Charge collection by capacitive influence through isolation oxides

This paper analyzes the collected charge in heavy ion irradiated MOS structures. The charge generated in the substrate induces a displacement effect which strongly depends on the capacitor structure. Networks of capacitors are particularly sensitive to charge sharing effects. This has important implications for the reliability of SOI and DRAMs which use isolation oxides as a key elementary structure. The buried oxide of presentday and future SOI technologies is thick enough to avoid a significant collection from displacement effects. On the other hand, the retention capacitors of trench DRAMs are particularly sensitive to charge release in the substrate. Charge collection on retention capacitors participate to the MBU sensitivity of DRAM. Index Terms--Capacitors, charge collection, charge sharing, device simulation, diodes, DRAMs, heavy ion irradiation, isolation oxides, MBU sensitivity, MOS structures, SOI technology, SRAMs, transient currents, trench capacitors.