Improved Test Structure for Thermnal Resistance Scaling Study in Power Devices

Power MOSFET's suffer from a strong self-heating effect. This phenomenon is currently modeled with a thermal resistance Rth. Understanding the evolution of the Rth with device scaling is today an important issue. This paper presents an improved test structure for temperature measurements in multifinger LDMOS power devices. This structure allows to access the temperature of every device finger. With this approach, impact of boundary effects and thermal coupling on Rth can be investigated. Measurements results are presented and a basic distributed model is used to reproduce Rth behavior.