JPH06280059A - Device for generating plasma excited by electron beam - Google Patents

Abstract

PURPOSE:To carry out good dry etching of a substrate material under masking by lowering ion energy while suppressing the quantity of arrival of the incident electrons from an electron beam acceleration region at a target sample and generating high-density plasma by lowering the electron temp. in a reaction chamber in the device for generating the plasma excited by electron beams having excellent performance. CONSTITUTION:The front part of the sample 11 in the reaction chamber 8 is provided with magnets 13, 13' facing each other inside and outside a casing 9. The incident electrons 4 from the electron beam acceleration region 7 are trapped by magnetic lines 14 of force of these magnets as magnetic filters and are uniformly distributed in the front part of the sample, and, the quantity of the arrival of the electrons 4 at the target sample is suppressed, and the electron temp. in the reaction chamber 8 is lowered. The electron temp. is lowered, while the high-density plasma is formed in the reaction chamber 8, the dry etching efficiency by the ions of low energy is enhanced, and the selection ratio is increased. The working of the target sample is thereby controlled and the production ratio of the sample is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The disclosed technology belongs to the technical field of the structure of an electron beam excitation ion irradiation apparatus that irradiates a target sample such as a silicon wafer with ions generated through an electron beam to perform dry etching processing or the like. .

[0002]

2. Description of the Related Art As is well known, the remarkable rise of industrial society is strongly backed up by highly developed science, especially, electronic engineering, and therefore further development of such electronic engineering is strongly demanded. .

[0003] Therefore, in the electronic engineering, more and more precise and accurate processing of information processing of data and the like is required more and more at ultra-high speed. Therefore, more detailed processing of such data is required. In addition, high tech, downsizing, and the like of devices that perform accurate ultra-high-speed arithmetic processing are strongly demanded.
A more precise dry etching technique for a silicon wafer or the like forming a highly integrated circuit such as that described above is required, and in order to cope with this, for example, an ion irradiation technique has been developed as disclosed in the invention of JP-A-61-290629. The so-called DCE, RFE, ECR (electron cyclotron resonance),
Furthermore, a system in which plasma is generated by an electron beam or the like and only ions are extracted from the plasma through an electric field to irradiate a target sample such as a silicon wafer has been developed and put into practical use.

However, in order to effectively carry out good ion beam dry etching without leaving a large amount of damage to a target sample having a large diameter such as a silicon wafer due to ion irradiation, a large cross-sectional area is required in a low energy region. It has been found that it is necessary to irradiate the target sample with an ion beam having a uniform large current density, and the ion beam must be performed under such conditions that are basically contradictory.

However, in the old-type ion irradiation apparatus, when the current density of the ion beam is increased in low energy ions, it is impossible to irradiate the target sample with the ion beam uniformly over the cross-sectional area. there were.

To address this, for example, Japanese Patent Application No. 3-2
As disclosed in the invention, a so-called electron beam excited plasma technology (EBEP) capable of generating high-density plasma capable of obtaining a large ion beam current density has been developed, and electron beam excited ions as shown in FIG. 4 have been developed. It is becoming possible to design the irradiation device 1 for practical use.
Development studies have been conducted which have advantages other than the (electron cyclotron resonance) method and can be put to practical use.

That is, in the conventional electron beam excitation ion irradiation apparatus 1 shown in FIG. 4, in the plasma region 2, an argon gas for electron beam formation is supplied from a port (not shown), and the cathode electrode 3 is supplied by a DC power supply. To the red hot state,
Plasma is generated, electrons 4 in the plasma are accelerated by an accelerating cathode 5 and an accelerating anode 6 in an electron beam accelerating region 7, and subsequently supplied from a port (not shown) in the reaction chamber 8 in the ion generating region. The chlorine gas is turned into plasma, and only the ions excited by the electron beam are irradiated to the target sample 11 such as a silicon wafer supported by the holder 10 which is masked in a predetermined manner, and the predetermined fine processing is performed by dry etching. Is being done.

