Method for forming a mixed voltage circuit having complementary devices

Abstract

A mixed voltage circuit is formed by providing a substrate (12) having a first region (20) for forming a first device (106), a second region (22) for forming a second device (108) complementary to the first device (106), and a third region (24) for forming a third device (110) that operates at a different voltage than the first device (106). A gate layer (50) is formed outwardly of the first, second, and third regions (20, 22, 24). While maintaining a substantially uniform concentration of a dopant type (51) in the gate layer (50), a first gate electrode (56) is formed in the first region (20), a second gate electrode (58) is formed in the second region (22), and a third gate electrode (60) is formed in the third region (24). The third region (24) is protected while implanting dopants (72) into the first region (20) to form source and drain features (74) for the first device (106). The first region (20) is protected while implanting dopants (82) into the third region (24) to form disparate source and drain features (84) for the third device (110).

Dependencies are inferred from the claim text.