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Etching reactions for silicon with F atoms: Product distributions and ion enhancement mechanisms

Conference · · Journal of Vacuum Science and Technology. B, Microelectronics Processing and Phenomena; (United States)
OSTI ID:5945610
;  [1]
  1. IBM Research Div., San Jose, CA (United States)

Spontaneous and ion-enhanced etching reactions were investigated for the interaction of F atoms with Si(111) using modulated beam mass spectrometry. The F atoms were generated using a microwave plasma source which was compatible with ultrahigh vacuum. An impurity free surface, which was characterized by x-ray photoelectron spectroscopy (XPS), could be obtained even after long exposures. The atom source and the experimental system are described in detail. It is shown that spontaneous etching at room temperature produces the stable gases SiF{sub 4}, Si{sub 2}F{sub 6}, and Si{sub 3}F{sub 8} with SiF{sub 4} being the dominant product. It is suggested that previous mass spectrometric investigations incorrectly ascribed SiF{sup +} and SiF{sub 2}{sup +} peaks to a significant SiF{sub 2} product, whereas these peaks should be assigned to Si{sub 2}F{sub 6} and Si{sub 3}F{sub 8}. As the surface temperature is increased, the relative contributions of the etch products SiF{sub 4}, Si{sub 2}F{sub 6}, and Si{sub 3}F{sub 8} decrease while SiF{sub 2} increases and eventually becomes the major product. Ion bombardment significantly enhances the production rate for all products. However, the type of mechanism and magnitude of ion-enhanced etching depend upon the type of product being observed. In contrast to spontaneous etching, ion-induced etching produces a significant amount of SiF{sub 2} as well as other products. Evidence is presented that suggests that chemical sputtering and an increased spontaneous etch rate are the primary mechanisms leading to ion-enhanced etching. It will be shown that physical sputtering makes only a minor contribution under the conditions of these experiments.

OSTI ID:
5945610
Report Number(s):
CONF-9009402--
Journal Information:
Journal of Vacuum Science and Technology. B, Microelectronics Processing and Phenomena; (United States), Journal Name: Journal of Vacuum Science and Technology. B, Microelectronics Processing and Phenomena; (United States) Vol. 9:2; ISSN 0734-211X; ISSN JVTBD
Country of Publication:
United States
Language:
English