JPH02260412A - Aligner - Google Patents

Abstract

PURPOSE:To enhance resolution and to make a pattern to be exposed fine by providing the following so as to be capable of being changed over alternately on a light path: a bandpass filter which transmits light of an exposure wavelength; a filter which does not transmit the light of the exposure wavelength and which transmit light of a wavelength for alignment use. CONSTITUTION:When a workpiece (object to be exposed to light) 5 is aligned with a mask 2 and a B.P.F.(bandpass filter) 19 is situated on a light path, most of light of wavelengths other than an exposure wavelength is removed, light of a wavelength required for an alignment operation is hardly transmitted and the alignment operation cannot be executed. Accordingly, the B.P.F. 19 is withdrawn from the light path by using a driving apparatus 19a; a filter 18 is inserted into the light path instead; an image of a pattern of the mask 2 is formed on the workpiece 5 by using the light of the wavelength required for the alignment operation. Since light of a short wavelength which is sensitive to a resist of a prescribed wavelength or lower is removed by using the filter 18, the alignment operation can be executed effectively without exposing the resist to light. Thereby, resolution of this aligner is enhanced and fine processing of the pattern is possible.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an exposure apparatus used, for example, in the production of crystal resonators, and in particular, to an exposure apparatus that is provided with necessary means for aligning an object to be exposed. This relates to an exposure device.

[Prior Art] Conventionally, for example, in the production of crystal resonators and printed circuit boards, a thin photoresist layer such as liquid resist or tri-film resist is provided on the substrate, and the photoresist layer is passed through a photomask on which a pattern to be transferred is drawn. A desired pattern is provided on the photoresist layer through a step of exposing it to light at a wavelength to which the photoresist is sensitive.

Recently, however, as with ICs, LSIs, etc., products and devices into which printed circuit boards are incorporated have become more precise, and there has been a demand for finer patterns.

FIG. 2 is a schematic explanatory diagram of the main parts of a conventional exposure apparatus, in which 1 is a light source such as a mercury lamp, 12 is an elliptical collector mirror that collects light from the light source 1, 13.15 is a flat reflecting mirror, 14 is an integrator lens, 16 is a condenser lens, and an elliptical condenser mirror 12. Planar reflector ta, ts, integrator lens 14. The condenser lens 16 forms an illumination optical system. Also, 2 is a mask with a pattern drawn on it,
Reference numeral 3 denotes a projection lens that forms an image of the pattern of the mask 2 onto the object to be exposed, 4 an alignment optical system installed in the optical path for aligning the object 5 to be exposed, and 5 the object to be exposed (hereinafter referred to as the workpiece). Furthermore, 17 is a sharp cut filter (hereinafter simply referred to as filter 17) that is always fixed on the optical path and that transmits light of the exposure wavelength (for example, 436.) and cuts light of shorter wavelengths. ), 1
Reference numeral 8 denotes an alignment filter that transmits light of an alignment wavelength (for example, 546n) and cuts light of a lower exposure wavelength, etc., and 18a designates a filter 18 for installing the filter 18 on the optical path or removing it from the optical path. It is a driver for Further, 6 is a monitoring filter that transmits a wavelength for alignment.

FIG. 4 is a diagram showing the spectral characteristics of a mercury lamp, the spectral sensitivity characteristics of a resist, and the transmission characteristics of filters 17 and 18 in FIG.

As is clear from FIG. 4, the filter 17 transmits light having a wavelength equal to or greater than the exposure wavelength 436, and removes light having a shorter wavelength as unnecessary light. Therefore,
By providing a filter 17 on the optical path during exposure, 4
36. , which transmits light with a wavelength of 405., which has a shorter wavelength and may cause the resist to be exposed to light. The blur caused by monochromatic aberration is reduced by removing light of wavelengths above and below.

Further, the filter 18 transmits light having a wavelength of 546□ or more to which the resist serving as the workpiece 5 has no sensitivity, and does not transmit light having a shorter wavelength than that. Therefore, when aligning the mask 2 and the workpiece 5, by providing the filter 18 on the optical path, alignment can be performed without unnecessary exposure of the resist.

Note that the projection lens 3 is 43611. The light and 546. , chromatic aberration correction is applied so that both of the lights form the image of the mask on the same plane where the workpiece is placed.

Therefore, if the filter 18 is provided on the optical path during alignment, 546. It transmits light with a wavelength of , but does not transmit light with a shorter wavelength, so it is possible to align the workpiece without exposing the resist to light.

Furthermore, at the time of exposure, if the filter 18 is present, it will not transmit light with a wavelength of 436n, which is the exposure wavelength. There are 436. It is exposed by transmitting light with a wavelength of .

[Problems to be Solved by the Invention] As described above, the projection lens in such an exposure apparatus is designed to image a mask pattern on a workpiece using light of both wavelengths 436n and 546n.

In this case, as mentioned above, at the time of exposure, the sensitivity of the resist is 405. , , 365n, etc., are removed by a filter, so they do not form a blurred image on the resist on the workpiece. However, light with a longer wavelength than the exposure wavelength, e.g. The resist is also sensitive to side light. Light of this wavelength is the area surrounded by diagonal lines in Figure 4, and due to chromatic aberration of these lights, the image of the mask pattern becomes blurred, and as a result, the resist pattern formed after development is not sharp. Therefore, there is a problem that it is not possible to miniaturize the pattern on the wafer. In other words, when exposing fine patterns with a resolution of 31 to 21 or II, it is necessary to use a filter to remove light with wavelengths other than the exposure wavelength, even if the illuminance is small, to eliminate blurred images and improve accuracy. There is a problem that it must be done.

