Optical Proximity Correction Methodology to Counteract Mask Error Effects in Sub-0.25 µm Lithography Generations

A new methodology for optical proximity correction design is required for sub-0.25 µm device generation, to predict and counteract mask error effects. We applied a new concept of virtual mask technology to design an optical proximity correction (OPC), which involves adding a small dummy mask pattern on a simulation mask layout, to realize mask error effect. The aerial image simulation results for the new methodology suggested a totally different type of OPC.

Experimental results were more accurately predicted by the new methodology than the old methodology. For 0.25 µm features hammerhead OPC shows much improved results of intra-field CD uniformity of 20 nm, of 3 sigma, and wide usable process window of 14% exposure latitude and 0.8 µm depth of focus, compared with serif OPC that was selected by the old methodology. This new methodology with virtual mask technology will be applied to sub-0.25 µm generations.