JPH05217949A - Dryetching device and its method - Google Patents

Abstract

PURPOSE:To acquire fast neutron of specified directional property and monochromatic energy distribution and to realize rapid etching of high anisotropy. CONSTITUTION:A generation chamber 15 of fast neutron is formed in an upper part of an approximately central part of an etching chamber 10 with an aperture 16 formed in an lower end thereof facing toward a sample installation part 21 and a first evacuation tube 14 is provided to one sidewall of the etching chamber 10 for evacuating gas inside the etching chamber 10. A second evacuation tube 18 is provided to a sidewall of the generation chamber 15 with its evacuation port 18a opened externally. Each pressure inside the etching chamber 10 and outside the generation chamber 15 is set at an optimum value, fast neutron is generated using light element such as He, H2, and etching species is generated by etching gas for dryetching the sample 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry etching apparatus and method for assisting a neutral particle assisted etching of a sample by using etching species and neutral particles in an IC manufacturing process.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a conventional dry etching apparatus for performing neutral particle assist etching on a sample using an etching species and neutral particles. In the figure, reference numeral 1 denotes a chamber, and a discharge tube 2 for generating radicals as an etching species is disposed above the chamber 1, and an etching gas supply tube 6 is connected to the discharge tube 2. Also chamber 1
An ion source 3 for generating ions that have been accelerated with high directionality is provided on one side wall of the column, and a gas supply pipe 7 for an ion generating gas is connected to the ion source 3. On the other hand, a sample installation unit 5 is attached to the other side wall of the chamber 1 facing the ion source 3 via a grid electrode 4 composed of several stages of grids. Is prevented from entering the sample setting section 5. Further, an exhaust pipe 8 for exhausting the gas in the chamber 1 is provided below the chamber 1.

When a Si sample having SiO ₂ formed on its surface is dry-etched using the apparatus constructed as described above, first, the sample is set in the sample setting section 5. Then, CHF ₃ which is a reaction gas is supplied from the supply pipe 6 into the discharge tube 2 and the chamber 1, and Ar which is an ion generating gas is supplied to the ion source 3 from the gas supply pipe 7. Then, the gas in the discharge tube 2 and the chamber 1 is exhausted from the exhaust tube 8 while adjusting the exhaust amount, and the chamber 1 is exhausted at a predetermined pressure such that the etching rate and the anisotropy are compatible, for example, 7 × 10 ^-2 P
Set to a. After that, each grid of the grid electrode 4 is applied to a positive or negative potential, and the discharge tube 2 and the ion source 3 are operated. Then, CHF ₃ in the discharge tube 2
Are plasmatized to supply radicals, ions, and electrons having CHF ₃ as a generation source into the chamber 1, and Ar ⁺ is ejected from the ion source 3 toward the grid electrode 4.
On the way, a part of the ejected Ar ⁺ is neutralized by the charge exchange scattering without losing the kinetic energy and the directionality, and becomes high-speed neutral particles, and goes to the sample. Here, slow Ar ⁺ generated by charge exchange scattering, high speed Ar ⁺ without charge exchange scattering, ions in the plasma are repelled by the positive potential in the grid electrode 4, and electrons in the plasma are also in the grid electrode 4. It is repelled by the negative potential of. On the other hand, the radicals generated from the discharge tube 2 reach the sample without being affected by the grid electrode 4 and are adsorbed on the sample surface. Then, the adsorbed radicals are irradiated with high-speed neutral particles to start etching, and the sample is dry-etched. In the conventional dry etching, Ne, Kr or the like is used as the ion generating gas in addition to Ar.

[0004]

As described above, the pressure in the chamber 1 at the time of dry etching is set to a value at which the etching rate and etching anisotropy are compatible with each other.
However, when dry etching is performed at this set pressure, the probability that high-speed neutral particles are generated by elastic scattering is higher than that of charge-exchange scattering, so that the directionality of high-speed neutral particles cannot be maintained. That is, the conventional set pressure is high to maintain the directionality of high-speed neutral particles, and conversely, the pressure value that can maintain the directionality of high-speed neutral particles is low to achieve both etching rate and etching anisotropy. It was Moreover, there has been a problem that the energy of high-speed neutral particles is widely distributed. Further, in the above-mentioned conventional apparatus, since the etching gas and the ion generating gas are mixed in the chamber 1 during the dry etching, it is difficult to control the directionality and the amount of the fast neutral particles. There was also a problem. In addition, in the conventional apparatus, the etching gas may flow back to the ion source 3 and damage the ion source 3.

