JP2668834B2 - Exposure equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exposure apparatus used, for example, in the manufacture of a crystal oscillator, and in particular, has provided means necessary for alignment of an object to be exposed. The present invention relates to an exposure apparatus.

[Prior Art] Conventionally, for example, when manufacturing a crystal oscillator or a printed circuit board, a thin photoresist layer such as a liquid resist or a dry film resist is provided on the substrate, and the above-described method is performed 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 the photoresist to light having a photosensitive wavelength.

However, recently, as with ICs, LSIs, and the like, with the precision of products and devices in which a printed circuit board is incorporated, finer patterns have been required.

FIG. 2 is a schematic explanatory view of a main part of a conventional exposure apparatus.
Is a light source such as a mercury lamp, 12 is an elliptical focusing mirror that collects the light from the light source 1, 13 and 15 are plane reflecting mirrors, 14 is an integrator lens, 16 is a condenser lens, and the elliptical focusing mirror 1
2. The illumination optical system is formed by the plane reflecting mirrors 13 and 15, the integrator lens 14, and the condenser lens 16. Reference numeral 2 denotes a mask on which a pattern is drawn. Reference numeral 3 denotes a projection lens that forms an image of the pattern of the mask 2 on an object to be exposed. Reference numeral 4 denotes an alignment path provided in an optical path for aligning the object to be exposed 5. The optical system 5 is an object to be exposed (hereinafter referred to as a work). Furthermore, 17 is always fixed on the optical path,
A sharp cut film (hereinafter simply referred to as a filter 17) that transmits light having an exposure wavelength (for example, 436 nm) and cuts light having a wavelength shorter than the exposure wavelength, and 18 transmits light for alignment wavelength (for example, 546 nm) An alignment filter 18a for cutting light having a wavelength equal to or shorter than the exposure wavelength, and a driver 18a for providing the filter 18 on the optical path or retracting the filter 18 from the optical path. Reference numeral 6 denotes a monitor filter that transmits a wavelength for alignment.

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

As is apparent from FIG. 4, the filter 17 transmits light having a wavelength of 436 nm which is the exposure wavelength or more, and removes light having a shorter wavelength than that as unnecessary light. Therefore, at the time of exposure, by providing the filter 17 on the optical path,
Of light having a wavelength of 405 nm or less, which is a short wavelength and may cause the resist to be exposed, to reduce blurring due to chromatic aberration.

Further, the filter 18 transmits light having a wavelength of 546 nm or more, which is insensitive to the resist as the work 5, and does not transmit light having a shorter wavelength than that. Therefore, the mask 2 and the work 5
By providing the filter 18 on the optical path at the time of alignment with, the alignment can be performed without unnecessary exposure of the resist.

The projection lens 3 has been corrected for chromatic aberration so that both the light of 436 nm and the light of 546 nm form an image of the mask on the same plane where the work is placed.

Therefore, when the filter 18 is provided on the optical path during alignment, the wavelength of 546 nm for alignment is transmitted, but light of shorter wavelength is not transmitted, so the work must be aligned without exposing the resist. Can be.

Further, at the time of exposure, the presence of the filter 18 does not allow light having a wavelength of 436 nm, which is the exposure wavelength, to pass therethrough.
To drive the filter 18 to retreat out of the optical path and to transmit light having a wavelength of 436 nm, which is an exposure wavelength, for exposure.

[Problems to be Solved by the Invention] As described above, the projection lens in such an exposure apparatus is designed so as to form an image of a mask pattern on a workpiece with light having wavelengths of 436 nm and 546 nm.

In this case, as described above, at the time of exposure, light having a sensitivity of the resist, which is shorter than the exposure wavelength such as 405 nm or 365 nm, is removed by the filter, so that a blurred image is not formed on the resist on the work. However, the resist is sensitive to light having a wavelength longer than the exposure wavelength, for example, 436 nm. Light of this wavelength is the portion surrounded by the diagonal lines in FIG. 4, and the image of the mask pattern is blurred due to the chromatic aberration of these lights. As a result, there is a problem that the pattern of the resist formed after the development is not sharply formed and the pattern on the wafer cannot be miniaturized. That is, when exposing a fine pattern having a resolution of 3 μm to 2 μm or 1 μm, light having a wavelength other than the exposure wavelength should be filtered out even with a slight illuminance to eliminate blurring of image formation and improve accuracy. There is a problem that must be.

The present invention has been made in order to solve such a conventional problem, and an object of the present invention is to provide an exposure apparatus in which an image formed by light, such as a resist, formed by a photosensitive work is not shifted or blurred. .

[Means for Solving the Problems] In order to achieve the above-mentioned object, the exposure apparatus of the present invention is provided with a filter on the optical path that transmits light having an exposure wavelength and cuts light having a wavelength shorter than the exposure wavelength. , On the optical path subsequent to the filter, a bandpass filter that transmits light of an exposure wavelength, and a filter that transmits light of a wavelength for alignment without transmitting light of the exposure wavelength,
It is provided so that it can be switched alternately.

