Method for making very shallow junctions in silicon devices

摘要

A processing method for forming very shallow junctions 25 utilizing the differential diffusion coefficients of impurity dopants 38 in germanium as compared to silicon to confine the dopants 38 to very shallow regions made of substantially pure germanium 34. This processing method takes advantage of known and reliable process steps to create thin layers of Ge 34 with well-controlled thicknesses by conventional methods. The processing method includes the steps of forming a film layer of germanium of a desired thickness on the substrate 28; introducing a dopant material to the germanium film layer 34; and diffusing the dopant material in the germanium film layer 34.