JPH07272894A - Small electron beam excitation plasma generator - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the performance and downsize an electron beam excited plasma generator having an excellent dry etching function. A magnetic field coil 17 'for the reaction chamber 3 is externally provided at the base of the electron beam gun 2 concentrically with a magnetic field coil 16' corresponding to the accelerating electrode 13, and the accelerating electrode 13 is tapered to form a discharge electrode. 11, and a magnetic field coil or a permanent magnet is built into either of the electrodes to solidify the discharge electrode 11 to form a porous electrode plate. [Effect] The electron beam is rapidly diffused in the plasma chamber, the target sample 24 is uniformly irradiated with ions, and the apparatus is made compact, the performance is improved, and the cost is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The disclosed technique relates to a structure of an electron beam excitation ion irradiation apparatus for irradiating a target sample such as a silicon wafer with ions from plasma excited by an electron beam to perform a predetermined fine dry etching process or the like. Belong to the technical field.

[0002]

As is well known, the remarkable rise of industrial society is strongly backed up by highly developed science, especially electronic engineering and quantum mechanics. Therefore, further development of such electronic engineering is required. There is a strong demand.

[0003] In the electronic engineering, when processing various data and the like, it is more and more strongly demanded that more advanced, precise and accurate processing be performed at ultra-high speed. There is a strong demand for high-tech, down-sizing, etc. of devices that perform ultra-high-precision and accurate ultra-high-speed arithmetic processing of such data. Therefore, it is more desirable for silicon wafers, etc. that form highly integrated circuits such as ICs and LSIs. A precise processing technique such as dry etching is required, and in order to cope with this, for example, an ion irradiation technique has been developed as shown in the invention of JP-A-61-290629, and so-called DC plasma and RF plasma have been developed. , ECR (electron cyclotron resonance) plasma,
Further, a system in which plasma is excited by an electron beam or the like, ions in the plasma are accelerated through an electric field, and a target sample such as a silicon wafer is irradiated with predetermined light has been researched and developed and put into practical use. ing.

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

However, in the old ion irradiation apparatus, in the case of low kinetic energy ions, when the current density of the ions is increased, there is a problem that it is not possible to uniformly irradiate the target sample with the ions over a large 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 (EBEP) technique capable of generating high-density plasma capable of obtaining a large ion current density has been developed, and electron beam excited ion irradiation as shown in FIG. 12 has been developed. Device 1
Has been put to practical use, and has been used for various development researches and actual production with advantages other than the ECR (electron cyclotron resonance) method.

That is, the conventional electron beam excitation ion irradiation apparatus 1 shown in FIG. 12 is composed of an electron beam gun 2 in the front stage and a reaction chamber 3 in the rear stage, which are integrated in a plasma region 2 '. 7, an argon gas 8 for forming an electron beam is supplied, a filament 5 of the cathode electrode 4 is heated to a red heat state by a DC power source 6, thermoelectrons are generated, and a plasma is generated by the discharge power source 10 in the argon gas 8. , Electrons in the plasma, auxiliary electrode 9, power supply 10
Is discharged in the discharge region 14 by the discharge electrode 11 connected to the, and electrons in the plasma are accelerated in the electron beam acceleration region 15 by the accelerating electrode 13 connected to the power supply 12, and the electrons are injected into the plasma chamber 3 ', and the port 18 The chlorine gas 19 supplied from the plasma is turned into plasma, and the ions excited by the electron beam are irradiated onto the target sample 24 such as a silicon wafer supported by the holder 23 in the plasma chamber 3'which is masked in a predetermined manner. The predetermined fine processing is performed by dry etching.

Reference numeral 25 is a probe, 21 is a multi-pole magnet, 22 is an electron beam target sample 24.
It is a magnetic electromagnetic shutter provided to mitigate the collision with.

In order to perform the fine dry etching of the target sample 24 having a large diameter in the plasma chamber 3'according to the design and surely, the amount of ions (the number of ions) is increased. Target sample 24 of material to be etched
Of a so-called selectivity ratio for increasing the etching rate of the target sample 24 and improving the productivity, and reducing the ion speed to reduce the processing amount of masking as much as possible to ensure the processing of the target sample 24. 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 above.

