Compatibility of POCl3 Gate Process with the Fabrication of Vertical 4H-SiC MOSFETs

Tomokatsu Watanabe; Munetaka Noguchi; Shingo Tomohisa; Naruhisa Miura

doi:10.4028/www.scientific.net/MSF.1004.565

Paper Titles

Surface Treatment of 4H-SiC MOSFETs Prior to Al₂O₃ Deposition
p.541

Development of High-Quality Gate Oxide on 4H-SiC Using Atomic Layer Deposition
p.547

Effect of Phosphorus Doped Poly Annealing on Threshold Voltage Stability and Thermal Oxide Reliability in 4H-SiC MOSFET
p.554

4H-SiC Power VDMOSFET Manufacturing Utilizing POCl₃ Post Oxidation Annealing
p.559

Compatibility of POCl₃ Gate Process with the Fabrication of Vertical 4H-SiC MOSFETs
p.565

Wafer-Level near Zero Field Spin Dependent Charge Pumping: Effects of Nitrogen on 4H-SiC MOSFETs
p.573

Low-Energy Muons as a Tool for a Depth-Resolved Analysis of the SiO₂/4H-SiC Interface
p.581

Profiling with Depth Resolution of Sub-nm for SiO₂/ SiC Interface by Dual-Beam TOF-SIMS Combined with Simulation
p.587

Monitoring on Creation and Annihilation of Interface Trap Levels with NO Oxidation, Re-Oxidation and N₂ Annealing with Conductance Measurements
p.595

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Compatibility of POCl₃ Gate Process with the Fabrication of Vertical 4H-SiC MOSFETs

Abstract:

We used the POCl₃ gate technique for the fabrication of 4H-SiC vertical MOSFETs, and examined its effect on the V_TH-R_ON tradeoff and the compatibility with device fabrication. The gate oxide film was formed by thermal dry O₂ oxidation followed by POCl₃ or NO annealing. The POCl₃ process reduced R_ON by about 30% compared with the NO process for the ones having V_TH of 1.1 V, being attributed to the channel mobility enhancement. Moreover, the improvement was more effective for higher V_TH designs. The conventional thermal treatment after the gate process considerably spoiled the channel mobility improvement brought by the POCl₃ annealing and strengthened negative charge trapping in the gate oxide. The presumed extra-formed defects also affected the E_OX dependence of t_BD on the TDDB tests, being expected to shorten the gate oxide lifetime under practical device operation stress. Successful insertion of the POCl₃ process into production lines depends upon careful low-temperature post processing.