Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Having insulated electrode
Reexamination Certificate
2011-08-02
2011-08-02
Tran, Thien F (Department: 2895)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Having insulated electrode
C257S411000, C257SE21625
Reexamination Certificate
active
07989902
ABSTRACT:
A stack of a high-k gate dielectric and a metal gate structure includes a lower metal layer, a scavenging metal layer, and an upper metal layer. The scavenging metal layer meets the following two criteria 1) a metal (M) for which the Gibbs free energy change of the reaction Si+2/y MxOy→2x/y M+SiO2is positive 2) a metal that has a more negative Gibbs free energy per oxygen atom for formation of oxide than the material of the lower metal layer and the material of the upper metal layer. The scavenging metal layer meeting these criteria captures oxygen atoms as the oxygen atoms diffuse through the gate electrode toward the high-k gate dielectric. In addition, the scavenging metal layer remotely reduces the thickness of a silicon oxide interfacial layer underneath the high-k dielectric. As a result, the equivalent oxide thickness (EOT) of the total gate dielectric is reduced and the field effect transistor maintains a constant threshold voltage even after high temperature processes during CMOS integration.
REFERENCES:
patent: 2004/0185198 (2004-09-01), Sisson et al.
patent: 2010/0187643 (2010-07-01), Chudzik et al.
Hubbard et al., “Thermodynamic stability of binary oxides in contact with silicon”, J. Mater. Res. vol. 11, No. 11, Nov. 1996, pp. 2757-2776.
Ando Takashi
Choi Changhwan
Frank Martin M.
Narayanan Vijay
Alexanian Vazken
International Business Machines - Corporation
Scully , Scott, Murphy & Presser, P.C.
Tran Thien F
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