A high-speed bipolar technology featuring self-aligned single-poly base and submicrometer emitter contacts

An experimental bipolar transistor structure with self-aligned base-emitter contacts formed using one polysilicon layer is presented with geometries and frequency performance comparable to those of double-polysilicon structures. This structure, called STRIPE (self-aligned trench-isolated polysilicon electrodes), provides a 0.2- mu m emitter-base polysilicon contact separation. A 0.4- mu m emitter width is achieved with conventional 0.8- mu m optical lithography. Scaling of the emitter width of 0.3 mu m has been performed with minimal degradation of device performance, and scaling of the emitter width pattern to 0.2 mu m has been demonstrated. These dimensions are the smallest achieved in single-polysilicon structures with polysilicon base contacts and are comparable to those achieved in double-polysilicon structures. The STRIPE structure has been used to fabricate transistors with f/sub t/ as high as 33.8 GHz.<
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