Metal stack templates for suppressing secondary grains in sca1n
| DWPI Title: Piezoelectric device comprises substrate, metal stack formed on surface of substrate, where metal stack comprising post-CMOS process compatible metals, and highly textured hexagonal {002} oriented scandium aluminum nitride (ScAlN) piezoelectric film formed on template surface of metal stack |
| Abstract: A metal stack for templating the growth of AlN and ScAlN films is disclosed. The metal stack comprises one, two, or three layers of metal, each of which is compatible with CMOS post-processing. The metal stack provides a template that promotes the growth of highly textured c-axis {002} AlN and ScAlN films. The metal stacks include one or more metal layers with each metal layer having either a hexagonal {002} orientation or a cubic {111} orientation. If the metal stack includes two or more metal layers, the layers can alternate between hexagonal {002} and cubic {111} orientations. The use of ScAlN results in a higher piezoelectric constant compared to that of AlN for ScAlN alloys up to approximately 44% Sc. The disclosed metal stacks resulted in ScAlN films having XRD FWHM values of less than approximately 1.1° while significantly reducing the formation of secondary grains in the ScAlN films. |
| Use: Piezoelectric device. |
| Advantage: The device promotes growth of high crystal quality ScxAl1-xN in the desired c-axis direction, resulting in a ScAlN film having a high piezoelectric constant. |
| Novelty: Piezoelectric device comprises a substrate (200), a metal stack (210) formed on a surface of the substrate, where the metal stack comprising post-CMOS process compatible metals, and a highly textured hexagonal {002} oriented scandium aluminum nitride (ScAlN) piezoelectric film (220) formed on a template surface of the metal stack. The metal stack adapted to provide a template for the highly textured hexagonal {002} oriented ScAlN piezoelectric film, the highly textured hexagonal {002} oriented ScAlN piezoelectric film having a composition of between aluminum nitride (AlN) and Sc0.44Al0.56N. |
| Filed: 10/23/2019 |
| Application Number: US16661393A |
| Tech ID: SD 14846.1 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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