Doping effects in reactive plasma etching of heavily doped silicon.

Etch rates of heavily doped silicon films (n and p type) and undoped polycrystalline silicon film were studied during plasma etching and also during reaction ion etching in a CF[sub 4]/O[sub 2] plasma. The etch rate of undoped Si was lower than the n[sup +]-Si etch rate, but higher than the p[sup +]-Si etch rate, when the rf inductive heating by the eddy current was minimized by using thermal backing to the water-cooled electrode. This doping effect may be explained by the opposite polarity of the space charge present in the depletion layer of n[sup +]-Si and p[sup +]-Si during reactive plasma etching. [ABSTRACT FROM AUTHOR]