Method of Retrograding N-Wells
Original Publication Date: 1985-Feb-01
Included in the Prior Art Database: 2005-Feb-18
This article relates generally to integrated circuit fabrication and more particularly to a technique of lowering donor concentrations at the surface of deep N regions in silicon substrate. Antimony has been found to move preferentially into silicon dioxide-silicon interface while annealed in an inert atmosphere. The concentration of antimony in the silicon dioxide-silicon interface is at least an order of magnitude greater than that in the silicon when the substrate is annealed. Antimony can be used more efficiently as a dopant in retrograde N-well fabrication. Instead of using arsenic or phosphorous, antimony is implanted in a silicon substrate and then allowed to diffuse to the desired depth in an inert atmosphere.