Impact of Gate Poly Depletion on Evaluation of Channel Temperature in Silicon-on-Insulator Metal-Oxide-Semiconductor Field-Effect Transistors with Four-Point Gate Resistance Measurement Method

Self-heating effects (SHEs) in silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistors (MOSFETs) is evaluated and an accurate measurement method for device temperature is developed using the four-point gate resistance measurement method. Although the method of using a polysilicon gate as a temperature sensor was proposed more than 20 years ago, the accuracy of the technique has not been checked. In this work, it is demonstrated that the channel temperature estimated by the conventional method is not accurate under some special conditions. The measurements of gate resistance under various biases revealed that the depletion of the polysilicon gate had a significant impact on gate resistance. We propose a method of accurately evaluating channel temperature, where the effect of poly depletion is successfully subtracted. At an input power of 5mW the increase in channel temperature is approximately 30 K, corresponding to a thermal resistance of 6: 0KW(-1) m(-1). (C) 2012 The Japan Society of Applied Physics