JPH02309626A - Aligner - Google Patents

Abstract

PURPOSE:To reduce variations of a focal point plane as well as variations of projection magnification by providing a shutter for controlling the irradiation of light rays into a resist film between a projection lens system and the resist film formed on the surface of a semiconductor substrate. CONSTITUTION:Light rays 1a emitted from a mercury lamp 1 pass through a flying eye lens 2 and is converted to illumination light rays by a condenser lens 3. The light rays transmitted through a transparent part of a reticle 4 is reduced by a projection lens system 5 with which rays a resist film 9 formed on the surface of a semiconductor substrate 8 mounted on a stage 7 is irradiated. A shutter 6 for controlling the irradiation onto the resist film 9 is provided between the projection lens system 5 and the resist film 9 formed on the surface of the semiconductor substrate. Accordingly, the projection lens system 5 can be kept at a thermal equilibrium state, permitting the light rays 1a to be transmitted through the projection lens system 5. Hereby, the movement of a focal point plane and the variations of projection magnification can be restricted to the minimum irrespective of the shutter 6 being opened or closed.

Description

[Detailed Description of the Invention] [Summary] Regarding the improvement of the placement position of the shutter that controls the exposure of the light beam of the exposure device, by simply and easily changing the placement position of the shutter, it is possible to improve the optical system by absorbing the exposure light. The purpose of this is to provide an exposure device that can prevent movement of the focus plane and fluctuations in projection magnification. An exposure apparatus that reduces a light beam by a projection lens system and irradiates a resist film formed on the surface of a semiconductor substrate mounted on a stage, the shutter controlling the irradiation of the light beam to the resist film. The projection lens system is configured to be provided between the projection lens system and the resist film formed on the surface of the semiconductor substrate.

[Industrial application field]

The present invention relates to an exposure apparatus, and relates to an improvement in the arrangement position of a shutter that controls exposure of light beams.

In the lithography process in the manufacturing process of electronic devices, where the line width has become finer in recent years to about 0.5 μm,
It has become essential to improve the performance of exposure apparatuses in terms of resolution and overlay accuracy during exposure when forming electronic circuit patterns.

For exposure of electronic circuit patterns with such fine line widths, the tolerance of the focus plane is ±0.3 μm or less, and it is necessary to stabilize the projection magnification at ±3 ppm or less.

Under the above circumstances, there is a demand for an exposure apparatus that can expose patterns of miniaturized electronic devices.

[Conventional technology]

A conventional exposure apparatus will be explained in detail with reference to FIG.

The schematic structure of a conventional exposure apparatus is shown in FIG. 2. A light beam 1a emitted from a light source, for example, a mercury lamp 1, passes through a fly's eye lens 2, becomes an illumination beam at a condenser lens 3, and is illuminated by a transparent portion of a reticle 4. The light beam 1a that has passed through is reduced by the projection lens system 5 and irradiated onto a region of a resist film 9 formed on the surface of a semiconductor substrate 8 mounted on a stage 7, which is normally 15 times thicker. In such an exposure apparatus, a shutter 16 is provided between the fly's eye lens 2 and the condenser lens 3 to block the light beam 1a and to transmit the light beam 1a during exposure.

In such exposure equipment, the numerical aperture (NA) of the optical system
If is not very large, the depth of focus at the focal plane is ±
The projection magnification was within the manufacturing tolerance of ±0.30 μm for overlay accuracy, and there were no problems in the manufacturing process of electronic devices.

However, as the wavelength of the light source became shorter and the aperture of the optical system became larger, it became possible to have high resolution.
In recent exposure equipment that has become capable of high-precision positioning, in order to fully demonstrate its advanced performance, the two points mentioned above, movement of the focal plane and fluctuation of projection magnification, must be maintained. It has become impossible to ignore it.

[Problem to be solved by the invention]

In the conventional exposure apparatus described above, the shutter is provided between the fly-eye lens and the condenser lens, so the light rays emitted from the mercury lamp pass through the fly-eye lens during non-exposure and are blocked by the shutter. Only while the shutter is open during exposure, the light beam passes through the condenser lens, reticle, and projection lens system and is irradiated onto the lens (film) formed on the surface of the semiconductor substrate on the stage.

