Thermal stability of laser welded thermocouple contacts to Si for high temperature thermal sensor application

We report on the development of high temperature stable thermocouple contac ts to Si for thermal sensor applications. Such contacts can be used as a le ad for electrical signals while at the same time measuring the temperature immediately at the semiconductor surface. Contacts are fabricated by laser welding with a pulsed Nd:YAG laser. 50 mu m thick tungsten sheets are used as a. diffusion barrier. The long term stability of the contacts has been i nvestigated during heat treatment up to 500 degrees C in air and 700 degree s C in vacuum for up to 1000. hours, respectively. (C) 2000 Elsevier Scienc e Ltd. All rights reserved.