AVS 51st International Symposium
    Surface Science Tuesday Sessions
       Session SS-TuP

Paper SS-TuP10
Sublimation Behavior of SiO@sub 2@ from Low and High-Index Si Surfaces Studied by Atomic Force Microscopy

Tuesday, November 16, 2004, 4:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: J.C. Moore, Virginia Commonwealth University
Authors: J.C. Moore, Virginia Commonwealth University
A.A. Baski, Virginia Commonwealth University
Correspondent: Click to Email
We have used atomic force microscopy (AFM) to investigate the sublimation behavior of 100-nm thick oxide layers on the low-index Si(001) and high-index Si(5 5 12) surfaces. During high vacuum anneals, we have observed the formation of holes that nucleate at defects and grow laterally with annealing time (1 to 4 min, 1150@degree@C to 1350@degree@C). The depth of these holes is ~200 nm, or approximately twice the thickness of the oxide film. This is consistent with the thermal decomposition of SiO@sub 2@, where Si is extracted from the bulk in equal ratio to SiO@sub 2@ in order to form volatile SiO. As expected, the lateral growth of these holes is linear with annealing time (2 @micron@/min for 1200@degree@C). Interestingly, it is possible to obtain hole diameter data vs. annealing time by performing sequential anneals in vacuum, and then observing by AFM the formation of rings correlated to each anneal cycle at the bottoms of the holes. With regard to shape, holes formed on Si(5 5 12) have smooth edges and are circular, while those on Si(001) typically are not as circular. For both surface orientations, the holes oftentimes incorporate pits (5 @micron@ dia, 500-700 nm depth) or vertical structures (1 @micron@ dia, 150 nm height) at their centers. The conditions resulting in such structures, as well as their formation mechanism, are now under investigation. @FootnoteText@ This work is supported by the National Science Foundation.