Substrate Temperature and Bias Voltage Dependent Properties of Sputtered AlN Thin Films for BAW Applications

We investigated the influence of substrate temperature and biasing during reactive DC magnetron sputter deposition on the properties of aluminum nitride thin films for bulk acoustic wave applications. We demonstrate that higher substrate temperatures of up to 400°C result in thin films with improved crystallographic properties and smoother surfaces. In addition, the application of increased bias voltage levels during deposition allow to tailor the film stress over a wide range.