Method of forming fine patterns

Abstract

It is disclosed a method of forming fine patterns comprising: covering a substrate having photoresist patterns with an over-coating agent for forming fine patterns, applying heat treatment to cause thermal shrinkage of the over-coating agent so that the spacing between adjacent photoresist patterns is lessened by the resulting thermal shrinking action, and removing the over-coating agent substantially completely by way of bringing thusly treated substrate into contact with a remover solution for over 60 seconds.

Description

BACKGROUND OF THE INVETNION[0001] 1. Field of the Invention[0002] This invention relates to a method of forming fine patterns in the field of photolithographic technology. More particularly, the invention relates to a method of forming or defining fine patterns, such as hole patterns and trench patterns, that can meet today's requirements for higher packing densities and smaller sizes of semiconductor devices.[0003] 2. Description of the Related Art[0004] In the manufacture of electronic components such as semiconductor devices and liquid-crystal devices, there is employed the photolithographic technology which, in order to perform a treatment such as etching on the substrate, first forms a film (photoresist layer) over the substrate using a so-called radiation-sensitive photoresist which is sensitive to activating radiations, then performs exposure of the film by selective illumination with an activating radiation, performs development to dissolve away the photoresist layer selecti...

AI Technical Summary

Benefits of technology

[0033] It is particularly preferred to employ at least one member selected from the group consisting of alkylene glycol polymers, cellulosic derivatives, vinyl polymers and acrylic polymers. Acrylic polymers are most preferred since they provide ease in pH adjustment. Copolymers comprising acrylic polymers and water-soluble polymers other than acrylic polymers are also preferred since during heat treatment, the efficiency of shrinking the spacing between the adjacent photoresist patterns (mask patterns) can be increased while maintaining the shape of the photoresist pattern. The water-soluble polymers can be employed either singly or in combination.

[0042] The surfactant is preferably employed that, when added to the water-soluble polymer, exhibits certain characteristics such as high solubility, non-formation of a suspension and miscibility with the polymer component. By using surfactants that satisfy these characteristics, the occurrence of defects can be effectively controlled that is considered to be pertinent to microforming upon coating the over-coating agent.

Problems solved by technology

However, in these methods, it is difficult to control the thickness of layers to be formed on the sidewalls of resist patterns.

In addition, the in-plane heat dependency of wafers is as great as ten-odd nanometers per degree Celsius, so it is extremely difficult to keep the in-plane uniformity of wafers by means of the heater employed in current fabrication of semiconductor devices and this leads to the problem of occurrence of significant variations in pattern dimensions.

On the other hand, it is difficult to control the resist deformation and fluidizing on account of heat treatment, so it is not easy to provide a uniform resist pattern in a wafer's plane.

However, the use of polyvinyl alcohol singly is not highly soluble in water and cannot be readily removed completely by washing with water, introducing difficulty in forming a pattern of good profile.

The pattern formed is not completely satisfactory in terms of stability over time.

In addition, polyvinyl alcohol cannot be applied efficiently by coating.

Because of these and other problems, the method disclosed in JP-7-45510 has yet to be adopted commercially.

Further, those publications do not describe or suggest the effects of reducing the occurrence of defects by way of adjusting the times of removing step by washing with water.

If the water-soluble amine is incorporated in an amount of less than 0.1 mass %, the coating fluid may deteriorate over time.

If the water-soluble amine is incorporated in an amount exceeding 30 mass %, the photoresist pattern being formed may deteriorate in shape.

If the concentration of the aqueous solution is less than 3 mass %, poor coverage of the substrate may result.

If the concentration of the aqueous solution exceeds 50 mass %, there is no appreciable improvement in the intended effect that justifies the increased concentration and the solution cannot be handled efficiently.

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