US Patent 7791123 Soft error protection structure employing a deep trench

A deep trench containing a doped semiconductor fill portion having a first conductivity type doping and surrounded by a buried plate layer having a second conductivity type doping at a lower portion is formed in a semiconductor layer having a doping of the first conductivity type. A doped well of the second conductivity type abutting the buried plate layer is formed. The doped semiconductor fill portion functions as a temporary reservoir for electrical charges of the first conductivity type that are generated by a radiation particle, and the buried plate layer functions as a temporary reservoir for electrical charges of the second conductivity type. The buried plate layer and the doped semiconductor fill portion forms a capacitor, and provides protection from soft errors to devices formed in the semiconductor layer or the doped well.