TERMINATION STRUCTURE WITH MULTIPLE EMBEDDED POTENTIAL SPREADING CAPACITIVE STRUCTURES FOR TRENCH MOSFET

摘要

A termination structure with multiple embedded potential spreading capacitive structures (TSMEC) and method are disclosed for terminating an adjacent trench MOSFET atop a bulk semiconductor layer (BSL) with bottom drain electrode. The BSL has a proximal bulk semiconductor wall (PBSW) supporting drain-source voltage (DSV) and separating TSMEC from trench MOSFET. The TSMEC has oxide-filled large deep trench (OFLDT) bounded by PBSW and a distal bulk semiconductor wall (DBSW). The OFLDT includes a large deep oxide trench into the BSL and embedded capacitive structures (EBCS) located inside the large deep oxide trench and between PBSW and DBSW for spatially spreading the DSV across them. In one embodiment, the EBCS contains interleaved conductive embedded polycrystalline semiconductor regions (EPSR) and oxide columns (OXC) of the OFLDT, a proximal EPSR next to PBSW is connected to an active upper source region and a distal EPSR next to DBSW is connected to the DBSW.

主权项

1. A termination structure with multiple embedded potential spreading capacitive structures (TSMEC) for terminating an active area semiconductor device being located along the top surface of a bulk semiconductor layer (BSL) of a first conductivity type having a proximal bulk semiconductor wall (PB SW) separating the TSMEC from the active area semiconductor device, the TSMEC comprises an oxide-filled large deep trench (OFLDT) being bounded by the PBSW and a distal bulk semiconductor wall (DBSW) wherein the OFLDT further comprises:
a large deep oxide trench of trench size TCS and trench depth TCD into the BSL; and a plurality of embedded capacitive structures (EBCS) each formed of a conductive embedded polycrystalline semiconductor region (EPSR) surrounded by an oxide located inside the large deep oxide trench, the plurality of EBCS sequentially placed between the PBSW and the DBSW and completely filling an entire space between the PBSW and the DBSW; wherein a proximal EPSR located next to the PBSW is electrically connected to a doped region of a second conductivity type opposite the first conductivity type disposed on a top portion of the PB SW.