Further, in the prior art, FIG. 4 (a), (b),
As shown in (c), as an ion-generating gas for generating high-speed neutral particles, Ar, N having an elastic scattering cross section whose size is equal to or larger than that of the charge exchange scattering cross section.
Since a heavy gas such as e is used, a large number of high speed neutral particles are generated due to elastic scattering, which also causes deterioration of the directionality and energy distribution of the high speed neutral particles. 4A, 4B, and 4C are He and N, respectively.
e and Ar show changes in each scattering cross section due to changes in ion energy of each gas, s is elastic scattering, T is charge exchange scattering,
t indicates t = s + T. Then, the deterioration of the directionality and energy distribution of the high-speed neutral particles causes the deterioration of the shape of the etching pattern, the increase of the microloading effect, and the deterioration of the controllability of the etching amount.

The present invention has been made in view of the above problems, and it is possible to obtain high-speed neutral particles having a predetermined directionality and a monochromatic energy distribution, and also to realize high-speed etching with high anisotropy. An object of the present invention is to provide a dry etching apparatus and a method therefor.

[0007]

In order to solve the above-mentioned problems, the present invention comprises an etching chamber in which a sample setting section is installed, and a slit or aperture for generating neutral particles is provided in the etching chamber for setting the sample. And a second exhaust pipe is provided in the etching chamber, and a second exhaust pipe is opened in the generation chamber with its exhaust port facing outward. It is arranged to be provided in the state where it is opened. In the above device,
An exhaust unit for exhausting the gas around the slit or the aperture of the generation chamber is provided above the sample installation unit with its exhaust port opened to the outside. In addition, the dry etching method of the present invention uses at least a light element of He or H ₂ to generate charged particles, then neutralizes the charged particles to generate the neutral particles, and etches the neutral particles. A sample placed in the etching chamber is etched using seeds.

[0008]

According to the dry etching apparatus of the present invention, during dry etching, the pressure inside the etching chamber and the pressure inside the generation chamber are independently controlled by the first exhaust pipe and the second exhaust pipe, respectively. Is set to a proper pressure. Further, the generation chamber and the etching chamber are in a state of communicating via the aperture or slit,
The etching gas does not flow back to the ion source.
Moreover, most of the high-speed neutral particles having lost the directivity and the monochromaticity of energy distribution are removed by the apertures or slits. Further, according to the dry etching method of the present invention, the elastic scattering cross section is smaller than the charge exchange scattering cross section, and the charged particles are generated after generating the charged particles using at least a light element of He or H _2. When activated, a large amount of high-speed neutral particles are generated due to charge exchange scattering, and the generation of high-speed neutral particles that have lost the directionality and monochromaticity of energy distribution due to elastic scattering is suppressed.

[0009]

Embodiments of the dry etching apparatus and method according to the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an example of the dry etching apparatus of the present invention. In the figure, reference numeral 10 denotes an etching chamber having a substantially rectangular cross section, and a sample mounting portion 21 for mounting a sample 22 is provided on the lower side of the etching chamber 10 at the substantial center. The sample setting unit 21 includes a moving mechanism (not shown), and the sample setting unit 2
1 is an aperture 16 which will be described later by this moving mechanism.
And the surface of the sample 22 can be moved in the horizontal direction while maintaining a constant distance. In the upper part of the substantially center of the etching chamber 10, a hollow substantially cylindrical generation chamber 15 for high-speed neutral particles,
The aperture 16 formed at the lower end of the sample mounting portion 2
The aperture 16 is formed to have a diameter of about 2 mm, for example. A second grid electrode 17 for removing charged particles is attached above the aperture 16 in the generation chamber 15, and the upper end of the generation chamber 15 is an ion for generating ions accelerated in a good direction. A source 19 is arranged. The ion source 19 is connected to a second gas introducing pipe 20 for an ion generating gas composed of a light element such as He and H ₂ , and the side wall of the generating chamber 15 is provided with a second exhaust pipe 18 having an exhaust port. 18
It is provided in a state of opening a toward the outside. On the other hand, a first exhaust pipe 14 for exhausting gas in the etching chamber 10 is provided on one side wall of the etching chamber 10, and a discharge tube 11 for generating etching species is provided on the other side wall.
Are lined up. Etching chamber 10 for this discharge tube 11
A first grid electrode 13 for removing charged particles is attached to the side, and a first gas introduction tube 12 for etching gas is connected to the discharge tube 11.

