A Bird´s Beak Free Local Oxidation Technology Feasible for VLSI Circuits Fabrication

This paper presents a bird´s beak free and fully recessed local oxidation-isolation structure employing only conventional LSI processing techniques; no additional masking step is required. A SideWAll Masked Isolation (SWAMI) process employing anisotropic plasma silicon etching and anisotropic plasma silicon nitride etching was implemented to form this new isolation structure. The SWAMI isolation scheme almost completely eliminates the reduction in effective channel width from drawn mask dimensions. The effective channel width obtained with the SWAMI isolation structure is independent of field-oxide thickness unlike the conventions LOCOS process. Fabrication technology and device characteristics of MOSFET´s fabricated with the SWAMI isolation structure will be compared with the conventional LOCOS isolated MOSFET´s.