USE OF TRANSMITTED COLOR TO CALIBRATE THE THICKNESS OF SILICON SAMPLES

In preparing silicon-based semiconductors for transmission electron mi croscopy (TEM), it has been widely observed that a backlit silicon sam ple displays a series of colors in the thinnest regions. These colors result from absorption and optical interference of light within the si licon sample and depend upon the type of light source and the silicon sample thickness. These colors can range from deep red for thicknesses greater than or equal to 5 mu m, through orange and yellow in the thi nner regions, to essentially colorless at the thinnest regions. In thi s work we present the first direct measurement of silicon color versus thickness and discuss the factors that influence this relationship. C rown copyright (C) 1997 Published by Elsevier Science Ltd.