[Operation] With the above configuration, most of the light other than the exposure wavelength is removed at the time of exposure, so the resolution is improved and the pattern to be exposed can be miniaturized.

[Embodiment] FIG. 1 is a diagram for explaining a schematic configuration of an exposure apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 19 is a bandpass filter (hereinafter referred to as BPF) that transmits only light having a wavelength of 436 nm as an exposure wavelength.
Is a driver for providing the BPF 19 on the optical path or removing the BPF 19 from the optical path, and may be a rotary solenoid, a DC motor, an air cylinder or a rotary actuator, or any other means for moving the filter. Further, the same reference numerals as those in FIG.

FIG. 3 shows the spectral characteristics of a water lamp as a light source and B.
FIG. 9 is a diagram showing the transmittance of P.F19.

In the apparatus of FIG. 1, since the filter 17 is on the optical path, it is possible to prevent the BPF 19 and the filter 18 from being deteriorated by the far ultraviolet rays from the light source 1.

In the apparatus shown in FIG. 1, when the work 5 is aligned with the mask 2, if the BPF 19 is on the optical path, most of the light with a wavelength other than 436 nm as the exposure wavelength is removed, and the 546 nm wavelength required for alignment is reduced. Since light of the wavelength is hardly transmitted and alignment cannot be performed, the driving device 19a
Causes the BPF 19 to retreat from the optical path and instead insert the filter 18 in the optical path. Thereby, an image is formed with light having a wavelength of 546 nm necessary for aligning the pattern of the mask 2 on the work 5. Further, light having a short wavelength sensitive to the resist having a wavelength of 500 nm or less is removed by the filter 18. Therefore, the alignment operation can be effectively performed without exposing the resist.

When the work 5 is exposed, the BPF 19 is inserted in the optical path and the filter 18 is retracted by the driver 18a. As a result, the resist on the work 5 is irradiated with only light in a narrow band having an exposure wavelength of 436 nm. Therefore, after development, there is no blurring of the image due to chromatic aberration due to wavelengths other than around 436 nm.
A clear resist pattern is formed, and the circuit pattern can be miniaturized.

The moving mechanism for installing the filter 18 and the BPF 19 on the optical path or retracting the filter 18 has the following means.
That is, when one of the two shutter blades is constituted by the filter 18 and the other is constituted by the BPF 19, one of the shutter blades is on the optical path at the time of alignment and at the time of exposure, respectively. The other one retreats, and when the other one is on the optical path, the other one retreats, so that any one is moved by the motor etc. so that it is placed on the optical path. And a filter 18 and a BPF 19 are attached to the left and right ends of one shutter blade.
There are various means such as a configuration in which when one of P.F19 is on the optical path, the other moves away, and this shutter blade is rotationally driven by the above-mentioned motor or the like.

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

Further, as described above, since the filter 17 is fixedly provided on the exposure regardless of the alignment and the exposure,
On the optical path, a BP provided after the filter 17
There is an advantage that the F19 and the filter 18 can be prevented from being damaged by far ultraviolet rays.

[Advantages of the Invention] As described above, the exposure apparatus of the present invention includes a bandpass filter that transmits light having an exposure wavelength and a filter that transmits light having a wavelength for alignment without transmitting light having the exposure wavelength. Since it is provided so that it can be switched alternately on the optical path, the resolution of the device is increased and fine processing of the pattern is possible. Furthermore, since a filter that transmits light having an exposure wavelength and cuts light having a wavelength shorter than the exposure wavelength is permanently provided on the optical path, the bandpass filter and the wavelength for alignment that does not transmit the light having the exposure wavelength are transmitted. The filter that transmits the light is not damaged by the far ultraviolet light.

Also, at the time of alignment, the BPF is retracted from the optical path, so that it does not hinder the alignment, and does not require a large change in structure in comparison with the conventional apparatus, so that the improvement cost is low.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a schematic configuration of an exposure apparatus which is an embodiment of the present invention, FIG. 2 is a schematic explanatory view of a main part of a conventional exposure apparatus, and FIG. 3 is a diagram of a mercury lamp which is a light source. FIG. 4 is a diagram showing the spectral characteristics and the transmittance of the BPF, and FIG. 4 is a diagram showing the spectral characteristics of the mercury lamp as the light source, the sensitivity characteristics of the resist, and the transmittance of each filter. In the figure. 1: Light source 2: Mask 3: Projection lens 4: Alignment optical system 5: Workpiece 12: Elliptical condensing mirror 13, 15: Planar reflecting mirror 14: Integrator lens 16: Condenser lens 17, 18: Filter 18a, 19a: Drive Vessel 19: BPF

Claims (1)

(57) [Claims] In an exposure apparatus having a light source, an illumination optical system, a mask, and a projection lens, a filter for transmitting light having an exposure wavelength and cutting light having a wavelength shorter than the exposure wavelength is provided on an optical path. A bandpass filter that transmits light having an exposure wavelength on an optical path subsequent to the filter,
An exposure apparatus comprising: a filter that does not transmit light having the exposure wavelength but transmits light having a wavelength for alignment, which is alternately switchable.