Levenson type phase shift mask and production method therefor

Abstract

A Levenson type phase shift mask which has light shielding portions and openings formed on a transparent substrate, and which is repeatedly provided with shifter openings formed by partially digging the transparent substrate portions of the openings or partially laying transparent films on the transparent substrate portions of the openings and with non-shifter openings to reverse the phase of a transmitted light by the shifter openings, wherein light shielding patterns each held by adjacent openings of the same kind from the opposite sides are provided, and a bias correction is made for widening the light shielding pattern a specified amount toward the opposite sides with respect to specified design line width defined by mask designing.

Description

technical field [0001] The present invention relates to a Levenson type phase shift mask for manufacturing semiconductor elements such as LSI and a manufacturing method thereof. Background technique [0002] Recently, with the increase in density and miniaturization of semiconductor elements, high-resolution characteristics are required even in projection exposure devices. Therefore, in the field of photomasks, there is a phase shift method proposed by Levenson et al. of IBM Corporation in 1982 as a technique for improving resolution characteristics of transcribed patterns. The principle of this phase shift method is as follows: a phase shift part (phase shifter opening) is provided in one opening so that the phase of the transmitted light passing through the adjacent opening is reversed to reduce the light at the boundary part when the transmitted light interferes with each other. Strong, thereby improving the resolution characteristics and depth of focus of the transcribe...

AI Technical Summary

Problems solved by technology

[0007] The first problem is that since the transmitted light 3a passing through adjacent openings 21a and 22a has the same phase (Л-Л in the case of Fig. The light intensity in the portion 23a between the openings of the type increases, resulting in a reduction in the resolution characteristics of this intervening portion

[0008] The second problem is that the light-shielding film 12b present in the portion 23a inserted between openings of the same type is easily peeled off (or peeled off)

There is no problem when the non-phase shifter openings adjoin each other, but when the same type of phase shifter openings 21a and 22a adjoin each other as in the pattern shown in FIG. The undercut 16 in the transparent substrate 11 in the portion 23a between the device openings 21a and 22a reduces the contact area between the light shielding film 12b and the transparent substrate 11.

Therefore, the light-shielding film 12b in the insertion portion 23a is easily peeled off from the transparent substrate 11.

Mask design is greatly restricted due to measures to prevent the light-shielding film 12b from coming off, and the amount of undercut cannot be properly selected, and mask performance deteriorates

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