In order to dry-etch the target sample 11 in the reaction chamber 8 as designed and as designed, the amount of ions (the number of ions) is increased to improve the productivity. In addition, the etching rate for the masking is increased, the etching rate of the base material 11 of the material to be etched is increased, and the processing amount of the masking is reduced as much as possible so that the base material 11 is processed as desired. It has been found that it is preferable to satisfy the contradictory conditions of decreasing the kinetic energy while increasing the ion current density in order to improve the selection ratio.

By the way, the target sample 11 is the holder 1
When it is supported by 0, it is in a so-called floating state in which it is electrically insulated, and when an electron beam is incident thereon from the acceleration region 7, it is negatively charged, and therefore, the reaction chamber is mediated by the potential difference formed. Since the ions in 8 are irradiated to perform desired dry etching,
In order to lower the ion energy in order to increase the selectivity of the etching rate of the target sample covered with the above masking to achieve the desired state, the state where the target sample is negatively charged by the electron beam in order to reduce the ion kinetic energy. It is necessary to suppress the potential difference of No. 2, and the following method has been adopted so far in order to lower the electron temperature of plasma in the vicinity of the target sample 11.

First, the accelerating voltage in the electron beam accelerating region 7, that is, the voltage of the accelerating cathode 5 and the accelerating anode 6 is lowered to reduce the energy of the electron beam incident on the reaction chamber 8 and the target. This is a method of reducing the potential difference by reducing the negative charging voltage of the sample 11 to suppress the mass ion irradiation amount. Secondly, the magnet 12 or the like is used as a magnetic shutter immediately before the holder 10 of the target sample 11. Electrons 4 that enter the reaction chamber 8 from the electron beam acceleration region
Is scattered to lower the electron temperature of plasma in the vicinity of the sample 11.

[0011]

However, the method of lowering the electron temperature of plasma in the vicinity of the target sample 11 in the reaction chamber 8 has the following problems.

That is, in the first method, by receiving the accelerating voltage in the electron beam accelerating region 7, the plasma generating efficiency in the reaction chamber 8 is naturally lowered in the plasma generating region. However, there is a drawback that a sufficient plasma density cannot be obtained and the ion current density cannot be improved.

In the second method, the plasma density on the entire surface of the target sample 11 is not uniform, a non-uniform distribution is generated in the plasma region for the target sample 11, and the electron temperature of the plasma is lowered uniformly. There is a difficulty that it is difficult.

Therefore, in either case, there is a problem in that it is not possible to generate a phenomenon in which both conditions of increasing the number of plasma ions and decreasing the ion energy are compatible with each other.

[0015]

OBJECT OF THE INVENTION The object of the invention of this application is to solve the problem of electron temperature control in the reaction chamber of an electron beam excited plasma generator, which originally has excellent merits based on the above-mentioned prior art. As a subject, while making it possible to increase the number of ions in the plasma generation region, the target of the electron injected from the electron acceleration region into the reaction chamber of the plasma generation region is utilized by utilizing the physical property that electrons are easily trapped in the magnetic field lines. Suppressing the amount reaching the sample, lowering the ion energy, lowering the electron temperature of plasma, and increasing the selection ratio while increasing the number of ions. The present invention is intended to provide an excellent electron beam excited plasma generator that is beneficial to users.

