In the ECSEL project HiPERFORM, which commenced in 2018, Fraunhofer FEP is working on the sputter deposition of epitaxially grown aluminum nitride (AlN) and gallium nitride (GaN) films on (111) silicon substrates. These are intended to serve as buffer layers, and prospectively as active layers in components for power electronics based on GaN semiconductors deposited on low-cost silicon wafers.
Together with the project’s equipment manufacturer partners scia Systems GmbH and CREAVAC-Creative Vakuumbeschichtung GmbH, the necessary technical requirements for sputter deposition of the layers on 8“ wafers have been met. These include excellent vacuum levels, low contamination of the components, and means of heating the substrate to approx. 900°C. At Fraunhofer FEP, a magnetron sputtering process was developed to deposit the layers via reactive sputtering from the metal target in an argon-nitrogen atmosphere at deposition rates of up to 2 nm/s. X-ray analysis of the first AlN layers shows the intended epitaxial layer growth (see Fig.).