JPS63216339A - Composite exposure using electron beam and light - Google Patents

Abstract

PURPOSE:To obtain a high-resolution pattern by a method wherein, after a fluorescent material has been installed between an electron beam radiating part and a photographic plate, a resist is exposed to light after an electron beam has been transformed into the light energy and the local heating of a substrate or the accumulation of an electric charge is suppressed. CONSTITUTION:An electron beam radiating part 11 forms an electron beam 14, which is accelerated by a voltage of 20 keV by using a conventional electron beam lithography aligner, in accordance with a pattern to be formed by an optoelectronic system; it controls the optoelectronic system in such a way that it exposes the pattern one after another. The controlled electron beam 14 irradiates a fluorescent material 13 where a quartz glass plate is coated with a fluorescent substance. The electron beam 14 is converted into the light 15 due to the action of the fluorescent substance; it passes through the fluorescent material 13; the light 15 corresponding to the shape of the electron beam is emitted rom the opposite face. The converted light 15 which corresponds to the shape of the electron beam 14 exposes a photoresist 12c in accordance with the shape of the pattern without causing the scattering.

Description

[Detailed Description of the Invention] [(Summary)] The present invention converts the electron beam emitted from the electron beam irradiation section into light through a fluorescent material, and exposes the dry plate with this light, thereby eliminating the proximity effect caused by the electron beam and the dry plate. Exposure of the dry plate can be performed at high speed and high resolution while suppressing heating and charge accumulation.

[Industrial application field]

The present invention relates to an electron beam/light composite exposure method, and in particular to an electron beam exposure method that converts the electron beam at the stage of exposing a dry plate into light using a fluorescent material to perform light exposure while maintaining the high-speed drawing performance of electron beam exposure. -Relating to optical compound exposure method.

[Conventional technology]

Conventional exposure equipment, such as electron beam lithography equipment used in the manufacturing process of semiconductor devices, has become increasingly finer due to the high integration of semiconductor devices in recent years. It is attracting attention as a material for processing.

The electron beam exposure device (see Fig. 3) uses an electron beam 1
4 as electronic lens 16.17.18 or slit 19.20
The circuit pattern is formed into a thin beam of 0.5 μm or less or a rectangular beam of 10 μm or less using an electron optical system, and then drawn directly onto a wafer. When creating a mask or reticle, a circuit pattern is quickly drawn on a dry plate coated with resist, etc. It is used for drawing exposure.

Figure 6 shows the conventional exposure! It is a cross-sectional view showing an imaginary state.

When directly writing on a wafer (quartz substrate 32b) with the electron beam 34, the electrons can be accelerated so that they pass through to the wafer, but when forming a mask reticle, the electron beam is The electron beam 34 must be accelerated to about 50 KeV, and therefore the electron beam 34 penetrates the resist 32 and hits the quartz substrate 32b, and the substrate is locally heated by emitting energy from the electron beam (heated portion 37). It is known. Note that the quartz substrate 32b, the chromium film 32a, the resist 3
A three-layer structure consisting of two is called a dry plate.

Further, the electron beam 34 accelerated by the electron beam exposure device hardly exposes the resist 32, but the secondary electrons 35 generated when the electron beam 34 hits the resist 32 expose the resist. 2 generated in such a scattering process
Since the secondary electrons 35 have different directions, it is difficult to control the exposed portion.

[Problems to be Solved by the Invention] As described above, in the prior art, when an accelerated electron beam is used to improve processing accuracy, more electrons pass through the resist and reach the quartz substrate 32b, and the electron beam damages the substrate. is locally heated (heated portion 37), and the heat causes a crosslinking reaction in the resist (especially in the case of a negative resist), or a proximity effect occurs due to heat, making it impossible to obtain the desired pattern shape. There is.

Furthermore, since electrons have a negative charge, there is a problem in that the charges accumulated in the resist and substrate portions due to electron beam irradiation give shape to the electron beam.

