Patent ID: 9620620
Date: 2017-04-11
CPC Classifications: H01L

Claim:
1. A method of preventing a contact metal from protruding into neighboring gate devices to affect work functions of the neighboring gate devices, comprising: exposing dummy polysilicon in a gate structure of each of P-type field effect transistors (pFETs) on a substate; exposing dummy polysilicon of regions of a local interconnect that are under contact plugs and are adjacent to a gate structure of each of N-type field effect transistors (nFETs), wherein the nFETs are connected to the regions of the local interconnect, and the regions of the local interconnect and neighboring nFETs of the nFETs are on same word lines of a static random access memory (SRAM) cell; removing the exposed dummy polysilicon in the gate structure of each of the pFETs and in the regions of the local interconnect; depositing a P-type work function layer on the substrate with openings resulting from removal of the exposed dummy polysilicon in the gate structure of each of the pFETs and in the regions of the local interconnect, wherein the P-type work function layer covers sidewalls of the openings and prevents the contact metal from protruding into the gate structure of each of the nFETs connected to the regions of the local interconnect to affect the work functions of the gate structure of each of the nFETs; forming a gate metal layer on the P-type work function layer and having a void in the gate structure of each of the pFETs; and forming a contact plug of the contact plugs over the gate metal layer in the gate structure of each of the pFETs, wherein the contact plug of the contact plugs protrudes into the void.