Abstract A thin film of a readily volatizable metal, such as cadmium, is formed on the surface of a semiconductor slice. A programmed electron beam forms a masking pattern by volatizing portions of the metal film, for example, defining the emitter windows for a transistor. Without breaking the vacuum ambient an ion implantation introduces the first impurity through the openings in the mask. The electron beam then defines a second mask pattern, enlarging the first openings to define, for example, the base windows, and forming separate new openings, as for diodes and resistors. A second ion implantation puts in a second impurity, again without impairing the original vacuum. These steps are followed by conventional heat treatment for annealing or drive-in of impurities and the device fabrication is completed using conventional metallization techniques and wafer separation.
The method in accordance with claim 1 which includes the step of forming on the surface of the silicon semiconductor body a layer of silicon oxide prior to forming the metal film for improving the adherence thereof.
Claim 2
Independent Claim
162 words
The method of fabricating a semiconductor device including the steps of forming a metal mask on a surface of a silicon semiconductor body by depositing a thin film of a volatizable metal selected from the group consisting of cadmium and bismuth, impinging on said thin metal film an electron beam in accordance with a desired mask pattern to remove selected portions of said metal film, then subjecting said masked surface of said silicon semiconductor body to an ion beam composed of a significant impurity to alter the conductivity of underlying portions of said silicon semiconductor body as determined by said metal mask, impinging a beam of electrons in accordance with another pattern to selectively remove other portions of said thin metal film, thereby forming a second series of openings in said thin metal film, subjecting said masked surface to an ion beam of another significant impurity to alter the conductivity of underlying portions of said body as determined by said metal mask.
Claim 3
Dependent Claim
31 words
The method in accordance with claim 3 in which at least one of said second series of openings is an enlargement of one of said first openings in said metal film.