JPH08264142A - Electron beam apparatus - Google Patents

Abstract

PURPOSE: To provide an electron beam apparatus which has a simple structure and of which electric current flow (electric current density) of electron beam can be changed at high speed. CONSTITUTION: Electron beam EB with which a cross-over image is focused near a grid electrode 2 is focused before an aperture part of a diaphram 17 by a lighting lens 7. When a signal corresponding to a prescribed electron beam electric current flow is supplied to an electric power source 31 for a lens for modulation, exciting electric current corresponding to the signal is supplied to a lens 30 for modulation from the electric power source 31 for a lens. As a result, electron beam is defocused in the diaphram 17, expanded, and radiated to the diaphram 17. Consequently, a part of the electron beam is shielded by the diaphram 17 and the quantity of the electron beam which passes an aperture of the diaphram 17 is lessened, so that the quantity of the electron beam which passes the aperture of the diaphram 17 and is radiated to a material 9 can be changed optionally by the defocusing degree.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam apparatus such as an electron beam annealing apparatus capable of scanning an electron beam on a material and further varying the current density of the electron beam with which the material is irradiated.

[0002]

2. Description of the Related Art Polysilicon on a silicon wafer is recrystallized (single crystallized) by an electron beam annealing apparatus. In this case, the material is scanned with an electron beam to carry out the desired recrystallization. FIG. 1 shows an example of an electron beam apparatus used for such electron beam annealing.

In the figure, 1 is a cathode that emits electrons,
The cathode 1 constitutes an electron gun by the grid electrode 2 and the anode electrode 3 having a ground potential. A negative high voltage is applied to the cathode 1 from the high-voltage generating power source 4 to the anode electrode 3 at the ground potential, and a heating current for heating the cathode 1 is supplied from the heating power source 5. A control voltage is applied to the grid electrode 2 from the control power supply 6.

In such a structure of the electron gun, the cathode 1
Are heated to radiate thermoelectrons, electrons are taken out from the grid electrode 2 in accordance with a control voltage applied from the control power supply 6 between the cathode 1 and the grid electrode 2, and the electrons are supplied to the cathode 1 and the anode electrode 3. The acceleration voltage is applied from the high-voltage generating power source 4 during this period. The electron beam EB generated and accelerated by the electron gun is focused on the material 9 by the illumination lens 7 and the objective lens 8.
The illumination power is supplied to the illumination lens 7 from the lens power supply 10, and the excitation current is supplied to the objective lens 8 from the lens power supply 11.

Two types of alignment coils 12 and 13 are arranged below the electron gun. The alignment coil 12 is a tilting alignment coil, and the alignment coil 13 is a horizontal alignment coil. An alignment current for correcting the axis shift of the electron beam is supplied from the alignment power supply 14 to the two types of alignment coils 12 and 13. A blanking electrode 15 is provided below the illumination lens 7, and the blanking electrode 14 has a blanking power supply 1
A blanking signal is supplied from 6.

Electron beam E generated and accelerated by an electron gun
Two diaphragms 17 and 18 are arranged along the optical path of B. The apertures 17 and 18 have a small opening,
When the electron beam passes through this opening, the electron beam has a relatively uniform energy. In addition,
A sluice valve 19 is provided between the throttles 17 and 18. The sluice valve 19 is provided with an electron gun portion that needs to be maintained at a relatively high vacuum and a material that relatively deteriorates the degree of vacuum. It is provided for vacuum separation from the material chamber in which it is located. Of course, when the material 9 is irradiated with the electron beam EB, the gate valve 19 is opened.

Reference numeral 20 is a deflector for scanning the electron beam in the horizontal direction, and an electrostatic type is used. Further, 21 is a deflector for scanning the electron beam in the vertical direction, and an electromagnetic type is used. A horizontal scanning signal is supplied from a horizontal deflection power source 22 to the horizontal deflector 20. The vertical deflection power supply 23 supplies a vertical scanning signal to the vertical deflector 21.

Reference numeral 24 is an astigmatism corrector, 25 is a dynamic focus lens, and the astigmatism corrector 24 is supplied with a correction signal for correcting the distortion of the electron beam diameter from an astigmatism correction power source 26. Further, a correction current synchronized with the horizontal and vertical scanning signals is supplied from the lens power supply 27 to the dynamic focus lens 25. The operation of such a configuration will be described below.

First, the electron beam EB generated and accelerated by the electron gun is focused on the material 9 by the illumination lens 7 and the objective lens 8. At this time, the current of the electron beam applied to the material 9 is controlled according to the voltage supplied from the control power supply 6 to the grid electrode 2. The electron beam emitted from the grid electrode 2 forms a crossover image between the grid electrode 2 and the anode electrode 3. The image forming position of the crossover image is determined by the shape of each electrode, the potential applied to each electrode, and the distance between the electrodes. This combined image is focused on the material 9 by the illumination lens 7 and the objective lens 8. At this time, the distortion of the diameter of the electron beam with which the material 9 is irradiated is corrected by the astigmatism corrector 24.

