Amorphorized tantalum-nickel binary films for metal gate applications

Journal Article · Mon Apr 13 00:00:00 EDT 2015 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4918375· OSTI ID:22398891

Ouyang, Jiaomin; Wongpiya, Ranida; Clemens, Bruce M. ^[1]; Deal, Michael D.; Nishi, Yoshio ^[2]

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1. Department of Materials Science and Engineering, Stanford University, Stanford, California 94305 (United States)
2. Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States)

Amorphous metal gates have the potential to eliminate the work function variation due to grain orientation for poly-crystalline metal gate materials, which is a leading contributor to threshold voltage variation for small transistors. Structural and electrical properties of TaNi alloys using co-sputtering with different compositions and multilayer structures with different thicknesses are investigated in this work. It is found that TaNi films are amorphous for a wide range of compositions as deposited, and the films stay amorphous after annealing at 400 °C in RTA for 1 min and up to at least 700 °C depending on the composition. The amorphous films eventually crystallize into Ni, Ta, and TaNi{sub 3} phases at high enough temperature. For multilayer Ta/Ni structures, samples with individual layer thickness of 0.12 nm and 1.2 nm are amorphous as deposited due to intermixing during deposition, and stay amorphous until annealed at 500 °C. The resistivity of the films as-deposited are around 200 μΩ·cm. The work function of the alloy is fixed at close to the Ta work function of 4.6 eV for a wide range of compositions. This is attributed to the segregation of Ta at the metal-oxide interface, which is confirmed by XPS depth profile. Overall, the excellent thermal stability and low resistivity makes this alloy system a promising candidate for eliminating work function variation for gate last applications, as compared to crystalline Ta or TiN gates.

• OSTI ID: 22398891
• Journal Information: Applied Physics Letters, Vol. 106, Issue 15; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANNEALING
COMPARATIVE EVALUATIONS
DEPOSITION
ELECTRIC CONDUCTIVITY
ELECTRIC POTENTIAL
EV RANGE
FILMS
GRAIN ORIENTATION
INTERFACES
LAYERS
NICKEL
OXIDES
SPUTTERING
TANTALUM
THICKNESS
TITANIUM NITRIDES
TRANSISTORS
VARIATIONS
WORK FUNCTIONS
X-RAY PHOTOELECTRON SPECTROSCOPY