JPH1040851A - Electron beam exposing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron-beam exposing device equipped with a photoelectron emitting element realizing cost reduction and having a long life, by constituting a photoelectron-emitting element, for emitting a photoelectron pattern when an optical pattern is irradiated, by an electron field emission type photoelectron element by pn junction. SOLUTION: Light LZ, emitted from a light source 1, is irradiated to an optical mask 2 to be adopted as an optical pattern OP, and is irradiated to a photoelectron-emitting element 12 installed in the optical window 11a of a vacuum vessel 11. The optical pattern OP, irradiated to the optical electron- emitting element 12, becomes a photoelectron pattern EP, to project an electron image EBI into a wafer WH via an accelerator 13, an electron lens 14, and a deflector 15. At this time, the photoelectron emitting element 12 is adopted as an electric field emission type photoelectric element by a pn junction, wherein p-type and n-type semiconductor layers are jointed, and the p-type semiconductor layer is formed of a thin coat so that light can sufficiently enter into a joining surface. This can obtain an exposure device, having a long life at low cost, utilizing an element which uniformly emits photoelectrons.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus for forming an electron image with a charged particle beam such as an electron beam and transferring the image onto a sensitive substrate such as a wafer.

[0002]

2. Description of the Related Art Japanese Patent Publication No. 7-44144 discloses an optical pattern projecting means for projecting an optical pattern, and an optical pattern projected by the optical pattern projecting means. There is disclosed an exposure apparatus including a photoelectron emitting element for emitting light, and electronic image projection means for accelerating photoelectrons emitted from the photoelectron emitting element and projecting an electron image on a projection surface. As this photoelectron emitting element, a thin film of a material having a high photoelectron emitting ability such as cesium iodide (CsI) is formed on the surface of fused quartz, and an optical pattern is projected on a surface opposite to the surface on which the thin film is formed. is there.

[0003]

However, in this type of photoelectric surface, it is necessary to reduce the non-uniformity of photoelectron emission to a few percent or less, and there is a problem that manufacturing is difficult and expensive. In addition, there is a problem in that the photocathode undergoes an alteration phenomenon such as islanding with the use thereof, so that the photoelectron emission becomes non-uniform and the life is very short.

An object of the present invention is to provide an electron beam exposure apparatus including a photoelectron emitting element which can be reduced in cost and has a long life.

[0005]

A description will be given with reference to the accompanying drawings showing an embodiment. (1) According to the first aspect of the present invention, optical pattern projecting means 1 and 2 for projecting an optical pattern, and an optical pattern projected by the optical pattern projecting means are incident, and photoelectrons are formed in a pattern corresponding to the pattern. The present invention is applied to an exposure apparatus including a photoelectron emitting element 2 that emits light, and electron image projection means 14 that accelerates photoelectrons emitted from the photoelectron emitting element 2 and projects an electron image on a sensitive substrate WH. And
The above object is achieved by configuring the photoelectron emission element from a field emission type photoelectric element using a pn junction. (2) The field emission type photoelectric element 12 can be configured by two-dimensionally arranging cone-shaped emitters 12e having a diode structure at minute intervals. (3) A photoelectron intensity detector 25 for detecting the intensity of photoelectrons emitted from the photoelectron emission device 12, and an electric field of the field emission photoelectric device 12 based on the pn junction based on the photoelectron intensity detected by the photoelectron intensity detector 25. It is preferable to provide adjusting means 22 and 26 for adjusting the strength. (4) With the field emission photoelectric element 12 fixed, the optical mask 2 and the sensitive substrate WH are moved in the same direction or opposite directions to project photoelectrons emitted from the field emission photoelectric element 12 onto the sensitive substrate. You can also. (5) A reduction lens system 40 for reducing the optical pattern transmitted through the optical mask 2 may be provided. (6) A reduction electron lens system for reducing a photoelectron pattern emitted from the field emission photoelectric element 12 may be further provided.

