Mar 3, 2022 San Jose, California

Imaging of Buried Overlay and Alignment Markers Using Picosecond Acoustic Microscopy

Manjusha Mehendale

Presentation at SPIE Advanced Lithography 2022
2:30pm — 3:30pm

We present picosecond acoustic microscopy technique as an alternative to standard optical techniques to image alignment and overlay targets buried under opaque magnetic tunnel junction (MTJ) layer stack in the MRAM process flow. By tracking the reflection of laser induced acoustic waves from buried structures we can generate 2D lateral images with good resolution. We also show the potential of this technique to generate images of embedded structures at different z planes with a resolution of several nm.