Transistor device and fabrication method thereof

摘要

In the fabrication of a transistor device, particularly a low-voltage high-frequency transistor for use in mobile telecommunications, a method for improving the transistor performance and the high-frequency characteristics, comprising the steps of: providing a semiconductor substrate (1) with an n-doped collector layer (5) surrounded by isolation areas (4); implanting antimony ions into said collector layer such that a thin highly n-doped layer (18) is formed in the uppermost portion of said collector layer; and forming a base on top of said thin highly n-doped layer (18).