Novel Approach for Improving Interface Quality of 4H-SiC MOS Devices with UV Irradiation and Subsequent Thermal Annealing

2013 ◽  
Vol 740-742 ◽  
pp. 741-744 ◽  
Author(s):  
Heiji Watanabe ◽  
Daisuke Ikeguchi ◽  
Takashi Kirino ◽  
Shuhei Mitani ◽  
Yuki Nakano ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Thermal Annealing ◽  
Uv Irradiation ◽  
Uv Light ◽  
Interface State ◽  
State Density ◽  
Mos Devices ◽  
Novel Approach ◽  
Subsequent Thermal Annealing ◽  
Thermally Grown

We report on the harmful impact of ultraviolet (UV) light irradiation on thermally grown SiO2/4H-SiC(0001) structures and its use in subsequent thermal annealing for improving electrical properties of SiC-MOS devices. As we previously reported [1], significant UV-induced damage, such as positive flatband voltage shift and hysteresis in capacitance-voltage curves as well as increased interface state density, was observed for SiC-MOS devices with thermally grown oxides. Interestingly, the subsequent annealing of damaged SiO2/SiC samples resulted in superior electrical properties to those for untreated (fresh) devices. These findings imply that UV irradiation of the SiO2/SiC structure is effective for eliciting pre-existing carbon-related defects and transforming them into a simple configuration that can be easily passivated by thermal treatment.

Impact of UV Irradiation on Thermally Grown 4H-SiC MOS Devices

2012 ◽  
Vol 717-720 ◽  
pp. 765-768 ◽  
Author(s):  
Daisuke Ikeguchi ◽  
Takashi Kirino ◽  
Shuhei Mitani ◽  
Yuki Nakano ◽  
Takashi Nakamura ◽  
...  
Keyword(s):  
Uv Irradiation ◽  
Uv Light ◽  
Irradiation Time ◽  
Marked Change ◽  
Intrinsic Property ◽  
State Density ◽  
Oxide Semiconductor ◽  
Mos Capacitors ◽  
The Impact ◽  
Thermally Grown

The impact of ultraviolet (UV) light irradiation on thermally grown SiO2/4H-SiC structures was investigated by characterizing the 4H-SiC metal-oxide-semiconductor (MOS) capacitors fabricated with and without UV irradiation onto the oxide layers. The UV irradiation was found to significantly increase a hysteresis in capacitance-voltage (C-V) characteristics and cause a positive flatband voltage (VFB) shift, suggesting the generation of oxide charges and traps. Since the values of C-V hysteresis and VFB shift depend on the UV irradiation time, the electrical defects were considered to be induced during UV irradiation. In contrast, UV irradiation caused no marked change for the reference Si-MOS capacitors, indicating that the generation of UV-induced electrical defects was an intrinsic property of thermally grown SiO2/SiC structures. A detailed characterization of SiC-MOS capacitors with terraced SiO2 layers revealed that the UV-induced defects were located near the SiO2/SiC interface. The interfacial fixed charge density (QOX) was estimated to be 1.7×1012 cm-2 for the sample with UV irradiation, while that of the sample without UV irradiation was 1.0×1012 cm-2. Also, a slight increase was found in interface state density (Dit) due to UV irradiation. These results imply that the UV-induced defect generation correlates with residual carbon impurities at the SiO2/SiC interface.

Impact of a Treatment Combining Nitrogen Plasma Exposure and Forming Gas Annealing on Defect Passivation of SiO2/SiC Interfaces

2009 ◽  
Vol 615-617 ◽  
pp. 525-528 ◽  
Author(s):  
Heiji Watanabe ◽  
Yuu Watanabe ◽  
Makoto Harada ◽  
Yusuke Kagei ◽  
Takashi Kirino ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Energy Levels ◽  
Interface State ◽  
Nitrogen Plasma ◽  
State Density ◽  
Carbon Clusters ◽  
Plasma Exposure ◽  
Fixed Charges ◽  
Mos Devices ◽  
Defect Passivation

We propose a treatment combining nitrogen plasma exposure and forming gas annealing (FGA) to improve the electrical properties of SiO2/SiC interfaces. Although conventional FGA at 450°C alone is not effective for reducing interface traps and fixed charges, our combination treatment effectively reduces both even at moderate temperatures. We achieved further improvement by applying our treatment at higher (over 900°C) FGA temperatures, including lower interface state density (Dit) values for both deep and shallow energy levels (1 - 4 x 1011 cm-2eV-1). Considering that nitrogen incorporation promotes hydrogen passivation of interface defects, a possible mechanism for the improved electrical properties is that interface nitridation eliminates carbon clusters or Si-O-C bonds, which leads to the formation of simple Si and C dangling bonds that can be readily terminated by hydrogen. We therefore believe that our treatment is a promising method for improving the performance of SiC-based MOS devices.

