Chemical approach to make the most of EUVL: stochastic effect mitigation with developer and rinse

Abstract

EUV lithography has been one of the key factors that enables the continuation of semiconductor scaling beyond N7. While it is a vital technique for the HVM of the most recent advanced logic and DRAM devices, the EUVL still needs more efforts in order to fully exploit its capability and extend the application. One particular aspect that has been considered as of critical importance is the optical/chemical stochastic effects which may cause L/S, contact pattern defects limiting the efficiency of EUVL. The simplest way to alleviate the stochastic effects is to employ the higher EUV exposure dose; however, this approach is impractical as it obviously leads to even lower productivity. In this work, the alternative chemicals -such as EUV PTD developer and NTD rinse which are specifically prepared to overcome the stochastic effects -are examined to enhance the performance efficiency of EUVL. The focused features that thoroughly explored are EUV dose, local CD uniformity, PR swelling, pattern collapse, and defects. It is found that, with the chemical composition modification of developer and rinse, EUV pattern fidelity can be effectively optimized resulting in extended process window and improved productivity. It is expected that this work would not only facilitate the extension of EUV application but also help understand how EUV resists behave when they are under the influence of ancillaries.

Electrical analysis of a stochastically simulated 2 nm node electrical test structure

“…While the industry put a lot of effort into understanding, characterizing, and mitigating the impact of stochastic effects in 0.33 NA EUV lithography [3][4][5][6][7], the focus is shifting to 0.55 NA high NA EUV which is planned for introduction beyond the sub-3nm technology node. Here, stochastic effects are expected to play an even more significant role, including their impact on device performance [8,9].…”