Thermal conductivity of PECVD silicon-rich silicon nitride films measured with a SiO2/SixNy bimaterial microbridge test structure

In order to balance the compressive stress of a silicon dioxide film and compose a steady MEMS structure,asilicon-rich silicon nitride film with tensil estressis deposited by plasma enhanced chemical vapor deposition process. Accurately measuring the thermal conductivity of the film is highly desirable in order to design, simulate and optimize MEMS devices. In this paper, a SiO2/SixNy bimaterial microbridge structure is presented to measure the thermal conductivity of the silicon-rich silicon nitride film by single steady-state measurement. The thermal conductivity is extracted as 3.25 W/(m K). Low thermal conductivity indicates that the silicon-rich silicon nitride film can still be utilized as thermally insulating material in thermal sensors although its thermal conductivity is slightly larger than the values reported in literature.