JPH07107602B2 - Pattern forming material - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to an improvement of a pattern forming material for upper lamination for resist pattern formation suitable for microfabrication.

[Technical background of the invention and its problems]

The degree of integration of integrated circuits has been increased by a factor of four in a few years, and along with this, the size of patterns required for fine processing of elements has also been reduced in size. As a new resist pattern forming method for these requirements, B,
Contrast enhancement layer proposed by F, Griffing et al. (Hereinafter referred to as CEL) IEEE, Electron Dev
ices Lett, EDL-4 (1) 14 (1983), which is the first
A photosensitive thin film 2 containing a photobleaching material as shown in the figure is laminated on an ordinary photoresist 1 in the step of FIG. 1 (b). Next, exposure 3 is performed, and after CEL peeling, development is performed to obtain a resist pattern 4 having an improved profile and good dimensional accuracy. Ie CE
The L film has an extremely strong light absorption property at first, and the irradiated part is bleached by exposure, and the light passes through the CEL and exposes the resist below. On the other hand, in a portion not irradiated with light or a portion irradiated with a weak light which is not enough to bleach the CEL, the light is continuously shielded and the resist cannot be exposed. Based on the above principle, the contrast of an optical image is increased to obtain high resolution.

Here are some important points when designing a CEL. Second
The figure shows how the contrast of the CEL transparent film is amplified when a line and space pattern of 0.6 μm is exposed. Curve 5 shows the input vs. contrast curve 6 shows the output exposure of the input against the CEL transparent film. Is represented. Here, it can be seen that there is an optimum exposure amount that maximizes the contrast. In FIG. 2, the maximum contrast is 0.8 when the input exposure amount is 240 mj / mm ² . The output exposure amount (exposure amount applied to the resist) at this time is 150 mj / mm ² . However, 150 mj / mm ² is an excessive exposure amount for the resist, and 100 mj / mm ² is optimal. However,
When such exposure is applied, the contrast is 0.7 or less, which is a value below the peak value. In this way, it is necessary to match the sensitivity of the underlying resist with the CEL contrast peak value. Such a thing is called matching with a resist here.

On the other hand, whether or not this matching can be obtained largely depends on the sensitivity of the bleaching photosensitive group used for CEL. However, once the type of photosensitive group is decided, it is naturally decided, and it is very difficult to control the matching freely.

[Object of the Invention]

The present invention has been made in view of the above points, and an object thereof is to obtain a resist pattern with high resolution by performing matching by a simple method.

[Outline of Invention]

In order to achieve the above object, the present invention is a pattern forming material laminated on a photoresist and having a characteristic that the transmittance increases by exposure, when irradiating the photoresist with an optical image of a photomask, A pattern forming material having a transmittance that is adjusted so that the contrast of the optical image intensity distribution on the photoresist has a peak value and the exposure amount of the exposure light has an optimum value with respect to the sensitivity of the photoresist. provide.

〔The invention's effect〕

According to the present invention, matching with the underlying resist sensitivity can be achieved, and the effect of CEL can be fully used. That is, as shown in FIG. 3, by increasing the optical density of CEL by adding a dye, the output exposure dose curve becomes 7 to
8 and at this time the contrast curve 5 was found to be almost constant through computer simulation. That is, according to the present invention, the optimum output exposure amount of 100 mj / mm ² to the resist was given when the input was 240 mj / mm ² , and it was found from the theoretical calculation that the peak exposure contrast was matched at this time.

Example of Invention

Spin-coat the underlying positive resist to a thickness of 1 μm and then 2.
5-Diethoxy-4-morpholinobenzenediazonium chloride 1/2 zinc chloride 20 mmol, polyvinylpyrrolidone
A CEL material consisting of 10 g and 200 ml of water was spin-coated to a thickness of 0.5 μm. Further, after the pattern was exposed at 80 ° C. for 10 minutes, the pattern was exposed by an exposure device, and the optimum exposure amount at this time was 300 mj / mm ² , and a resolution of 0.8 μm was obtained. So, next, the C
When 0.1 mg of coumarin was dissolved in EL and the same exposure was performed, the exposure amount increased to 500 mj / mm ² , but the resolution was 0.6.
μm was obtained. Since it is difficult to measure the output contrast as shown in FIG. 3, it cannot be confirmed. However, as shown in FIG. 3, the improvement of the resolution is obtained when the contrast peak value and the input exposure amount for obtaining it are given. It is considered that the output exposure amount of 1 matched the resist sensitivity.

As described above, the present invention makes it possible to fully utilize the effect of CEL and obtain a resist pattern with higher resolution.

[Brief description of drawings]

Fig. 1 is a process drawing for explaining the CEL process, and Fig. 2 is C
FIG. 3 is a characteristic diagram showing the contrast amplification effect of EL, and FIG. 3 is a characteristic diagram showing how the peak value of the contrast is moved by the method of the present invention. 1 ... Photoresist, 2 ... CEL material, 3 ... Exposure light,
4 ... Resist pattern, 5 ... Input-to-output contrast, 7 ... Input-to-output exposure before dye addition, 6 ... Input-to-output exposure, 8 ... Input-to-output exposure after addition of dye.

Claims (1)

[Claims] 1. A pattern forming material, which is laminated on a photoresist and contains a photobleaching material whose transmittance is increased by exposure, wherein the photoresist is used for irradiating the photoresist with an optical image of a photomask. It was confirmed that the contrast of the optical image intensity distribution on the resist had a peak value, and that the transmittance was adjusted by adding an absorbing dye so that the exposure amount of the exposure light had an optimum value with respect to the sensitivity of the photoresist. Characteristic pattern forming material.