Electron beam lithography process for advanced optical masks

Abstract

The requirements for advanced optical masks have been tightened according to the accelerated lithography roadmap for semiconductor manufacturing. The accuracy of the optical mask may be affected by the pattern exposure tools, the materials, and the processes. Higher acceleration voltage e-beam pattern exposure was evaluated with a chemically amplified resist. With the higher acceleration voltage e-beam system, proximity effect correction is needed to control the critical dimension (CD). CD linearity is maintained down to 400 nm for different kinds of patterns by adopting the 50 kV e-beam system and proximity effect correction. The results show that the method is an attractive candidate for fabrication of next generation optical masks. Dry etching is effective in achieving small feature sizes, such as optical proximity correction (OPC), with high pattern fidelity. Loading effects were evaluated, and inductively coupled plasma dry etching was found to be stable against those effects. Fabrication of the OPC pattern designed for a 0.15 μm rule device was demonstrated with these methods.