Feasibility of 50-nm device manufacture by 157-nm optical lithography: an initial assessment

The normalized process latitude (NPL) is used to assess the feasibility of 50-nm device manufacture by 157-nm optical lithography. A first NPL quantification assuming steady improvement of processing technology shows that 157-nm optical lithography is infeasible. A second NPL quantification investigates the amount of technology acceleration required to make 50-nm manufacture possible. It is concluded that photolithography is a viable lithography technique for the 50-nm technology generation only with significant improvements in focus control, photomask making, photoresist contrast, as well as aberration levels.