By the way, the target sample 24 is the holder 2
Although it is in a so-called floating state in which it is electrically insulated in a state of being supported by 3, the electron beam is negatively charged when it is incident from the acceleration region 15, and thus
Since the ions in the plasma chamber 3 ′ are irradiated through the potential difference (plasma potential−surface potential) formed on the surface to perform a desired dry etching process, the target sample 24 covered with the masking described above. In order to increase the selection ratio and perform the etching process as desired, it is necessary to suppress the potential difference in the state of being negatively charged by the electron beam in order to reduce the kinetic energy of the ions. Was adopted.

That is, first, the accelerating voltage in the electron beam accelerating region 15, that is, the voltage between the accelerating electrode 13 and the discharge anode 11 is lowered to lower the energy of the electron beam incident on the plasma chamber 3 '. Then, by reducing the negative charging voltage of the target sample 24, the target sample 2
4 is a method of suppressing the irradiation energy of ions by lowering the potential formed on the surface of No. 4, and secondly, the magnet 2 as a magnetic shutter immediately before the holder 23 of the target sample 24.
2 and the like, and the electrons incident on the plasma chamber 3'from the acceleration region 15 of the electron beam are scattered and the target sample 2
This is a method in which high-energy electrons do not directly enter 4.

[0012]

However, the higher technology of the recent industry is promoted, the diameter of the wafer of the target sample 24 is increased, and the performance of the electron beam excited plasma generator 1 is promoted accordingly. However, when it is desired to make itself compact and downsize, and further cost reduction is pursued, uniform and early diffusion of the electron beam in the plasma chamber 3 ′ is required, Therefore, as shown in FIG. 12, in addition to disposing the magnet 22 of the magnetic shutter so as to face the target sample 24, the reverse magnetic field coil 17 is arranged outside the reaction chamber 3 and the multi-pole magnet 21 is arranged inside. Various modes are adopted.

Further, a means for disposing the magnetic field coil 16 for electron beam control and 16 'outside the discharge electrode 11 and the acceleration electrode 13 has also been taken.

The discharge electrode 11 is shown in FIG.
As shown in (1), one hole 26 through which the electron beam passes is provided in the central portion of the hole so as to accelerate the acceleration of the electron beam by the acceleration electrode 13.

By the way, as shown in FIG. 12, since the inverse magnetic field coil 17 is disposed outside the reaction chamber 3, its diameter is inevitably large, and the magnetic field coil 16,
Also, there is a problem that it is extremely difficult to accurately align with 16 '. As a result, the distribution of the magnetic field lines in the plasma chamber 3'is non-uniform, and the orbit of the electron beam becomes non-axisymmetric. In addition, the rapid diffusion of the magnetic field lines is insufficient, and the electron beam is radiated along the magnetic field lines so that it cannot spread sufficiently and there is a drawback that a uniform plasma cannot be formed. Since the diameter and length of the plasma chamber 3'need to be considerably increased in order to promote the diffusion and homogenization, there is an inconvenience that the device cannot be shortened, and the ion current density is lowered, and However, there was a problem that it was inevitable to cause non-uniformity.

Further, there is a disadvantage that the energy loss due to heat generation when electrons and ions are generated in the plasma chamber 3'becomes large, and moreover, cooling pipes for the probe 25 and the magnetic shutter 22 and the magnetic shutter 22 are provided.
Since the support of the or multi-pole magnet 21 is erected in a complicated manner in the reaction chamber 3, the loss of ions and electrons occurs on their surfaces, and the effect of disturbing the uniformization of the electron beam and good diffusion is avoided. There was a negative point that there was no.

In the system using the magnetic shutter 22, the electron beam is emitted from the magnetic shutter 22 and the multi-pole magnet 2.
1 and 21 pass through the narrow path between the magnetic fields to reach the front surface of the wafer of the target sample 24, the amount of the electron beam passing through the narrow path between the magnetic shutter 22 and the multi-pole magnet 21 becomes small, which is so-called. This causes a decrease in passage efficiency, a decrease in plasma density on the front surface of the wafer of the target sample 24, and a problem in that sufficient uniformity cannot be obtained.

