High Temperature Nitridation of 4H-SiC MOSFETs

2016 ◽  
Vol 858 ◽  
pp. 623-626 ◽  
Author(s):  
Hua Rong ◽  
Yogesh K. Sharma ◽  
Tian Xiang Dai ◽  
Fan Li ◽  
M.R. Jennings ◽  
...  
Keyword(s):  
High Temperature ◽  
Threshold Voltage ◽  
Field Effect ◽  
Annealing Process ◽  
Interface Trap Density ◽  
Interface Trap ◽  
Gate Oxides ◽  
Mos Capacitors ◽  
Channel Mobility ◽  
Lower Temperature

This paper presents and analyse the experimental results of 4H-SiC(0001) lateral MOSFETs and MOS capacitors with gate oxides grown directly in N2O environment or in O2 ambient followed by a N2O post oxidation annealing process. Different nitridation temperatures of 1200°C, 1300°C, 1400°C and 1500°C have been investigated. Results have demonstrated that at high temperature (>1200°C) there is a significant improvement in the interface trap density (~1.5×1011 cm-2eV-1 at 0.2 eV) and field effect channel mobility (19 cm2/V.s) of 4H-SiC MOSFET compare with those at lower temperature (1×1012 cm-2eV-1 at 0.2 eV and 4 cm2/V.s). Among those nitridation temperatures, 1300°C has found to be the most effective in increasing the field effect channel mobility and reducing threshold voltage.

Analysis of Interface Trap Density and Channel Mobility in 4H-SiC NMOS Capacitors and Lateral MOSFETs

2017 ◽  
Vol 897 ◽  
pp. 115-118
Author(s):  
Martin Domeij ◽  
Jimmy Franchi ◽  
Krister Gumaelius ◽  
K. Lee ◽  
Fredrik Allerstam
Keyword(s):  
Threshold Voltage ◽  
Interface State ◽  
State Density ◽  
Interface State Density ◽  
Trap Density ◽  
Interface Trap Density ◽  
Interface Trap ◽  
Subthreshold Slope ◽  
Gate Oxides ◽  
Channel Mobility

Lateral implanted SiC MOSFETs and NMOS capacitors were fabricated and used to extract channel mobility and interface state density DIT for three different gate oxides. DIT values were extracted using the high(1 MHz)-low(1 kHz) method for NMOS capacitors and the subthreshold slope for MOSFETs. The subthreshold slope extraction gave 6-20 times higher DIT values compared to the high-low method, presumably because the high-low method cannot capture the fastest traps [1]. None of the methods resulted in clear proportionality between the inverse channel mobility and DIT. The subthreshold slope gave similar DIT values for samples with different surface p-doping concentrations indicating that the method is not sensitive to the threshold voltage.

Effect of NH3 Post-Oxidation Annealing on Flatness of SiO2/SiC Interface

2013 ◽  
Vol 740-742 ◽  
pp. 723-726 ◽  
Author(s):  
Narumasa Soejima ◽  
Taishi Kimura ◽  
Tsuyoshi Ishikawa ◽  
Takahide Sugiyama
Keyword(s):  
Nitrous Oxide ◽  
Field Effect ◽  
Inversion Layer ◽  
Trap Density ◽  
Interface Trap Density ◽  
Interface Trap ◽  
Field Effect Mobility ◽  
Interfacial Roughness ◽  
Cross Sectional ◽  
Mos Capacitors

We investigated the effects of the post-oxidation annealing (POA) atmosphere on the electrical properties and interfacial roughness of SiO2 deposited on a 4H-SiC (0001) face and SiC. POA in ammonia (NH3) gave MOS capacitors with a lower interface trap density and n-channel MOSFETs with higher field-effect mobility than POA in nitrous oxide (N2O) or nitrogen (N2). In contrast, POA in N2O gave a lower interface trap density than POA in N2, but it gave the lowest field-effect mobility of all the samples. Cross-sectional TEM observations revealed that N2O POA gave a higher interfacial roughness than NH3 POA. We thus considered that N2O POA degraded the inversion-layer mobility due to increased roughness scattering.

Stable Phosphorus Passivated SiO2/4H-SiC Interface Using Thin Oxides

2014 ◽  
Vol 806 ◽  
pp. 139-142 ◽  
Author(s):  
Yogesh K. Sharma ◽  
A.C. Ahyi ◽  
Tamara Issacs-Smith ◽  
M.R. Jennings ◽  
S.M. Thomas ◽  
...  
Keyword(s):  
Metal Oxide Semiconductor ◽  
Trap Density ◽  
Oxide Semiconductor ◽  
Interface Trap Density ◽  
Interface Trap ◽  
Polar Material ◽  
Mos Capacitors ◽  
Channel Mobility ◽  
Inversion Channel ◽  
Phosphosilicate Glass

The NO (nitric oxide) passivation process for 4H-SiC MOSFETs (silicon carbide metal-oxide-semiconductor filed effect transistors) effectively reduces the interface trap density and increases the inversion channel mobility from less that 10 to around 35cm2/V.s, only 5% of the bulk mobility. Recent results on the phosphorous passivation of the SiO2/4H-SiC interface have shown that it improves the mobility to about 90 cm2/V.s. Phosphorous passivation converts oxide (SiO2) into phosphosilicate glass (PSG) which is a polar material and results in device instabilities under abias-temperature stress (BTS) measurements. To limit the polarization effect, a new thin PSG process has been developed. The interface trap density of 4H-SiC-MOS capacitors using this process is as low as 3x1011cm-2eV-1. BTS results on MOSFETs have shown that the thin PSG devices are as stable as NO passivated devices with mobility around 80 cm2/V.s.

