APPARATUS FOR THE THERMAL CHARACTERIZATION OF HIGH CONDUCTIVITY SUBSTRATES AND MATERIALS FOR MICROELECTRONICS

The thermal characterization of aluminum nitride AlN substrates is an important task for microelectronics. The usual method, so called << la ser-flash >>, can hardly been used for substrates, as it needs samples with a thickness higher than 3 mm. This method has been recently modi fied, but involves a heavy equipment to be used. We have developed in C.N.E.T. Lannion a method on the principle of the measurement of the t hermal flux through a sample placed in a known thermal gradient. This method was first developed to characterize low thermal conductivity sa mples. We then adapted it to the new problem related to the characteri zation of high thermal conductivity substrates as AlN ones, the therma l conductivity of which being as high as 200 W/m.K. The apparatus we d eveloped, that is now commercially available, allows to measure direct ly in some minutes the thermal conductivity of samples with an accurac y of 10 % in a range values of 10 to 400 W/m.K.