METALLIZATION OF ALUMINUM NITRIDE SUBSTRATES BY ELECTROLESS COPPER PLATING

Abstract

The metallization of AIN substrates by electroless Cu plating was investigated for as-received unpolished and mechanically polished AIN substrates. Four-percent NaOH aqueous solution was employed as the chemical etchant before plating to create sites for mechanical interlocking. For the unpolished substrates, the adhesion increased from 1.3 kg/MM2 for the sample with an average surface roughness of 0.2 mum to 2.3 kg/MM2 for those with an average surface roughness of 0.82 mum. Mechanical interlocking is suggested as the major cause for adhesion in the Cu-unpolished AIN system. The adhesion strength of Cu with respect to the mechanically polished AIN substrate increases to a value larger than 7.6 kg/mm2. This makes electroless Cu plating a good candidate for AIN metallization. Nevertheless, the mechanism that causes the increased adhesion strength for the mechanically polished case needs further investigation.