Metal stack templates for suppressing secondary grains in sca1n

US11482660B1 · kind B1 · utility

Assignee

• National Technology & Engineering Solutions of Sandia, LLC · US

Inventors

• Giovanni Esteves · Albuquerque, US
• Erica Ann Douglas · Albuquerque, US
• Michael David Henry · Tucson, US
• Benjamin Griffin · Midleton, IE
• Morgann Berg · Albuquerque, US

Key dates

• Filing date: Oct 23, 2019
• Grant date: Oct 25, 2022
• Expiry date: Apr 25, 2041

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10N30/853

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.