Method for fabricating a transistor having a variable threshold voltage

摘要

A method for fabricating a transistor having a variable threshold voltage is disclosed. Energy levels of a transistor can be represented by a valance band, a conduction band, and a Fermi level. In order to fabricate a transistor with a variable threshold voltage, a region of the transistor is initially doped with a first dopant having a first energy level below the Fermi level. The region of the transistor is subsequently doped with a second dopant having a second energy level above the Fermi level. Alternatively, the region of the transistor can be initially doped with a first dopant having a first energy level above the Fermi level, and then the region of the transistor can be subsequently doped with a second dopant having a second energy level below the Fermi level.