In this work, carbon-added tungsten (W1-x Cx, x≤0.19) and thin carbon layer-inserted tungsten (Wtop /C/ W bottom, the thickness of Wbottom is set to be 2 nm and 10 nm) gate stacks are deposited on Si O2 /Si to fabricate metal-oxide-semiconductor capacitors. Grazing incident angle X-ray diffraction reveals that the W1-x Cx films become amorphous when the concentration of added C is lower than 16 atom %. However, when the C concentration is as high as 19 atom %, a trace of γ phase of tungsten carbide phase appears in the W0.81 C0.19 film. No interdiffusion between C-added W and Si O2 is observed by Auger electron spectroscopy depth profiling. The resistivity of W, W0.88 C0.12, W0.84 C0.16, and W0.81 C 0.19 are 132, 151, 163, and 337 μcm, respectively. The work function of W0.81 C0.19, W0.84 C 0.16, W0.88 C0.12, W, W/C/W (10 nm), and W/C/W (2 nm) on Si O2 are 4.82, 4.75, 4.73, 4.66, 4.52, and 4.32 eV, respectively. The C-related dipole shows apparent influence on the work function. The leakage current densities of C-added W films are smaller than 2× 10-5 A/ cm2 in the range from 0 to 5 × 107 V/cm. No significant influence of these gate electrodes on the fixed oxide charge and the leakage behavior of Si O2 are observed.
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