Ion beam milling of n-type mercury cadmium telluride for photoconductive devices

The fabrication of mercury cadmium telluride (MCT) photoconductive detector arrays for thermal imaging involves the delineation by etching upto 10 mu m, of a large number of detector elements with dimensional variation within +/- 2.5 mu m. The conventional wet etching technique yields a dimensional control of only +/- 4 mu m in the lateral dimension. This necessiates the use of dry etching techniques. We have used ion beam milling (IBM) for achieving structural delineation of the elements with dimensional variation within +/-1 mu m. Topographical study of etched walls has been done by using scanning electron microscope (SEM), which shows nearly vertical walls of etched patterns. Statistical data analysis has been performed and 3-sigma values of 0.75 mu m has been achieved.