The electron beam EB irradiated on the material 9 is scanned by the horizontal deflector 20 and the vertical deflector 21, and as a result, a predetermined region of the material 9 is two-dimensionally scanned. The signals from the horizontal deflection power supply 22 and the vertical deflection power supply 23 are also supplied to the dynamic focus lens power supply 27, and this lens power supply 27 supplies the dynamic focus signal according to the deflection of the electron beam to the dynamic focus lens 25. From the electron beam EB
Is always in focus even by deflection.

As described above, by focusing the electron beam EB on the material and further scanning on the material 9,
The material 9 can be annealed. When the material 9 is polysilicon, the control voltage from the control power supply 6 to the grid electrode 2 is changed as appropriate to change the electron beam current amount,
That is, the current density of the electron beam with which the material 9 is irradiated is changed.

[0012]

In the electron beam apparatus described above, two methods have been taken to change the amount of current (current density) of the electron beam with which the material 9 is irradiated. The first method is, as described above, the grid electrode 2
This is a method of changing the voltage applied to. By this method,
The amount of the electron beam passing through the grid electrode 2 changes.
The second method is to change the heating current of the cathode 1 and change the temperature of the cathode 1 to change the emission current.

In the first method described above, since the grid voltage is changed, the divergence angle of the electron beam emitted from the electron gun changes, the Z direction position of the crossover image shifts, and the surface of the material 9 is changed. Out of focus. Therefore, it is necessary to readjust the exciting currents of the illumination lens 7 and the objective lens 8. From this, in the first method, for example,
When it is desired to change the beam current at a high speed on the order of μsec, it is difficult to realize it because the illumination lens 7 and the objective lens 8 are electromagnetic lenses. Further, in this method, since the grid voltage applied from the control power supply 6 to the grid electrode 2 is on the high voltage (−several tens KV) from the high-voltage generation power supply 4, the floating capacity and reactance in the electron gun chamber are large. Now, it is technically extremely difficult to change at high speed.

In the second method, the heating current from the heating power source 5 is changed in order to change the temperature of the cathode 1. However, even if the current is changed, the temperature of the cathode 1 is immediately set to a desired value. You cannot do it. The response speed when changing the current in this way is in seconds, and therefore μ
It is impossible to change the current density of the electron beam with which the material 9 is irradiated at a high speed on the order of sec.

The present invention has been made in view of the above circumstances, and an object thereof is to realize an electron beam apparatus capable of changing a current amount (current density) of an electron beam at a high speed with a simple structure. is there.

[0016]

According to another aspect of the present invention, there is provided an electron beam apparatus in which a first lens system for forming an electron beam from an electron gun on an aperture portion of an aperture and an aperture image of the aperture on a material. The lens system that forms an image on the diaphragm and the electron beam that is provided above the diaphragm and that irradiates the diaphragm are defocused arbitrarily.
And a modulation lens for changing the amount of the electron beam passing through the aperture of the diaphragm.

The electron beam apparatus according to the invention of claim 2 is characterized in that the modulating lens used in the invention of claim 1 is composed of an air-core coil.

[0018]

In the electron beam apparatus according to the present invention, the electron beam generated from the electron gun and applied to the diaphragm is arbitrarily defocused to change the amount of the electron beam passing through the aperture of the diaphragm.

In the electron beam apparatus according to the second aspect of the present invention, an air-core coil is used as a modulation lens for arbitrarily defocusing the electron beam, and the current amount of the electron beam is changed at high speed.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 shows an electron beam apparatus according to the present invention. The same or similar components as those of the conventional apparatus of FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted.
The difference between this embodiment and the conventional apparatus of FIG.
The modulation lens 30 is provided on the upper part of, and the size of the aperture formed in the diaphragm 17 is reduced to the size of the crossover image of the electron beam. An exciting current is supplied to the modulating lens 30 from a modulating lens power source 31. The aperture of the diaphragm 17 is rectangular or circular.

The modulation lens 30 uses an air-core coil and is capable of responding at high speed. The modulation lens power supply 31 is connected to a control device 32 such as a computer, and changes the degree of focusing of the electron beam on the modulation lens 30 based on a signal from the control device 32 corresponding to the amount of current of the electron beam. An exciting current is supplied to cause this. The controller 32 also controls the horizontal deflection power supply 22 and the vertical deflection power supply 23, and supplies the deflection power supply with a signal corresponding to the scanning range of the electron beam on the material 9 and the scanning speed. The frequency of the scanning signal from this deflection power supply is
The scanning speed is about 0 KHz.

A signal synchronized with the horizontal and vertical scanning signals is supplied from the control device 32 to the lens power supply 27 for the dynamic focus lens 25, so that the electron beam on the material 9 is irrespective of the deflection position of the electron beam. Is normally focused. The lens power source 11 of the objective lens 8 supplies an exciting current to the objective lens 8 so that the aperture image of the diaphragm 17 is formed on the material 9 by the objective lens 8. The operation of such a configuration will be described below.

