US 5,853,923 AGranted

Double layer method for fabricating a rim type attenuating phase shifting mask

AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.

InventorSan-De Tzu

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Abstract

A method of forming a rim type attenuating phase shifting mask which requires only one resist layer and one resist developing step using a single developing solution. A transparent mask substrate has a layer of attenuating phase shifting material, a layer of opaque material, and a layer of resist material formed thereon. The layer of resist is exposed to a first pattern using a first exposure dose and a second pattern using a second exposure dose. The first exposure dose is sufficient to expose the first pattern in the entire thickness of the layer of resist material. The second exposure dose is sufficient only to expose the second pattern in a top portion of the layer of resist material. The resist is developed and the first pattern is used to etch the first pattern in the layer of opaque material and the layer of attenuating phase shifting material. The resist is then partially etched using an O.sub.2 plasma etch leaving the second pattern in that part of the layer of resist which remains. The second pattern is then etched in the layer of opaque material and the remaining resist material is stripped.

Claims27

Dependent claims

A method of forming a photomask, comprising the steps of:

providing a transparent mask substrate having a layer of first mask material formed on said transparent mask substrate and a layer of second mask material formed on said layer of first mask material;
forming a layer of resist material having a top portion and a bottom portion on said layer of second mask material;
exposing a first pattern in said top portion and said bottom portion of said layer of resist material using a first exposure dosage;
exposing a second pattern in said top portion of said layer of resist material using a second exposure dosage, wherein said second exposure dosage is such that said second pattern is not exposed in said bottom portion of said layer of resist material;
developing said layer of resist material, thereby forming said second pattern in said top portion of said layer of resist material and said first pattern in said bottom portion of said layer of resist material;
etching said first pattern into said layer of second mask material using a first etching method and said first pattern formed in said bottom portion of said layer of resist material as a mask;
etching said first pattern into said layer of first mask material using a second etching method and said first pattern formed in said bottom portion of said layer of resist material as a mask;
etching away part of said layer of resist material using a third etching method, thereby forming said second pattern in the remaining part of said layer of resist material;
etching said second pattern in said layer of second mask material, using a fourth etching method and said second pattern formed in said remaining part of said layer of resist material as a mask;
and
removing said remaining part of said layer of resist material.

8 more elements

A method of forming a photomask, comprising the steps of:

providing mask substrate, wherein said mask substrate is transparent to light having a characteristic wavelength;
providing a layer of attenuating phase shifting material on said mask substrate, wherein said layer of attenuating phase shifting material provides a phase shift and partial transmission of light having said characteristic wavelength;
providing a layer of opaque material on said layer of attenuating phase shifting material, wherein said layer of opaque material is opaque to light having said characteristic wavelength;
forming a layer of resist material having a top portion and a bottom portion on said layer of opaque material;
exposing a first pattern in said top portion and said bottom portion of said layer of resist material using a first exposure dosage;
exposing a second pattern in said top portion of said layer of resist material using a second exposure dosage, wherein said first pattern lies within said second pattern and said second exposure dosage is such that said second pattern is not exposed in said bottom portion of said layer of resist material;
developing said layer of resist material after exposing said first pattern and partially exposing said second pattern in said layer of resist material, thereby forming said second pattern in said top portion of said layer of resist material and said first pattern in said bottom portion of said layer of resist material;
etching said first pattern into said layer of opaque material using a first etching method and said first pattern formed in said bottom portion of said layer of resist material as a mask;
etching said first pattern into said layer of attenuating phase shifting material using a second etching method and said first pattern formed in said bottom portion of said layer of resist material as a mask;
partially etching away said layer of resist material using a third etching method, thereby forming said second pattern in the remaining part of said layer of resist material;
etching said second pattern in said layer of opaque material, using a fourth etching method and said second pattern formed in said remaining part of said layer of resist material as a mask, after partially etching away said layer of resist material;
and
removing said remaining part of said layer of resist material after etching said second pattern in said layer of opaque material.

10 more elements

Dependencies are inferred from the claim text.