Polyoxide edge tunnelling current reduction by top corner rounding

The scaleability of polyoxide as interpoly dielectric is limited by the large electric fields which occur at the edges of the polysilicon layers. Due to this edge effect large tunnelling currents exist at moderate electric fields. Calculation of the electric field distribution at these edges shows the importance of the corner radius. It is also demonstrated that this edge field enhancement can be reduced by performing a rounding etch.