| CPC H01L 29/4966 (2013.01) [H01L 21/28088 (2013.01); H01L 27/0924 (2013.01); H01L 29/0653 (2013.01); H01L 29/66545 (2013.01); H01L 29/66795 (2013.01); H01L 29/7848 (2013.01); H01L 29/785 (2013.01); H01L 29/165 (2013.01)] | 20 Claims | 

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               1. A semiconductor device, comprising: 
            a first transistor of a first type comprising a first work function layer, the first work function layer comprising a first underlying layer; and 
                a second transistor of the first type comprising a second work function layer, the second work function layer comprising a second underlying layer, 
                wherein the first and second underlying layers, each comprises a metal nitride layer with at least two kinds of metals, and a thickness of the first underlying layer is greater than a thickness of the second underlying layer. 
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