Half-tone self-aligning phase shifting mask
AssigneeUnited Microelectronics Corp.
InventorsWen-An Loong, Shyi-Long Shy, Hong-Tsz Pan, Ming-Tzong Yang, Guey-Chi Guo, Yueh-Lin Chou
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Abstract
This invention describes the fabrication and use of a self-aligning phase shifting mask comprised of phase shifting material formed over a patterned layer of half-tone or partially transmitting material. The interaction of light passing through the phase shifting and partially transmitting areas of the mask, the phase shifting only areas of the mask, and the non phase shifting transparent areas of the mask provides greater image resolution and depth of focus tolerance than other lithography methods including other known phase shifting techniques.
Claims20
A self aligning phase shifting mask, comprising:
- a substrate of transparent non phase shifting material;
- a patterned layer of half-tone or light attenuating material having pattern edges formed on said non phase shifting substrate;
- and
- a patterned layer of phase shifting material having pattern edges formed on said half-tone or light attenuating material wherein said pattern edges of said phase shifting material extend beyond said pattern edges of said half-tone or light attenuating material.
A method of forming a self aligning phase shifting mask, comprising the steps of:
- providing a transparent substrate of non phase shifting material;
- forming a layer of half-tone or light attenuating material over said substrate of non phase shifting material;
- forming a layer of phase shifting material over said layer of said half-tone material;
- forming a layer of photoresist over said layer of phase shifting material;
- exposing and developing said photoresist layer to form a desired pattern with pattern edges;
- etching said desired pattern with pattern edges in said phase shifting material;
- removing said photoresist material;
- etching said desired pattern with pattern edges in said half-tone or light attenuating material using said pattern with pattern edges in said phase shifting material as a mask;
- and
- over etching said half-tone or light attenuating material so that said pattern edges of said pattern in said phase shifting material overhangs said pattern edges of said pattern in said half-tone or light attenuating material.
Dependencies are inferred from the claim text.