Patent ID: 7541249

Claim:
A method for producing a base connection of a bipolar transistor having active regions of a first conductivity type, active regions of a second conductivity type, and low-resistivity regions of semiconductor/metal mixed crystals that connect to an inner subregion of the active regions of the second conductivity type in an electrically conductive manner, the method comprising the steps of: providing a semiconductor structure, which includes the active regions of a second conductivity type as a base region; providing, on the semiconductor structure, a three-dimensional sacrificial structure that is selectively removable with respect to adjacent regions; depositing a first semiconductor layer; depositing a second layer of dielectric material; partially exposing the first semiconductor layer by partial removal of the second layer, with parts of the first semiconductor layer remaining covered by the remainder of the second layer; depositing a first reaction layer that reacts with the first semiconductor layer to form reaction products which are selectively removable with respect to the adjacent regions; reacting the first reaction layer with the first semiconductor layer to thereby obtain first reaction products; removing the first reaction products; removing remaining material of the first reaction layer that was not reacted with the first semiconductor layer; removing the second layer; depositing a second reaction layer to react with the first semiconductor layer to form a low-resistivity compound; reacting the second reaction layer with the first semiconductor layer into the low-resistivity compound; removing remaining material of the second reaction layer that has not reacted with the first semiconductor layer; depositing an additional dielectric layer; exposing of sacrificial structure by partially removing the additional dielectric layer; selectively removing the sacrificial structure; and introducing dielectric inner spacers in an aperture created by removal of the sacrificial structure.