Fermi Level Depinning Failure for Al/GeO2/Ge Contacts

Yu, Hao; Xie, Qi; Jiang, Yu-Long; Deduytsche, Davy; Detavernier, Christophe

doi:10.1149/2.004206ssl

Cited by 10 publications

(7 citation statements)

References 28 publications

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“…6(c). However, the GeOxNy is not observed by the SAD diffraction pattern, this indicated the GeOxNy layer is amorphous, which consistent with the report of Hao Yu [32].…”

Section: The Application Of N2 Plasma Passivation On the Pt/hfo2/ge Msupporting

confidence: 89%

Impact of nitrogen plasma passivation on the Al/n-Ge contact

Lai

Mao

Ruan³

et al. 2016

Materials Science and Engineering: B

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Severe Fermi level pinning at the interface of metal/n-Ge leads to the formation of a Schottky barrier. Therefore, a high contact resistance is introduced, debasing the performance of Ge devices. In this study, a Ge surface was treated by nitrogen plasma to form an ultra-thin Germanium oxynitride (GeOxNy) passivation layer. It was found that the Schottky barrier height (SBH) of metal/n-Ge contact was strongly modulated by the GeOxNy interlayer, indicating alleviation of Fermi-level pinning effect. By adjusting the principal parameters of N2 plasma treatment and additional post anneal, a Quasi-ohmic Al/n-Ge contact was achieved. Furthermore, the introduced GeOxNy layer gave extremely lower leakage current density of the gate stack for HfO2/Ge devices. These results demonstrate that GeOxNy formed by N2 plasma would be greatly beneficial to the fabrication of the Ge-based devices.

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“…6(c). However, the GeOxNy is not observed by the SAD diffraction pattern, this indicated the GeOxNy layer is amorphous, which consistent with the report of Hao Yu [32].…”

Section: The Application Of N2 Plasma Passivation On the Pt/hfo2/ge Msupporting

confidence: 89%

Impact of nitrogen plasma passivation on the Al/n-Ge contact

Lai

Mao

Ruan³

et al. 2016

Materials Science and Engineering: B

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“…As for a general MIS contact, it is similarly difficult to keep its active low-WF metal from reacting with its ultrathin insulator during the BEOL process, and this reaction between the metal and the ultrathin insulator is commonly accompanied by a loss of the MIS merits-the insulator passivation and low qϕ b . The combination of low-WF metal and ultrathin insulator is so fragile that, in some MIS studies, even the step of low-WF metal deposition already degrades the insulator due to the metal depositioninduced heating [10], [30], [31]. The thermal vulnerability is thus a major obstacle for the MIS contact application.…”

Section: Characterizations and Discussionmentioning

confidence: 99%

“…In comparison, nitride is probably better at thermal stability than oxide: compared with O, N generally has less solubility and much less diffusivity in low-WF metals [34], [35], and the metal nitridation rates are usually slower than oxidation [32]. In a case study of Al and Ge-based MIS contacts, it is found that a lightly nitrided GeO x N y (x:y = 92%:8%) interlayer provides a much more robust MIS contact than that with a GeO x interlayer [34]: the incorporation N in the interlayer effectively retards the reaction of Al and the interlayer [31]. Therefore, nitrides or nitrided dielectrics-based MIS contacts probably have better thermal stability than the oxide-based ones and are thus more suitable for application in the realistic IC.…”

Section: Characterizations and Discussionmentioning

confidence: 99%

Thermal Stability Concern of Metal-Insulator-Semiconductor Contact: A Case Study of Ti/TiO₂/n-Si Contact

