By a News Reporter-Staff News Editor at Life Science Weekly — A patent by the inventors Cartier, Eduard A. (New York, NY); Liang, Qingqing (Fishkill, NY); Liang, Yue (San Jose, CA); Wang, Yanfeng (Fishkill, NY), filed on March 14, 2013, was published online on July 1, 2014, according to news reporting originating from Alexandria, Virginia, by NewsRx correspondents (see also International Business Machines Corporation).
Patent number 8766378 is assigned to International Business Machines Corporation (Armonk, NY).
The following quote was obtained by the news editors from the background information supplied by the inventors: “Negative Bias Temperature Instability (NBTI) is a key reliability issue that is of immediate concern in p-channel MOS devices operating with negative gate voltages. This same mechanism also affects nMOS transistors when biased in the accumulation regime, i.e., with a negative bias applied to the gate. NBTI manifests as an increase in the threshold voltage and consequent decrease in drain current and transconductance. The degradation exhibits log law dependence with time.
“In sub-micrometer devices, nitrogen has been incorporated into the silicon gate oxide to reduce the gate current density and prevent boron penetration. However, incorporating nitrogen enhances NBTI. For this reason, in new technologies, e.g., 32 nm and shorter nominal channel lengths, high-k metal gate stacks, are used as an alternative to improve the gate current density for a given equivalent oxide thickness (EOT). Even with the introduction of new materials like Hafnium Oxides, NBTI still remains a concern. In addition, Hafnium Oxide based metal gates exhibit V.sub.t shift.
“Vt-shift by oxygen-ingress is an issue causing Vt variation in high-k dielectric metal gate technology. It is believed that the Vt shift is due to two components: stable component and meta-stable component. The stable component refers to the removal of oxygen vacancies in HfO.sub.2 and the meta-stable component refers to the formation of oxygen interstitials in HfO.sub.2.
“Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.”
In addition to the background information obtained for this patent, NewsRx journalists also obtained the inventors’ summary information for this patent: “In an aspect of the invention, a method of controlling Vt shift in a high-k dielectric metal gate structure comprises applying a current to a gate contact of the high-k dielectric metal gate structure to raise a temperature of a metal forming a gate stack. The temperature is raised beyond a temperature needed fro oxygen induced Vt shift on high-k materials.
“In yet another aspect of the invention, a method of controlling Vt shift in a TiN metal gate structure with a hafnium based dielectric comprises raising a temperature of the TiN metal to above a Vt shift threshold by applying a current through contacts of the TiN metal gate structure.
“In still yet another aspect of the invention, a structure comprises a metal gate structure comprising a Ti based metal formed on a hafnium based dielectric material and a poly material formed on the Ti based metal. The Ti based metal exhibits a Vt shift control effect due to a current induced temperature increase.
“In yet a further aspect of the invention, a method in a computer-aided design system for generating a functional design model of a programmable field effect transistor (FET). The method comprises generating a functional representation of a metal gate structure comprising a Ti based metal formed on a hafnium based dielectric material and a poly material formed on the Ti based metal. The Ti based metal exhibits a Vt shift control effect due to a current induced temperature increase.
“In another aspect of the invention, a design structure tangibly embodied in a machine readable storage medium for designing, manufacturing, or testing an integrated circuit is provided. The design structure comprises the structures of the present invention. In further embodiments, a hardware description language (HDL) design structure encoded on a machine-readable data storage medium comprises elements that when processed in a computer-aided design system generates a machine-executable representation of the programmable FET, which comprises the structures of the present invention. In still further embodiments, a method in a computer-aided design system is provided for generating a functional design model of the programmable FET. The method comprises generating a functional representation of the structural elements of the programmable FET.”
URL and more information on this patent, see: Cartier, Eduard A.; Liang, Qingqing; Liang, Yue; Wang, Yanfeng. Programmable FETs Using Vt-Shift Effect and Methods of Manufacture. U.S. Patent Number 8766378, filed March 14, 2013, and published online on July 1, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=\%2Fnetahtml\%2FPTO\%2Fsrchnum.htm&r=1&f=G&l=50&s1=8766378.PN.&OS=PN/8766378RS=PN/8766378
Keywords for this news article include: Hafnium, Chalcogens, Heavy Metals, Transition Elements, International Business Machines Corporation.
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