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

Paper PS1+MS+NM-TuM9
Bias Frequency Effect on SOC Film Degradation in sub-45 nm Line and Space Pattern SiO@sub 2@ RIE using S-MAP

Tuesday, November 14, 2006, 10:40 am, Room 2009

Session: Plasma Patterning
Presenter: H. Hayashi, Toshiba Corporation, Japan
Authors: H. Hayashi, Toshiba Corporation, Japan
K. Kikutani, Toshiba Corporation, Japan
J. Abe, Toshiba Corporation, Japan
A. Kojima, Toshiba Corporation, Japan
T. Oohashi, Toshiba Corporation, Japan
I. Sakai, Toshiba Corporation, Japan
T. Ohiwa, Toshiba Corporation, Japan
Correspondent: Click to Email
Sub-45 nm line and space pattern etching of SiO@sub 2@ film was studied using a stacked mask process (S-MAP) which consists of photoresist, spin-on-glass (SOG) and spun-on-carbon (SOC) film stacked structure. Maintaining pattern integrity becomes more challenging with the decrease of pattern size. Reduction of the hydrogen content of SOC, suppressed the fluorination reaction of its C-H bonds during SiO@sub 2@ etching which lead to line pattern wiggling, and as a result, 56 nm line and space pattern etching was realized.@footnote 1@ This time, the effect of ion energy distribution on SOC degradation in the SiO@sub 2@ etch process was investigated for sub-45 nm line and space pattern etching. The ion energy distribution was varied by dual frequency superimposed (DFS) RIE, using the conditions of 100 MHz rf supply with 3.2 MHz superimposed compared with 100 MHz with 13.56 MHz superimposed. The other SiO@sub 2@ etch conditions were the same, that is, C@sub 4@F@sub 8@ gas chemistry with the same electron density and self-bias voltage (-Vdc) of 6x10@super 10@ cm@super -3@ and 350 V, respectively. As a result, SOC line pattern wiggling was observed in the 3.2 MHz case, but it was suppressed in the 13.56 MHz case, even though the SiO@sub 2@ etch rates were 241 nm/min and 254 nm/min, respectively, and about the same. This shows that, by using DFS RIE with 13.56 MHz superimposed, SOC degradation can be suppressed while maintaining the SiO@sub 2@ etch rate for sub-45 nm line and space pattern etching. The maximum ion energy in the 13.56 MHz case should be lower than that of the 3.2 MHz case under the same -Vdc conditions, because with higher rf frequency, it would have a narrower ion energy distribution. In this way, SOC degradation was suppressed without decrease of the SiO@sub 2@ etch rate. In conclusion, S-MAP combined with 100 MHz/13.56 MHz DFS RIE realized sub-45 nm line and space pattern SiO@sub 2@ etching. @FootnoteText@ @footnote 1@ J. Abe et al., Symp. Dry Process, (2005) 11.