Atmospheric Pressure Selective Epitaxial Growth of Heavily In Situ Phosphorous-Doped Si(C) Raised Sources and Drains
Résumé
We have developed an innovative atmospheric pressure process for the selective co-flow deposition of Si(C) P Raised Sources and Drains (RSDs) at 700 degrees C-800 degrees C. Layers of Si P were grown with SiH2Cl2, HCl and a PH3 1% in H-2 bottle (with no dependence on growth temperature) resulting in a Si P growth rate that increased as the PH3 mass-flow increased, together with a P+ ion concentration that reached 7 x 10(19) cm(-3). For even higher phosphine flows, we have switched to PH3 5% in H2 bottles and studied the growth kinetics and n-type doping of Si at 700 degrees C. The Si P growth rate increased, stabilized then decreased (which is most likely due to surface poisoning) as the PH3 mass-flow increased. This was associated with a sharp increase then a stabilization at nearly 10(20) cm-3 of the P+ ion concentration. The resulting Si P layers were single crystalline and slightly rough. Full selectivity versus SiO2 (isolation) and SiN sidewall spacers was achieved on patterned wafers with this heavily chlorinated chemistry. Finally, we have evaluated the feasibility of adding SiCH6 to the gaseous mixture to obtain SiC P layers. The substitutional C concentration was rather small (at most 0.55%). Meanwhile, the resistivity was at first stable then increased, while the SiC P growth rate monotonously decreased as the SiCH6 mass-flow went up.