The Impact of Oxygen Flow Rate on the Oxide Thickness and Interface Trap Density in 4H-SiC MOS Capacitors

2014 ◽  
Vol 806 ◽  
pp. 149-152
Author(s):  
Stephen M. Thomas ◽  
M.R. Jennings ◽  
Y.K. Sharma ◽  
C.A. Fisher ◽  
P.A. Mawby
Keyword(s):  
Flow Rate ◽  
Oxide Thickness ◽  
Trap Density ◽  
Oxygen Flow ◽  
Interface Trap Density ◽  
Interface Trap ◽  
Mos Transistors ◽  
Mos Capacitors ◽  
Channel Mobility ◽  
The Impact

Silicon carbide based devices have the potential to surpass silicon technology in high power, high frequency and high temperature applications. 4H-SiC MOS transistors currently suffer from a low channel mobility due to a high density of traps near the oxide/SiC interface. In this work, oxides have been grown on the Si face of 4H-SiC using oxygen flow rates ranging from 2.5 l/min to 0.05 l/min. Capacitance-voltage measurements on MOS capacitors revealed approximately a fourfold reduction in the interface trap density and a 25% increase in oxide thickness by reducing the flow rate from 2.5 l/min to 0.05 l/min.

Comparative Study of 4H-SiC DMOSFETs with N2O Thermal Oxide and Deposit Oxide with Post Oxidation Anneal

2014 ◽  
Vol 778-780 ◽  
pp. 989-992
Author(s):  
Cheng Tyng Yen ◽  
Chien Chung Hung ◽  
Aleksey Mikhaylov ◽  
Chwan Ying Lee ◽  
Lurng Shehng Lee ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Comparative Study ◽  
Breakdown Field ◽  
Interface Trap Density ◽  
Interface Trap ◽  
Gate Oxides ◽  
Channel Mobility ◽  
Thermal Oxide ◽  
Multiple Breakdown ◽  
Post Deposition

Two kinds of gate oxides, direct thermal oxidation in a nitrous oxide ambient at 1250°C(TGO) and a PECVD oxide followed by a post deposition oxidation in nitrous at 1150°C (DGO) were studied. DGO showed a lower interface trap density and was able to provide a higher current as being implemented in MOSFETs through the improved channel mobility. However the 6.45 MV/cm average breakdown field of DGO is lower than the 10.1 MV/cm breakdown field of TGO. The lower breakdown field, more leaky behavior and the existence of multiple breakdown mechanisms suggest that DGO needs further improvements before it can be used in real applications.

Borosilicate Glass (BSG) as Gate Dielectric for 4H-SiC MOSFETs

2018 ◽  
Vol 924 ◽  
pp. 502-505 ◽  
Author(s):  
Yong Ju Zheng ◽  
Tamara Isaacs-Smith ◽  
Ayayi Claude Ahyi ◽  
S. Dhar
Keyword(s):  
Borosilicate Glass ◽  
Field Effect ◽  
Gate Dielectric ◽  
Trap Density ◽  
Interface Trap Density ◽  
Interface Trap ◽  
Interface Traps ◽  
Field Effect Mobility ◽  
Channel Mobility

In this work, we investigate the effect of borosilicate glass (BSG) as gate dielectric on dielectric/4H-SiC interface traps and channel mobility in 4H-SiC MOSFETs. The interface trap characterization by C−ψs analysis and I-V characterization show lower fast interface trap density (Dit) as well as significant improvement of channel field-effect mobility on devices with BSG than that on devices with standard NO anneal. In addition, the results indicate interface trap density decreases with increasing B concentration at the interface of BSG/4H-SiC, which in turn, results in higher channel mobility.

scholarly journals Interface trap density and mobility extraction in InGaAs buried quantum well metal-oxide-semiconductor field-effect-transistors by gated Hall method

2014 ◽  
Vol 104 (13) ◽  
pp. 131605 ◽  
Author(s):  
Thenappan Chidambaram ◽  
Dmitry Veksler ◽  
Shailesh Madisetti ◽  
Andrew Greene ◽  
Michael Yakimov ◽  
...  
Keyword(s):  
Quantum Well ◽  
Metal Oxide ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Metal Oxide Semiconductor ◽  
Trap Density ◽  
Oxide Semiconductor ◽  
Interface Trap Density ◽  
Interface Trap ◽  
Hall Method

Gamma Irradiation Effects on 4H-SiC MOS Capacitors and MOSFETs

2006 ◽  
Vol 527-529 ◽  
pp. 1063-1066 ◽  
Author(s):  
Ayayi Claude Ahyi ◽  
S.R. Wang ◽  
John R. Williams
Keyword(s):  
Field Effect ◽  
Gamma Dose ◽  
Interface Traps ◽  
Valence Band Edge ◽  
Field Effect Mobility ◽  
Irradiation Effects ◽  
Mos Capacitors ◽  
Channel Mobility ◽  
Radiation Induced ◽  
Radiation Tolerant

The effects of gamma radiation on field effect mobility and threshold voltage have been studied for lateral n-channel 4H-SiC MOSFETs passivated with nitric oxide. MOS capacitors (n and p) and n-channel lateral MOSFETs were irradiated unbiased (floating contacts) for a total gamma dose of 6.8Mrad (Si). The MOS capacitors were used to study the radiation-induced interface traps and fixed oxide charge that affect the performance of the MOSFETs. Radiationinduced interface traps were observed near the SiC valence band edge and just above mid-gap, and field effect channel mobility was reduced by 18-20% following irradiation. Even so, 4HMOSFETs appear to be more radiation tolerant than Si devices.

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