Patent ID: 11910586
Assignee: TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H  G | IPC G  H

Claim 16:
17. A device, comprising:
a substrate;
a first SRAM cell formed over the substrate, the first SRAM cell comprising a first N-type transistor having a first gate structure, the first gate structure having a first work function metal layer; and
a second SRAM cell formed over the substrate, the second SRAM cell comprising a second N-type transistor having a second gate structure, the second gate structure having a second work function metal layer,
wherein the first work function metal layer is a stacked film of a first layer and a second layer, the second work function metal layer is a stacked film of a third layer and a fourth layer, the first layer of the first work function metal layer is thicker than the third layer of the second work function metal layer, and the second layer of the first work function metal layer has a thickness substantially the same as a thickness of the fourth layer of the second work function metal layer.