JPS60212731A - Liquid crystal photomask - Google Patents

Abstract

PURPOSE:To shorten the time required from a design to a finish of an LSI, etc. by varying (erasing) a pattern of a photomask whose pattern is limited, by an electric signal, in the same way as a photomask designed by a user for manufacturing a mask ROM and a gate array. CONSTITUTION:A light shielding metallic layer 5 of chromium, titanium, etc. is provided on an electrode end part and a part where there is no electrode. By taking disturbance in the end part of this electric field, and scattering and diffraction in case when light passes through a liquid crystal layer 9 having a thickness of about 5-20mum into consideration a picture element part crossed by the electrode, and the light shielding metal 5 require a superposition exceeding the same extent as the thickness of its liquid crystal layer. Also, in order to prevent the light shielding metal 5 and a transparent electrode 7 from being short-circuited, an insulating layer 6 is formed. The shape of opening parts 15, 16 of the light shielding metal 5 is optional, as long as it is within the almost same extent as the liquid crystal layer 9 from the picture element part crossed by the electrode. By forming the shape of this opening part 15 to a desired mask pattern, a fine pattern which is different from the electrode shape is obtained.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a photomask used in semiconductor manufacturing, and in particular to a photomask using a pattern-variable liquid crystal channel, which is suitable for prototyping and manufacturing of mask OM and gate arrays. Regarding liquid crystal photomasks.

[Background of the invention]

Recent advances in semiconductor manufacturing technology have been supported by advanced photolithography technology. What photomask is required for this photolithography?

Conventionally, 1 was deposited on a transparent glass substrate 1 as shown in FIG.
A chromium-based light-shielding metal 2 with a thickness of about 0.000A'' is placed in a variable pattern pattern.

FIG. 2 shows the conventional procedure from setup to exposure. After designing the mask pattern, create data for the 7-otoprotester, use a photoplotter to make a reticle (a type of photomask) that is 10 times the size of the mask pattern, and use this reticle to print 1.
A large number of identical LSI patterns are created on a single photomask. In particular, when a high-precision pattern is required, a 1/10M reticle or a copy of the 10x reticle is used.
There is also a method of performing LSI patterning using a small projector aligner, turning a photomask through electron beam exposure, or creating a variable pattern directly on the LSI.

But in the traditional way of making reticles.

Since it takes at least one to several days from L 51 pattern design to photomask or reticle formation, it takes several days to two weeks or more to complete the modified LSI after the design change, resulting in extremely poor throughput. On the other hand, photomask creation using electron beam exposure and %LSI direct patterning can improve the time from design to completion of LSI prototype production, but the electron beam exposure equipment is extremely expensive, making it difficult to manufacture general LSIs. It had some drawbacks that made it difficult to use.

[Purpose of the invention]

The object of the present invention is to provide an inexpensive and modified LS from design changes.
1 by the completion of I etc.! The aim was to shorten the time required to do so. Our goal is to provide photomasks.

[Summary of the invention]

For the above purpose, a liquid crystal panel whose light transmittance is partially changed by an electric signal is used as a photomask, and at the same time as the design is changed, the liquid crystal panel driving electric signal is changed to obtain a photomask with a desired pattern. It is characterized in that the time required for manufacturing is negligible.

[Embodiments of the invention]

FIG. 5 is a sectional view of a liquid crystal photomask according to an embodiment of the present invention, and FIG. 4 is a plan view thereof.

As with normal liquid crystal display panels, the initial alignment control film 8.1
A polarizing plate 5.13 is attached to the surface of a panel in which a twisted nematic liquid crystal is sealed in a space surrounded by a transparent substrate 4.12 having transparent electrodes 7 and 11 attached thereto and a sealing material 14. This LCD panel.

Depending on the electric field applied between transparent electrodes 7 and 11.

The light transmittance of each pixel portion changes.

At this time. Disturbance of the electric field at the edge of the transparent electrode (an electric field perpendicular to the electrode is generated at the center of the electrode, or the electric field at the edge is tilted from the direction perpendicular to the electrode). In order to prevent unevenness in transmittance, a light-shielding metal layer 5 made of chromium, titanium, or the like is provided at the end of the electrode and the part without the electrode. disturbances at the edges of this electric field.

Considering scattering and diffraction when light passes through the liquid crystal layer 9, which has a thickness of about 5 to 20 μm, the pixel area where the electrodes intersect and the light-shielding metal 5 should have a thickness that is approximately the same or more than the thickness of the liquid crystal layer. Overlapping is required. He's talented.

K to prevent a short circuit between the light-shielding metal 5 and the transparent electrode 7.

An insulating layer 6 is formed therebetween.

The shape of the openings 15 and 16 in the light-shielding metal 5 is arbitrary as long as the inner pressure from the pixel portion where the electrodes intersect is approximately equal to or more than the thickness of the liquid crystal layer 9. The shape of this opening 15 is
By forming a desired mask pattern, a fine pattern different from the electrode shape can be obtained. Therefore, the electrode shape accuracy is inferior to the normal mask accuracy. The opening 16 is an example of an alignment mark required for mask alignment.

