| 摘要 |
This invention pertains to a self-aligned trench-isolated emitter structure and the method for forming same. The emitter structure comprises a portion of a bipolar transistor which exhibits improved function due to the emitter structure. A single layer of conductive material forms both the emitter and base contacts in the transistor structure, which structure has particularly shallow emitter and base junctions (about 0.15 micrometer or less). The self-aligned emitter contact, isolated from the base contact by a dielectric filled trench, permits overall size reduction of the device, whereby junction area and accompanying leakage across junctions is reduced. In addition, when the structure of the bipolar transistor is such that the trench isolates the emitter area from both the base contact and the extrinsic base, it is possible to provide improved base conductivity without generating peripheral transistor effects. The bipoloar transistor can be either N-P-N type or P-N-P type depending on the materials of fabrication, although high speed devices are typically of the N-P-N type. The method includes forming a sidewall spacer (246), creating an etch-masking layer (250), removing the spacer, and etching an isolation trench at the location previously occupied by the spacer.
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