PLASMA AND PROCESSING EFFECTS OF ELECTRODE SPACING FOR TUNGSTEN ETCHBACK USING A BIPOLAR ELECTROSTATIC WAFER CLAMP

Citation
Wf. Marx et al., PLASMA AND PROCESSING EFFECTS OF ELECTRODE SPACING FOR TUNGSTEN ETCHBACK USING A BIPOLAR ELECTROSTATIC WAFER CLAMP, Journal of vacuum science & technology. A. Vacuum, surfaces, and films, 12(6), 1994, pp. 3087-3090
Citations number
8
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
3087 - 3090
Database
ISI
SICI code
0734-2101(1994)12:6<3087:PAPEOE>2.0.ZU;2-Z
Abstract
A tungsten etchback process has been developed using a bipolar electro static clamp (ESC) in a parallel-plate, single wafer etcher with a 13. 56 MHz power applied to the top electrode. The transfer of a SF6/N-2 e tchback process from a mechanically clamped to a bipolar electrostatic ally clamped system was not straightforward. Initially, the ESC system produced more tungsten residue and a lower etch rate than a mechanica lly clamped system. By optimizing the rf grounding circuit of the ESC, the residue was reduced. A Langmuir probe study demonstrated that the ion current profile varied strongly with electrode spacing for SF6 bu t not for gases such as Cl-2 or Ar. Both the tungsten residue and the anomaly in the ion current profile were eliminated by the proper choic e of electrode spacing. Energetic electrons have been proposed as the cause of the unusual ion current profile. Process results have been op timized with the new electrode spacing, allowing the fabrication of su bmicrometer tungsten plugs on 200 mm wafers. The tungsten plug recess, which is controllable by wafer temperature and process conditions, is typically 0.1 mu m.