Reduction of interface states by hydrogen treatment at the aluminum oxide/4H-SiC Si-face interface

Yoshioka, Hironori; Yamazaki, Masashi; Harada, Shinsuke

doi:10.1063/1.4966041

Cited by 16 publications

(7 citation statements)

References 26 publications

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“…Peak field effect mobility of 106 cm 2 V −1 s −1 using a gate dielectric of thin nitrided SiO 2 and Al 2 O 3 was reported by Lichtenwalner et al [13]. Hydrogen plasma treatment was found to be effective at decreasing the interface state density at the Al 2 O 3 -SiC interface [14,15], resulting in a peak field effect of mobility of 57 cm 2 V −1 s −1 with a density of interface traps of 1.7 × 10 12 at E C − E = 0.2 eV using the C-ψ technique.…”

Section: Introductionmentioning

confidence: 75%

Increased Mobility in 4H-SiC MOSFETs by Means of Hydrogen Annealing

Idris

Horsfall

2022

Crystals

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Enhancement-mode 4H-SiC MOSFETs utilising an aluminium oxide (Al2O3) dielectric without the requirement for an underlying silicon oxide (SiO2) layer have been shown to have a field effect mobility of 150 cm2V−1s−1 and a subthreshold swing of 160 mV/dec. The fabricated devices utilised a forming gas (3% H2 in N2) anneal immediately prior to the deposition of the Al2O3 by Atomic Layer Deposition (ALD). A comparison MOSFET using an identical Al2O3 deposition process with a 0.7 nm SiO2 layer had a field effect mobility of approximately 20 cm2V−1s−1. The hydrogen annealed device had a lower density of interface traps (Dit), a lower subthreshold swing, and a significantly reduced hysteresis in the transconductance data than the thin SiO2 sample. This finding solves the issue of inconsistency of device performance using thin film gate dielectric as an interfacial layer by offering a simple and controllable process.

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Section: Introductionmentioning

confidence: 75%

Increased Mobility in 4H-SiC MOSFETs by Means of Hydrogen Annealing

Idris

Horsfall

2022

Crystals

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“…A variety of SiC surface-cleaning treatments have been proposed, based either on wet chemical solutions [44][45][46] or plasma [47][48][49]. The most used chemical solutions for SiC cleaning are combinations of diluted sulfuric acid, hydrogen peroxide, isopropanol, diluted hydrofluoric acid.…”

Section: Growth Of Amorphous High-κ Oxides On Sicmentioning

confidence: 99%

“…Suvanam et al [46] demonstrated that RCA treatment [45], followed by HF diluted solution and finally isopropanol, was a good route to improve the interfacial electrical characteristics of Al 2 O 3 films on SiC, obtaining a density of interface states D it = 1.5 × 10 11 eV −1 cm −2 at E C − E t = 0.2 eV below the 4H-SiC conduction band edge, which was about two orders of magnitude lower than the values found with thermal SiO 2 . In regard to plasma treatment before high-κ deposition, H 2 plasma has been also evaluated in some works [47][48][49], since it represents an efficient route for the passivation of dangling bonds on SiC surfaces. Heo et al [49] measured promising values of interface state density (D it = 6 × 10 12 eV −1 cm −2 at E C − E t = 0.2 eV) when a 15 min long H 2 plasma treatment was performed before deposition and after the post-metallization step.…”

Section: Growth Of Amorphous High-κ Oxides On Sicmentioning

confidence: 99%

“…Clearly, because of the large differences in the mobility behaviour of the MOSFETs processed under different conditions, this topic has been strongly debated. In particular, Yoshioka et al [47] demonstrated optimization of the interface of aluminium oxide and SiC without a SiO 2 interlayer, resulting in a low D it for the metal oxide semiconductor (MOS) capacitor of 1.7 × 10 12 cm −2 eV −1 at E C − E t = 0.2 eV and a peak field-effect mobility of 57 cm 2 V −1 s −1 that was quite constant with the variation of the gate bias. Other works have tried to figure out the right combination of semiconductor surface pre-treatments and postdeposition annealing in order to improve the electrical properties of Al 2 O 3 /SiC interfaces [41,46].…”