The accelerated electron beam emits secondary electrons 35 with different directions during the scattering process when it hits the resist 32.
This exposes the resist. Therefore, as shown in FIG. 6, even if the beam is applied accurately to the desired position of the resist (the part indicated by the broken line), the resist pattern (exposed part 36) that is formed will be, for example, in the shape of a cone larger than the beam. If the beam is exposed to light or the beam is narrowed down, a pattern may not be formed due to scattering in some cases. This is an important issue because it affects the final resolution of the pattern.

The present invention was created in view of the above points, and provides an exposure method that prevents local heating of a substrate and accumulation of charges caused by an electron beam, as well as a reduction in pattern resolution due to scattering of secondary electrons. The purpose is to

[Means for solving problems]

In order to solve the above problems, the present invention interposes a fluorescent material 13 between the electron beam irradiation section 11 and the sample 12, as shown in FIGS. The sample 12 is exposed by converting it into light 15.

As the electron beam irradiation section 11, a conventional electron beam exposure apparatus can be used as is.

As shown in FIG. 3, the electron beam irradiation section 11 includes an electron gun 21
Electron lenses such as the irradiation lens 16, the projection lens 17, and the reduction imaging lens 18 that reduces and projects the beam, and the first lens that shapes the beam, emit negatively charged electrons accelerated by about 10 to 50 KeV. The beam is formed into a thin beam of 0.5 μm or less or a rectangular beam of 10 μm or less using an electron optical system such as a second slit 19° 20. The vinyl deflector 23 and the slit deflector 22 function to change the deflection and shape of the beam position.

The fluorescent material 13 means any fluorescent material that converts an electron beam into light and transmits it, and does not necessarily have to be made of only a fluorescent material. For example, a quartz glass plate coated with a fluorescent substance can be preferably used.

Alternatively, a layer of fluorescent material may be formed by directly coating the resist.

The sample 12 includes a substrate 12a and a chromium film 12b on the substrate.
It has a three-layer structure of a resist 12c on a chromium film, and is also called a dry plate, and the resist 12c is exposed to light 15 obtained by converting the electron beam 14 by the fluorescent material 13. The resist 12c is, for example, a commonly used photoresist (positive type, negative type).

A fluorescent material 1 is provided between the electron beam irradiation section 11 and the dry plate 12.
3 means that the accelerated and shaped electron beam 14 coming out of the electron beam irradiation unit 11 passes through the fluorescent material 13 and is converted into light, and then the fluorescent material 13 is transferred to the electron beam so that it reaches the register 12c. This means that it is placed between the irradiation section 11 and the dry plate 12. It is desirable that the fluorescent material 13 and the dry plate 12 be as close to each other as possible and parallel to each other. This is because the converted light 15 needs to be faithfully irradiated onto the dry plate 12.

[Effect]

In the present invention, the fluorescent material 13 is interposed between the electron beam irradiation section 11 and the dry plate 12 to convert the electron beam into light energy and expose the resist 12c. Local heating and charge accumulation can be suppressed, and scattered exposure due to secondary electrons generated when the electron beam 14 hits the resist I/12c is reduced, so a desired pattern with high resolution can be obtained. Can be done.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a configuration diagram of the present invention, FIG. 2 is an explanatory diagram of the exposure state of the present invention, FIG. 3 is a configuration sectional view of Embodiment 1 of the present invention, and FIG. 4 is a sectional view of the support member of Embodiment 2, its ( If al, the standby state diagram, (
b) is a diagram of the dry plate insertion state, (C) is a diagram of the completed support state, 5th
The figure is a partially enlarged view of FIG. 4 (C1).

Embodiment 1 In Embodiment 1, the electron beam irradiation unit 11 is irradiated with 20 KeV using a conventional electron beam exposure apparatus as shown in FIG.
The electron beam 14 accelerated at a voltage of 1 is shaped by an electron optical system according to the pattern to be formed, and the electron optical system is controlled so as to sequentially expose the inside of the pattern.

Returning to FIG. 2 again, the controlled electron beam 14 is irradiated onto a fluorescent material 13 made of quartz glass coated with a fluorescent material. Due to the action of the fluorescent substance, the electron beam 14 becomes light 1
5, and passes through the fluorescent material 13 and emerges from the opposite surface as light 15 corresponding to the shape of the electron beam.

