AVS 45th International Symposium
    Plasma Science and Technology Division Tuesday Sessions
       Session PS2-TuM

Paper PS2-TuM2
Microloading Effect in Ultra-Fine SiO@sub 2@ Hole/Trench Etching

Tuesday, November 3, 1998, 8:40 am, Room 318/319/320

Session: Oxide Etching
Presenter: Y. Feurprier, Toyo University, Japan
Authors: Y. Chinzei, Toyo University, Japan
T. Kikuchi, Toyo University, Japan
M. Ozawa, Toyo University, Japan
M. Ogata, Toyo University, Japan
Y. Feurprier, Toyo University, Japan
T. Ichiki, Toyo University, Japan
H. Shindo, Tokai University, Japan
Y. Horiike, Toyo University, Japan
Correspondent: Click to Email
The 10% trimethylsilane (TMS) added CF@sub 3@-O-CHF-CF@sub 3@ (HFE227)@footnote 1@ and CF@sub 3@-CO-CF@sub 3@ gas chemistries were found to provide high aspect ratio SiO@sub 2@ contact hole using Neutral Loop Discharge plasma. No microloading effect was found down to 0.15µm contact holes provided the bias voltage is high enough (500 V). A new XPS method was employed to analyse the SiO@sub 2@ bottom contact hole surface (aspect ratio about 2) in the course of etching. Prior to XPS analysis a very thin Al film is deposited to cover the resist layer. Then negatively biasing the substrate allowed the discrimination of the SiO@sub 2@ bottom contact hole surface from the top surface contribution. Playing an important role in the occurrence of microloading the bias voltage influence on the bottom SiO@sub 2@ surface composition was investigated for 0.45µm contact hole in the 200 V to 600 V range. The C1s distribution demonstrated C-rich polymer film as evidenced by the C-C component as the major contribution. The total amount of carbon was observed to decrease with increasing the bias voltage while that of F did not change significantly. This strongly suggested that increased bias voltages effectively decrease the polymer film thickness. Futhermore in order to clarify the limits of the HFE227-based chemistry a newly developped 75 keV EB lithography system was used to define line and space patterns of 40 nm to 250 nm using calixarene resist. The percentage of added TMS was slightly varied between 5% to 13%. High TMS addition to the fluorocarbon gas resulted in the occurrence of microloading. For example in the HFE227-based chemistry the microloading appeared for trench width below 50 nm and 110 nm for 10% and 13% TMS respectively. The space width measured at the top of the feature takes into account the increasing resist width due to the film deposition on the sidewalls. Finally no microloading was observed for the addition of 5% TMS then allowing the fabrication of 30 nm trenches. The fine effects of the TMS addition are not yet fully understood due to the complicated plasma and surface reactions involved. EB patterned fine hole array were also fabricated to further evaluate the microloading limits of this fluorocarbon gas chemistry. @FootnoteText@ @footnote 1@Y. Chinzei, M. Ogata, J. Takekawa, N. Hirashita, T. Hayashi, H.Shindo, T. Ichiki and Y. Horiike, PS-WeA10 AVS44th.