Electron-beam fabrication of submicrometer bipolar transistors for high-frequency low-current operation

A submicrometer device technology has been developed for the design and fabrication of bipolar transistors capable of high-frequency operation at low currents. Direct write electron-beam lithography is used with a single-level resist process that is compatible with high dose ion implants and dry etching, and is capable of producing feature sizes to at least the 0.5-µm level. A low temperature local oxidation process is used to minimize parasitic capacitances. Both process and device models are used in the design, which must consider the two-dimensional nature of the base-emitter region, since for these structures, the emitter junction depth is comparable in size to the emitter width. Data are presented and compared on 0.5-, 0.75-, and 1.0-µm devices.