In order to make the device compact in order to meet the needs of the research community and industry, it is desirable to shorten the length of the electron beam gun, which is the basis of the overall complicated structure, and the discharge electrode in the acceleration region 15 is preferable. The shorter the distance between 9 and the accelerating electrode 13, the smaller the scattering of the electron beam in the accelerating region 15, and the ratio of the electrons that pass through the accelerating region 15 and are driven into the plasma chamber 3 ′, that is, the passage efficiency is Although it is desirable in terms of heightening, if the capacity and the diameter of the pump connected to the exhaust port 20 in the electron beam gun 2 are uniquely determined, the discharge electrode 9 and the accelerating electrode 13 are connected to each other. There is a restriction that the distance is determined and, as a result, the electron beam gun 2 cannot be shortened.

To deal with this, Japanese Patent Laid-Open No. 10553/1989
No. 9 invention, JP-A-1-105540 invention, further JP-A-1-176633 invention, JP-A-56-10.
Although various inventions such as the invention of 2100 have been devised, none of the disclosed techniques can easily generate highly uniform and high-density plasma, and the obstacle to miniaturization of the device is fundamentally solved. It was an unsatisfactory one, and there was an insufficiency that the economical use of operating power could not be achieved.

[0020]

OBJECT OF THE INVENTION The object of the invention of this application is that, although it has a potentially very excellent advantage for dry etching processing of a target sample such as a wafer which is indispensable for semiconductor technology based on the above-mentioned prior art, it is highly uniform. Various problems that hinder the generation of plasma and the downsizing and downsizing of the apparatus are technical problems to be solved, and the magnetic field lines in the plasma chamber can be rapidly diffused, so that the electron beam is generated in the plasma chamber. Highly uniform spread, high-precision irradiation of ions to be irradiated on the wafer, and high uniformity of electron beam in the plasma chamber can be achieved. The target sample wafer can be advanced and the plasma chamber can be shortened,
As a result, the plasma density is improved, downsizing is achieved, the electron beam gun is downsized, the power source is downsized, the entire device is compact, the power consumption is reduced, and the operability is improved. The present invention aims to provide an excellent small-sized electron beam excited plasma generator that is useful in the field of processing technology application in the electronics industry.

[0021]

In order to solve the above-mentioned problems, the structure of the invention of this application, which is based on the above-mentioned object, is applied to a device of an electronic apparatus for performing ultra-high-speed operation. In order to perform ultra-precision dry etching processing on a silicon wafer forming a highly integrated circuit such as IC and lSI used, the silicon wafer or the like is used as a target sample through a holder in a plasma chamber of a reaction chamber of an electron beam excitation plasma generator. The hot cathode filament of the electron beam gun, which is installed in a predetermined position in the reaction chamber, is heated to a predetermined temperature, argon gas or the like is supplied to the plasma region to generate plasma, and the electron beam is induced by the auxiliary electrode and the discharge electrode. , Further accelerate it by the acceleration electrode in the acceleration region and lead it to the plasma chamber of the reaction chamber,
At that time, in the discharge electrode, the central portion of the electrode plate is made solid, an electron beam passage hole is formed around the central portion to form a porous plate, and the passing electron beam forms a central portion of the plasma chamber. The central area of the wafer of the target sample is not irradiated intensively, and the discharge electrode and the acceleration electrode are arranged so that one side is relatively close to the other side, and the size of the electron beam gun is reduced. In addition, it is possible to shorten the length, and to equip the support of the acceleration electrode and the discharge electrode with a magnetic field coil, or to install it as a permanent magnet, etc. In addition, arrange a magnetic shield in this part, The electron beam is less likely to be scattered in the acceleration region, the penetration efficiency of the acceleration electrode is good, the magnetic force lines in the plasma chamber are rapidly diffused, and the electron beams are also rapidly diffused along the magnetic force lines. Highly uniform ion generation and electron distribution are performed, and fine dry etching processing for a large-diameter target sample wafer is performed with high efficiency, and the backflow of plasma forming gas from the plasma chamber to the acceleration region is reduced. By making it possible to reduce the exhaust volume of the pump required in the region, the pump can be downsized, and as a result, downsizing of the acceleration region, downsizing by advancing the wafer, and downsizing are promoted. Not only initial assembly, but also maintenance and operation such as management, maintenance, inspection and maintenance during the operation period are easy, initial cost as well as running cost are reduced, equipment is simple and durability is improved. However, the technical measures have been taken so as to significantly improve the operation efficiency.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the invention of this application is shown in FIGS.
It will be described below based on 1.

