Use of antireflective coating in bilayer resist process

A new multilayer resist process consisting of a thin antireflective (AR) film between the thick bottom PMMA layer and the top photoresist layer of the conventional bilayer resist process is reported in this paper. Aluminum features of micron and submicron size over topography have been achieved with this novel resist process by using a conventional 10:1 reduction GCA DSW 4800 stepper to expose the top photoresist layer. Excellent linewidth control over steps is demonstrated. Both the standing wave effect in the top resist layer and the interference from the light scattered by the substrate topography are eliminated in this AR coating approach. The mixing of the two resist layers encountered in the original bilayer resist process does not appear in this new process. The plasma etch resistance of this new multilayer resist process is improved by retaining the capping top photoresist layer, which also eliminates the delamination of the AR layer during the PMMA development. This novel resist process provides ...