Effect of Heat Treatment on Thermal OCnductivity and Microstructure of Aluminum Nitride

摘要

Aluminum nitride ceramics are in high demand for applications involving substrate materials for high speed, high capacity, and complex integated circuits requiring high thermal ocnductivity. However, there is a challenge in botaining high thermal conductivity values for polycrystalline AIN substrates ocmpared ot that of single crystal AIn which has a thermal conductivity of 320 W/m.k. A study fo the post-sintering heat-treatment of AIN in varios reducing atmosphered was perfrmed to determine the influence on thermal conductivity. It was found that the ocmposition of the secondary phase and temperature of the heat treatment are the most influential facotors ocntrolling the termal ocnductivity values. The results indicate that such a heat-treatment can improve the thermal ocnductivity of AIN upto nearly 200 W/m.K. This is due to further oxygen removal from both the AIn lattice and secondary phase, simultaneously. The chemical ocmposition of the secondary phase for both YAG and 3e compositions change with time. The maor secondary phae in hte as-sintered YAG ocmposition was 3Y sub 2 O sub 3, 5Al sub 2O sub 3, but it transformedto 2Y sub 2O sub 3, Al usb 2 O sub 3 after 1 and 2 hours and thne gradually Y sub 2 O sub 3 was formed after 6 and 8 hours of heat-treatment.