Method for Avoiding Autodoping in the Epitaxial Process
Original Publication Date: 1985-Oct-01
Included in the Prior Art Database: 2005-Feb-19
For producing integrated circuits - in particular CMOS circuits - a slightly doped epitaxial layer is frequently grown on the front side of a heavily doped silicon substrate. Typical doping concentrations are, e.g., 1x 1015 atoms/cm³ for the epitaxial layer and 1 x 1019 atoms/cm³ for the silicon substrate. During the growth of the epitaxial layer, the dopant, say, boron, is transferred from the rear side of the silicon substrate in the gas phase to the front side, doping the epitaxial layer, in particular along the edge of the silicon substrate, more heavily than is desirable (autodoping). This is detrimental to components subsequently introduced into the epitaxial layer. To avoid autodoping, a slightly doped epitaxial layer of the same thickness as that on the front side is grown on the rear side of the silicon substrate.