Most feasible curing process for ArF resists in device integration aspect

ArF lithography has been successfully implemented for the development of sub-100nm DRAM devices. Such issues as CD (critical dimension) slimming during in-line SEM inspection and low dry etch resistance especially for SiN etch conditions, however, are still latent showstoppers for the production with ArF process. To overcome these problems, there are many efforts for continuous improvements in terms of material and process together with intensive study of new inspection tool and dry etch system. The curing process is one of promising candidates to stabilize the weak ArF resists. Many kinds of curing processes including e-beam curing, thermal curing, plasma curing, UV curing, and VUV (172nm) curing have been studied, and some of them have shown good effects until now. The new curing process with VUV (172nm) showed the most promising results. SEM induced CD slimming of ArF resist improved with 10 sec curing and D/E resistance highly increased with the curing. And there was no particle increase unlike e-beam curing process. And we also found that the re-flow of ArF resist with high Tg above degradation temperature was possible with the VUV curing. In this paper, the mechanism and properties of VUV curing processes will be discussed.