The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 07, 2013
Filed:
Apr. 05, 2012
Xin Wang, New York, NY (US);
Zhiqiang Wu, Plano, TX (US);
Ramesh Venugopal, Richardson, TX (US);
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
A gate stack for an NMOS transistor in an IC to induce tensile stress in the NMOS channel is disclosed. The gate stack includes a first layer of undoped polysilicon, a second layer of n-type polysilicon to establish a desired work function in the gate, layer of compressively stressed metal, and a third layer of polysilicon to provide a silicon surface for subsequent formation of metal silicide. Candidates for the compressively stressed metal are TiN, TaN, W, and Mo. In a CMOS IC, the n-type polysilicon layer and metal layer are patterned in NMOS transistor areas, while the first polysilicon layer and third polysilicon layer are patterned in both NMOS and PMOS transistor areas. Polysilicon CMP may be used to reduce topography between the NMOS and PMOS gate stacks to facilitate gate pattern photolithography.