Patent ID: 7378322

Claim:
A method of manufacturing a semiconductor device having a silicon substrate having an active area defined by isolation layers, the method comprising the steps of: i) forming a gate oxide layer comprising a first oxide layer formed on the active area of semiconductor substrate and a second oxide layer formed on the first oxide layer; ii) forming a photoresist layer having a hole on the second oxide layer to expose a gate area; iii) isotropically etching the second oxide layer exposed by the hole such that an under-cut portion being larger than the area of the hole is formed in the second oxide layer below the photoresist layer; iv) removing the photoresist layer; v) sequentially forming a gate conductive layer and a hard mask layer on the isotropically etched second oxide layer; and vi) sequentially etching the hard mask layer, the gate conductive layer, all layers of the gate oxide layer including at least the isotropically etched second oxide layer wherein the isotropically etched portion of the second oxide layer corresponds to the center portion of a channel area of the gate such that the thickness of the gate oxide layer corresponding to the center portion of the gate channel area is thinner than the thickness of the gate oxide layer corresponding to an edge portion of the gate channel area.