Metallurgical stability of ohmic contacts on thin base InP/InGaAs/InP HBT's

Chor, Eng Fong; Malik, R. J.; Hamm, R. A.; Ryan, R. W.

doi:10.1109/55.484124

Cited by 23 publications

(9 citation statements)

References 9 publications

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“…A 4.3 ϫ 10 −8 ⍀ cm 2 contact resistivity to n-InGaAs was achieved with Ti/ Pt/ Au layers by Ar + sputter cleaning the semiconductor surface before contact deposition. 6 Ti contacts diffuse 7 into InGaAs at high temperatures and hence can impair reliability, 8 particularly in high-f max devices, where semiconductor junctions typically lie within 20-30 nm of the contact surface. While ex situ Ohmic contacts can provide low resistivity, reproducibility is often problematic.…”

Section: Introductionmentioning

confidence: 99%

Ultralow resistance, nonalloyed Ohmic contacts to n-InGaAs

Baraskar

Wistey

Jain

et al. 2009

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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The authors report ultralow specific contact resistivity (ρc) in nonalloyed, in situ Ohmic contacts to heavily doped n-type In0.53Ga0.47As:Si layers with 6×1019cm−3 active carrier concentration, lattice matched to InP. The contacts were formed by depositing molybdenum (Mo) immediately after the In0.53Ga0.47As growth without breaking vacuum. Transmission line model measurements showed a contact resistivity of (1.1±0.6)×10−8Ωcm2 for the Mo∕InGaAs interface. The contacts show no observable degradation in resistivity after annealing at 300 and 400°C for 1min duration.

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Section: Introductionmentioning

confidence: 99%

Ultralow resistance, nonalloyed Ohmic contacts to n-InGaAs

Baraskar

Wistey

Jain

et al. 2009

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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“…Several refractory metals (Mo, W, Ru, Ir) are excellent diffusion barriers [15], can sustain high currents without degradation, are thermally stable, and yield reproducibly low ρ c to p-InGaAs [6]. However, we have been unable to directly integrate refractory base metallization into processes similar to [5] and [12]: direct refractory metal evaporation or sputtering requires high energies hence damages photoresist.…”

Section: Mesa Hbt Base-collector Parasiticsmentioning

confidence: 99%

Indium Phosphide Heterobipolar Transistor Technology Beyond 1-THz Bandwidth

Rode¹,

Chiang²,

Choudhary³

et al. 2015

IEEE Trans. Electron Devices

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Recent improvements in the fabrication technology of InGaAs/InP heterobipolar transistors have enabled highly scaled transistors with power gain bandwidths above 1 THz. Limitations of the conventional fabrication process that reduce RF bandwidth have been identified and mitigated, among which are high resistivity base ohmic contacts, resistive base electrodes, excessive emitter end undercut, and insufficient undercut of largediameter base posts. A novel two-step deposition process for self-aligned metallization of sub-20-nm bases has been developed and demonstrated. In the first step, a metal stack is directly evaporated onto the base semiconductor without any lithographic processing so as to minimize contamination from resist/developer chemistry. The composite metal stack exploits an ultrathin layer of platinum that controllably reacts with base, yielding low contact resistance, as well as a thick refractory diffusion barrier, which permits stable operation at high current densities and elevated temperatures. Further reduction of overall base access resistance is achieved by passivating base and emitter semiconductor surfaces in a combined atomic layer deposition Al 2 O 3 and plasma-enchanced chemical vapor depositon SiN x sidewall process. This technology enables the deposition of low-sheetresistivity base electrodes, further improving overall base access resistance and f max bandwidth. Additional process enhancements include the significant reduction of device parasitics by scaling base posts and controlling emitter end and base postundercut.

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“…The variation in contact resistivity with UV-ozone oxidation time for different etch chemistries is shown in Fig 4. Active dopant concentration for all these samples was kept same at 5 4 OH etch is not effective in removing surface oxides in the case of long UV-Ozone oxidation (longer than 5 minutes based on the observed contact resistivities), causing an increase in the measured contact resistivity.…”

Section: A Uv-ozone Oxidation and Etch Chemistrymentioning

confidence: 99%

“…However, under thermal stress and cycling, Ti-based ohmic contacts deteriorate making Ti incompatible with high temperature processing and also raising concerns for high current density operations (4)(5). Low resistance ohmic contacts to III-V semiconductors are attainable by alloying AuGe eutectic and semiconductor (6) but the semiconductor surfaces must be free of surface oxides and defects before metal deposition.…”

Section: Introductionmentioning

confidence: 99%

Effect of surface preparations on contact resistivity of TiW to highly doped n-InGaAs

Jain

Baraskar

Wistey

et al. 2009

2009 IEEE International Conference on Indium Phosphide &Amp; Related Materials

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We report the effects of UV-ozone oxidation, oxide removal etch chemistry (dilute HCl or concentrated NH 4 OH), semiconductor doping, and annealing on the contact resistivity ( c ) of Ti 0.1 W 0.9 refractory alloy to ntype InGaAs. The semiconductor surface was oxidized through exposure to UV-ozone, then subsequently etched by either dilute HCl or concentrated NH 4 OH before TiW contacts were deposited by blanket sputtering. InGaAs samples doped at 5 × 10 19 cm -3 , treated with 10 minutes of UV-Ozone then one minute dilute HCl exhibited  c of (1.90 ± 0.35) × 10

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Metallurgical stability of ohmic contacts on thin base InP/InGaAs/InP HBT's

Cited by 23 publications

References 9 publications

Ultralow resistance, nonalloyed Ohmic contacts to n-InGaAs

Ultralow resistance, nonalloyed Ohmic contacts to n-InGaAs

Indium Phosphide Heterobipolar Transistor Technology Beyond 1-THz Bandwidth

Effect of surface preparations on contact resistivity of TiW to highly doped n-InGaAs

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