JPH0685385B2 - Exposure method - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to an exposure method for forming a pattern on a substrate of a solid-state electronic device when manufacturing a solid-state electronic device represented by an integrated circuit.

[Technical background of the invention and its problems]

In a manufacturing process of a solid-state electronic device represented by an integrated circuit, photolithography technology is frequently used, and exposure of a pattern by an exposure apparatus is indispensable.

The exposure apparatus has a contact method in which a mask on which a predetermined pattern is drawn and a substrate of a solid-state electronic device to which the pattern of this mask is transferred are overlapped and exposed, and the mask and the substrate are overlapped with a distance of about 10 to 50 μm. There are a proximity exposure method in which the mask and the substrate are sufficiently separated, and a projection exposure method in which the mask and the substrate are arranged in a projection optical system and exposed.

There are devices for various substrate sizes in the contact method and proximity method, but since the mask and the substrate are stacked, the photoresist applied to the surface of the substrate may adhere to the mask or the mask may be scratched. It is easy and there are many defects in the pattern transferred to the substrate, and as a solution to this, a projection exposure type exposure apparatus has appeared, and it is becoming the mainstream in the field of integrated circuits. Are spaced far enough apart that photolithographic defects are greatly reduced.

Currently used projection exposure apparatuses include those that project the mask pattern on the substrate at the same size and those that reduce the size to 1/5 or 1/10, and the projection optical system uses a mirror. There are a reflective type using a lens and a refractive type using a lens.

On the other hand, looking at the current performance of the mask, in the case of a glass mask, a 7-inch square substrate and an effective pattern area of 6-inch square are the ones that satisfy the high-precision specifications with an error of 1 μm or less with a 10 μm pattern. However, if the size is larger than this, it is difficult to obtain a high-precision mask due to problems such as maintaining the flatness of the substrate, accumulated pitch error amount, and glass mask manufacturing apparatus.

Therefore, when projection exposure is performed using a high precision mask, only a pattern with a maximum size of about 6 inches square can be obtained, but at the same time, with a mask up to the above 7 inches square size, an ultrahigh precision 1 μm pattern It is also possible to obtain an error of about 0.1 μm.

In addition, recently, a so-called active matrix type liquid crystal display element has been actively developed, and a high-precision and high-performance display device using a substrate in which thin film transistors (TFT) are arranged in a matrix is actively developed. The outline is introduced in Proceedings of the Joint Conference of Japan, Lecture No. 16-6 (p.3-41).

Display devices are required to have a certain size and resolution in view of human eyes. For example, a device with a diagonal of 10 inches or 14 inches and a pixel count of 400 × 640 is one of the goals of display device development. Therefore, the active matrix type liquid crystal display element is a promising one that can realize a large-sized display device, but it is necessary to perform lithography several times in order to form a thin film transistor (TFT). , A high-precision mask of about 10 μm pattern,
A high-performance exposure apparatus is required, and it is necessary to perform exposure by a projection exposure method in order to obtain a defect-free pattern.

However, in the combination of a high-precision mask with a pattern of 10 μm and an error of about 1 μm as described above, and a conventional projection exposure apparatus for equal-magnification exposure or reduction exposure, the active matrix type liquid crystal display element is about 6 inches square. There was a problem that I could only get it.

[Object of the Invention]

The present invention has been made in view of the above points, and an object thereof is to expose a pattern on a substrate of a large-sized solid-state electronic device.

[Outline of Invention]

The exposure method of the present invention is an exposure method for forming a pattern on a substrate of a solid-state electronic device such as an active matrix type liquid crystal display device, a multiplex type liquid crystal display device, and other integrated circuits, which comprises: Through the pattern drawn on the ultra-high-precision mask positioned by the mask positioning means, onto the photoresist applied to the substrate positioned by the substrate positioning means at a magnification of more than 1 ×, and relatively projected. By using a small ultra-high precision mask, the photoresist of a relatively large substrate is exposed with high precision to the enlarged mask pattern.

Example of Invention

 An embodiment of the exposure method of the present invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment.

