Improving Performance of Tantalum Resonators through Deposition, Part I

The cubic phase of tantalum is a very promising material for superconducting transmon qubits, due to its self-limiting surface oxide, low bulk losses, and low kinetic inductance. However, sputtering high-quality tantalum films on silicon often requires using either a seeding layer or high substrate temperatures, both of which introduce possible sources of loss. We present a novel method of growing state-of-the-art tantalum films on silicon with magnetron sputtering using a significantly lower substrate temperature than found in literature. In this first part of a two-part talk, we will present on characterization of these films with a variety of techniques, including AFM, SEM, and SIMS. We find significant changes in the morphology and structure of our films, as compared to ones deposited with more conventional techniques.