Section: Binary High-κ Oxides In 4h-sic Mosfetsmentioning

confidence: 99%

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Structural and Insulating Behaviour of High-Permittivity Binary Oxide Thin Films for Silicon Carbide and Gallium Nitride Electronic Devices

et al. 2022

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High-κ dielectrics are insulating materials with higher permittivity than silicon dioxide. These materials have already found application in microelectronics, mainly as gate insulators or passivating layers for silicon (Si) technology. However, since the last decade, the post-Si era began with the pervasive introduction of wide band gap (WBG) semiconductors, such as silicon carbide (SiC) and gallium nitride (GaN), which opened new perspectives for high-κ materials in these emerging technologies. In this context, aluminium and hafnium oxides (i.e., Al2O3, HfO2) and some rare earth oxides (e.g., CeO2, Gd2O3, Sc2O3) are promising high-κ binary oxides that can find application as gate dielectric layers in the next generation of high-power and high-frequency transistors based on SiC and GaN. This review paper gives a general overview of high-permittivity binary oxides thin films for post-Si electronic devices. In particular, focus is placed on high-κ binary oxides grown by atomic layer deposition on WBG semiconductors (silicon carbide and gallium nitride), as either amorphous or crystalline films. The impacts of deposition modes and pre- or postdeposition treatments are both discussed. Moreover, the dielectric behaviour of these films is also presented, and some examples of high-κ binary oxides applied to SiC and GaN transistors are reported. The potential advantages and the current limitations of these technologies are highlighted.

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“…The D it of the ALD-Al 2 O 3 /4H-SiC interface was lower than that of the SiO 2 /4H-SiC interface without a post-annealing process at high temperatures. 21,22) The third was Al 2 O 3 formed via metal layer oxidation (MLO). We proposed MLO in a previous work.…”

Section: Introductionmentioning

confidence: 99%

Impact of oxide/4H-SiC interface state density on field-effect mobility of counter-doped n-channel 4H-SiC MOSFETs

Doi¹,

Shibayama²,

Sakashita³

et al. 2022

Jpn. J. Appl. Phys.

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We investigated the effect of interface state density on the field-effect mobility (μ FE) of 4H-SiC counter-doped MOSFETs. We fabricated counter-doped MOSFETs with three types of gate oxides i.e., SiO2, Al2O3 formed via atomic layer deposition, and Al2O3 formed via metal layer oxidation (MLO). A maximum μ FE of 80 cm2/Vs was obtained for the MLO-Al2O3 FET, and this value was 60% larger than that of the SiO2 FET. In addition, we evaluated the electron mobility in the neutral channel (μ neutral) and the rate of increase in the free electron density in the neutral channel with respect to the gate voltage (dN neutral/dV G), which are factors determining μ FE. μ neutral depended only on the channel depth, independent of the type of gate oxide. In addition, dN neutral/dV G was significantly low in the SiO2 FET because of carrier trapping at the high density of interface states, whereas this effect was smaller in the Al2O3 FETs.

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Reduction of interface states by hydrogen treatment at the aluminum oxide/4H-SiC Si-face interface

Cited by 16 publications

References 26 publications

Increased Mobility in 4H-SiC MOSFETs by Means of Hydrogen Annealing

Increased Mobility in 4H-SiC MOSFETs by Means of Hydrogen Annealing

Structural and Insulating Behaviour of High-Permittivity Binary Oxide Thin Films for Silicon Carbide and Gallium Nitride Electronic Devices

Impact of oxide/4H-SiC interface state density on field-effect mobility of counter-doped n-channel 4H-SiC MOSFETs

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