[0006] In the means and means for solving the above-mentioned problems which explain the constitution of the present invention, reference numerals and figures of the embodiments are used to make the present invention easy to understand. Is not limited to the embodiment.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. -First Embodiment- FIG. 1 is a sectional view of an electron image exposure apparatus using an electron beam according to the present embodiment. In FIG. 1, light LZ emitted from a light source 1 is applied to an optical mask 2. The mask 2 is obtained by forming a circuit pattern on a glass substrate with a light-shielding material such as chrome. The irradiation light LZ passes through a region other than the light-shielding material, and the optical pattern OP is projected from the mask 2. The light source 1 is, for example, a mercury lamp. In this case, ultraviolet light is used, but electromagnetic waves in a wavelength range from infrared light to X-rays can be used, and various light sources can be used.

The electron beam projector 10 has an optical window 11a.
And a vacuum vessel 11 in which the inside is maintained in a vacuum state.
A photoelectron emitting element 12 installed in the optical window 11a and irradiated with the optical pattern OP;
An accelerator 13 for accelerating photoelectrons emitted from the photoelectron device 12, an electron lens 14 for reducing and projecting a photoelectron pattern EP emitted from the photoelectron emitting element 12 and accelerated by the accelerator 13 as an electronic image EBI on the wafer WH. A deflector 15 for deflecting the passed photoelectron beam. In FIG. 1, for convenience, the photo-emissive element 12 and the wafer WH
Are shown at the same magnification. The acceleration voltage applied to the accelerator 13 is approximately 1 to 1
The reduction ratio is, for example, about 20 kV and 1/20. The wafer WH is, for example, a silicon substrate, and its surface is coated with a resist prior to the electron beam transfer processing. Further, the deflector 15 is installed as needed and is not essential.

The photoelectron emitting element 12 includes a p-type semiconductor layer and an n-type semiconductor layer.
This is a field emission type photoelectric device using a pn junction in which a p-type semiconductor layer is bonded to a p-type semiconductor layer. The p-type semiconductor layer is formed in a thin film so that light can sufficiently enter the bonding surface. 1 to several k for Pn junction element
When a voltage of about V is applied, photoelectrons are emitted from the surface of the n-type semiconductor layer on the back surface of the region where light is incident, according to the optical pattern OP incident on the surface of the p-type semiconductor layer. Therefore, the photoelectric pattern EP is the same as the optical pattern OP.

As the field emission type photoelectric element 12, a field emission type minute emitter having a so-called pn junction can be used. As shown in FIG. 2, one of the cone-type emitters 12e having a diode structure formed by micromachining of silicon is used.
They are two-dimensionally arranged at intervals of μm. When a resolution of 1 μm or more is required, an element having a planar emitter is used.

The operation of projecting and transferring a circuit pattern on a wafer by such an exposure apparatus will be described. When the light LZ emitted from the light source 1 is incident on the optical mask 2, the light is transmitted only from the portion where the light shielding material is not formed, and the optical pattern OP is formed. The optical pattern OP is incident on the surface of the p-type semiconductor layer of the photo-emissive element 12. Free electrons are generated inside the photoelectron emitting element 12 by the incidence of the optical pattern OP. A predetermined voltage is applied with a reverse bias between the p-type semiconductor layer and the n-type semiconductor layer, and free electrons of the p-type semiconductor layer excited by light move across the junction surface to the n-type semiconductor layer, Photoelectrons are emitted from the surface of the n-type semiconductor layer. That is, since photoelectrons are emitted only from the region corresponding to the region where the light has entered, the photoelectron pattern EP is the same pattern as the optical pattern OP.
The emitted photoelectrons are accelerated by an accelerator 13, converged by an electron lens 14, and further deflected by a deflector 15.
An electronic image EBI is projected onto a predetermined area of No. 3.

