Radiation hardness comparison of MOS capacitors using tungsten polycide and cobalt polycide as gate electrode materials

[[abstract]]In this letter, we investigate the radiation hardness of metal-oxide-semiconductor (MOS) capacitors with tungsten polycide (WSix) and those with cobalt polycide (CoSi2) as gate electrode materials. COSi2 has been considered as a gate/contact material for MOS devices in 0.18 mu m integrated.circuit fabrication due to its low resistivity and good thermal stability. However, we found that MOS capacitors with a COSi2 gate electrode exhibited an increase in radiation-induced interface trap density shift of more than one order of magnitude, and more than eighteen times larger in radiation-induced flatband voltage shifts compared with those with the WSix gate electrode, after 1 Mrad Co-60 gamma-ray irradiation under no applied bias.[[note]]SC