AVS 53rd International Symposium
    Plasma Science and Technology Tuesday Sessions
       Session PS1+MS+NM-TuM

Invited Paper PS1+MS+NM-TuM3
ArF Resist Friendly Etching Technology

Tuesday, November 14, 2006, 8:40 am, Room 2009

Session: Plasma Patterning
Presenter: T. Hayashi, ULVAC Inc., Japan
Authors: T. Hayashi, ULVAC Inc., Japan
Y. Morikawa, ULVAC Inc., Japan
K. Suu, ULVAC Inc., Japan
Correspondent: Click to Email
The requirements for dry etching technology in semiconductor processes beyond 90 nm node come to be very complicated and difficult. In photolithography, the introduction of ArF resist has started. ArF resists generally have very weak plasma resistance and are deformed in the etching process. However, as for the fundamental mechanism of deformation of resists in dry etching, sufficient discussions have not been done yet. So far ArF resist deformation has been thought to be caused by ion impinging damage. However, in our experiments, the deformation was not found in the high density NLD plasma in lower pressure than 1Pa, which gives relatively higher ion flux to the surface. So if ion energy is the main origin of the ArF resist deformation, then the NLD plasma might give a large resist deformation. Contrary to this expectation, however, the etched profiles in the NLD plasma showed low line edge roughness and almost nothing of striation. Considering these facts, the ArF resist deformation is clearly caused by concerted working of ion impinging damage and subsequent radical reactions at the resist-damaged area. This means if either of ion damage or radical reaction is nothing then the ArF resist deformation is nothing or is suppressed considerably lower. Therefore, the lower pressure process below 1 Pa or the lower reactive radical density process is necessitated. The latter is achieved by using highly effective radical scavenger. Generally H or CO has been used as the scavenger of F atoms. However, Br and I may be more effective as the scavenger, because Br and I react with F atoms and form stable inter-halogen compounds. So use of iodine or bromine contained perfluoro-hydrocarbon compounds like CF3I gives the ArF resist friendly etching process. Actually very smooth etched surfaces were obtained for patterned ArF resist/ARC/CAP/low-k/BARC/Si wafers. This work was partly supported by NEDO (New Energy and Industrial Technology Development Organization) in Japan.