Schaekers

Schram

et al. 2016

IEEE Trans. Electron Devices

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This work discusses the thermal stability of metal-insulator-semiconductor (MIS) contacts. A case study is performed on a typical low-Schottky barrier height (qϕ b ) MIS contact: Ti/TiO 2 /n-Si. By incorporating different levels of donor concentration in n-Si, we perform a systematic Ti/TiO 2 /n-Si thermal stability study under different electron conduction mechanisms. We find that both qϕ b and contact resistivity (ρ c ) of the Ti/TiO 2 /n-Si MIS contacts vary dramatically after mere 300°C-500°C 1-min rapid thermal treatments. The variations in qϕ b and ρ c are related to the thermally driven TiO 2 decomposition. This thermal stability study of Ti/TiO 2 /n-Si reveals a general concern for the MIS contact application: since the MIS contacts on n-type semiconductor generally utilize a reactive low-work function metal and an ultrathin insulator, it is difficult to maintain their interface quality considering the thermal budget in standard manufacturing of integrated circuits. Possible solutions to this MIS thermal stability issue are discussed.

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“…Plasma-enhanced ALD (PEALD) is widely used in the semiconductor process, and plasma oxygen generated by PEALD is highly energetic which makes it able to react with Ge to form high oxidation state GeO x . Although a mere GeO x layer can effectively passivate Ge surface, the metal may penetrate into GeO x and thus FL depinning may fail [17]. It has been reported that inserting 1.5 nm oxygen plasma oxidised GeO x prior to 1 nm TiO 2 deposition, results in a nearly symmetric I-V curve, which shows better electrical characteristics compared with no GeO x case [18].…”

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confidence: 99%

Improving metal/ n ‐Ge ohmic contact by inserting TiO ₂ deposited by PEALD

Zhang

Liu

Han

et al. 2018

Micro & Nano Letters

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A simple method is used to improve metal/n-germanium (Ge) contact characteristics by inserting plasma-enhanced atomic layer deposition (PEALD) deposited titanium dioxide (TiO 2)/GeO x. Cross-sectional transmission electron microscope results confirm the thickness of the 30 PEALD cycles TiO 2 /GeO x is 1.62/1.38 nm. By inserting 1.62/1.38 nm TiO 2 /GeO x between aluminium (Al) and n-Ge, current densities increased by about 1800 times at −0.1 V compared with contacts without insertion layer (IL). With IL, ρ c of 9.52 × 10 −3 Ω cm 2 for Al/IL/n-Ge with an n-Ge concentration of 6 × 10 16 cm −3 was achieved. ρ c reduced by a factor 83 compared with no TiO 2 IL, and it also shows 4.72 times reduction compared with ρ c extracted from samples inserting thermal ALD-deposited TiO 2. X-ray photoelectron spectroscopy (XPS) results shows that the valence state for GeO x was 3.682, thus Ge surface may be passivated. It was also determined by XPS that TiO 2 was oxygen-vacancies rich, which may dope TiO 2 and may contribute to lower tunnelling resistance. All of the characteristics will be beneficial for low contact resistivity.

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Fermi Level Depinning Failure for Al/GeO2/Ge Contacts

Cited by 10 publications

References 28 publications

Impact of nitrogen plasma passivation on the Al/n-Ge contact

Impact of nitrogen plasma passivation on the Al/n-Ge contact

Thermal Stability Concern of Metal-Insulator-Semiconductor Contact: A Case Study of Ti/TiO₂/n-Si Contact

Improving metal/ n ‐Ge ohmic contact by inserting TiO ₂ deposited by PEALD

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Fermi Level Depinning Failure for Al/GeO2/Ge Contacts

Cited by 10 publications

References 28 publications

Impact of nitrogen plasma passivation on the Al/n-Ge contact

Impact of nitrogen plasma passivation on the Al/n-Ge contact

Thermal Stability Concern of Metal-Insulator-Semiconductor Contact: A Case Study of Ti/TiO2/n-Si Contact

Improving metal/ n ‐Ge ohmic contact by inserting TiO 2 deposited by PEALD

Contact Info

Product

Resources

About

Thermal Stability Concern of Metal-Insulator-Semiconductor Contact: A Case Study of Ti/TiO₂/n-Si Contact

Improving metal/ n ‐Ge ohmic contact by inserting TiO ₂ deposited by PEALD