| 摘要 |
A simplified process for forming a phase shifting mask is disclosed. A chrome layer is formed on a transparent substrate and patterned. A resist layer is patterned to define the phase shifting areas and the substrate is dry etched to a first predetermined depth, stripped and cleaned. Another resist layer is patterned to define the phase shifting areas and the substrate is dry etched a second predetermined depth, stripped and cleaned. A further resist layer is patterned to define the phase shifting areas and the substrate is wet etched a third predetermined depth, stripped and cleaned. The sum of the three predetermined depths is such that it corresponds to a 180 DEG phase shift of light passing through the substrate. The third predetermined depth is at least about one third of the total depth.
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