[0016]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the structure of the invention of this application, which has been made in line with the above-mentioned object, has the purpose of solving the above-mentioned problems by means of ions in an electron beam excited plasma. When performing microfabrication to form a highly integrated circuit such as IC or LSI on a target sample such as a liquid crystal via dry etching, an electron beam excited plasma device is used to ionize argon gas or the like enclosed in the plasma region and plasma discharge To generate plasma and accelerate the electron beam emitted from the discharge tube or the like in the acceleration region to excite ions in the plasma generation region,
A sample such as a silicon wafer supported by a holder is irradiated with only ions, and fine dry etching of a highly integrated circuit such as IC and LSI as designed is performed. At that time, in front of the holder, parallel to the target sample, that is, A magnet filter is installed inside or outside the casing so that the magnetic field lines pass perpendicularly to the incident electron beam, and a magnetic filter is installed to trap the electrons in the magnetic field lines and thereby reach the target sample. The electron temperature of the plasma near the target sample is lowered and the plasma density is obtained by diffusion of the high-density plasma generated between the acceleration region and the magnetic filter. By increasing the number of ions and increasing the selection ratio, dry etching can be performed on the target sample as designed. In which it took technical means to.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the invention of this application is shown in FIGS.
The explanation is based on the following.

The same parts as in FIG. 4 will be described using the same reference numerals.

In the embodiment shown in FIG. 1, reference numeral 1'denotes an electron beam excitation plasma generator which forms the subject of the invention of this application, and a hot electrode 3 is provided in the plasma region 2 at the front end thereof, which is not shown in advance. The argon gas sealed from the port is ionized to generate plasma, and the electrons 4 from the hot electrode 3 are accelerated by the accelerating cathode 5. Further, the accelerating anode 6 causes the electron beam accelerating region 7 as in the conventional mode. Target sample 1 such as a silicon wafer masked by a mask (not shown) supported by a holder 10 so as to accelerate into the reaction chamber 8 in the plasma generation region.
It is designed to be oriented toward 1.

Thus, in the invention of this application, the magnets 13 for forming the magnetic filter are arranged outside the casing 9 of the reaction chamber 8 and at a predetermined position in front of the holder 10 with the opposite poles facing each other. The magnetic lines 14 'of the magnets 13, 13
Is in front of the target sample 11
The magnetic field lines 14 'are formed in parallel with the electron beam, that is, perpendicular to the electron beam to form a magnetic filter, and the electron beam acceleration region 7 is formed.
The electrons 4 incident from are trapped.

The electron beam incident from the electron beam accelerating region 7 produces a high-density plasma in the reaction chamber 8. In the invention of this application, the target sample 11 is immediately before the target sample 11. Since the magnetic filters are formed in parallel, the electrons 4 are trapped in the magnetic force lines 14 ′ of the magnetic filters and the target sample 11
Therefore, the electron temperature of plasma in the vicinity of the target sample 11 can be lowered.

As described above, since a high plasma density can be obtained, the number of ions can be made sufficiently large, the productivity can be improved, and the electron temperature can be increased. Since it can be lowered, the selection ratio can be increased, the kinetic energy of electrons can be lowered, and the etching amount of masking can be reduced.
It is possible to increase the processing amount of the first base material by etching and to form a desired highly integrated circuit or the like.

Next, in the embodiment shown in FIG. 2, the magnets 13 'and 13' forming the magnetic filter are provided inside the casing 9 while being in the vicinity of the target sample 11 and the magnetic field lines 14 'are similarly provided. The target sample 11 is formed in parallel to the target sample 11, that is, orthogonal to the electron beam, and the electrons 4 incident from the electron beam acceleration region 7 are trapped in the magnetic filter 14 ′.
1 can be reduced, the potential difference can be reduced, and the momentum of ions can be reduced, and high-concentration plasma generation and plasma with a low electron temperature can be generated in the reaction chamber 8. This is the same as the above-mentioned embodiment.

Next, the embodiment shown in FIG. 3 will be described with reference to FIGS.
Is a combination of the above embodiments, and magnets 13, 13, 13 for forming a magnetic filter are provided outside and inside the casing 9 in front of a predetermined portion of the target sample 11.
', 13' are arranged to face each other, and their magnetic field lines 14, 1
Electrons 4'are formed in parallel to the target sample 11, that is, inwardly in the direction orthogonal to the electron beam, and the electrons incident from the electron beam acceleration region 7 are trapped by the magnetic filter 14 'and reach the target sample 11 in the same manner. In this embodiment, the electron temperature can be lowered to increase the selection ratio while the electron temperature is lowered by lowering the electron temperature to generate the plasma at a high density. It is virtually unchanged.

