Elimination of Interfacial Barrier in Diffusion of Boron From Polysilicon Into Single Crystal for Base Diffusion
Original Publication Date: 1984-Jul-01
Included in the Prior Art Database: 2005-Feb-04
This approach suggests the use of a technique which forms a protective monolayer of chemisorbed iodine over a freshly etched silicon surface in order to prevent the formation of any surface film prior to the deposition of a polysilicon base. The presence of such films could be the cause of subsequent diffusion barrier problems during the base diffusion. The technique as taught by R. Lieberman and D. L. Klein [*] involves dipping the wafer into a solution of iodine in an anhydrous solvent. The iodine chemisorbs on the surface and also displaces other contaminant ions, such as F and water, by the law of mass action. The wafer is withdrawn and dried. The iodine layer protects the surface until the wafer is placed in the polysilicon deposition furnace.