Method of forming an mnos/monos by employing large tilt angle ion

Abstract

A new method of forming an integrated circuit MNOS/MONOS device with suppressed off-cell leakage current is described. A silicon oxide layer is formed on the surface of a semiconductor substrate. A layer of silicon nitride is deposited over the silicon oxide layer and patterned. A first ion implantation is performed at a tilt angle to form channel stop regions in the semiconductor substrate not covered by the patterned silicon nitride layer wherein the channel stop regions partially extend underneath the patterned silicon nitride layer. The silicon substrate not covered by the patterned silicon nitride layer is oxidized to form field oxide regions within the silicon substrate wherein the channel stop regions extend under the full length of the field oxide regions. The patterned silicon nitride layer is removed. An insulating layer of silicon nitride/silicon oxide (NO) or silicon oxide/silicon nitride/silicon oxide (ONO) is deposited over the surface of the semiconductor substrate. A layer of polysilicon is deposited overlying the insulating layer and patterned. Source and drain regions are formed within the semiconductor substrate to complete the MNOS/MONOS device with constant threshold voltage in the fabrication of an integrated circuit.