Abstract
I n situ arsenic 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) has been investigated. The growth rate and morphology of films deposited by silane VLPCVD are degraded in the presence of arsine. The overall activation energy for deposition increases and the apparent silane reaction order decreases relative to VLPCVD in the absence of arsine. VLPCVD arsenic incorporation depends sublinearly on the arsine partial pressure and appears to saturate for incorporation fractions above 1018 As atoms/cm3. PECVD growth rates are less sensitive to arsine, and plasma enhancement is seen to provide significant advantages for n-type doping of epitaxial silicon at low temperatures. PECVD deposits show an order-of-magnitude increase in active dopant incorporation, exhibit superior morphology relative to VLPCVD, and allow for increased doping flexibility. Incorporation remains proportional to arsine partial pressures over the entire range investigated and allows for doping to at least 7×1019 As atoms/cm3 for PECVD. Both VLPCVD and PECVD arsenic-incorporation fractions increase with decreasing temperature. PECVD incorporation also exhibits a weak plasma power dependence. Ion-bombardment-induced disruption of arsenic surface aggregation is proposed to account for the observed doping behavior and plasma enhancement. A companion paper discusses boron doping during low-temperature epitaxial growth.

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