Setup used for anisotropic PET vapor phase etching with the aid of ultra-violet illumination.

SEM micrograph of a square shape etched out of PET

 The picture on the left shows the top view of PET where cracks in the Ge/Cu masking layer are superficial (the mask layer is removed here). The image at right shows the same feature from the back side. Sharp edges and high aspect ratio vertical etching is observable.

Schematic illustrating the process flow.