Ultra-high resolution temperature measurement and thermal management of RF power devices using heat pipes

Abstract

A new technique, designated pyrospectroscopy, for measuring temperatures with ultra-high resolution in semiconductor devices is demonstrated. This technique is based on Raman spectroscopy and offers a spatial resolution of about 1 /spl mu/m and a temperature resolution in the 1-2/spl deg/C range. The ability to resolve temperatures at this spatial resolution is demonstrated experimentally in functioning RF power amplifier devices, where heat is concentrated in extremely small emitter regions. Highly localized temperature gradients in a 900-1200 MHz Si power amplifier die are shown. In contrast, these data indicate that the temperatures measured separately by infrared microscopy underestimate the localized device temperature at the same position by as much as 20/spl deg/C. Finally, a unique thermal management approach using heat pipes is demonstrated, which results in a 20% decrease in temperature of a RF power device accompanied by a 55% reduction in thermal resistance for the case investigated.