This invention was made to solve the conventional problem, and an object of the present invention is to provide an exposure apparatus in which an image formed by the light that a workpiece such as a resist is exposed to is not shifted or blurred. shall be.

[Means for Solving the Problems] In order to achieve the above object, an exposure apparatus of the present invention includes a bandpass filter that transmits light at the exposure wavelength, and a bandpass filter that does not transmit the light at the exposure wavelength, and a bandpass filter that transmits the light at the exposure wavelength. A filter that transmits light is provided on the optical path in a switchable manner.

[Function] By having the above configuration, most of the light other than the exposure wavelength is removed during exposure, so the resolution is increased and it becomes possible to miniaturize the pattern to be exposed.

[Embodiment] FIG. 1 is a diagram for explaining the schematic configuration of an exposure apparatus that is an embodiment of the present invention. In Fig. 1, 19 is a bandpass filter (hereinafter referred to as B, P, and F) that transmits only light centered at a wavelength of 436° as the exposure wavelength.
19a is a driver for placing B, P, and F2O on the optical path or removing them from the optical path, and it can be a rotary solenoid, a DC motor, an air cylinder, a rotary actuator, or any other mechanism for moving the filter. Also, since the same reference numerals as in FIG. 2 indicate the same or corresponding parts, the explanation will be omitted.

Furthermore, Figure 3 shows the spectral characteristics of the mercury lamp, which is the light source, and B
, P, and F19 transmittance.

Although the filter 17 in the apparatus shown in FIG. 1 is not necessarily required, if the filter 17 is on the optical path, B, P, F l
Since the filter 9 and the filter 18 can be prevented from being deteriorated by the far ultraviolet rays from the light source 1, if the filter 17 is provided, it is fixed on the optical path.

In the apparatus shown in FIG. 1, when aligning the workpiece 5 with respect to the mask 2, if B, P, and F2O are on the optical path, N
Most of the light at wavelengths other than 436n is removed, and almost no light at the wavelength of 546□, which is necessary for alignment, is transmitted, making alignment impossible.
The driver 19a causes 11, P, and F2O to retreat from the optical path, and the filter 18 is inserted into the optical path instead. Thereby, an image is formed with light having a wavelength of 546 necessary for aligning the pattern of the mask 2 onto the workpiece 5. In addition, the filter 18 removes short wavelength light that is sensitive to the resist below SOO. Therefore, the alignment operation can be performed effectively without exposing the resist.

Further, when exposing the workpiece 5, B, P, and F 19 are inserted on the optical path, and the filter 1B is retreated by the driver 18a. Thereby, the exposure wavelength is 436n.

The resist on the workpiece 5 is irradiated with only a narrow band of light. Therefore, 436. There is no blurring of the image due to chromatic aberration caused by wavelengths other than those in the vicinity, and a clear resist pattern is formed after development, making it possible to miniaturize circuit patterns.

The following means are available as a moving mechanism for moving the filter 18 and the filters B, P, and F 19 along the optical path and retracting them. That is, ■ One of the two shutter blades is composed of filter 1B, and the other one is composed of B, P, and F2O,
During alignment and exposure, when one of the shutter blades is on the optical path, the other one retreats, and when the other one is on the optical path, the first one retreats. In this way, a means for moving one of the shutter blades by the aforementioned motor or the like is installed so that one of them is placed on the optical path, and filters 18, B, P, and F2O are attached to both the left and right ends of the shutter blade 01, and the filters 18 and B are moved. .

In this embodiment, any of the above means can be used.

Furthermore, as mentioned above, it is not necessary to provide the filter 17, but if it is provided, it may be fixedly provided on the optical path regardless of the time of alignment or exposure. On the road, the filter 17
B, P, F 19 and filter 1 provided at a later stage
8 from being damaged by deep ultraviolet rays.

[Effects of the Invention] As explained above, the exposure apparatus of the present invention includes a bandpass filter that transmits light at the exposure wavelength, and a filter that does not transmit the light at the exposure wavelength but transmits light at the alignment wavelength. , are provided on the optical path so that they can be switched alternately, increasing the resolution of the device and enabling fine pattern processing.

Furthermore, during alignment, B, P, and F are retracted from the optical path, so they do not interfere with alignment, and structurally, compared to conventional devices, no major changes are required, so the cost of improvement is low.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the schematic configuration of an exposure apparatus which is an embodiment of the present invention, FIG. 2 is a schematic illustration of the main parts of a conventional exposure apparatus, and FIG. FIG. 4 is a diagram showing the spectral characteristics and the transmittance of B, P, and F. FIG. 4 is a diagram showing the spectral characteristics of the mercury lamp as a light source, the sensitivity characteristics of the resist, and the transmittance of each filter. In the figure. l: Light source 2: Mask 3: Projection lens 4: Alignment optical system 5: Workpiece 12: Elliptical condenser mirror 1: l, Is: Plane reflector 14: Integrator lens 16: Condenser lens Figure 17.18: Filter 18a , 19a: Driver 19: B, P, F

Claims (1)

[Claims] In an exposure apparatus having a light source, an illumination optical system, a mask, and a projection lens, a bandpass filter that transmits light at an exposure wavelength, and a bandpass filter that does not transmit light at the exposure wavelength but transmits light at an alignment wavelength. What is claimed is: 1. An exposure apparatus characterized in that an exposure apparatus is provided with a filter that can be switched alternately on an optical path.