INVESTIGATION OF SELECTIVE SIO2-TO-SI ETCHING IN AN INDUCTIVELY-COUPLED HIGH-DENSITY PLASMA USING FLUOROCARBON GASES

Citation
Fh. Bell et al., INVESTIGATION OF SELECTIVE SIO2-TO-SI ETCHING IN AN INDUCTIVELY-COUPLED HIGH-DENSITY PLASMA USING FLUOROCARBON GASES, Journal of vacuum science & technology. A. Vacuum, surfaces, and films, 12(6), 1994, pp. 3095-3101
Citations number
23
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics, Applied","Materials Science, Coatings & Films
ISSN journal
0734-2101
Volume
12
Issue
6
Year of publication
1994
Pages
3095 - 3101
Database
ISI
SICI code
0734-2101(1994)12:6<3095:IOSSEI>2.0.ZU;2-Q
Abstract
A recent, important development in low-pressure plasma processing is t he radio frequency inductively (RFI) coupled high density discharge. I ts ability to create high densities of excited and charged species at low pressures (<10(-3) Torr) makes it an attractive etching tool. In t his work we have examined selective etching of SiO2 over Si using a ho me-built RFI source. CHF3, C2F4, C3F6 and their mixtures with hydrogen were examined. Without biasing of the substrate strong fluorocarbon d eposition occurs over. the investigated pressure range from 5 to 20 mT orr. As the pressure increases the ion current density decreases, wher eas the fluorocarbon deposition rate increases. Both parameters increa se roughly linearly with inductive rf power from 500 up to 1250 W. Etc hing was achieved by rf biasing. When the pressure is reduced from 20 to 6 mTorr, the oxide and silicon etch rates decrease less than 20% fo r all gases. The highest oxide etch rate of 830 nm/min at 350 W rf bia s power is achieved for C3F6. Adding H-2 decreases the etch rates for oxide and silicon for all gases. The drop of the silicon etch rate is considerably higher than for the oxide etch rate resulting in a better selectivity. The best selectivity of 45 is achieved for C2F4 when 30% H-2 is added into the discharge. The results obtained with the RFI so urce are compared to results with a microwave electron cyclotron reson ance discharge.