In this way, in any of the examples, since the magnetic filter is provided, unlike the case where the target sample is reached with a high energy component when the conventional mode is not provided, It is possible to decrease the ion energy and increase the selection ratio while decreasing the amount of electrons that reach and decreasing the electron temperature and increasing the number of ions.

Incidentally, various modes such as electromagnets used for the magnets 13 and 13 and the electromagnets being excited by an alternating current can be adopted.

[0027]

As described above, according to the invention of this application, basically, the plasma ions in the reaction chamber are formed by the electron beam excitation, and the target sample supported by the holder in the reaction chamber is irradiated with the ions. When performing dry etching to process a highly integrated circuit or the like, the amount of processing of the target sample is reduced by increasing the number of ions and suppressing the energy to increase the selection ratio, and the amount of processing of the target sample is increased. Advantages are surely obtained, and by not controlling the accelerating voltage in the electron beam acceleration region, the electron beam can generate high-density plasma in the reaction chamber as in the conventional mode. In addition, a plasma with a uniform distribution is obtained in the vicinity of the target sample in parallel with the target sample, and the electron temperature is lowered uniformly to drive the plasma. Performing the proper exact ion irradiation to a target sample to be etched, while increasing productivity,
An excellent effect is obtained that a good dry etching can be performed by increasing the selection ratio.

[Brief description of drawings]

FIG. 1 is a schematic sectional perspective view of an embodiment of the invention of this application.

FIG. 2 is a schematic cross-sectional perspective view of another embodiment.

FIG. 3 is a schematic sectional perspective view of another embodiment.

FIG. 4 is a schematic cross-sectional perspective view of a conventional electron beam excitation plasma generator.

[Explanation of symbols]

 4 Electron 2 Discharge Chamber 7 Electron Beam Acceleration Region 8 Ion Reaction Chamber 11 Etched Sample 10 Holder 14, 14 'Magnetic Field (Line of Magnetic Force) 1'Electron Beam Excited Plasma Generator 13, 13' Magnet

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location H01J 37/32 9172-5E H01L 21/302 Z 9277-4M H05H 1/24 9014-2G (72) Inventor Manabu Hamagaki, 2-1, Hirosawa, Wako-shi, Saitama, RIKEN (72) Inventor, Masayuki Sakiyama 1-1, Kawasaki-cho, Akashi-shi, Hyogo, Kawasaki Heavy Industries, Ltd. (72) Inventor, Hiroshima Ans Hyogo Kawasaki Heavy Industries, Ltd. 1-1 Kawasaki Heavy Industries, Ltd. Akashi Plant Co., Ltd. (72) Inventor Masato Ban 1-1, Kawasaki-cho, Akashi City, Hyogo Prefecture Kawasaki Heavy Industries Ltd. Akashi Plant (72) Inventor Ryuji Shin Akashi, Hyogo Prefecture 1-1 Kawasaki-cho, Ichikawa Akashi Factory, Kawasaki Heavy Industries, Ltd.

Claims (4)

[Claims] 1. An electron beam accelerating region is provided adjacent to an electron beam discharge chamber, and a sample to be etched is supported by a holder in an ion reaction chamber adjoining the electron beam accelerating region, and a magnetic field is provided in front of the sample to be etched. The electron beam excited plasma generator in which the magnetic filter which forms a magnetic force line parallel to the sample to be etched is provided in front of the holder in the electron beam excited plasma generator. 2. The electron beam excited plasma generator according to claim 1, wherein the magnetic filter is formed by magnetic lines of force by a magnet. 3. An electron beam excited plasma generator according to claim 2, wherein said magnet is provided side by side with at least one of the inside and outside of the ion reaction chamber. 4. The electron beam excited plasma generator according to claim 2, wherein the magnet is a magnet excited by an alternating current.