Channel Constrained Metallization of Aluminum Nitride for the Fabrication of Electronic Packages with Efficient Thermal Management

The densification of electronic packages has demanded better solutions to the thermal management problem created by these advancements. The use of substrate materials with high thermal conductivity is a cost-effective approach to increased heat dissipation. In this paper, a method is described for the fabrication of interconnect structures on aluminum nitride using a fully additive channel-constrained electroless metallization process. Chemical functionalization of the AlN substrates, optimization of the photolithographic technique, and the selective metallization of interconnects are issues addressed. AlN surface functionality was found to be critical in controlling the binding efficiency of the Pd(II) plating catalyst and contact with the aqueous plating solutions. Rapid hydrolysis of the AlN surface was used to facilitate functionalization with N -(2-aminoethyl)-3-aminopropyltrimethoxysilane and provide a modified surface for subsequent selective catalysis and metallization and followed by X-ray photoelectron spectroscopy. Lithographic processes were optimized and found to require exposure dosage 30% lower than on substrates of alumina. Interconnect structures composed of nickel and copper (100 nm-2 μm thick, 10-100 μm in diameter) with good adhesion to the AlN (1 mm thickness) have been shown with the use of thermal measurements to outperform similar circuit patterns fabricated on chemical vapor deposited diamond 300 μm thick.