Reference numeral 1 is a light source, 2 is a lens system as an optical system for converting emitted light L0 from the light source 1 into parallel light L1, and M is a relatively fine pattern on the surface of which a fine pattern (shown as AB in the drawing) is drawn. A small glass mask, 3 is a mask positioning means for vertically positioning the glass mask M with respect to the parallel light L1, and 4 is a light source after the parallel pattern light L2 transmitted through the glass mask M positioned by the mask positioning means 3 is once condensed. , A lens system as an optical system for expanding the radial pattern light L3, a lens system 5 as an optical system for converting the expanded radial pattern light L3 into a parallel pattern light L4, and a surface B coated with a photoresist. Substrate of relatively large solid-state electronic device,
Reference numeral 6 denotes a substrate positioning means for vertically positioning the substrate B with respect to the enlarged parallel pattern light L4, and the housing and the like are omitted for simplification of description.

In the case of this embodiment, the glass mask M having a predetermined pattern is positioned on the mask positioning means 4 and
The substrate B coated with the photoresist is used as the substrate positioning means 6
The light source 1 is turned on for a predetermined time in the state where
Alternatively, when the shutter (not shown) provided between the light source 1 and the substrate B is opened for a predetermined time while the light source 1 is turned on,
The pattern of the glass mask M is projected as pattern light L4 parallel to the photoresist on the substrate B at a magnification greater than 1, and the pattern is enlarged and transferred to the photoresist.

A stable pattern is left on the substrate B after the exposure step, the development step and the fixing step, and the pattern is used as an etching mask on the substrate B in the same manner as in the manufacture of a normal integrated circuit. Etch a thin film.

In this enlargement transfer, as described above in the section [Technical background of the invention and its problems], when the substrate B is an active matrix type liquid crystal display device, a highly accurate pattern of about 10 μm is formed. Required, but a glass mask M
Since an extremely high precision pattern of about 1 μm can be obtained, the magnification of the lens system 4 can be set up to about 10 times.

Since the glass mask M and the substrate B can be sufficiently separated from each other, they do not come into contact with each other. Therefore, if the environment of the substrate B is dust-free and the photoresist of the substrate B has no dust or the like, it is enlarged and transferred to the photoresist. The formed pattern is a defect-free pattern.

Further, when the substrate B is for a multiplex type liquid crystal display element, only one layer of wiring is required, so exposure is only required once. However, when the substrate B is for an active matrix type liquid crystal display element, a thin film transistor ( To form a TFT, a plurality of glass masks M are used, and each glass mask M
Are sequentially positioned on the mask positioning means 3 and exposed several times. At this time, it is necessary to match the pattern of the next glass mask M with the pattern formed on the substrate B in a predetermined relationship. In such a case, the alignment mark M corresponding to each glass mask M and substrate B
1, B1 may be provided, and the marks M1, B1 may be aligned by moving the substrate positioning means 6, for example.

In addition, as a positioning mechanism for aligning the pattern of the next glass mask M with the pattern previously formed on the substrate B in a predetermined relationship, an aligner that is usually added to this type of exposure apparatus is used. A so-called aligning mechanism is used. As a method of aligning, a manual method in which an operator looks at each mark M1 and B1 with a microscope and moves the substrate positioning means 6, or a substrate B by laser beam scanning is used. In the method of certifying the position of the substrate B and automatically aligning it, and the method of certifying the position of the substrate B by the interference of the laser beam and automatically aligning it, the CCD is used instead of the human eye.
There are various methods such as a method of automatically aligning using.

If the substrate positioning means 6 is provided with a step & repeat function so that the substrate B can be moved vertically to the optical axis, the same glass mask M is used to form the substrate B.
It is also possible to expose the same pattern to a plurality of locations of the photoresist of (1), and naturally, it is also possible to draw a plurality of patterns on the glass mask M and simultaneously expose each of these patterns to the photoresist of the substrate B. it can.

FIG. 2 shows a modification of the first embodiment shown in FIG.

In this modification, in order to make the exposure apparatus compact, the optical axis is bent at a right angle between the lens system 2 and the glass mask M of the mask positioning means 3 by the plane mirror 11 as an optical system.

FIG. 3 shows a second embodiment.