The same parts as in FIGS. 12 and 13 will be described using the same reference numerals.

In the embodiment shown in FIG. 1, reference numeral 1'denotes a small-sized electron beam excited plasma generator for industrial use, which is the subject matter of the invention of the present application, and is a plasma of a target sample 24 of a large-diameter silicon wafer. This is a mode in which ultrafine dry etching is performed by ions, and substantially the same operation as in the conventional mode shown in FIG. 12 is performed.

In this embodiment, therefore, the relatively small diameter cylindrical electron beam gun 2 at the front stage and the relatively large diameter cylindrical reaction chamber 3 at the rear stage are directly connected and integrated into a horizontal type. These are made of SUS or Al, and in the electron beam gun 2, the filament 5 of the electrode 4 of the hot cathode on the proximal end side is connected to the heating electrode 6 and the plasma region 2'is A port 7 is provided so that the argon gas 8 for plasma formation is supplied in a predetermined manner as in the conventional mode.

An auxiliary electrode 9 is provided on the filament 5, and a discharge electrode 11 is provided between the auxiliary electrode 9 and the acceleration electrode 13 in the subsequent acceleration region 15 and connected to the power sources 10 and 12, respectively. They are connected to form an acceleration region 15.

The exhaust port 2 is provided in front of the acceleration electrode 13.
0 is formed and is connected to a predetermined exhaust pump.

A magnetic field coil 16 is concentrically provided on the discharge electrode 11, and a magnetic field coil 16 'is provided on the outer side of the acceleration electrode 13 and on the outer side of the magnetic field coil 16'. Is concentrically provided with a reverse magnetic field coil 17 'on the outside thereof.

In the reaction chamber 3 connected to the electron beam gun 2, a chlorine gas supply port 18 is provided on the wall surface near the electron beam gun 2 to provide the chlorine gas 1
9 is supplied to form a predetermined plasma in the plasma chamber 3 ', and an exhaust port 20' is provided on the opposite wall surface.

A multi-pole magnet 21 is fitted outside the reaction chamber 3, and a holder 23 is inserted near the inner rear end to set a target sample 24 of a silicon wafer in a predetermined manner. In the invention of this application, the conventional magnetic shutter 22 shown in FIG. 12 is not provided.

Reference numeral 25 is a probe.

Further, in the mode of this embodiment, unlike the conventional mode shown in FIG. 12, the reverse magnetic field coil 17 is not provided outside the reaction chamber 3, and the electron beam gun 2 is installed as described above. The magnetic field coil 1 is provided outside the accelerating electrode 13 at the end.
A magnetic field coil 17 'is concentrically fitted to the outer side of 6'to form a double coil.

Therefore, in this embodiment, the electron beam trajectory is formed so as to be symmetrical with respect to the axis, and the reverse magnetic field coil 17 is provided outside the reaction chamber 3 as in the conventional mode shown in FIG. In the case of the embodiment, there are few restrictions on positioning and centering, the axis alignment becomes accurate, and the trajectory of the electron beam tends to be the axial target in terms of design. Moreover, the magnetic field coil 16 'and the inverse magnetic field coil 17' The electron beam can be diffused early along the magnetic field in the plasma chamber 3'of the reaction chamber 3, and the electrons diffused in the radial direction are efficiently reflected by the magnetic field created by the multi-pole magnet 21,
As a result, the uniform dispersion of the electron beam in the plasma chamber 3 ', that is, the flux of the excited ions to the target sample 24 and the uniform irradiation of energy are surely performed.

Thus, in the invention of this application, a magnetic shield made of a predetermined material such as permalloy, low carbon steel, electromagnetic soft iron, or mumetal is formed on the outer wall surface of the reaction chamber 3 near the electron beam gun 2. 27 is appropriately attached so as to block the propagation of the magnetic field lines from the magnetic field coil 16 ′ and the inverse magnetic field coil 17 ′ into the plasma chamber 3 ′, and therefore, from the acceleration electrode 13 into the plasma chamber 3 ′. The diffusion of the emitted electron beam is designed to be performed as rapidly as possible.

As a result, electrons and excited ions are irradiated onto the target sample 24 with a highly uniform and large spread.

