The effect of nitrogen plasma anneals on interface trap density and channel mobility for 4H–SiC MOS devices

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.

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

Materials Science Forum ◽

10.4028/www.scientific.net/msf.806.139 ◽

2014 ◽

Vol 806 ◽

pp. 139-142 ◽

Cited By ~ 1

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.

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Single transistor technique for interface trap density measurement in irradiated MOS devices

Microelectronics Reliability ◽

10.1016/s0026-2714(99)00020-7 ◽

1999 ◽

Vol 39 (4) ◽

pp. 497-505 ◽

Cited By ~ 1

Author(s):

V.S Pershenkov ◽

S.V Cherepko ◽

R.E Ivanov ◽

A.V Shalnov ◽

V.V Abramov

Keyword(s):

Density Measurement ◽

Trap Density ◽

Interface Trap Density ◽

Interface Trap ◽

Mos Devices

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Hall Effect and Admittance Measurements of n-Channel 6H-SiC MOSFETs

Materials Science Forum ◽

10.4028/www.scientific.net/msf.556-557.791 ◽

2007 ◽

Vol 556-557 ◽

pp. 791-794

Author(s):

Kin Kiong Lee ◽

Michael Laube ◽

Takeshi Ohshima ◽

Hisayoshi Itoh ◽

Gerhard Pensl

Keyword(s):

Comparative Study ◽

Hall Effect ◽

Hall Mobility ◽

Trap Density ◽

Interface Trap Density ◽

Interface Trap ◽

Channel Mobility ◽

A Value ◽

Dry Oxidation ◽

Effective Channel

In this paper we give a comparative study of two types of gate oxidation of n-channel 6HSiC MOSFETs. One set of transistors was fabricated using pyrogenic oxidation with no postoxidation annealing, and for the second set the oxide was grown in dry O2 with post-oxidation annealing. The lateral MOSFETs show a Hall mobility of ~ 75 cm2/Vs which is essentially same for both types of oxide. From the IV characteristics curves, the latter devices exhibit an average effective channel mobility of 72 (± 5) cm2/Vs, whereas the former has a value of 30 (± 3) cm2/Vs. From the capacitance and conductance measurements, the interface trap density for pyrogenicgrown oxide using is roughly a factor of 2 greater than those grown by dry oxidation. We found that the pyrogenic post-oxidation anneal at 1073K helps to reduce the interface states density and improves the effective channel mobility of 6H-SiC MOSFETs.

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

Materials Science Forum ◽

10.4028/www.scientific.net/msf.806.149 ◽

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.

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Degradation in Oxide Reliability Due to the Presence of Nitrogen in the Oxidation Ambient

MRS Proceedings ◽

10.1557/proc-318-645 ◽

1993 ◽

Vol 318 ◽

Author(s):

Greg A. Hames ◽

J. J. Wortman ◽

S. E. Beck ◽

B. J. Shemanski

Keyword(s):

Photoelectron Spectroscopy ◽

Current Drive ◽

Trap Density ◽

Oxide Semiconductor ◽

Interface Trap Density ◽

Interface Trap ◽

Subthreshold Slope ◽

Channel Mobility ◽

Nitrogen Incorporation ◽

Slope Channel

ABSTRACTUltrathin rapid thermal oxides have been formed in oxygen with varying levels of nitrogen incorporated into the oxidation ambient. Metal-oxide-semiconductor capacitors and MOSFET devices were subsequently fabricated and tested. Device reliability was degraded by the addition of nitrogen into the oxidation ambient. Time-independent catastrophic breakdown measurements showed a large increase in the number of extrinsic breakdowns in devices formed in higher levels of nitrogen. Device performance was measured by interface trap density, subthreshold slope, channel mobility and threshold voltage. A small increase in the interface trap density was observed for increasing levels of nitrogen in the oxidation ambient. However, no trends were observed for MOSFET devices in terms of subthreshold slope, channel mobility or current drive. No improvement in the interface state generation rate due to nitrogen incorporation in the oxidation ambient was observed in this study. X-ray photoelectron spectroscopy detected no nitrogen in the oxides indicating less than 1% nitrogen incorporation.

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

Materials Science Forum ◽

10.4028/www.scientific.net/msf.924.502 ◽

2018 ◽

Vol 924 ◽

pp. 502-505 ◽

Cited By ~ 1

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.

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