Photolithographic linewidth control considerations on ultrathin fully depleted SOI devices

Linewidth control of printed patterns on thin film on silicon-on-insulator wafers is addressed. Investigations were conducted to understand how variations in the buried oxide layer and the ultrathin Si layer affect linewidth control during printing and measurement operations. The photolithography characteristics were studied, including both printed lines and printed spaces, at a number of process steps. SIMOX wafers and bulk Si wafers exposed with focus/exposure matrices, exposure matrices (fixed focus), and fixed focus/exposure were studied using Hg G line (436-nm) exposure wavelength. Linewidths ranged from 1 to 2.5 μm. Linewidths were measured using a scanning electron microscope and a confocal scanning laser microscope