In this way, since light does not pass through the projection lens system at all times, the amount of exposure light absorbed by the projection lens system fluctuates over time. There is a problem in that the focal plane shifts and the projection magnification changes due to changes in the ratio and expansion and contraction of the light beam due to heat.

The present invention was developed based on the above-mentioned circumstances, and it is possible to prevent movement of the focal plane of the optical system and fluctuation of projection magnification due to absorption of exposure light by changing the placement position of the shutter, which can be done easily and easily. The purpose of the present invention is to provide an exposure apparatus with the following characteristics.

[Means to solve the problem]

The exposure apparatus of the present invention reduces light beams emitted from a light source, passes through a fly-eye lens and a condenser lens, and passes through a transparent part of a reticle using a projection lens system, and projects the light beams onto the surface of a semiconductor substrate mounted on a stage. An exposure device for irradiating the formed resist film, and configured to include a shutter for controlling the irradiation of the resist film with the light beam between the projection lens system and the resist film formed on the surface of the semiconductor substrate. do.

[Effect]

That is, in the present invention, since the shutter is disposed between the projection lens system and the resist film formed on the surface of the semiconductor substrate on the stage, light rays are constantly transmitted through the projection lens system. Since a thermal equilibrium state can be maintained, movement of the focal plane and fluctuations in projection magnification can be minimized regardless of whether the shutter is opened or closed.

〔Example〕

An exposure apparatus according to an embodiment of the present invention will be explained in detail below with reference to FIG.

The schematic structure of the exposure apparatus of this embodiment is as shown in FIG. The exposure apparatus is the same as the conventional exposure apparatus except that it is between the exposed resist film 9 and the exposed resist film 9.

In such an exposure apparatus, the light source has a wavelength of 4.
36nm g! A mercury lamp 1 that emits fIA is used, the numerical aperture of the optical system is 0.45, the exposure area on the resist film 9 is 15 angles, and the exposure amount to the normal projection lens system 5 is lOO~200 mJ. / cut, in the conventional exposure apparatus, the variation Δf of the focus plane was ±1 to 2 μm and the variation ΔM of the projection magnification was ±5 to loppm, but in this embodiment, the variation Δr is ±0. 3 μm, and it is possible to reduce the projection magnification variation ΔM to ±3 ppm or less.

In the new exposure equipment, the shutter 6 is arranged at the bottom surface of the projection lens system 5, and the projection lens system 5 and the shack 6 can be integrated and built in. , the distance between the projection lens system 5 and the resist film 9 formed on the surface of the semiconductor substrate 8 on the stage 7 is about 1
0 am, the projection lens system 5 of the existing exposure equipment
It is also possible to additionally provide a shutter 6 for the same.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the projection lens system is maintained in a thermal equilibrium state by changing the arrangement position of the shutter and allowing the light beam to enter the projection lens system at all times and pass through it. Therefore, it is possible to provide an exposure apparatus that can be expected to have significant economic and reliability effects.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a schematic structure of an exposure apparatus according to an embodiment of the present invention, and FIG. 2 is a side view showing a schematic structure of a conventional exposure apparatus. In the figure, l is a water pump, 1a is a light beam, 2 is a fly-eye lamp, 3 is a condenser lens, 4 is a reticle, 5 is a projection lens system, 6 is a shutter, 7 is a stage, 8 is a semiconductor substrate, FIG. 1 is a side view showing a schematic structure of an exposure apparatus according to an embodiment of the present invention.

Claims (1)

[Claims] A projection lens system (1a) emits a light beam (1a) emitted from a light source (1), passes through a fly-eye lens (2) and a condenser lens (3), and passes through a transparent part of a reticle (4). 5) and irradiates the resist film (9) formed on the surface of the semiconductor substrate (8) mounted on the stage (7), the exposure apparatus comprising: ) is provided with a shutter (6) for controlling irradiation onto the projection lens system (5) and the resist film (8) formed on the surface of the semiconductor substrate (8).
9) An exposure apparatus characterized by being provided between.