Method for forming a mask pattern

Details Method for forming a mask pattern Method for forming a mask pattern

2002-09-30

2004-06-15

Lebentritt, Michael (Department: 2824)

Semiconductor device manufacturing: process

Making device or circuit emissive of nonelectrical signal

Including integrally formed optical element

C438S027000, C438S030000, C438S065000, C438S069000

Reexamination Certificate

active

06750073

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a method for forming a mask pattern on a substrate such as a silicon substrate, a ceramic substrate, a metal layer or a polymer layer; and, more particularly, to a method for forming on a substrate a microscale mask pattern having a size ranging from several nm to several tens &mgr;m by way of employing a polymer mold in fabricating an integrated circuit, an electronic device, an optical device, a magnetic device, a surface acoustic wave (SAW) filter and the like.
BACKGROUND OF THE INVENTION
It is well known in the art that a microscale pattern is formed on a substrate in order to fabricate, e.g., semiconductor, electronic, optical, and magnetic devices. Two microscale pattern forming methods have been conventionally employed: one is a micro-contact printing method and the other is an imprinting method.
The micro-contact printing method involves the steps of: wetting a pattern structure, formed on a surface of a polymer mold with a chemical mask material; bringing the pattern structure of the polymer mold into contact with a surface of the substrate to transfer the chemical mask material to the substrate and thus to change the surface condition thereof; and etching the substrate by using the transferred chemical mask material as a resist mask. Though the conventional micro-contact printing method has an advantage that an external force need not to be applied to the substrate, it also has a defect that the chemical mask material may be readily etched during the etching process since the thickness of the chemical mask material is merely several nm. Furthermore, the micro-contact printing method is not adequate for the fabrication of three-dimensional microstructures since the minute adjustment of the thickness of the mask material is very difficult.
Meanwhile, in another conventional micro pattern forming process called the imprinting method, a hard mold with a surface of a desired pattern formed thereon is compressed into a polymer film featuring low fluidity to form a mask pattern on the polymer film. Then, the mask pattern is delivered to an underlying substrate by using, for example, a reactive ion etching technique. Since, however, the imprinting method involves applying a high physical pressure ranging from 3000 to 15000 W/cm
2
for the imprinting of the mold pattern into the substrate, the substrate and the polymer mask patterns formed thereon may be deformed or even destroyed.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a method for forming a microscale mask pattern on a substrate by using an elastomeric and solvent-absorbent polymer mold.
In accordance with a preferred embodiment of the present invention, there is provided a method for forming a mask pattern on a substrate by using a solvent absorbent mold having a pattern structure with a relief and an intaglio portion, the method including: (a) forming a mask layer on the substrate, the mask layer being dissolved in a solvent to obtain fluidity; (b) placing the mold onto the mask layer with a predetermined pressure so that a portion of the mask layer that contacts with the relief portion of the mold is allowed to be introduced into the intaglio portion thereof and the mold is allowed to absorb the solvent contained in the mask layer to thereby solidify the mask layer; (c) separating the mold from the substrate; and (d) removing the portion of the mask layer that contacts with the relief portion of the mold to thereby obtain the mask pattern.
In accordance with another preferred embodiment of the present invention, there is provided a method for forming a mask pattern on a substrate by using a solvent absorbent mold having a pattern structure with a relief and an intaglio portion, wherein the relief portion has a surface roughness larger than a predetermined level, the method including: (a) forming a mask layer on the substrate, the mask layer being dissolved in a solvent to obtain fluidity; (b) placing the mold onto the mask layer with a predetermined pressure so that a portion of the mask layer that contacts with the relief portion of the mold is allowed to be introduced into the intaglio portion thereof and the mold is allowed to absorb the solvent contained in the mask layer to thereby solidify the mask layer; (c) separating the mold from the substrate so that the portion of the mask layer that contacts with the relief portion of the mold is allowed to have a porous structure having a comparatively low density; and (d) rendering the porous structure lifted-off to thereby obtain the mask pattern.


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