Thus, the embodiment shown in FIG.
3 is a mode in which a magnetic field coil 16 ′ attached to 3 is housed in the support of the accelerating electrode 13 or inside the accelerating electrode itself to form a built-in coil type. As the inner diameter of the coil becomes smaller, the electron beam is rapidly diffused in the plasma chamber 3 ', and uniform excitation ions are irradiated to the target sample 24, and the magnetic field coil 16' is also provided. Since the size of the electron beam gun 2 is reduced, the power consumption is suppressed, and the electron beam gun 2 can be made shorter and compact.

Further, in this embodiment, the acceleration electrode 13
By attaching a magnetic shield 27 'made of a predetermined material such as permalloy or low carbon steel to the back surface of the plasma chamber 3', it is possible to prevent magnetic field lines from penetrating into the plasma chamber 3 '. Similar to the embodiment, the rapid diffusion of the electron beam in the plasma chamber 3'is also achieved, and the highly homogenized ion beam can be similarly applied to the target sample 24.

In this case, as in the embodiment shown in FIG.
It is possible to provide flanges on the inner and outer edges of the magnetic shield 27 'and further provide supply / discharge ports 29, 29' for the cooling water 28, and it is also possible to combine magnetic shields of a plurality of materials.

By disposing the magnetic shield 27 'on the accelerating electrode 13 as shown in FIG. 4, the abscissa Z (m) represents the distance into the plasma chamber 3'in the electron beam extraction direction.
When the magnetic force H (Oe) Gauss is taken on the vertical axis, as shown in the lower part of FIG. 4, a mode without the magnetic shield 27, a mode with a flat magnetic shield 27 ', and a magnetic field with flanges at both ends. In the mode in which the shield 27 '' is additionally provided, as shown in the characteristic curve graph in the upper stage, the peak of the magnetic force at the desired portion is attenuated and the electron beam is restrained by reducing the electron beam. Experiments have shown that the beam divergence can be rapid.

The shape of the magnetic shield can be designed in addition to the above-mentioned ones, as shown in the lower part of FIG.

Further, as described above, in the conventional electron beam excitation plasma generator 1 shown in FIG. 12, the discharge electrode 11 in the electron beam gun 2 is provided with the electron beam passage hole 26 penetrating through the central portion thereof. Since the central portion of the energy region of the electron beam is led out into the plasma chamber 3 ′, it does not spread because it has the above-described form, and in the state without the magnetic shutter 22, the electron beam directly reaches the target sample 24 of the silicon wafer. The high energy portion of the central portion of the electron beam was abruptly irradiated, but in the invention of this application, as in the embodiment shown in FIG. The discharge electrode plate 11 'is made solid and has pores 26', 26 'arranged in a ring shape around the center as shown in the mode (a), or as shown in (b), the pores 26'. '...
Discharge electrode plate 1 in which the holes are formed in a double ring shape
1 '' or as shown in (c), the radial holes 2
6 ″ ″ electrode plate 11 ″ ″, or as shown in (d), a through hole 26 ″ ″ electrode plate 1
It can be set to "". By doing so, the electron beam having a high energy region is not irradiated on the axial centerline of the plasma chamber 3'of the reaction chamber 3, so that the plasma chamber 3 ' In that case, the average diffusion of the electron beam is achieved, and it is not necessary to dispose a magnetic shutter.
Further, the magnetic shields 27, 27 'and the like are arranged together, so that irradiation with uniform diffusion of the electron beam can be achieved more reliably.

In the embodiment shown in FIG. 6, the discharge electrode 11 is used.
A magnetic field coil 16 corresponding to the discharge electrode 11 or a magnetic field coil 16 'corresponding to the accelerating electrode 13 is built into the support itself or the electrode itself. By making the magnetic field coils 16 and 16 ′ corresponding to the inside of the discharge electrode 11 and the acceleration electrode 13 of the electron beam gun 2 both internal, the power consumed by the magnetic field coils 16 and 16 ′ is reduced, and The diameter is small, downsizing is promoted, the transmitted electron beam is rapidly diffused in the plasma chamber 3 ', and uniformization can be achieved at the same time.

Further, since the diameters of these coils can be made small, it is easy to increase the magnetic field strength of the electrode portion. As a result, the electron beam convergence is improved and the electron beam passage hole of the electrode is made small. It becomes possible to make it size,
Therefore, the reverse flow rate of the chlorine gas 19 from the plasma chamber 3'to the electron beam gun 2 is small, and the exhaust pump capacity is small accordingly, so that the apparatus can be made compact and downsized. become.

