ETCH-RATE CHARACTERIZATION OF IRRADIATED SIO2 AND ITS APPLICATION IN THE FABRICATION OF A T-GATE STRUCTURE

Experiments to determine the effect of the e-beam irradiation dose on the etch rate enhancement of SiO2 in p etch have been performed. These experiments have been carried out across the dose range of 0-1.5X10(-2) C/m and at various acceleration voltages in the 100-350 kV range. The results clearly show the existence of a saturation in the etch rate around a line dose of 3X10(-3) C/m. The first direct observation of the resulting trench profiles in the SiO2 have been obtained. These clearly show the effect of the accelerating voltage on the minimum achievable linewidth. Preliminary results of the application of the SiO2 irradiation process to the fabrication of T-gate type structures are also shown.