Shallow trench isolation structure for a bipolar transistor

摘要

A semiconductor device has an isolation area having a shallow trench isolation (STI) structure for isolating device areas for transistor elements. The isolation area for a bipolar transistor (12) has a first annular trench (20a) encircling a n-type collector well (22), a second annular trench (20b) encircling the first annular trench (20a) and an annular p-type diffused region (21) disposed between the first annular trench (20a) and the second annular trench (20b) while in contact with the annular trenches (20a, 20b). The plurality of isolation trenches (20a, 20b) in a single isolation area prevents a dishing portion of the substrate after a CMP process without causing a short-circuit failure. <IMAGE>