FIELD OXIDE THINNING IN POLY BUFFER LOCOS ISOLATION WITH ACTIVE AREA SPACINGS TO 0.1-MU-M

Field oxide thinning in a modified LOCOS process is examined. Using electron beam lithography, thinning in active area spacings as narrow as 0.1 µm has been observed for the first time. Also, the cause of thinning is shown to be compressive stress in the field oxide, not two-dimensional oxidant diffusion as has been previously asserted. A phenomenological model for field oxide thinning is given. Finally, a new figure of merit is defined which assesses the combined effects of encroachment and field oxide thinning in isolation processes for submicron integrated circuits. © 1990, The Electrochemical Society, Inc. All rights reserved.