Next, a method of dry etching SiO ₂ formed on the surface of the sample 22 using the apparatus configured as described above will be described. First, He is used as an ion generating gas from the second gas introducing pipe 20 to supply He to the ion source 19
And CHF ₃ as a reaction gas is introduced into the discharge tube 11 through the first gas introduction tube 12. Then, the gas in the etching chamber 10 is exhausted from the first exhaust pipe 14 while adjusting the exhaust amount, and the inside of the etching chamber 10 is set to a pressure value, for example, 3 Pa at which a sufficient etching rate is obtained. At the same time, the gas in the generation chamber 15 is exhausted from the second exhaust pipe 18 while adjusting the exhaust amount, and the pressure inside the generation chamber 15 is made low in order to suppress the generation of high-speed neutral particles due to elastic scattering. Set. Specifically, in the generation chamber 15, a pressure value such that the mean free path of the ions generated from the ion source 19 is longer than the distance from the ion source 19 to the second grid electrode 17, or the aperture from the ion source 19 is increased. The pressure value is set so that the distance up to 16 and the mean free path of the ions are almost the same. In this embodiment, since the distance from the ion source 19 to the aperture 16 is 50 cm, the inside of the generation chamber 15 is set to 3 × 10 ^-2 Pa.
Further, the distance between the aperture 16 and the surface of the sample 22 is set to about 1 mm, for example. If this distance is increased, the conductance defined by the sample 22 and the lower end of the generation chamber 15 increases, the pressure around the aperture 16 increases, and the directionality of the high-speed neutral particles and the monochromaticity of the energy distribution are lost.
As described above, the pressure in the etching chamber 10 and the generation chamber 15
It becomes difficult to set the internal pressure independently. Subsequently, a positive or negative potential is applied to the first grid electrode 13 and the second grid electrode 17, and the acceleration energy of the ions generated from the ion source 19 is set to, for example, 150 eV to operate the discharge tube 11. Also activate.

Then, the operation of the discharge tube 11 causes the discharge tube 1 to operate.
CHF _{3 in} 1 is turned into plasma and goes into the etching chamber 10. At this time, the ions and electrons in the plasma are repelled by the positive potential or the negative potential applied to the first grid electrode 13 and do not reach the sample 22, and the radicals in the plasma reach the first grid electrode 13. It is diffused into the etching chamber 10 without being affected, reaches the sample 22, and is adsorbed on the surface. The sample 22 is cooled to −100 ° C. in advance, and the radicals adsorbed on the surface do not react spontaneously. On the other hand, due to the operation of the ion source 19, He ⁺ is ejected from the ion source 19 toward the second grid electrode 17 in the generation chamber 15, and about 50% of He ⁺ is charged in the generation chamber 15 during the charge exchange. It is converted into high-speed neutral particles without losing directionality and kinetic energy due to scattering. Since the elastic scattering cross section of He is smaller than the charge exchange scattering cross section, the generation of high-speed neutral particles that have lost the directionality and monochromaticity of the energy distribution is suppressed as compared with the case of Ar. Of He ⁺ that has reached the second grid electrode 17, slow He ⁺ generated by charge exchange scattering and H that has not undergone charge exchange scattering
e ⁺ is repelled by the positive potential applied to the second grid electrode 17 and does not reach the sample 22, and the slightly generated fast neutral particles that have lost the directionality and the monochromaticity of the energy are generated by the aperture 16. Most of it is removed. And
Only high-speed neutral particles having a predetermined directionality and energy distribution are ejected from the aperture 16 toward the sample 22.
Then, the radicals adsorbed on the surface of the sample 22 are irradiated with the high-speed neutral particles emitted from the aperture 16 to start etching, and the sample 22 is dry-etched. Here, when the etching region of the sample 22 is larger than the etching region defined by the aperture 16, the moving mechanism moves the sample setting part 21 horizontally to etch a desired region.

In the above embodiment, the case where the moving mechanism is provided on the sample setting section 21 side has been described, but it is sufficient if the sample setting section 21 and the aperture 16 can move relatively, and the moving mechanism moves to the aperture 16 side. It is also possible to move the aperture 16 side by providing. Further, in the above embodiment, the case where the aperture 16 is formed at the lower end of the generating chamber 15 has been described, but a slit may be provided instead of this. Further, in the above embodiment, the case where He was used as the ion generating gas was described.
Instead of e, a light element such as H ₂ can be used.