Resist 1.2c exposed by converted light 15
A quartz substrate 12 with a thickness of 2.5 cm was used for the photoresist.
After forming a metal film such as a chromium film 12b with a thickness of 1000 mm on top of a to release accumulated charges, a photoresist 12c was coated on top of it with a thickness of 5000 mm (the film thickness in the figure is the actual thickness for convenience of explanation). ratio).

The positional relationship between the fluorescent material 13 and the dry plate 12 is such that the photoresist and the fluorescent material are fixed in parallel and close positions. Therefore, the converted light 15 corresponding to the shape of the electron beam 14 exposes the photoresist according to the pattern shape without being scattered.

When exposing a pattern using the exposure apparatus of Example 1, the electron beam is converted into light while maintaining the high-speed rtM image quality that is an advantage of the conventional electron beam exposure apparatus, so the electron beam does not cause local heating of the substrate or It is possible to reduce the adverse effect on the pattern shape due to the accumulation of charges, and it is also possible to prevent the image of the pattern shape from becoming blurred due to the scattering of secondary electrons.

Example 2 In Example 2, exposure was performed using the same apparatus as in Example 1, but the difference was that exposure was performed after the fluorescent material 13 and dry plate 12 were closely supported using a dedicated support member. It is.

As shown in FIG. 4 (C1), in the support member of Example 2, the leaf spring 26 of the holder 25 supporting the fluorescent material 13 is connected to the dry plate 12.
The substrate 12a on which the fluorescent material 12a is placed is pressed against the lower surface of the fluorescent material 13 to bring them into close contact.

In the figure fa), the board 12a on which the dry plate 12 is mounted is not attached, and the leaf spring 26 is pressed down in the direction of the arrow by a pressing jig (not shown), waiting for the dry plate 12 to be inserted.

In FIG. 2B, the dry plate 12 is inserted from the front side of the drawing and placed on the ten-tan wire 26 held down by the above-mentioned holding jig.

In the same figure (C1, the holding jig is removed and the dry plate 12 and the fluorescent material 13 are supported in close contact with each other by being urged in the upward arrow direction by the restoring force of the temporary spring 26.The fluorescent material 13 is attached to the 5
As shown in the figure, means for fixing to the holder 25 with fixing screws 27 was used.

When exposure is performed using such a support member, the shape of the shaped electron beam is directly converted into light and the dry plate is directly exposed, making it possible to perform exposure faithful to the desired pattern shape.

〔Effect of the invention〕

As described above, the electron beam/light composite exposure method of the present invention can suppress local heating of the substrate and accumulation of charges caused by the electron beam, and further reduce scattering of secondary electrons.
A pattern with a desired shape and high resolution can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of the present invention, FIG. 2 is an explanatory diagram of the exposure state of the present invention, FIG. 3 is a configuration sectional view of Embodiment 1 of the present invention, and FIG. 4 is a sectional view of the support member of Embodiment 2, its ( Jl) is a standby state diagram, (b
) is a diagram of the dry plate inserted state, (C) is a diagram of the completed support state, FIG. 5 is a partially enlarged view of FIG. 4 (C1), and FIG. 6 is a sectional view showing the conventional exposure state. Regarding Figure 5, 11 is an electron beam irradiation unit, 12 is a dry plate (sample), 12a is a substrate, 12b is a chrome film, 12c is a resist, 13 is a fluorescent material, 14 is an electron beam, 15 is light, 16 is an irradiation lens, 17 18 is a projection lens, 18 is a reduction imaging lens, 19 is a first slit, 20 is a second slit, 21 is an electron gun, 22 is a slit deflector 1, 23 is a beam deflector 1, 24 is an exposure part, 25 is a holder, 26 is a temporary spring, and 27 is a fixing screw.

Claims (1)

[Claims] A fluorescent material (13) is interposed between the electron beam irradiation unit (11) and the sample (12), and the fluorescent material (13) converts the electron beam (14) into light (15) to illuminate the sample (12). )
A combined electron beam/light exposure method characterized by performing exposure.