ON THE LINK BETWEEN ELECTRON SHADOWING AND CHARGING DAMAGE

Charging and topography evolution simulations during plasma etching of high aspect ratio line-and-space patterns reveal that electron shadow ing of the sidewalls critically affects charging damage. Decreasing th e degree of electron shadowing by using thinner masks decreases the po tentials of the etched features with a concomitant reduction in Fowler -Nordheim tunneling currents through underlying thin gate oxides. Simu ltaneously, the potential distribution in the trench changes, signific antly perturbing the local ion dynamics which, in turn, cause the notc hing effect to worsen. Since the latter can be reduced independently b y selecting an appropriate etch chemistry, the use of thinner (hard) m asks is predicted to be advantageous for the prevention of gate oxide failure. (C) 1997 American Vacuum Society. [S0734-211X(97)00205-9].