| 摘要 |
An attenuated phase shifting mask employs regions of increased light transmissivity adjacent the defined circuit pattern features. Such regions can be provided by partially oxidizing a secondary region of the halftone masking layer. The result is improved image resolution and depth of focus, and a minimization of image shortening effects. In a second primary embodiment, similar improvements, as well as well as sharper corner definition, are obtained by providing on a mask (conventional or phase shifting) a generally rounded, light diffracting topography at edges of the defined circuit pattern features. This can be accomplished, for an elongated hole feature, by depositing a layer of light transmissive material on a conventional mask structure to form a generally convex light transmitting surface overlying an edge of the masking layer. In the case of a line feature, the substrate can be etched to form a recessed region including a generally concave light transmissive surface extending beneath an edge portion of the masking layer.
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