Next, in the embodiment shown in FIG. 7, in order to enhance the function of each of the above-mentioned embodiments, the acceleration electrode 13 'is made closer to the discharge electrode 11 side by making the electron beam passage portion taper. This is a mode in which the distance between the discharge electrode 11 and the acceleration electrode 13 'is shortened, the electron beam gun 2 is shortened, and the plasma chamber 3'is lengthened, and the target sample 2
4 to the electron beam gun 2 side, the apparatus is downsized as a whole, and the electron beam in the acceleration region 15 is not largely scattered, and the transmission efficiency of the acceleration electrode 13 'is increased. This is the mode.

Therefore, in this embodiment, the acceleration electrode 13 is used.
Since the electron beam transmission hole in the chamber can be made small in size, the backflow of chlorine gas 19 from the plasma chamber 3'to the electron beam gun 2 side is also suppressed, and the gas pressure in the acceleration region 15 is reduced. Since the exhaust pump can be increased in size as compared with the conventional one and the capacity of the exhaust pump can be reduced, it is possible to reduce the initial cost and the running cost associated with downsizing of the acceleration region 15 by using a small pump.

In addition, the accelerating electrode 13 'is located in the plasma chamber 3'.
Since it is formed in an enlarged taper shape toward the side, the rapid diffusion of the electron beam in the plasma chamber 3'is further assisted together with the influence of the potential of the acceleration electrode 13 '.

Thus, in the embodiment shown in FIG.
8 is an embodiment in which the embodiment of FIG. 8 is added, and the electron beam transmitting hole portion of the accelerating electrode 13 'is brought close to the discharge electrode 11 side, and a magnetic field coil 16' is further built in the portion. It is an expression and combines these functions and effects.

Thus, in the embodiment shown in FIG. 9, the permanent magnet 1 is the magnet incorporated in the acceleration electrode 13 'of the embodiment shown in FIG.
In the embodiment, the direction of the lines of magnetic force of the permanent magnet 16 '' is reversed at a predetermined axial position. Due to the magnetic field formation by the magnetic field coil 16, the combined magnetic field with the permanent magnet 16 ″ built into the accelerating electrode 13 ′ does not reverse in the accelerating region 15 but reverses on the plasma chamber 3 ′ side. The lines of magnetic force rapidly spread in 3 ', the electron beam introduced along the lines of magnetic force converges in the acceleration region 15, and rapidly diffuses in the plasma chamber 3', so that in the plasma chamber 3 '. The excitation of the ions and the expansion of the electron beam are uniformly performed, and the target sample 24 is irradiated with the ions having the uniform flux and energy in the plane.

In the mode of this embodiment, the lines of magnetic force produced by the permanent magnet rapidly spread, so that the electron beam can sufficiently spread in the plasma chamber 3'without using the reverse magnetic field coil 17 '.

Next, in the embodiment shown in FIG. 10, contrary to the embodiment shown in FIGS. 7 to 9, the discharge electrode 11 ′ is tapered toward the accelerating electrode 13 side, and the accelerating region 15 is formed.
Is extended to the vicinity of the plasma chamber 3 ', and even in this mode, the distance from the accelerating electrode 13 is reduced, and the plasma chamber 3'through the accelerating electrode 13 without the electron beam being strongly scattered.
To improve the electron beam passing efficiency of the accelerating electrode 13 and promote the downsizing and downsizing of the accelerating region 15 by reducing the capacity of the exhaust pump, thereby improving the efficiency and further improving the electron beam gun 2. This is a mode in which the cost can be reduced by making it compact.

Then, in the embodiment shown in FIG.
This is a mode in which the magnetic field coil 16 corresponding to the rearward extending discharge electrode 11 'of the embodiment of FIG. 10 is built in the discharge electrode 11' itself or its support, and the power consumption of the magnetic field coil 16 is reduced. In this mode, further downsizing of the apparatus, electron beam passage efficiency, and spread can be improved.

Of course, the embodiment of the invention of this application is not limited to the above-mentioned embodiments, and in the embodiment shown in FIG. 11, the magnet 16 built in the acceleration electrode 13 'is used.
It is possible to adopt various modes such as using a permanent magnet instead of the magnetic field coil for ', or combining FIG. 9 and FIG. 11.