Reference numeral 21 denotes a lens system as an optical system that collects the emitted light L0 from the light source 1 and irradiates the glass mask M positioned by the mask positioning means 3 evenly, and 22 positions the pattern light L5 transmitted through the mask M on the substrate. Substrate B positioned by means 6
In the case of the second embodiment, the pattern projected onto the substrate B is not parallel light, but the substrate B is a lens system as an optical system for forming an image on the photoresist of FIG.
If the flatness is good, it can be applied without problems.

In the second embodiment, as compared with the first embodiment, the number of lens systems can be reduced by one, and the aperture of the lens system 22 for projecting a pattern on the substrate B can be reduced.

FIG. 4 shows a third embodiment.

Reference numeral 31 is a plane mirror as an optical system that bends the optical axis of the parallel pattern light L2 transmitted through the glass mask M positioned by the mask positioning means 3 at a right angle, and 32 is the substrate for positioning the parallel pattern light L2 bent by the plane mirror 31. A plane mirror as an optical system for obliquely irradiating the photoresist of the substrate B positioned by the means 6 and projecting it at a magnification greater than 1, in the case of the third embodiment, the first embodiment and its modification. And instead of enlarging the pattern of the glass mask M by a refraction type optical system such as the lens systems 4 and 22 as in the second embodiment, the pattern of the glass mask M by a reflection type optical system such as a plane mirror 32. Is to be expanded.

As an optical system having a magnifying function for magnifying a pattern, not only a refracting lens or a reflecting plane mirror but also a reflecting curved mirror such as a concave mirror or a convex mirror or a refracting prism can be used. However, in any case, the distortion and aberration of the optical system must be extremely small in order to form a highly accurate pattern of about 10 μm.

Although the glass mask is used in the above description, a film mask or a metal mask can be used depending on the purpose.

〔The invention's effect〕

As described above, according to the present invention, since a relatively small mask is used and a pattern is enlarged and exposed on a substrate of a relatively large solid-state electronic device, an ultrahigh precision mask is used. As a result, it is possible to form a highly precise pattern on a large-sized substrate, and thus it is possible to make a highly accurate display device such as an active matrix type liquid crystal display device large in size, and to mass-produce such a display device. And it becomes possible to provide it at low cost.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of an exposure method according to the present invention. FIG. 1 is a block diagram of the first embodiment, FIG. 2 is a block diagram of a modification thereof, and FIG. FIG. 4 is a block diagram of the third embodiment, and FIG. 4 is a block diagram of the third embodiment. 1 ... Light source, 2,4,5,21,22 ... Lens system as optical system, 3 ... Mask positioning means, 6 ... Substrate positioning means, 11,31,32 ... Flat mirror as optical system, M: mask, B: substrate.

Claims (6)

[Claims] 1. An exposure method for forming a pattern on a substrate of a solid-state electronic device, comprising a light source, a mask positioning unit for positioning a mask on which a pattern is drawn, and a substrate positioning unit for positioning the substrate coated with photoresist. And an optical system for irradiating the substrate positioned by the substrate positioning means with the light of the light source through the mask positioned by the mask positioning means to project the pattern of the mask onto the photoresist of the substrate to expose the photoresist. And an exposure method, wherein the optical system magnifies and projects the pattern of the mask onto the photoresist of the substrate at a magnification exceeding 1x. 2. The exposure method according to claim 1, wherein the optical system projects the enlarged pattern of the mask as parallel light on the photoresist of the substrate. 3. The exposure method according to claim 1 or 2, wherein the optical system is mainly composed of a refracting optical system. 4. The exposure method according to claim 1, wherein the optical system is mainly composed of a reflection type optical system. 5. A plurality of masks are sequentially positioned on the mask positioning means, and the mask positioning means or the substrate positioning means is moved so that the patterns of each mask are aligned with each other in a predetermined relationship. The exposure method according to any one of claims 1 to 4, wherein the photoresist on the substrate is sequentially exposed. 6. The substrate according to any one of claims 1 to 5, wherein the substrate positioning means is moved to expose the same pattern at a plurality of locations on the photoresist of the same substrate by the same mask. The exposure method as described in 1.