Measurement of trench depth by infrared interferometry

Measurement and control of high-aspect-ratio structures such as dynamic random-access memory trenches is an important step in the manufacture of modern memory devices. We present a novel technique based on infrared interferometry that has been implemented in manufacturing and is capable of measuring sub-0.25-μm-wide and 10-μm-deep trenches nondestructively and with an accuracy of better than 0.1 μm. © 1999 Optical Society of America.