AVS 49th International Symposium
    Plasma Science Monday Sessions
       Session PS1-MoA

Paper PS1-MoA3
Effects of Ar Gas Dilution on Precise SiO@sub 2@ Etching using CF@sub 3@I/ C@sub 2@F@sub 4@ Plasma

Monday, November 4, 2002, 2:40 pm, Room C-103

Session: Dielectric Etch I
Presenter: H. Ohtake, Tohoku University, Japan
Authors: S. Samukawa, Tohoku University, Japan
H. Ohtake, Tohoku University, Japan
H. Ishihara, Tokyo Electron AT, Japan
A. Koshiishi, Tokyo Electron AT, Japan
Correspondent: Click to Email
The @phi@0.1µm high-aspect-ratio SiO@sub 2@ contact etching has successfully done using the parallel-plate commercialized etcher with the Ar-dilution C@sub 2@F@sub 4@/ CF@sub 3@I plasma. In the XPS analysis of deposition film, the radical-density ratio (for example, CF@sub 3@/ CF@sub 2@) in C@sub 2@F@sub 4@/ CF@sub 3@I does not change when Ar flow increases. However, it drastically changes in C@sub 4@F@sub 8@ gas chemistry. This could be because the C@sub 4@F@sub 8@ has complex dissociation processes. On the other hand, the radical-density ratio does not change with Ar dilution because the C@sub 2@F@sub 4@/ CF@sub 3@I gas chemistry has simple dissociation processes. Accordingly, the control of the radical densities in the C@sub 2@F@sub 4@/ CF@sub 3@I plasma could be easy by controlling the Ar flow. In this Ar/ C@sub 2@F@sub 4@/ CF@sub 3@I gas chemistry, the SiO@sub 2@ etching rate does not decrease even when Ar flow increases. However, the etching selectivity of SiO@sub 2@ to photo-resist increases when increasing the Ar dilution. Since the effect of the ion bombardment increase with Ar dilution, the C/F ratio in the deposited film on the photo-resist increases. As a result, the etching selectivity of SiO@sub 2@ to the photo-resist increases. With these conditions, the @phi@0.1µm, 10- aspect- ratio SiO@sub 2@ etching in C@sub 2@F@sub 4@/ CF@sub 3@I Ar plasma has successfully. Additionally, we investigated the leak current of MOSFET (L=0.1um, Tox: 20A) with multiple contact holes. In the threshold voltage and leak current measurement, the charging damages are not observed. Accordingly, the Ar dilution for C@sub 2@F@sub 4@/ CF@sub 3@I gas chemistry is very effective on the control of the radical densities and the increase of selectivity.