Further, it goes without saying that the magnetic shield can be provided on both the outer wall surface of the reaction chamber and the back surface of the acceleration electrode.

[0054]

As described above, according to the invention of this application, in an electron beam excitation plasma generator basically having various advantages as described above, a target sample such as a silicon wafer for which a large diameter is desired is desired. Rapid diffusion of the electron beam derived from the electron beam gun in the plasma chamber of the reaction chamber is made possible by reducing the diameter of the magnet. Therefore, the electron beam gun itself can be shortened, and accordingly, the plasma chamber can be shortened. The size of the target sample has been reduced and the size of the target sample has been reduced, and the downsizing of the entire device has been promoted. In addition, the uniformity of the center of the target sample has been promoted due to the rapid diffusion of the electron beam introduced into the plasma chamber. Collision of the central part of the electron beam with a high energy region with respect to the part is avoided, and the orbit of the electron beam is axisymmetrically made uniform. Plasma generation is achieved an excellent effect that is obtained.

Therefore, by omitting the magnetic shutter and the holder for holding the magnetic shutter as in the conventional method, the loss of electrons and ions on the surface is reduced, and high-quality fine dry etching as designed can be performed at high speed. The excellent effect is obtained.

The elimination of the magnetic shutter eliminates a bottleneck with the multi-pole, and from this point also, the electron beam loss is reduced and the homogenization by diffusion is promoted.

The position of the target sample can be determined by, for example, fitting a reverse magnetic field coil outside the reaction chamber to the outside of the acceleration electrode near the base of the electron beam gun, and the coil outside the electron beam gun. There is also an effect that the alignment can be easily carried out, the alignment can be easily centered, the lines of magnetic force are uniformly formed, and the orbit of the electron beam is formed axisymmetrically.

Further, at least one of the discharge electrode and the accelerating electrode is tapered so that the accelerating region can be shortened, so that the axial length in the electron beam gun can be reduced. This leads to the shortening of the beam gun, which not only shortens the entire apparatus, but also prevents the backflow of the plasma-generated gas in the plasma chamber to the electron beam gun, which makes it possible to reduce the capacity of the exhaust pump in the acceleration region. The size of the electron beam gun can be shortened and downsized from this point as well.

Further, it is possible to increase the amount of argon gas or the like introduced from the upstream portion of the electron beam gun by the amount of the reduced backflow of the plasma generating gas into the electron beam gun in the plasma chamber, and as a result, the discharge region There is also an effect that the gas pressure is increased and the amount of the electron beam extracted from the discharge part can be increased.

By making the magnets corresponding to the discharge electrodes and the acceleration electrodes built-in or using permanent magnets, the lines of magnetic force in the plasma chamber are rapidly expanded, and the electron beam along them is also rapidly diffused. As described above, the effect of adding uniformity is also added.

By disposing the magnetic shield on the side wall of the reaction chamber and the back surface of the accelerating electrode, lines of magnetic force do not penetrate into the plasma chamber and rapid diffusion of the electron beam in the plasma chamber is promoted. From this point, there is an excellent effect that the target sample can be uniformly irradiated with ions in the plasma chamber.

By making the electron beam transmitting hole of the discharge electrode a porous electrode around the center, irradiation of the electron beam in the high energy region along the center line toward the center of the target sample is avoided. As a result, a ring-shaped electron beam enters the reaction chamber and interacts with the effect of electron reflection by the multi-pole, and even if the magnetic shutter is omitted, a uniform plasma can be generated, and moreover, the casing of the magnetic shutter. It is possible to avoid obstacles such as metal contamination due to loss of electrons and ions generated in the cooling pipes and the like, and also from this point, it is possible to obtain a fine effect of fine dry etching.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a basic embodiment of the invention of this application.

FIG. 2 is a partial vertical cross-sectional view of another embodiment.

FIG. 3 is a schematic enlarged vertical sectional view of the acceleration electrode.

FIG. 4 is a model diagram of a magnetic field formation with a magnetic shield attached to the acceleration electrode.

FIG. 5 is a schematic surface view of a porous electrode of a discharge electrode.

FIG. 6 is a partial vertical sectional view of another embodiment.

FIG. 7 is an overall schematic vertical cross-sectional view of another embodiment.

