Resist Poisoning-Free Advanced PECVD-Based Anti-Reflective Coating (ARC) for 90nm Technology and Beyond

A nitrogen-free (N-free) dielectric anti-reflective coating (DARC®) was cost-effectively developed in a plasma-enhanced chemical vapor deposition (PECVD) reactor to eliminate the 193nm resist poisoning interaction caused when N 2 O is used as a precursor [1]. Although it was found that even a N-free ARC could poison sensitive 193nm resists with –OH radicals [2], which either exist inherently in the ARC or result from H 2 O absorption by the ARC surface, the current investigation has revealed that it was possible to minimize resist poisoning. Our investigation showed that compressive film stress directly correlates to H 2 O resistance. Therefore, it was possible to greatly improve the ARC resistance to H 2 O absorption by creating and maintaining a process regime that makes the ARC film dense. The dense ARC film demonstrated promising lithography performance with minimal resist poisoning as well as excellent shelf life and O 2 -ashing resistance. This paper explores the N-free DARC material, its development, lithographic integration results and implementation in a production environment to eliminate 193nm resist poisoning.