Mask structure and process to repair missing or unwanted phase-shifting elements

Abstract

Abstract A phase-shifting mask (21) is composed of material including a substrate carrying a first phase-shifting layer (22) having a phase-shift of 0, a second phase-shifting layer (24) stacked upon the first layer having a phase-shift of (21π- 0), and a third phase-shifting layer (26) stacked upon the second layer next with a phase-shift of 0. Missing phase-shifters, unwanted phase-shifters, or defects in the transparent films are repaired by removing one or two layers depending upon whether the phase-shifting status has to be retained or altered. In one alternative a large etch selectivity exists between the first, second and third layers, or else a lack of etch selectivity is complemented with etch stop layers embedded between the phase-shifting layers as follows : a) if an defect is found in a phase-shifted area and the defect must be removed without turning the phase-shifted area into a non-phase -shifted area, then two successive layers in the phase-shifted area are removed ; b) if an error is found in a non-phase-shift area, then the mask call be repaired in the area surrounding the error by removing the layer in the area to make the area a phase-shifted area ; c) if a defect is found in a non-phase-shifted area and the defect must be removed without turning the phase-shifted area into a phase-shifted area, then two successive layers in the non-phase-shifted area are removed.

Inventors

• 👤 Burn Jeng Lin

Bibliographic Details