FIG. 8 is a partial vertical cross-sectional view of still another embodiment.

FIG. 9 is a partial vertical cross-sectional view of another embodiment of the same.

FIG. 10 is a vertical sectional view of an electron beam gun of yet another embodiment.

FIG. 11 is a vertical sectional view of an electron beam gun of yet another embodiment.

FIG. 12 is an overall schematic cross-sectional view of a conventional electron beam excitation plasma generator.

FIG. 13 is a surface view of the electrode plate of the discharge electrode.

[Explanation of symbols]

 1'Small electron beam excitation plasma generator 24 Target sample 23 Target sample holder 3 Reaction chamber 15 Electron beam acceleration region 11 Discharge electrode 13 Accelerating electrode 16, 16 ', 17' Magnet 16 '' Permanent magnet 27, 27 'Magnetic shield 11 ', 11' 'electrode plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Manabu Hamagaki 2-1 Hirosawa, Wako-shi, Saitama, RIKEN (72) Inventor Katsunobu Aoyagi 2-1 Hirosawa, Wako-shi, Saitama (RIKEN) ( 72) Inventor Ryuji Makoto 1-1 Kawasaki-cho, Akashi-shi, Hyogo Inside the Akashi Plant, Kawasaki Heavy Industries, Ltd. (72) 1-1 Masato Kawasaki, Akashi-shi, Hyogo Inside Akashi Plant, Akashi Factory (72) Inventor Hiroshima An 1-1 Kawasaki-cho, Akashi-shi, Hyogo Prefecture Kawasaki Heavy Industries Ltd. Akashi factory (72) Inventor Masakuni Tokai Kawasaki-cho, Akashi-shi, Hyogo Prefecture 1-1 Kawasaki Heavy Industries Ltd. Akashi factory

Claims (11)

[Claims] 1. An electron beam gun in a front stage and a reaction chamber which is integrated with the electron beam gun and in which a target sample holder is installed. A front and rear discharge electrodes and a rear stage acceleration electrode are provided in an electron beam acceleration region of the electron beam gun. An electron beam excited plasma generator in which a reverse magnetic field for an electron beam is formed in the reaction chamber, wherein a magnet for forming the magnetic field has a small diameter. . 2. A small-sized electron beam excitation plasma generator according to claim 1, wherein said magnet is built in a support of an electrode in an acceleration region. 3. The small-sized electron beam excitation plasma generator according to claim 2, wherein the magnet is an electromagnet. 4. The small-sized electron beam excitation plasma generator according to claim 1, wherein the electromagnet is a double coil and is concentrically arranged on the electrode. 5. The small-sized electron beam excitation plasma generator according to claim 2, wherein the magnet is a permanent magnet. 6. A reaction chamber comprising an electron beam gun in the preceding stage and a target sample holder integrated with the electron beam gun, wherein front and rear discharge electrodes and post-acceleration electrodes are arranged in an electron beam acceleration region of the electron beam gun. In the electron beam excitation plasma generator in which a reverse magnetic field for the electron beam is formed in the reaction chamber, the magnet forming the magnetic field has a small diameter, and the electrode has a structure in which the acceleration region can be shortened. A small-sized electron beam excited plasma generator having a structure in which an electron beam in a plasma chamber can be expanded. 7. The small-sized electron beam excitation plasma generator according to claim 6, wherein the accelerating electrode of the electrodes is arranged close to the discharge electrode side. 8. A small-sized electron beam excitation plasma generator according to claim 5, wherein the discharge electrode of the electrodes is arranged close to the acceleration electrode side. 9. A miniature electron beam excited plasma generator according to claim 1, wherein a magnetic shield is provided on the side of the acceleration region of the reaction chamber. 10. The small electron beam excitation plasma generator according to claim 3, wherein the magnetic shield is provided inside a support in the acceleration electrode. 11. An electron beam gun in a front stage and a reaction chamber integrated with the electron beam gun in which a target sample holder is provided, wherein front and rear discharge electrodes and a rear stage acceleration electrode are provided in an electron beam acceleration region of the electron beam gun. In an electron beam excitation plasma generator in which a reverse magnetic field for an electron beam is formed in the reaction chamber, the magnet for forming the magnetic field is reduced in diameter, and the discharge electrode is formed of a solid porous electrode plate. A small electron beam excited plasma generator characterized in that