Gate Oxide Breakdown in a SOI CMOS Process Usilng MESA Isolatioon

We have studied the gate oxide breakdown behaviour in a CMOS process on SOI substrates, where the lateral isolation is obtained by the definition of individual islands (mesa) by using Reactive Ion Etching. Multiedge and edgeless transistors are compared to study the corner effects, such as early breakdown of the gate oxides. The breakdown voltage of the gate oxide at the corners has been improved by using an adequate local oxidation procedure of the edges of thc mesa, resulting in a softening of the upper corners of the mesa.