.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating the formation of two types of electron temperature regions according to the present invention.

FIG. 2 is a diagram showing the relationship between the formation of two types of electron temperature regions by controlling the magnetic field gradient and the F / CF ₂ generation ratio according to the present invention.

FIG. 3 is a diagram showing the relationship between the formation of two types of electron temperature regions by controlling the distance between the wafer and the wafer facing surface according to the present invention and the F / CF ₂ generation ratio.

FIG. 4 is a sectional view of a dry etching apparatus used in the present invention.

FIG. 5 is a sectional view of another dry etching apparatus used in the present invention.

FIG. 6 is a sectional view of another dry etching apparatus used in the present invention.

[Explanation of symbols]

1. 1. etching processing chamber; 2. microwave generator, Waveguide, 4. 4. solenoid coil; Processing table, 6. Workpiece, 7. Exhaust pump, 8. 8. exhaust valve, 10. conductance valve; 10. gas flow controller, Gas inlet, 12. 12. High frequency power supply for processing table, Quartz chamber, 101. High electron temperature region, 102. Low electron temperature region, 103. Wafer facing surface, 201. Magnetic field gradient and F /
Curve showing the relationship of CF ₂ generation ratio, 301. High electron temperature region, 302. Curve showing the relationship between the distance between the wafer-facing surface of the etching apparatus and the wafer and the F / CF ₂ generation ratio, 50
1. Gas inlet, 502. Antenna, 503. High frequency power supply, 601. First high frequency power supply, 602. Second high frequency power supply, 603. First ring antenna, 604. Second ring antenna.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Seiji Yamamoto 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo Inside the Hitachi, Ltd. Central Research Laboratory (72) Inventor Nobuyuki Negishi 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo Central Research Laboratory

Claims (17)

[Claims] 1. A dry etching method characterized in that a film is etched using a plasma having a first electron temperature region and a second electron temperature region. 2. The dry etching method according to claim 1, wherein a difference between the first electron temperature and the second electron temperature is 1 eV or more. 3. The dry etching method according to claim 1, wherein a difference between the first electron temperature and the second electron temperature is 5 eV or more. 4. The dry etching method according to claim 1, wherein the first electron temperature is 2 eV or more and 4 eV or less, and the second electron temperature is 5 eV or more. 5. The dry etching method according to claim 1, wherein the film is a silicon oxide film, and the gas for generating the plasma is a fluorocarbon gas. 6. The dry etching method according to claim 1, wherein the pressure of the gas for generating the plasma is 4 Pa or less. 7. A gas containing a fluorocarbon gas is introduced into a processing chamber, said gas is turned into plasma, and the amount of fluorine radicals, fluorocarbon radicals and ions in said plasma is controlled independently during etching, and said plasma is generated. A dry etching method characterized in that an insulating film is dry-etched by utilizing the same. 8. The dry etching method according to claim 7, wherein the amounts of the fluorine radicals and the fluorocarbon radicals change during the etching. 9. The plasma is formed by applying a magnetic field formed by a solenoid coil from outside the processing chamber to the processing chamber, and controlling a magnetic field gradient of the magnetic field by the solenoid coil to generate F radicals. 8. The dry etching method according to claim 7, wherein the ratio of the generation of hydrogen and fluorocarbon radicals is controlled. 10. The dry etching method according to claim 7, wherein said magnetic field gradient is increased as the etching of said insulating film progresses. 11. The dry etching method according to claim 7, wherein a gas pressure in the processing chamber is 4 Pa or less. 12. The dry etching method according to claim 7, wherein said plasma is formed by applying a high frequency, and the frequency of said high frequency is not less than 300 MHz and not more than 900 MHz. 13. The dry etching method according to claim 7, wherein said plasma is formed by applying at least two types of high frequencies having different input powers. 14. A processing chamber, and a table provided in the processing chamber for setting a substrate to be dry-etched,
A dry etching apparatus comprising: means for introducing a gas into the processing chamber; means for converting the gas into plasma; and means for forming first and second electron temperature regions in the plasma. 15. The plasma generating means may be 300 MH.
15. The dry etching apparatus according to claim 14, wherein the means is a means for applying a high frequency of not less than z and not more than 900 MHz. 16. The dry etching apparatus according to claim 14, wherein four or more solenoid coils are provided around the processing chamber. 17. A plasma processing apparatus according to claim 14, wherein said means for generating plasma is means for applying a high frequency to an antenna provided in a processing chamber, and a distance between said base and said antenna is 100 mm or less. Dry etching equipment.