Selective reactive ion etching of tungsten films in CHF/sub 3/ and other fluorinated gases

Journal Article · Fri Jul 01 04:00:00 EDT 1988 · J. Vac. Sci. Technol., B; (United States)

DOI:https://doi.org/10.1116/1.584300· OSTI ID:7224140

Pan, W S; Steckl, A J

The use of reactive ion etching (RIE ) with fluorinated gas plasmas, such as SF/sub 6/, CF/sub 4/, CBrF/sub 3/, and CHF/sub 3/ mixed with oxygen, to achieve selective patterning of tungsten films is reported. The etch rates of W, Si, and SiO/sub 2/ were measured as a function of oxygen percentage in fluorinated gas plasmas under various conditions. Experiments on selectivity indicate that a CHF/sub 3//70%O/sub 2/ mixture under 20 sccm, 200 W, 20 mTorr etching conditions results in W:Si and W:SiO/sub 2/ etch rate ratios of 1.6:1 and 1.8:1, respectively. Optimized W:Si and W:SiO/sub 2/ selectivity ratios 4:1 and 4.8:1 have been obtained at 60 mTorr/150 W and 260 mTorr/200 W plasma conditions. For reverse selectivity, the optimum W:SiO/sub 2/ etch rate ratio measured is 1:4.6 in pure CHF/sub 3/ gas. The optimum W:Si reverse selectivity of 1:11.6 is obtained with an SF/sub 6//5%O/sub 2/ mixture plasma. A vertical-to-lateral etch ratio of 4:1 was measured with CHF/sub 3//70%O/sub 2/, 200 W, 10 mTorr, 20 sccm. The etching mechanisms of tungsten due to chemical and physical processes in various fluorocarbon gases under the RIE mode have been investigated and the role of etching species such as fluorine, bromine, and oxygen is discussed.

• Research Organization: Rensselaer Polytechnic Institute, Center for Integrated Electronics and Department of Electrical, Computer and System Engineering, Troy, New York 12181
• OSTI ID: 7224140
• Journal Information: J. Vac. Sci. Technol., B; (United States), Journal Name: J. Vac. Sci. Technol., B; (United States) Vol. 6:4; ISSN JVTBD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101* -- Metals & Alloys-- Preparation & Fabrication
360106 -- Metals & Alloys-- Radiation Effects
CARBON COMPOUNDS
CARBON FLUORIDES
CHALCOGENIDES
COLLISIONS
ELECTRONIC CIRCUITS
ELEMENTS
ETCHING
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
HYDROCARBONS
INTEGRATED CIRCUITS
ION COLLISIONS
METALS
MICROELECTRONIC CIRCUITS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL RADIATION EFFECTS
RADIATION EFFECTS
SEMIMETALS
SILICON
SILICON COMPOUNDS
SILICON OXIDES
SURFACE FINISHING
TRANSITION ELEMENTS
TUNGSTEN