Autodoping in Silicon Epitaxy

Abstract

Vertical and lateral autodoping in silicon epitaxy deposited in a vertical pancake‐type reactor were examined as a function of pre‐epitaxial bake cycle, dopant type, source gas, and growth parameters. Boron, phosphorus, arsenic, and antimony were used as dopant elements to form a localized buried layer at the center of substrates. Silane, dichlorosilane, and silicon tetrachloride were used as the silicon source for epitaxial growth. The results show that higher prebaking temperature produces more lateral autodoping for boron and phosphorus, while the opposite holds for arsenic and antimony. Autodoping in both vertical and lateral directions decreases with increasing prebake time. A continual decrease in lateral autodoping is found with increasing growth rate for phosphorus; for arsenic, only a slight difference is noticed in the growth‐rate range studied. Phosphorus and arsenic show a similar trend at the deposition temperature of lateral autodoping, i.e., autodoping decreases at first, then increases with increasing temperature. For all the dopants studied, vertical and lateral autodoping decrease with increasing number of chlorine atoms in the source gases.