Submicron MOS process with 10:1 optical projection printing and anisotropic dry etching

We report on results of a n-MOS process with minimum feature sizes in the submicron range. Lithography is realized by 10:1 optical projection with step and repeat exposure. Minimum linewidths of 0.7 µm have been achieved using a high aperture projection optics with 0.42 N.A. In order to obtain a high fidelity in pattern definition anisotropic dry etching techniques have been used for all levels. Results are given for the patterning of the TaSi2/n⁺-poly stack using a RIE process with fluorine/chlorine chemistry and for the aluminum etching applying a BCl3- based etching process. With this technology various test structures with dimensions in the submicron range have been realized including exploratory dynamic RAM arrays with design features suitable for a 1M Bit DRAM.