Properties of Thin SiO2 Films with In-Situ Deposition of Poly Si Electrodes

1989 ◽  
Vol 146 ◽  
Author(s):  
Paihung Pan ◽  
Ahmad Kermani ◽  
Wayne Berry ◽  
Jimmy Liao
Keyword(s):  
Electrical Properties ◽  
Breakdown Strength ◽  
Chemical Vapor ◽  
Interface State ◽  
State Density ◽  
In Situ Deposition ◽  
Different Temperatures ◽  
Flatband Voltage ◽  
Si Films

ABSTRACTElectrical properties of thin (12 nm) SiO2 films with and without in-situ deposited poly Si electrodes have been studied. Thin SiO2 films were grown by the rapid thermal oxidation (RTO) process and the poly Si films were deposited by the rapid thermal chemical vapor deposition (RTCVD) technique at 675°C and 800°C. Good electrical properties were observed for SiO2 films with thin in-situ poly Si deposition; the flatband voltage was ∼ -0.86 V, the interface state density was < 2 × 1010/cm2/eV, and breakdown strength was > 10 MV/cm. The properties of RTCVD poly Si were also studied. The grain size was 10-60 rim before anneal and was 50-120 rim after anneal. Voids were found in thin (< 70 nm) RTCVD poly Si films. No difference in either SiO2 properties or poly Si properties was observed for poly Si films deposited at different temperatures.

Characterizations of Ultra-thin Dielectrics Grown by Microwave Afterglow O2/N2O Plasma Oxidation at Low Temperature with Rapid Thermal Annealing

1995 ◽  
Vol 387 ◽  
Author(s):  
Po-ching Chen ◽  
Klaus Yung-jane Hsu ◽  
Joseph J. Loferski ◽  
Huey-liang Hwang
Keyword(s):  
Low Temperature ◽  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Photoelectron Spectroscopy ◽  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Plasma Oxidation ◽  
X Ray ◽  
Thin Dielectrics

AbstractMicrowave afterglow plasma oxidation at a low temperature (600 °C ) and rapid thermal annealing (RTA) were combined to grow high quality ultra-thin dielectrics. This new approach has a low thermal budget. The mid-gap interface state density of oxides pretreated in N2O plasma was decreased to about 5×1010 cm−2eV−1 after rapid thermal annealing at 950 °C.It was found that RTA is very effective for relieving the oxide stress and reducing the interface state density. Nitrogen incorporated in oxides by the N2O plasma pretreatment of the Si surface helped to reduce the interface state density. Microstructures of ultra-thin oxide grown by microwave afterglow oxidation with or without RTA were revealed by extended-X-ray-absorption-finestructure (EXAFS) and X-ray photoelectron spectroscopy (XPS) analysis.

Effect of Interfacial Localization of Phosphorus on Electrical Properties and Reliability of 4H-SiC MOS Devices

2013 ◽  
Vol 740-742 ◽  
pp. 695-698 ◽  
Author(s):  
Tsuyoshi Akagi ◽  
Hiroshi Yano ◽  
Tomoaki Hatayama ◽  
Takashi Fuyuki
Keyword(s):  
Interface State ◽  
State Density ◽  
Oxide Semiconductor ◽  
Conduction Band Edge ◽  
Mos Capacitors ◽  
Mos Devices ◽  
Device Properties ◽  
Phosphorus Doped ◽  
Post Deposition ◽  
Mos Device

Metal-oxide-semiconductor (MOS) capacitors with phosphorus localized near the SiO2/SiC interface were fabricated on 4H-SiC by direct POCl3treatment followed by SiO2deposition. Post-deposition annealing (PDA) temperature affected MOS device properties and phosphorus distribution in the oxide. The sample with PDA at 800 °C showed narrow phosphorus-doped oxide region, resulting in low interface state density near the conduction band edge and small flatband voltage shift after FN injection. The interfacial localization of phosphorus improved both interface properties and reliability of 4H-SiC MOS devices.

