Impact of copper contamination on the quality of silicon oxides

• Published in: Journal of applied physics Vol. 65; no. 6; pp. 2402 - 2405
• Main Authors: WENDT, H, CERVA, H, LEHMANN, V, PAMLER, W
• Format: Journal Article
• Language: English
• Published: Woodbury, NY American Institute of Physics 15.03.1989
• Subjects: Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Physics; Solid surfaces and solid-solid interfaces; Surface and interface dynamics and vibrations; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Scanning electron microscopy; Temperature; Semiconductor materials; Impurity; Growth interface; Czochralski method; Silicon IV Oxides; Experimental study; Inorganic compound; Thin film; Characterization; Defect; Silicon; Copper; Diffusion; Heterojunction
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.342808

To study the impact of metal contamination on the quality of gate oxides, (100) silicon wafers were intentionally contaminated with copper from the backside. The in-diffusion of copper and/or oxidation were performed in a rapid thermal annealing system. Gate oxide areas with low breakdown fields of about 2–3 MV/cm were located in a pinhole detector and correlate very well with the contaminated areas revealed by Secco defect etching. Using various analytical tools the failure mechanism was found to be related to the formation of Cu-rich precipitates at the SiO2/Si interface. Depending on the in-diffusion temperature (and hence on the supersaturation of Cu in Si), two different mechanisms were observed: At high supersaturation (1200 °C/30 s) Cu-rich silicide particles can bend, crack, and finally penetrate the oxide layer. At lower in-diffusion temperatures (900 °C/60 s) lens-shaped Cu silicides form at the SiO2/Si interface and reduce the oxide thickness.