As described above, according to the above-described embodiment, the etching chamber 10 in which the radicals as the etching species are diffused.
And a first exhaust pipe 1 in each of the high-velocity neutral particle generation chambers 15.
4. Since the second exhaust pipe 18 is provided, the pressure in the etching chamber 10 and the pressure in the generation chamber 15 can be independently controlled, and each can be set to an optimum pressure. Therefore, high-speed neutral particles having a predetermined directionality and a monochromatic energy distribution can be obtained, and high-speed anisotropic etching can be performed. Further, in this embodiment, since He whose elastic scattering cross section is smaller than the charge exchange scattering cross section is used as the gas for ion generation, high-speed neutral particles that lose directionality due to elastic scattering and monochromaticity of energy distribution. Thus, the generation of particles is suppressed, and the directionality of the high speed neutral particles and the monochromaticity of the energy distribution can be improved. Furthermore, since the high-speed neutral particle generation chamber 15 and the etching chamber 10 are communicated with each other through the aperture 16 or the slit, it is possible to prevent the backflow of the etching gas to the ion source 19 and prevent the ion source 19 from being damaged. You can
Further, even if He is used, most of the high-speed neutral particles that have slightly lost the directionality and the monochromaticity of the energy distribution are removed by the aperture 16 or the slit. It is possible to irradiate high-speed neutral particles having monochromaticity of energy distribution.

FIG. 2 is a cross-sectional view showing another example of the dry etching apparatus of the present invention. The difference from FIG. 1 is that the exhaust unit 23 has an exhaust port 23a above the sample setting unit 21. The point is that it is provided so as to be open to the outside.
The exhaust unit 23 is for exhausting the gas around the aperture 16 or the slit of the generation chamber 15, and the exhaust species of the etching species in the region of the surface of the sample 22 irradiated with the fast neutral particles by the exhaust by the exhaust unit 23. The adsorption amount of is controlled.

When the Si sample 22 is dry-etched using such an apparatus, first, He, which is an ion generating gas, is introduced into the ion source 19 through the second gas introduction pipe 20, and the first gas is introduced. Cl ₂ as a reaction gas is introduced into the discharge tube 11 through the gas introduction tube 12. Then, the gas in the etching chamber 10 is exhausted from the first exhaust pipe 14 while adjusting the exhaust amount, and the inside of the etching chamber 10 is set to a pressure value, for example, 3 Pa at which a sufficient etching rate is obtained. At the same time, the gas in the generation chamber 15 is discharged to the second exhaust pipe 1
Evacuation is performed by adjusting the exhaust amount from No. 8, and the mean free path of the ions generated from the ion source 19 is generated in the generation chamber 15 in the same manner as in the above-described embodiment rather than the distance from the ion source 19 to the second grid electrode 17. Is set to be long, or the pressure value is set so that the distance from the ion source 19 to the aperture 16 and the mean free path of the ions are substantially the same. In this embodiment, since the distance from the ion source 19 to the aperture 16 is 50 cm, the inside of the generation chamber 15 is set to 1 × 10 ^-2 Pa. Further, the pressure in the exhaust part 23 is set to 1 × so that the adsorption amount of the etching species on the sample 22 becomes a single layer.
Set to 10 ⁻³ Pa. Aperture 16 and sample 2
The distance from the two surfaces is set to about 1 mm, for example. Subsequently, a positive or negative potential is applied to the first grid electrode 13 and the second grid electrode 17, and the acceleration energy of the ions generated by the ion source 19 is set to, for example, 100 eV to operate the discharge tube 11. Also activate.

