METHOD FOR MAKING ASYMMETRICAL GATE OXIDE THICKNESSES

摘要

A semiconductor device has gate with a first material having a first dielectric constant adjacent the semiconductor substrate and a second material having a second dielectric constant adjacent the semiconductor substrate. A conductor, such as polysilicon, is then placed on the gate so that the first and second materials are sandwiched between the conductor and the semiconductor substrate. Since the dielectric constants of the two materials are different, the gate acts like a gate having a single dielectric with at least two thicknesses. One dielectric constant is larger than the other dielectric constant. The higher dielectric constant material is comprised of a single spacer located within the gate at the sidewall nearest the drain of the semiconductor device. A layer of silicon dioxide is positioned on the semiconductor substrate between the spacer and the other sidewall of the gate. The thickness of the spacers can be adjusted to optimize the performance of the semiconductor device.