Macronix International Co., Ltd.

Chi-Yuan Hung

I-Pien Wu

Ching-Yu Chang

Henry Wei-Ming Chung

A method of fabricating a phase shift mask (PSM) is described. A patterned photoresist layer is formed on an opaque layer over a transparent plate. A thin mask layer is formed on the sidewalls of the patterned photoresist layer. The exposed opaque layer and transparent plate thereunder are then removed while using the patterned photoresist layer and mask layer as a mask. A phase shift opening is formed in the transparent plate, and thereby a phase shift layer is formed at the place where the phase shift opening is located. The patterned photoresist layer and the opaque layer thereunder are then removed to expose the transparent plate. The opaque layer under the mask layer can precisely self-align the phase shift layer to prevent alignment deviation caused by multiple lithography processes. The precision of the phase shift mask can be increased, and mask manufacture cost can be lowered.

Method of fabricating phase shift mask

A three dimensional mask can adjust the coherence of radiation passing through an edge pattern on the mask by increasing the thickness of an opaque layer to extend the passing path in the edge pattern, thereby reducing the optical proximity effect (OPE) caused by interference. Therefore, shape distortion and depth of focus (DOF) deficiencies occurring on the edge pattern can be prevented to expose a fine pattern to a photoresist layer.

Three dimensional mask

First of all, an adjusting step is performed to change a first optical parameter and a second optical parameter, so as to adjust the positions of two side-lobes of the main feature's exposure peak and overlap with the main feature's exposure peak and two side-lobes thereof, wherein the first optical parameter is the Numerical Aperture (NA) and the second optical parameter is the sigma(&sgr;). Afterward, a lithography process is performed by using a translucent mask to pattern the semiconductor devices, wherein the translucent mask can equalize the intensity of the main feature's exposure peak and the side-lobes thereof from each other. Therefore, this invention can reduce the pitch to decrease the critical dimension of the semiconductor devices.

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Ilan, Taiwan

Chi-Yuan Hung