Morphology and chemical termination of HF-etched Si3N4 surfaces

Several reports on the chemical termination of silicon nitride films after HF etching, an important process in the microelectronics industry, are inconsistent claiming N-Hx, Si-H, or fluorine termination. An investigation combining infrared and x-ray photoelectron spectroscopies with atomic force an...

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Bibliographic Details
Published in:Applied physics letters 2014-12, Vol.105 (26)
Main Authors: Liu, Li-Hong, Debenedetti, William J. I., Peixoto, Tatiana, Gokalp, Sumeyra, Shafiq, Natis, Veyan, Jean-François, Michalak, David J., Hourani, Rami, Chabal, Yves J.
Format: Article
Language:English
Subjects:
Applied physics
Atomic force microscopy
Deionization
Etching
Fluorine
Microcrystals
Morphology
Organic chemistry
Scanning electron microscopy
Silicon nitride
X ray spectra
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Summary:Several reports on the chemical termination of silicon nitride films after HF etching, an important process in the microelectronics industry, are inconsistent claiming N-Hx, Si-H, or fluorine termination. An investigation combining infrared and x-ray photoelectron spectroscopies with atomic force and scanning electron microscopy imaging reveals that under some processing conditions, salt microcrystals are formed and stabilized on the surface, resulting from products of Si3N4 etching. Rinsing in deionized water immediately after HF etching for at least 30 s avoids such deposition and yields a smooth surface without evidence of Si-H termination. Instead, fluorine and oxygen are found to terminate a sizeable fraction of the surface in the form of Si-F and possibly Si-OH bonds. The relatively unique fluorine termination is remarkably stable in both air and water and could lead to further chemical functionalization pathways.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4905282