Patent ID: 7811915

Claim:
A method for forming a semiconductor device, the method comprising: forming a first dielectric layer over a first portion of a substrate; forming a charge storage layer over the first dielectric layer; forming masks over portions of the first dielectric layer and the charge storage layer; etching a trench in the charge storage layer and the first dielectric layer, the trench extending to the substrate, where the masks prevent removal of portions of the first dielectric layer and the charge storage layer during etching of the trench; after etching the trench, implanting n-type impurities into the substrate to form an n-type region having a first depth and a first width ranging from about 1100 Å to about 1700 Å, where implanting the n-type impurities includes removing a portion of the masks to cause the first width of the n-type region to be greater than a width of the trench; implanting p-type impurities into the substrate after implanting the n-type impurities, the p-type impurities forming a p-type region having a second depth and a second width ranging from about 1200 Å to about 2000 Å, where the second depth is greater than the first depth and the second width is greater than the first width; forming a second dielectric layer over the charge storage layer, the second dielectric layer filling a portion of the trench; and forming a control gate over the second dielectric layer.