Processing and Characterization of MOS Capacitors Fabricated on 2°-Off Axis 4H-SiC Epilayers

2016 ◽  
Vol 858 ◽  
pp. 663-666
Author(s):  
Marilena Vivona ◽  
Patrick Fiorenza ◽  
Tomasz Sledziewski ◽  
Alexandra Gkanatsiou ◽  
Michael Krieger ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Interface State ◽  
State Density ◽  
Metal Oxide Semiconductor ◽  
Interface State Density ◽  
Device Fabrication ◽  
Oxide Semiconductor ◽  
Mos Capacitors ◽  
Oxide Breakdown

In this work, the electrical properties of SiO2/SiC interfaces onto a 2°-off axis 4H-SiC layer were studied and validated through the processing and characterization of metal-oxide-semiconductor (MOS) capacitors. The electrical analyses on the MOS capacitors gave an interface state density in the low 1×1012 eV-1cm-2 range, which results comparable to the standard 4°-off-axis 4H-SiC, currently used for device fabrication. From Fowler-Nordheim analysis and breakdown measurements, a barrier height of 2.9 eV and an oxide breakdown of 10.3 MV/cm were determined. The results demonstrate the maturity of the 2°-off axis material and pave the way for the fabrication of 4H-SiC MOSFET devices on this misorientation angle.

Structure and Surface Morphology of Thermal SiO2 Grown on 4H-SiC by Metal-Enhanced Oxidation Using Barium

2017 ◽  
Vol 897 ◽  
pp. 340-343 ◽  
Author(s):  
Atthawut Chanthaphan ◽  
Yoshihito Katsu ◽  
Takuji Hosoi ◽  
Takayoshi Shimura ◽  
Heiji Watanabe
Keyword(s):  
Electrical Properties ◽  
Surface Morphology ◽  
Silicon Dioxide ◽  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Surface Roughening ◽  
Oxide Surface ◽  
Capping Layer ◽  
Enhanced Oxidation

Surface morphology and electrical properties of silicon dioxide (SiO2) on 4H-SiC substrates formed by metal-enhanced oxidation (MEO) using barium (Ba) atoms were systematically investigated. It was found that severe surface roughening caused by Ba-MEO can be suppressed by using SiO2 capping prior to MEO. The Ba atoms at the SiO2/SiC interface were found to diffuse to the oxide surface through the deposited SiO2 capping layer, and then the Ba density reduced to ~1014 cm-2 before stable MEO. The resulting SiO2/SiC interface showed the reduced interface state density but the insulating property of the oxides was significantly degraded.

scholarly journals UV irradiation effect on the electrical properties of Pb2MoO5 single crystal

2018 ◽  
Vol 26 (2) ◽  
pp. 63-66
Author(s):  
I. P. Volnyanskaya ◽  
M. P. Trubitsyn ◽  
D. M. Volnianskii ◽  
D. S. Bondar
Keyword(s):  
Electrical Properties ◽  
Single Crystal ◽  
Uv Irradiation ◽  
Room Temperature ◽  
Uv Light ◽  
Dipole Moments ◽  
Irradiation Effect ◽  
Deep Traps ◽  
Temperature Dependences ◽  
Ac Field

Electrical properties of Pb2MoO5 single crystal were studied in AC field (f=1 kHz) after irradiation with UV light (290 K). It was found that UV irradiation caused appearance of maximums on permittivity ε and conductivity σ temperature dependences, which were observed around 530 K. The anomalies of ε and σ vanished after annealing at 700 K and could be restored by subsequent UV irradiation performed at room temperature. The magnitude of ε and σ peaks increased for higher exposition time. Above 600 K conductivity σ was practically independent on irradiation. It is proposed that photoelectrons induced by UV light, are trapped by Mo located -within the oxygen tetrahedrons with vacancy VO in one of the vertexes. The dipole moments of (MoO3) groups reorient at VO hopping through the tetrahedron vertexes. Annealing at 700 K thermally decomposes (MoO3)- complexes. For T>600 K behavior of σ(T) is determined by conduction currents and nearly insensitive to UV irradiation. At high temperatures the photoelectrons do not contribute to conductivity since they are bound in (MoO3)- centers, recombine with holes or re-captured by more deep traps.

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