Then, the operation of the discharge tube 11 causes the discharge tube 1 to operate.
Cl _{2 in} 1 is turned into plasma and goes into the etching chamber 10. At this time, the ions and electrons in the plasma are the first
Of the positive electrode or negative potential applied to the grid electrode 13 does not reach the sample 22, and radicals in the plasma diffuse into the etching chamber 10 without being affected by the first grid electrode 13. , Reaches the sample 22 and is adsorbed on the surface. The sample 22 is cooled to −100 ° C. in advance, and the radicals adsorbed on the surface do not react spontaneously. Then, of the adsorption layers of the radicals adsorbed in the etching region on the surface of the sample 22, unnecessary second and higher layers are exhausted by the exhaust of the exhaust unit 23. On the other hand, due to the operation of the ion source 19, He ⁺ is ejected from the ion source 19 toward the second grid electrode 17 in the generation chamber 15, and about 50% of He ⁺ is charged in the generation chamber 15 during the charge exchange. It is converted into high-speed neutral particles without losing directionality and kinetic energy due to scattering. Of He ⁺ that has reached the second grid electrode 17, low-speed H generated by charge exchange scattering
e ⁺ , He ^{+ which} has not been subjected to charge exchange scattering, is repelled by the positive potential applied to the second grid electrode 17 and does not reach the sample 22, and a slight directionality and monochromaticity of energy are generated. Most of the lost fast neutral particles are removed by the aperture 16. Then, only the fast neutral particles having a predetermined directionality and energy distribution have the aperture 1
6 is ejected toward the sample 22. And sample 22
The radicals adsorbed on the surface are irradiated with the high-speed neutral particles emitted from the aperture 16 to start etching, and the monoatomic layer of the sample 22 is dry-etched. Here, when the etching region of the sample 22 is larger than the etching region defined by the aperture 16, the sample mounting portion 21 is horizontally moved by the moving mechanism to etch a desired region, as in the above-described embodiment.

As described above, according to this embodiment, since the exhaust portion 23 for exhausting the gas around the aperture 16 of the generation chamber 15 or the slit is provided above the sample setting portion 21, the ion source is provided. Ion current flowing through 19,
The adsorption amount of the etching species can be controlled by controlling not only the pressure of the etching chamber 10 and the moving speed of the sample setting part 21 but also the pressure of the exhaust part 23. Therefore, according to this embodiment, in addition to the effect of the above embodiment, the etching amount can be strictly controlled.

[0018]

As described above, according to the dry etching apparatus of the present invention, the pressures in the etching chamber and the neutral particle generation chamber can be controlled independently, and each can be set to the optimum pressure. Therefore, high-speed neutral particles having a predetermined directionality and a monochromatic energy distribution can be obtained, and high-speed etching with high anisotropy can be realized. Therefore, it is possible to improve the shape of the etching pattern, reduce the microloading effect, and improve the controllability of the etching amount. Further, since the neutral particle generating chamber and the etching chamber are communicated with each other through the aperture or the slit, it is possible to prevent the etching gas from flowing back to the ion source and prevent the ion source from being damaged. Also, most of the high-speed neutral particles that have lost the directionality and monochromaticity of the energy distribution by the aperture or slit can be removed, and the high-speed neutral particles having a predetermined directionality and monochromaticity of the energy distribution on the sample surface. Only can be ejected. Furthermore, when an exhaust unit for exhausting gas around the aperture of the generation chamber or the slit is provided above the sample setting unit, the amount of etching species adsorbed can be controlled, so that the etching amount can be controlled. It can be controlled more tightly.
Further, according to the dry etching method of the present invention, the elastic scattering cross section is smaller than that of the charge exchange scattering cross section He, H ₂
Since the light elements such as are used, it is possible to improve the directionality of high-speed neutral particles and the monochromaticity of the energy distribution, improve the shape of the etching pattern, and reduce the microloading effect. The amount controllability can also be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a dry etching apparatus of the present invention.

FIG. 2 is a sectional view showing another example of the dry etching apparatus of the present invention.

FIG. 3 is a sectional view showing an example of a conventional dry etching apparatus.

FIG. 4 is a graph showing changes in each scattering cross section of each gas.

[Explanation of symbols]

 10 Etching Chamber 14 First Exhaust Pipe 15 Generation Chamber 16 Aperture 18 Second Exhaust Pipe 18a Exhaust Port 19 Ion Source 21 Sample Setting Section 22 Sample 23 Exhaust Section

Claims (3)

[Claims] 1. A dry etching apparatus comprising an etching chamber in which a sample setting section is installed, and in which a chamber for generating neutral particles is provided with a slit or an aperture facing the sample setting section. The dry etching apparatus is characterized in that a first exhaust pipe is provided in the etching chamber, and a second exhaust pipe is provided in the generation chamber with its exhaust port opened toward the outside. 2. An exhaust unit for exhausting gas around the slit or the aperture of the generation chamber is provided above the sample setting unit with its exhaust port opened to the outside. The dry etching apparatus according to claim 1, which is characterized in that. 3. A dry etching method for etching a sample placed in an etching chamber by using an etching species and neutral particles, wherein charged particles are generated by using at least a light element of He or H ₂ and then the charged particles are generated. Is neutralized to generate the neutral particles.