In such an exposure apparatus, since the optical mask 2 is provided outside the vacuum vessel 11, it is extremely easy to exchange a plurality of optical masks according to various circuit patterns. Further, since the field emission type photoelectric element 12 using a pn junction is used, unlike the conventional photocathode in which a photoelectric emission material such as cesium iodide (CsI) is provided on quartz glass, an islanding phenomenon occurs due to aging. Does not occur,
The problem that the photoelectron emission becomes non-uniform or the life is shortened with use is solved. Also, it is difficult to form a pattern with a line width of about 0.2 μm or less using light, but a pattern with an extremely small line width of 0.2 μm or less is formed by an electron beam using a conventional optical mask as it is. it can. Therefore, mask manufacturing costs can be reduced. Furthermore, since the optical mask is not placed in a vacuum,
Its exchangeability is also improved.

Second Embodiment In this second embodiment, as shown in FIG. 3, electrons emitted from the photoelectron emitting element 12 are detected by a photoelectron intensity detector 25.
, And the voltage applied to the field emission type photoelectric element 12 is controlled based on the detection result.

3 and 4, in this embodiment, the monitor light ML is emitted from the light source 1 to the outside of the area of the photoelectron emission device 12 where the optical pattern OP is irradiated, and the monitor electron ME is emitted from the photoelectron emission device 12. The light source 1, the optical mask 2, and the photoelectron emitting element 12 are respectively configured to emit light. An accelerator 20 for accelerating the emitted electrons in two stages is provided, and the accelerator 20 controls the intensity of the photoelectrons emitted from the photoelectron emitting element 12 to be substantially constant.

The accelerator 20 includes an extraction electrode 21, a first variable power supply 22 for applying a voltage between the extraction electrode 21 and the element 12, an acceleration electrode 23, an acceleration electrode 23 and the element 12.
, A detector 25 for detecting electrons extracted by the extraction electrode 21, and amplifying the output of the detector 25 to control the output voltage of the variable power supply 22. And an amplifier 26 that performs the operation.

The monitor electronics ME is detected by the photoelectric detector 25 and amplified by the amplifier 26 to control the output voltage of the first variable power supply 22. If the photoelectron intensity is low, the output voltage is increased, and if the photoelectron intensity is high, the output voltage is controlled to be low. Therefore, the deterioration of the performance of the photoelectron emission element 12 can be compensated for by increasing the electric field strength.
Alternatively, the emitted photoelectron intensity can be arbitrarily adjusted according to various conditions. The second variable power supply 2
The output voltage of 4 is set to a value sufficient for the photoelectrons emitted from the element 12 to be projected onto the wafer WH to expose the wafer.

Third Embodiment FIG. 5 shows a third embodiment. In this method, the optical mask 2 is placed on the XY stage 31, the wafer WH is placed on the XY stage 32, and both are scanned in directions different from each other as shown by arrows, and the electronic pattern is placed on the wafer WH.
The image is projected onto H and transferred. Here, an example in which the scanning is performed in the opposite direction is described, but scanning in the same direction may be performed. If the optical field cannot be large, the circuit pattern on the optical mask is used as a division pattern, and the mask 2 and the wafer WH are used.
Are scanned in opposite directions to suppress a decrease in throughput. In this case, there is no need to scan the photoelectron emission element 12, and a mechanism for movably holding the photoelectron emission element 12 in a vacuum is not required.

-Fourth Embodiment- FIG. 6 shows a fourth embodiment. In this method, the transmission pattern of the optical mask 2 is reduced by the reduction optical system 40 and projected onto the photoelectron emitting device 12. Therefore, the reduction ratio of the reduction electron lens system including the electron lenses 14A and 14B is α
1. If the reduction ratio of the reduction optical lens system 40 is α2, the circuit pattern on the optical mask 2 can be projected and transferred at a reduction ratio of α1 × α2. Thereby, the line width of the circuit pattern of the optical mask 2 can be increased.

