Tunneling Effects in NH3 Annealed 4H-SiC Trench MOSFETs

2020 ◽  
Vol 1004 ◽  
pp. 652-658
Author(s):  
Judith Berens ◽  
Gregor Pobegen ◽  
Tibor Grasser
Keyword(s):  
Effective Activation Energy ◽  
Charge Trapping ◽  
Gate Oxide ◽  
Device Performance ◽  
Trap Level ◽  
Effective Activation ◽  
Oxide Reliability ◽  
Trap Assisted Tunneling ◽  
Assisted Tunneling ◽  
Mos Structures

The interface between the gate oxide and silicon carbide (SiC) has a strong influence on the performance and reliability of SiC MOSFETs and thus, requires special attention. In order to reduce charge trapping at the interface, post oxidation anneals (POAs) are conventionally applied. However, these anneals do not only influence the device performance, such as mobility and on-resistance, but also the gate oxide reliability. We study the oxide tunneling mechanisms of NH3 annealed 4H-SiC trench MOSFET test structures and compare them to devices which received a NO POA. We show that 3 different mechanisms, namely trap assisted tunneling (TAT), Fowler-Nordheim (FN) tunneling and charge trapping are found for NH3 annealed MOS structures whereas only FN-tunneling is observed in NO annealed devices.The tunneling barrier suggest a trap level with an effective activation energy of 382 meV to enable TAT.

Performance Improvement of Trench-Gate SiC MOSFETs by Localized High-Concentration N-Type Ion Implantation

2020 ◽  
Vol 1004 ◽  
pp. 770-775
Author(s):  
Rina Tanaka ◽  
Katsutoshi Sugawara ◽  
Yutaka Fukui ◽  
Hideyuki Hatta ◽  
Hidenori Koketsu ◽  
...  
Keyword(s):  
Performance Improvement ◽  
Short Circuit ◽  
Effective Means ◽  
Gate Oxide ◽  
Device Performance ◽  
High Concentration ◽  
Safe Operation ◽  
Major Drawback ◽  
Oxide Reliability ◽  
Conventional Device

Gate oxide reliability of a trench-gate SiC MOSFET can be improved by incorporating a gate protection structure, but the resulting parasitic JFET resistance is one major drawback. For reduction of on-resistance, a new method of localized high-concentration n-type doping in JFET regions (JD) is developed. Utilizing process and device simulation by TCAD, the optimal condition of JD that enables maximum device performance is derived. By fabricating a device with the optimal JD structure, the on-resistance is successfully reduced by 25% compared to a conventional device without JD, while maintaining the withstand voltage and the gate oxide electric field at the same level. As a result, a device exhibiting a specific on-resistance of 1.84 mΩcm2 and a breakdown voltage of 1560 V is obtained. The optimal JD structure maintains the short-circuit safe operation area comparable to that for the structure without JD. Thus, by reducing the JFET resistance while minimizing effects on other characteristics, localized JD is shown to be an effective means of realizing a reliable, low-resistance SiC power device.

Effect of Phosphorus-Doped Polysilicon Anneal on Thin Oxide Reliability as Probed with X-Ray Damage Characterization

1994 ◽  
Vol 338 ◽  
Author(s):  
R. Nachman ◽  
F. Cerrina
Keyword(s):  
Gate Oxide ◽  
Radiation Sensitivity ◽  
Oxide Charge ◽  
X Ray ◽  
Damage Characterization ◽  
Oxide Reliability ◽  
The Creation ◽  
Thin Oxide ◽  
Phosphorus Doped ◽  
Mos Structures

ABSTRACTIn this paper we address the degradation of oxide reliability after annealing the phosphorusdoped polysilicon of MOS structures. The oxide reliability was studied in terms of X-ray radiation sensitivity as well as breakdown characteristics.We found that annealing the polysilicon increased the radiation sensitivity of the gate oxide. We believe that this increase is a result of the phosphorus out-diffusion from the polysilicon into the oxide and a result of the creation of phosphorus related traps in the oxide bulk. We also found that the oxide charge to breakdown (Qbd) degradation correlates well with the density of the phosphorus in the oxide.

The Roles of Several E′ Variants in Thermal Gate Oxide Reliability

1994 ◽  
Vol 338 ◽  
Author(s):  
John F. Conley ◽  
P.M. Lenahan ◽  
H.L. Evans ◽  
R.K. Lowry ◽  
T.J. Morthorst
Keyword(s):  
Thin Film ◽  
Electron Spin Resonance ◽  
Electron Spin ◽  
Vacuum Ultraviolet ◽  
Charge Injection ◽  
Charge Trapping ◽  
Gate Oxide ◽  
Oxide Reliability ◽  
Spin Resonance ◽  
Thermally Grown

ABSTRACTWe combine electron spin resonance measurements with vacuum ultraviolet, ultraviolet, and corona bias charge injection schemes to examine the properties and charge trapping roles of three E′ variants in conventionally processed thermally grown thin film SiO2 on Si.

Impact of boron penetration on gate oxide reliability and device performance in a dual-gate oxide process

2000 ◽  
Author(s):  
Yunqiang Zhang ◽  
Chock H. Gan ◽  
Xi Li ◽  
James Lee ◽  
David Vigar ◽  
...  
Keyword(s):  
Gate Oxide ◽  
Device Performance ◽  
Oxide Reliability ◽  
Dual Gate ◽  
Boron Penetration

Electrical Properties of MOS Structures on 4H-SiC (11-20) Face

2013 ◽  
Vol 740-742 ◽  
pp. 621-624 ◽  
Author(s):  
Junji Senzaki ◽  
Atsushi Shimozato ◽  
Kozutoshi Kajima ◽  
Keiko Aryoshi ◽  
Takahito Kojima ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Harmful Effect ◽  
Gate Oxide ◽  
The Other ◽  
Oxide Semiconductor ◽  
Power Devices ◽  
Channel Mobility ◽  
Oxide Reliability ◽  
Dry Oxidation ◽  
Mos Structures

Threshold voltage (VTH) instability, channel mobility and oxide reliability have been investigated for meta-oxide-semiconductor (MOS) structures on 4H-SiC (11-20) face using various gate oxidation procedures. Channel mobility of n-channel MOSFET with a gate oxide by pyrogenic oxidation is higher than that by dilute-DRY oxidation followed by a nitrous oxide (N2O) post-oxidation annealing (POA). On the other hand, oxide reliability for the pyrogenic oxides is poor compared with the dilute-DRY/N2O oxides. A Hydrogen POA is effective in an improvement of channel mobility for both oxides, but causes a harmful effect on VTH stability. Temperature dependence of VTH instability indicates that MOS structure grown by dilute-DRY followed by N2O POA is suitable for a practical use of SiC MOS power devices.

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