Method of substrate connection in the fabrication of bipolar transistor circuits separated by isolation trenches

摘要

The substrate trenches w2 provided for making the connection are produced at the same time as the isolation trenches w1, the width w2 of the substrate trenches being made at least twice as large as the width w1 of the isolation trenches. When the trenches w1 and w2 are filled with isolation material 8, a gap having a width of w2-w1 is left in the substrate trenches w2 and this is filled with the material 9 provided for substrate connection. The method eliminates the photolithographic step needed to define the substrate contact, while the collector/substrate capacitance remains negligible at the same time. The method is used in the fabrication of VLSI bipolar transistor circuits. <IMAGE>