Low-temperature deposition of high-quality aluminum nitride films for heat spreading applications

A method of forming a polycrystalline AlN film on a substrate comprising at least one cycle of:

• exposing a surface of the substrate to an organometallic chemical precursor comprising tris(dimethylamido)aluminum (TDMAA) or tris(diethylamido)aluminum (TDEAA);
• exposing the TDMAA or TDEAA precursor to a hydrazine (N2H4) co-reactant to provide an AlN layer on the substrate;
• and
• treating the AlN layer with an inert gas plasma to provide a polycrystalline AlN template layer on the substrate, wherein a DC bias voltage of about −25 V is applied during plasma treatment,
• the at least one cycle, or cycles, followed by:
• depositing a second polycrystalline AlN layer on the polycrystalline AlN template layer to provide the polycrystalline AlN film on the substrate,
• wherein the polycrystalline AlN template layer is treated with an inert gas plasma at a temperature of ≥350° C., wherein the carbon and/or oxygen (C/O) impurity concentration of the polycrystalline AlN template layer is less than 2 at %, and wherein the polycrystalline AlN template layer has a density of at least 3.0 g/cm3.