Berkovich Nanoindentation on AlN Thin Films

Area of Science:

• Materials Science
• Nanotechnology
• Solid Mechanics

Background:

• Aluminum Nitride (AlN) thin films are critical components in various electronic and optoelectronic devices.
• Understanding their mechanical behavior under stress is essential for device reliability and performance.
• Previous studies have not fully elucidated the deformation mechanisms at the nanoscale.

Purpose of the Study:

• To investigate the mechanical deformation mechanisms of AlN thin films induced by Berkovich nanoindentation.
• To determine the hardness and Young's modulus of AlN thin films.
• To correlate observed deformation features with nanoindentation load-displacement data.

Main Methods:

• Berkovich nanoindentation with continuous contact stiffness measurements (CSM).
• Atomic Force Microscopy (AFM) for surface analysis.
• Cross-sectional Transmission Electron Microscopy (XTEM) prepared by Focused Ion Beam (FIB) milling for subsurface analysis.

Main Results:

• Hardness of AlN thin films measured at 22 GPa and Young's modulus at 332 GPa.
• Multiple 'pop-ins' in load-displacement curves attributed to dislocation nucleation and propagation.
• Absence of discontinuities in unloading curves indicates no pressure-induced phase transitions.

Conclusions:

• The primary deformation mechanism in AlN thin films under nanoindentation is dislocation activity.
• The measured mechanical properties provide critical data for material selection and device design.
• Findings offer insights into potential mechanical damage during AlN-based device fabrication.