Exposure method

Abstract

An exposure method includes the steps of providing a mask that arranges a contact-hole pattern and a pattern smaller than the contact-hole pattern, and illuminating the mask using plural kinds of light so as to resolve the contact-hole pattern and restrain the smaller pattern from resolving on an object to be exposed via a projection optical system, wherein the following conditions are met A=−1.7k1+C1, 1.2≦C1≦1.3, 0.5≦B≦0.55 and B≦A−0.1, 0.80≦σ≦0.9 and σ≧A+0.1, k1=(L / λ) NA, where k1 is resolving power, L is a hole diameter of the contact-hole pattern, λ is a wavelength for exposure, NA is a numerical aperture of the projection optical system, σ is a ratio of a numerical aperture of an illumination optical system to the numerical aperture of the projection optical system, A and B are distances from two orthogonal axes to a boarder of a light-shielding part in an effective light source for illumination of plural kinds of light, the light-shielding part being symmetrical with respect to the two orthogonal axes.

Description

[0001] This application claims the right of priority under 35 U.S.C. § 119 based on Japanese Patent Application No. 2002-164978, filed on Jun. 5, 2002, which is hereby incorporated by reference herein in its entirety as if fully set forth herein. [0002] This is a continuation of co-pending application Ser. No. 10 / 456,387, filed on Jun. 5, 2003, which is hereby incorporated by reference herein in its entirety as if fully set forth herein.BACKGROUND OF THE INVENTION [0003] The present invention relates generally to a mask pattern and a method for setting an optimal illumination condition to the mask pattern, and more particularly to a mask pattern and a method for setting an illumination condition suitable of a method of exposing a mask that arranges a desired pattern and an auxiliary or dummy pattern (these terms are used interchangeably in this application) smaller than the desired pattern, by illuminating the mask (reticle) using plural kinds of light so as to resolve the desired p...

AI Technical Summary

Problems solved by technology

In general, the resolving power improves with a shortened wavelength of exposure light and increased NA, while the projection exposure apparatus, from its nature, resolves some patterns relatively easily but cannot resolve other patterns easily.

It is therefore an issue in fine processing in the photolithography to make a fine contact-hole pattern.

More specifically, exposure cannot easily obtain the resolving power, depth of focus (“DOF”), and exposure dose tolerance for contact holes.

In addition, the contact holes have a much larger mask error enhancement factor (“MEF”) that is a degree to emphasize a mask error, than the line pattern, which hinders fine processing.

These methods are effective to resolve contact holes of about 200 nm as in their embodiments but insufficient to resolve currently demanded 120 nm contact holes.

It is therefore understood that the methods disclosed in these applications may resolve holes with a size of 163 to 136 nm, but cannot resolve holes with a size of 120 nm or smaller.

Images