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

Abstract

In this letter, we investigate the radiation hardness of metal-oxide-semiconductor (MOS) capacitors with tungsten polycide (WSi ) and those with cobalt polycide (CoSi 2 ) as gate electrode materials. CoSi 2 has been considered as a gate/contact material for MOS devices in 0.18 m integrated circuit fabrication due to its low resistivity and good thermal stability. However, we found that MOS capacitors with a CoSi 2 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 WSi gate electrode, after 1 Mrad Co 60 -ray irradiation under no applied bias.