Patent ID: 7323420

Claim:
A method for manufacturing a semiconductor device including first and second transistors having different gate dielectric layer thicknesses, the method comprising: forming a first dielectric layer on a semiconductor substrate of a first thickness; forming a second dielectric layer of a second thickness on a top surface of the first dielectric layer, the second dielectric layer having a different dielectric material from that of the first dielectric layer; and selectively removing a portion of the second dielectric layer with etch selectivity to the first dielectric layer so as to selectively expose a portion of the top surface of the first dielectric layer under the second dielectric layer to form a gate dielectric layer including a thick portion formed of the first dielectric layer and remaining second dielectric layer in a first region of the semiconductor device and a thin portion formed of the exposed first dielectric layer in a second region of the semiconductor device, the thin portion being of the first thickness and the thick portion being of a combined thickness of the first thickness and the second thickness; forming a first transistor in the first region, the first transistor including a first gate dielectric layer comprising a portion of the thick portion of the gate dielectric layer and a second transistor in the second region, the second transistor including a second gate dielectric layer comprising a portion of the thin portion of the gate dielectric layer.