Characterization of nickel Germanide thin films for use as contacts to p-channel Germanium MOSFETs

Spann, John; Anderson, Robert A.; Thornton, Trevor; Harris, Gari; Thomas, S.G.; Tracy, Clarence

doi:10.1109/led.2004.842653

Cited by 81 publications

(61 citation statements)

References 11 publications

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“…This clearly shows only polycrystalline Ni-monoGermanide (NiGe) phase forms at the annealing temperatures. The lattice constants of the formed NiGe are determined to be a = 5.81 Å, b = 5.37 Å, and c = 3.40 Å from the XRD spectra, in agreement with the reported values [16], [17].…”

Section: Resultssupporting

confidence: 87%

High-Quality Schottky Contacts for Limiting Leakage Currents in Ge-Based Schottky Barrier MOSFETs

Husain

Groot

2009

IEEE Trans. Electron Devices

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Abstract-Schottky barrier (SB) Ge channel MOSFETs suffer from high drain-body leakage at the required elevated substrate doping concentrations to suppress source-drain leakage. Here, we show that electrodeposited Ni-Ge and NiGe/Ge Schottky diodes on highly doped Ge show low off current, which might make them suitable for SB p-MOSFETs. The Schottky diodes showed rectification of up to five orders of magnitude. At low forward biases, the overlap of the forward current density curves for the as-deposited Ni/n-Ge and NiGe/n-Ge Schottky diodes indicates Fermi-level pinning in the Ge bandgap. The SB height for electrons remains virtually constant at 0.52 eV (indicating a hole barrier height of 0.14 eV) under various annealing temperatures. The series resistance decreases with increasing annealing temperature in agreement with four-point probe measurements indicating the lower specific resistance of NiGe as compared to Ni, which is crucial for high drive current in SB p-MOSFETs. We show by numerical simulation that by incorporating such high-quality Schottky diodes in the source/drain of a Ge channel PMOS, a highly doped substrate could be used to minimize the sourceto-drain subthreshold leakage current.

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Section: Resultssupporting

confidence: 87%

High-Quality Schottky Contacts for Limiting Leakage Currents in Ge-Based Schottky Barrier MOSFETs

Husain

Groot

2009

IEEE Trans. Electron Devices

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“…The sheet resistance of the NiGe films on Ge-on-Si continues to become lower than that of NiSi on the Si substrate until 700 • C. For the NiGe on Ge-on-Si annealed at 600 • C, multiplying the NiGe film thickness of 49 nm, the resistivity is calculated to be ∼ 19 μΩ · cm. This value is in good agreement with 17-24 μΩ · cm of NiGe on bulk Ge and comparable to 17 μΩ · cm for NiSi [11]. We note that the temperature at which the sheet resistance of NiGe starts increasing is the same for both samples A and B, regardless of the difference of the initial tensile strain in the Ge epilayers.…”

Section: Characterization and Discussionsupporting

confidence: 86%

Thermal Stability of Nickel Germanide Formed on Tensile-Strained Ge Epilayer on Si Substrate

Tang

Huang

et al. 2010

IEEE Electron Device Lett.

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The thermal stability of a nickel germanide film formed on a tensile-strained Ge epilayer on a silicon substrate with a low-temperature Si 0.77 Ge 0.23 (50-nm)/Ge (50-nm) buffer is investigated. A record temperature of 700 • C for the stability of sheet resistance of nickel germanide is reported, which is increased by about 150 • C compared to that on bulk Ge and comparable to the temperature for nickel silicide on the Si substrate. The improvement of the thermal stability is demonstrated due to the delay of the agglomeration of the nickel germanide film on Ge-on-Si, which is proposed to be attributed to the increase of the tensile strain in the Ge epilayer during thermal annealing due to the thermal mismatch between Si and Ge.

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“…It can be seen that at each temperature the resistivity of the P implanted sample is lower than that of the As case. It was shown in [18] that increasing active dopant levels decreases ρ c for p-type Ge , and indeed with ρ c =R sh L T 2 in TLM structures, these results indicate that the P is more activated than the As. R sh values were extracted (data not shown here) and R sh of the As samples was in the 550-750 Ω/sq range whereas the R sh of the P samples was in the 140-150 Ω/sq range.…”

Section: Methodssupporting

confidence: 52%

“…The trend line fitted to the data shows that the resistivity is proportional to x -1.59 , where x is the implant dose. When NiGe TLMs were used to extract ρ c on p-type Ge [18], ρ c was found to be proportional to N A -0.62 , where N A was the acceptor concentration and was in the 10 17 -10 20 cm -3 range, i.e. increasing B concentration decreases ρ c .…”

Section: Methodsmentioning

confidence: 99%

N-type doped germanium contact resistance extraction and evaluation for advanced devices

Shayesteh

Daunt

O’Connell

et al. 2011

2011 Proceedings of the European Solid-State Device Research Conference (ESSDERC)

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The authors extract contact resistivity of NiGe layers on phosphorus-doped and arsenic-doped germanium, using the Transfer Length Method. It is shown experimentally that higher implant dose yields lower contact resistivity. Furthermore phosphorus is a better choice of dopant in terms of contact resistance and sheet resistance at low activation anneal temperatures, such as 500 °C. The impact of high contact resistance is evaluated for 22 nm technology NMOS germanium devices and beyond.

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Characterization of nickel Germanide thin films for use as contacts to p-channel Germanium MOSFETs

Cited by 81 publications

References 11 publications

High-Quality Schottky Contacts for Limiting Leakage Currents in Ge-Based Schottky Barrier MOSFETs

High-Quality Schottky Contacts for Limiting Leakage Currents in Ge-Based Schottky Barrier MOSFETs

Thermal Stability of Nickel Germanide Formed on Tensile-Strained Ge Epilayer on Si Substrate

N-type doped germanium contact resistance extraction and evaluation for advanced devices

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