Process optimization of AZ-2415/AZ-2400-17 resists for 0.5 micron E-beam direct write.
01 January 1988
A trilevel resist process for 0.5-micron e-beam lithography using AZ-2415/AZ-2400-17 as the imaging resist and the GHOST sup 7 proximity correction technique was developed. The process consist of an 85C prebake followed by a 16 microC/cm sup 2 20 kV on an electron beam exposure system (EBES). The 85C prebake provides better sensitivity than higher prebake temperatures without sacrificing pattern quality or process control. Next, a 2-step spray development is employed. The 2-step development was found to enhance the sensitivity by -30% over the conventional 1-step process. A mechanism for this enhancement is discussed. Further increasing the number of development steps provides no significant improvements. Dilution of the resist developer from 4:1 to 4.5:1 [water:AZ 2401] improves the contrast of the AZ-2415 from 1.8 to 2.2, which resulted in improved sidewall profiles and better pattern quality.