By forming this alignment mark on the electrode, when aligning the mask, this pixel part can be made transparent and the alignment mark can be used, and during exposure, it can be made opaque so that the alignment mark is not exposed, and the extra pattern can be removed on the LSI etc. It is also possible to prevent it from occurring. If it is acceptable to expose the reverse pressure alignment mark, the alignment mark may be formed in a portion where there is no transparent electrode by using a liquid crystal mode that becomes transparent when no electric field is applied. Furthermore, if a liquid crystal mode that becomes transparent in the absence of an electric field is used, patterns that do not need to be erased may be formed in areas where there is no transparent electrode. However, even at this time.

The pattern opening of the light-shielding metal 5 needs to be spaced from the end of the electrode by at least approximately the same thickness as the liquid crystal layer.

In this way, the liquid crystal photomask shown in FIGS. 5 and 4 has a pattern formed on the inside sandwiched between transparent substrates, unlike the conventional photomask shown in FIG. 1, which has a pattern formed on the surface. Because of this, contact exposure, which has been commonly used in the past, is not possible. In addition, since the liquid crystal layer has a thickness of about 5 to 20 μm and a fine pattern with a pitch of several μm or less cannot be realized, a pattern that is about 5 to 10 times larger than the pattern exposed on an actual LSI etc. can be formed using the liquid crystal photomask of the present invention. ,
It is preferable to use a reduced projection aligner. FIG. 5 shows an example of the procedure from design to exposure when the present invention is used. Compared to the conventional example shown in FIG. 2, this is because there is no step of forming a 10x reticle using a photoplotter.

This has the effect of shortening the time from design to prototyping.

A sectional view of another embodiment of the present invention is shown in FIG. 6, and a plan view is shown in FIG.
As shown in the figure. The embodiments in Figures 5 and 4 are simple Ma) IJ
6 and 7, it is difficult to selectively drive many pixels, that is, patterns, because the selection duty ratio becomes small, especially in liquid crystal photomasks that require a large fundus ratio. In the embodiment shown in , by using an active matrix drive method using so-called thin film transistors, even if the number of pixels or patterns is large, for example, 10,000 or more, the selected duty ratio can be maintained by sampling and holding each pixel switch and signal holding capacitor. Since it can be set to approximately 1, it has the advantage of easily obtaining a large fund-last ratio.

In FIG. 6, 17% of the thin film transistor and an insulating layer 18 between the thin film transistor and the transparent electrode are added to FIG. 5. In FIG. 7, the transparent electrodes 7 and 11 are arranged in a matrix in FIG. 4, whereas the transparent electrodes 7 are separated into each pixel or pattern.

The transparent electrode 11 constitutes a common electrode over the entire surface. In addition, since it is an active matrix system, the gate bus 19. The drain bus 20 runs avoiding the openings 15 and 16 in the light-shielding metal 5, and each pixel switching transistor 17 is formed at the intersection thereof, also avoiding the opening in the light-shielding metal 5. With this configuration, the gate bus 19. There is an advantage that the light transmittance of the drain bus 20 and the switching transistor 17 can be prevented from affecting the light transmittance of the opening of the liquid crystal photomask. Further, the light-shielding metal layer 5 can also be used as a pixel common electrode of a signal holding capacitor formed in each pixel.

The liquid crystal photomask of the embodiment shown in Figs. 6 and 7 also follows the procedure from design to exposure as shown in Fig. 5, as in the case of the embodiment shown in Figs. 6 and 4. The time required can be shortened.

In the above explanation, a twisted nematic liquid crystal that uses two polarizing plates is taken as an example, but there are also guest-host liquid crystals that only require one polarizing plate 5 or 15, and phase change liquid crystals that do not require a polarizing plate.

The present invention can be implemented regardless of the display mode of the liquid crystal.

〔Effect of the invention〕

According to the present invention, such as a user-designed photomask for mask ROM and gate array manufacturing.

This is because the no-turns on the photomask, which has a limited pattern, can be varied (erased) using electrical signals.

This has the effect of shortening the time from design to completion of LSI etc.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional photomask, Figure 2 is a procedure diagram from conventional pattern design to photolithography,
FIG. 5 is a cross-sectional view of a liquid crystal photomask as an embodiment of the present invention, FIG. 4 is a plan view thereof, and FIG. Fig. 6 is a sectional view of a liquid crystal photomask according to another embodiment of the present invention, and Fig. 7 is a plan view thereof. 1... Transparent glass, 210. Chromium. 5.15... Polarizing plate, 4 .12... Transparent substrate. 5... Light shielding metal 6.18... Insulating layer, 7.11.
...Transparent electrode 8.10...Orientation control film. 9...Liquid crystal, 14...Liquid crystal sticker. Representative Patent Attorney Akio Takahashi Figure 1, Figure 2, Figure 2, Figure 4, Figure 5, Figure 2, 3

Claims (1)

[Claims] 1. A light-shielding metal layer is provided insulated from the transparent electrode and has a mask pattern opening at least as thick as the thickness of the liquid crystal layer inward from the pixel-corresponding part of the transparent electrodes that sandwich the liquid crystal layer. A liquid crystal photomask characterized by the ability to select patterns.