Integration of dual workfunction metal gate CMOS devices
AssigneeInternational Business Machines Corporation
InventorsByoung H. Lee, Effendi Leobandung, Ghavam G. Shahidi
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Abstract
A dual work function CMOS metal gate device provides a composite metal gate electrode structure. The composite metal gate structure includes a bulk metal and a thin metal layer having an appropriate work function for the transistor type and desired threshold voltage, VT. Both N-channel and P-channel transistors are formed to have distinct threshold voltages by incorporating the metal material having the appropriate work function for the desired VT into the composite metal gate electrode. The two different electrodes of the N-channel and P-channel transistors are electrically connected by means of the bulk metal.
Claims16
In a semiconductor device which includes a P-channel transistor having a first metal gate formed of a first composite film including a bulk metal film formed over a first conductive film having a first work function, and an N-channel transistor having a second metal gate formed of a second composite film including said bulk metal film formed over a second conductive film having a second work function being different from said first work function, the improvement comprising said bulk metal film electrically connecting said first conductive film to said second conductive film.
In a method for setting threshold voltages, VT, of transistors within a semiconductor device, which includes the steps of:
- (a) providing a first substructure for a first transistor within said semiconductor device, said first substructure including a first channel formed within a first substrate type and a first gate dielectric formed over said first channel, and a second substructure for a second transistor within said semiconductor device, said second substructure including a second channel formed within a second substrate type and a second gate dielectric formed over said second channel;
- (b) prescribing a first VT for said first transistor and a second VT for said second transistor;
- (c) forming a first conductive layer over said first gate dielectric, said first conductive layer formed of a first conductive material chosen to have a first work function for producing said first VT;
- (d) forming a second conductive layer over said second gate dielectric, said second conductive layer formed of a second conductive material chosen to have a second work function for producing said second VT;
- (e) forming a bulk metal material over each of said first conductive layer and said second conductive layer, thereby forming a first composite gate structure including said bulk metal material and said first conductive layer, and a second composite gate structure including said bulk metal material and said second conductive layer, the improvement comprising forming the bulk metal material in said step (e) such that the bulk metal material electrically connects the first conductive layer to the second conductive layer.
Dependencies are inferred from the claim text.