AVS 65th International Symposium & Exhibition
    MEMS and NEMS Group Wednesday Sessions
       Session MN+NS+PS-WeM

Paper MN+NS+PS-WeM12
Suppressing Secondary Grain Growth in Sc0.125Al0.875N Using a CMOS Compatible Electrode

Wednesday, October 24, 2018, 11:40 am, Room 202B

Session: IoT Session: Multiscale Manufacturing: Enabling Materials and Processes
Presenter: Giovanni Esteves, Sandia National Laboratories
Authors: G. Esteves, Sandia National Laboratories
M. Berg, Sandia National Laboratories
M.D. Henry, Sandia National Laboratories
B.A. Griffin, Sandia National Laboratories
E.A. Douglas, Sandia National Laboratories
Correspondent: Click to Email
The electromechanical response of AlN can be enhanced by doping Sc into AlN up to ~43%. Challenges arise in processing high Sc doped AlN films due to the presence of secondary grain growth. Templating ScxAl1-xN (ScAlN) from a platinum bottom electrode has shown immense success in yielding highly textured c-axis ScAlN without the presence of secondary grain growth. However, platinum is not complementary metal-oxide-semiconductor (CMOS) compatible which makes it unattractive to those in industry. There is a need for a new bottom electrode that suppresses secondary grain growth while maintaining CMOS compatibility. In this work, Sc0.125Al0.875N and AlN films were grown on various underlying CMOS compatible metal stacks. Optimal film microstructure and texture was obtained for films deposited on highly textured {111} AlCu0.05 bottom metal. AlN and ScAlN thicknesses were 750 nm and 850 nm and showed rocking curves of 0.81° and 1.09°, respectively. Atomic force microscopy was used to determine the presence of secondary grain growth and film roughness. The success of this bottom metal stack is attributed to lattice matching and low surface roughness which allows for highly oriented c-axis textured AlN and ScAlN. This work presents a metal stack that allows for the creation of higher Sc-doped AlN films while maintaining a high-quality microstructure and texture. Therefore, allowing for commercialization of Sc-doped AlN technologies which are capable of higher electromechanical coupling coefficients than AlN devices.

This work was supported by the Laboratory Directed Research and Development program at Sandia National Laboratories. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA-0003525. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government.