High-Volume Production and Non-Destructive Piezo-Property Mapping of 33% SC Doped Aluminium Nitride Thin Films

Scandium doped aluminium nitride (ScAlN) exhibits an overall greater piezoelectric response as compared to pure aluminium nitride (AlN). Films with a Sc/(Sc+Al)content above 30% or more are of high interest for MEMS sensing and actuation, ultrasound generation, and energy harvesting applications. In this work we present the uniformity of the material properties of (002)-axis oriented $\text{Sc}_{33}\text{A}1_{67}\text{N}$ films deposited on 200-mm wafers. For this purpose, the dielectric constant $\varepsilon_{\text{r}}$ and dielectric loss tanδ, as well as the transversal and the longitudinal piezoelectric coefficients, $e_{31,\text{f}}$ and $d_{33,\text{f}}$ , were measured. Wafers exhibiting a great in-wafer uniformity of the piezoelectric coefficients up to $d_{33,\text{f}}=11.8\text{pm}/\text{V}$ and $e_{31,\text{f}}=-2.3 \text{C}/\text{m}^{2}$ were obtained ( $1\sigma$ uniformity $\approx$ 1-2%). The results are very promising for the fabrication and designing of devices, as well as for volume manufacturing.