Plasma-enhanced chemical vapor deposition of i n   s i t u doped epitaxial silicon at low temperatures. II. Boron doping

• Published in: Journal of applied physics 1989-02, Vol.65 (3), p.1067-1073
• Main Authors: Comfort, James H., Reif, Rafael
• Format: Article
• Language: English
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.343041

A comparison of in situ boron doping of epitaxial silicon films deposited from 700 to 800 °C by both very-low-pressure chemical vapor deposition (VLPCVD) and plasma-enhanced chemical vapor deposition (PECVD) is presented. Neither the growth rate nor the morphology of films deposited by silane VLPCVD or PECVD are affected by the addition of up to 500 ppm diborane at a total pressure of 6 mTorr. VLPCVD and PECVD boron incorporation depends linearly on diborane partial pressures, and films doped to 1020 B atoms/cm3 have been prepared. VLPCVD boron incorporation is found to increase with increasing temperature. No significant increase in boron incorporation is observed with increasing power for PECVD. Surface decomposition of diborane under low surface coverage conditions is proposed as the rate-controlling step for boron incorporation during doped epitaxial growth at low temperatures. Doping profiles with uniform concentrations in the range 1016–1020 B atoms/cm3 are readily achieved at low temperatures by VLPCVD from diborane-silane mixtures without the need for plasma enhancement.