Modeling the influence of arsenic autodoping on the sheet resistance of epitaxial silicon films and its application to statistical process control (SPC)

An epitaxial layer sheet resistance monitoring procedure has been developed to overcome the convolution between intentional epilayer doping and arsenic autodoping for multiwafer reactors. The procedure models the epilayer as an intentionally phosphorous-doped region plus an arsenic autodoped region by approximating the epilayer as two resistors in parallel. The resulting sheet resistance SPC monitoring procedure is sensitive to shifts in epilayer carrier concentration as well as arsenic autodoping induced by product lots.