AVS 51st International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS1-MoM

Paper PS1-MoM11
Highly Selective Etching of Si@sub 3@N@sub 4@ to SiOC by Precise Ion Energy Control for sub-90 nm Dual Damascene Formation

Monday, November 15, 2004, 11:40 am, Room 213A

Session: Low-k Dielectric Etching
Presenter: H. Hayashi, Toshiba Corporation, Japan
Authors: H. Hayashi, Toshiba Corporation, Japan
A. Kojima, Toshiba Corporation, Japan
A. Takase, Toshiba Corporation, Japan
K. Yamamoto, Toshiba Corporation, Japan
I. Sakai, Toshiba Corporation, Japan
T. Ohiwa, Toshiba Corporation, Japan
Correspondent: Click to Email
Sub-90nm LSIs designed for high speed and low power operations, demand introduction of low-k material for interlayer dielectric material. We have reported that the 100 MHz rf capacitive coupled plasma (CCP) RIE process is the most suitable for etching organic film because of its low ion energy@footnote 1@@super ,@@footnote 2@. Furthermore, for low-k SiOC film etching which requires a higher energy etch process, we have developed dual frequency superimposed (DFS) 100 MHz and 3.2 MHz rf CCP etch processes, which can control electron density and self-bias voltage independently in a wide range. In the damascene etch process of SiOC film using Si@sub 3@N@sub 4@ as etch mask, it was observed that the mask edge erosion is strongly dependent on ion energy regardless of selectivity. An excellent etch profile, as well as selectivity was realized by precise ion energy control@footnote 3@. We have newly developed a highly selective Si@sub 3@N@sub 4@ to SiOC etch process with CF@sub 4@/H@sub 2@ gas chemistry, which requires the reverse selectivity. Such a selective etch process enables dual damascene interconnects formation with a much lower dielectric constant. The blanket SiOC etch rate decreased as H@sub 2@ addition to CF@sub 4@ was increased, and became zero when the H@sub 2@ flow rate was equal to the CF@sub 4@ flow rate. The blanket Si@sub 3@N@sub 4@ etch rate did not decrease with H@sub 2@ addition, so high selectivity was achieved, regardless of ion energy. Next, this highly selective process condition was applied to Si@sub 3@N@sub 4@ etching using SiOC mask, where again, mask edge erosion was dependent on ion energy regardless of selectivity. Highly selective damascene etching of Si@sub 3@N@sub 4@ was realized by precise ion energy control using DFS RIE. @FootnoteText@ @footnote 1@H. Hayashi et. al., Symp. Dry. Process. (2002) p.195@footnote 2@H. Hayashi et. al., AVS 50th Symp. (2003) PS-TuA5@footnote 3@A. Kojima et. al., Symp. Dry. Process. (2003) p.13.