The electron beam EB on which the crossover image is formed in the vicinity of the grid electrode 2 is formed by the illumination lens 7 in front of the aperture of the diaphragm 17. At this time, the electron beam EB imaged in front of the diaphragm 17 diverges at a predetermined opening angle, but the size of the aperture of the diaphragm 17 is such that the diverging electron beam can almost pass through.
The aperture image of the diaphragm 17 is made by the objective lens 8 to form a material 9
Imaged above. When all of the imaged electron beams pass through the aperture of the diaphragm 17, the maximum beam current (current density) is obtained.

When a signal corresponding to a predetermined electron beam current amount is supplied to the modulating lens power source 31, the lens power source 31 supplies an exciting current corresponding to the signal to the modulating lens 30. As a result, the electron beam is in a defocused state on the diaphragm 17 and is enlarged and expanded.
Irradiated on. Therefore, some electrons are shielded by the diaphragm 17, and the amount of electron beams passing through the aperture of the diaphragm 17 is reduced. As a result, the amount of the electron beam that passes through the aperture of the diaphragm 17 and is irradiated on the material 9 is
It can be arbitrarily changed depending on the defocus amount of the electron beam above.

At this time, the relationship between the amount of the electron beam passing through the aperture of the diaphragm 17 and the magnitude of the exciting current supplied to the modulating lens 30 depends on the modulating lens 3 including an air-core coil.
It is determined by the number of coil turns of 0, the shape, and the installation position. In order to change the amount of the electron beam passing through the aperture of the diaphragm 17, even if the electron beam is defocused by the modulation lens 30, the objective lens is formed so that the aperture image of the diaphragm 17 is always formed on the material 9. 8 is adjusted, the diameter of the electron beam on the material 9 does not change even if the current amount of the electron beam with which the material 9 is irradiated is changed. Therefore, the current density of the electron beam with which the material 9 is irradiated changes in proportion to the change in the amount of current.

In the embodiment of FIG. 2, the control device 32 controls the modulation lens according to the scanning position of the electron beam on the material 9, and the current amount of the electron beam can be changed for each scanning position. . At this time, the changing rate of the electron beam current amount can be set to about several tens of MHz.

When the electron beam apparatus described in this embodiment is used as an electron beam annealing apparatus, a very great effect can be obtained when recrystallizing (single crystallizing) polysilicon on a silicon wafer. That is, in the past, the recrystallization condition was found by changing the electron beam scanning frequency in the material scanning range, but in the apparatus of FIG. 2, the electron beam current amount is changed by the modulation lens 30, and at the same time the electron beam scanning frequency is changed. By changing the scanning frequency of the beam, recrystallization can be easily performed and a single crystal with high purity can be manufactured.

Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment. For example, the lens that forms the electron beam at the aperture of the diaphragm 17 and the lens that forms the aperture image on the material 9 may be a plurality of lenses other than a single lens. The electron beam apparatus can be used for purposes other than electron beam annealing.

[0029]

As described above, in the electron beam apparatus according to the invention of claim 1, the first lens system for focusing the electron beam from the electron gun on the aperture portion of the aperture and the aperture image of the aperture are formed. A lens system that forms an image on a material, and a modulation lens that is provided above the diaphragm and that arbitrarily defocuses the electron beam with which the diaphragm is irradiated to change the amount of the electron beam that passes through the aperture of the diaphragm. It is configured to include. As a result, the amount of current of the electron beam with which the material is irradiated can be easily changed arbitrarily.

In the electron beam apparatus according to the second aspect of the present invention, since the modulating lens is composed of the air-core coil, the amount of current of the electron beam can be changed at high speed.

[Brief description of drawings]

FIG. 1 is a diagram showing a conventional electron beam apparatus.

FIG. 2 is a diagram showing an electron beam apparatus which is an embodiment of the present invention.

[Explanation of symbols]

 1 Cathode 2 Grid electrode 3 Anode electrode 7 Illumination lens 8 Objective lens 9 Material 12, 13 Alignment coil 15 Blanking electrode 17, 18 Aperture 20, 21 Deflector 24 Astigmatism corrector 25 Dynamic focus lens 30 Modulation lens 31 Modulation Lens power supply 32 Control device

Claims (2)

[Claims] 1. A first lens system for forming an image of an electron beam from an electron gun on an aperture portion of a diaphragm, a lens system for forming an aperture image of the diaphragm on a material, and a diaphragm provided above the diaphragm. An electron beam apparatus comprising: a modulation lens for arbitrarily defocusing an electron beam irradiated onto the aperture and changing the amount of the electron beam passing through the aperture of the diaphragm. 2. The electron beam apparatus according to claim 1, wherein the modulation lens comprises an air-core coil.