In the embodiment configured as described above,
The light source 1 and the optical mask 2 serve as an optical pattern projection unit, the field emission type photoelectric device 12 serves as a photoelectron emission device, and the electron lens 1
Reference numeral 4 denotes an electronic image projecting unit, and an amplifier 26 and a first variable power source 2
2 constitutes adjusting means, and the XY stages 31 and 32 constitute first and second moving means, respectively.

[0020]

(1) As described in detail above, according to the present invention, p
Since an optical pattern is converted into a photoelectron pattern by a field emission type photoelectric element by an n-junction, a long-life exposure apparatus can be provided using an element which uniformly emits photoelectrons at a low cost. (2) If the intensity of the emitted photoelectrons is detected and the electric field intensity of the field emission type photoelectric element by the pn junction is adjusted to a predetermined value, the deterioration of the photoelectron emission performance due to aging can be compensated. (3) The pattern on the optical mask is projected onto the field emission type photoelectric element while moving the optical mask and the sensitive substrate in the same direction or mutually opposite directions while the field emission type photoelectric element is fixed, and is emitted therefrom. If the photoelectrons are projected onto the sensitive substrate, a decrease in throughput can be suppressed even when the optical field is narrow and a divided pattern must be formed on the optical mask. (4) If the optical pattern transmitted through the optical mask is reduced and the photoelectron pattern emitted from the field emission photoelectric element is also reduced and transferred onto the sensitive substrate, the line width of the divided pattern can be increased, Creation of a mask pattern becomes easy.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an exposure apparatus according to a first embodiment.

FIG. 2 is a diagram illustrating a minute emitter having a diode structure.

FIG. 3 is a schematic configuration diagram of an exposure apparatus according to a second embodiment.

FIG. 4 is a diagram illustrating details of a two-stage accelerator according to a second embodiment;

FIG. 5 is a diagram illustrating details of a third embodiment;

FIG. 6 is a diagram for explaining details of a third embodiment;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 2 Optical mask 10 Vacuum container 12 Field emission type photoelectric element 13 Accelerator 14 Electron lens 15 Deflector 20 Two-stage accelerator 22 Variable power supply 25 Photoelectron intensity detector OP Optical pattern EP Photoelectron pattern WH wafer

Claims (6)

[Claims] 1. An optical pattern projecting means for projecting an optical pattern, a photoelectron emitting element which receives an optical pattern projected by the optical pattern projecting means and emits photoelectrons in a pattern corresponding to the pattern; An electron image projection means for projecting an electron image on a sensitive substrate by accelerating photoelectrons emitted from the element, wherein the photoelectron emission element comprises a pn junction field emission type photoelectric element. Electron beam exposure apparatus. 2. An electron beam exposure apparatus according to claim 1, wherein said field emission type photoelectric element is constituted by two-dimensionally arranging cone-type emitters having a diode structure at minute intervals. apparatus. 3. The exposure apparatus according to claim 1, wherein: a photoelectron intensity detector for detecting the intensity of photoelectrons emitted from the photoelectron emitting element; and a photoelectron intensity detected by the photoelectron intensity detector. Adjusting means for adjusting the electric field intensity of the field emission photoelectric device by the pn junction. 4. The exposure apparatus according to claim 1, wherein the optical pattern projecting unit has an optical mask, and a first moving unit of the optical mask and a second unit of the sensitive substrate. A moving unit, wherein the first and second moving units are moved in the same direction or in mutually opposite directions while the field emission type photoelectric device is fixed, so that the pattern on the optical mask is moved. An electron beam exposure apparatus, which projects onto a field emission photoelectric device and projects photoelectrons emitted therefrom onto the sensitive substrate. 5. The exposure apparatus according to claim 1, wherein the optical pattern projection unit includes a light source, an optical mask,
An electron beam exposure apparatus comprising: a reduction optical lens system configured to reduce an optical pattern transmitted through an optical mask. 6. An exposure apparatus according to claim 1, wherein said electronic image projection means has a reduction electron lens system for reducing a photoelectron pattern emitted from said field emission type photoelectric device. Electron beam exposure apparatus.