Semiconductor device having improved oxide thickness at a shallow trench isolation edge and method of manufacture thereof

One aspect of a semiconductor device includes an active region located in a semiconductor substrate and having an isolation region located therebetween. The active regions have corners adjacent the isolation region. An oxide layer is located over the active regions and the corners, which may also include edges of the active regions, and a ratio of a thickness of the oxide layer over the corners to a thickness of the oxide layer over the active regions ranges from about 0.6:1 to about 0.8:1. A gate is located over the active region and the oxide layer.