By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventors Adusumilli, Praneet (Albany, NY); Basker, Veeraraghavan S. (Schenectady, NY); Bu, Huiming (Glenmont, NY); Liu, Zuoguang (Schenectady, NY), filed on June 13, 2016, was published online on February 14, 2017.
The patent's assignee for patent number 9570574 is INTERNATIONAL BUSINESS MACHINES CORPORATION (Armonk, NY).
News editors obtained the following quote from the background information supplied by the inventors: "The present invention relates to integrated circuits, and more specifically, to a recessed metal liner contact with copper fill.
"A metal-oxide-semiconductor field-effect transistor (MOSFET) is a transistor used for switching electronic signals. Generally, the MOSFET includes a source, a drain, and a metal oxide gate electrode. The metal gate is electrically insulated from the main semiconductor n-channel or p-channel by a thin layer of insulating material such as, for example, silicon dioxide or a high dielectric constant (high-k) dielectric, which makes the input resistance of the MOSFET relatively high. The gate voltage controls whether the path from drain to source is an open circuit ('off') or a resistive path ('on').
"N-type field effect transistors (NFET) and p-type field effect transistors (PFET) are two types of complementary MOSFETs. The NFET uses electrons as the current carriers and with n-doped source and drain junctions. The PFET uses holes as the current carriers and with p-doped source and drain junctions. Complementary metal-oxide semiconductor (CMOS) general refers to complementary and symmetrical pairs of p-type and n-type MOSFETs for logic functions. A FinFET is a type of MOSFET. The FinFET is a double-gate or multiple-gate MOSFET device that mitigates the effects of short channels and reduces drain-induced barrier lowering. The 'fin' refers to the narrow channel between source and drain regions. A thin dielectric layer on either side of the fin separates the fin channel from the gate.
"In integrated circuits (ICs) such as those using complemental metal-oxide semiconductor (CMOS) technology, for example, pitch scaling is done to reduce device dimensions. Traditionally, source and drain contacts result from a contact metal (e.g., tungsten (W)) being used to fill in a trench formed above the source and drain regions. The fill metal is separated from the spacer that is used to form the trench by a liner. In current ICs, these liners have not been scaled along with the contacts. As a result, the volume of contact metal has been reduced according to the reduced contact size."
As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventors' summary information for this patent: "According to an embodiment of the present invention, a method of fabricating a contact above a source or drain region of an integrated circuit includes depositing a first liner conformally in a bottom and along a sidewall of a trench formed above the source or drain region; depositing a second liner conformally over the first liner; stripping the first liner and the second liner from a portion of the sidewall from an opening of the trench to a height above the bottom of the trench; depositing a third liner conformally over the second liner on the bottom and to the height above the bottom of the trench and on the portion of the sidewall; and depositing a metal fill to fill the trench.
"According to another embodiment, a contact for a source or drain region of an integrated circuit includes a first liner conformally disposed to cover a bottom of the contact and along a sidewall of the contact from the bottom to a height, the height being less than a full height of the contact such that a portion of the sidewall of the contact is not covered by the first liner; a second liner conformally disposed over the first liner on the bottom and up to the height of the sidewall of the contact; a third liner conformally disposed over the second liner one the bottom and up to the height of the sidewall and also covering the portion of the sidewall of the contact; and a metal fill filling a volume of the contact defined by the third liner."
For additional information on this patent, see: Adusumilli, Praneet; Basker, Veeraraghavan S.; Bu, Huiming; Liu, Zuoguang. Recessed Metal Liner Contact with Copper Fill. U.S. Patent Number 9570574, filed June 13, 2016, and published online on February 14, 2017. 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=9570574.PN.&OS=PN/9570574RS=PN/9570574
Keywords for this news article include: Electronics, Semiconductor, INTERNATIONAL BUSINESS MACHINES CORPORATION.
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