Masami Naito

Development of a 150 mm 4H-SiC epitaxial reactor with high-speed wafer rotation

A new type of 150 mm vertical 4H-SiC epitaxial reactor with high-speed wafer rotation has been developed. Multiple resistance heaters ensure uniform radial temperature distribution throughout a 150-mm-diameter wafer. Enhancement of the growth rates is realized by high-speed wafer rotation under a relatively high system pressure, and growth rates of 40?50 ?m/h are achieved on 4? off 4H-SiC substrates, maintaining a low defect density and a smooth surface without macrostep bunching. Excellent thickness and doping uniformities are simultaneously obtained for a 150-mm-diameter wafer at a high growth rate of 50 ?m/h.

3D Raman Spectroscopy Investigation of Defects in 4H-SiC Epilayer

In this report we were able to successfully identify and localize in 3D 3C and 6H foreign polytypes and stress in the embedded epilayer by high resolution 3D Raman spectroscopy, that were otherwise invisible under the microscope or SEM, in non-contact and non-destructive way. Stripe patterned deep trenches with aspect ratio about 2 (depth=3.0μm; width=1.5μm) were formed on 4H-SiC substrate by ICP. The epitaxial layer was embedded in these trenches by SiC CVD. Poly type defects and stress in the embedded epilayer were mapped by curve-fitting of spectra obtained from Raman measurement of the embedded SiC epilayer. The location of the foreign polytypes and the stress inside the stripe pattern allows speculating on the origin of the defects and correlating it to the manufacturing process.

Simulation Study of High-Speed Wafer Rotation Effects in a Vertical Reactor for 4H-SiC Epitaxial Growth on 150 mm Substrates

The effects of high-speed wafer rotation for 4H-SiC epitaxy in newly developed 150 mm vertical reactor is investigated by simulation analysis. The simulation model shows a good agreement with experimental results. It is revealed that a combination of high-speed wafer rotation as high as 1000 rpm and relatively high system pressure of 267 mbar is effective to reducing boundary layer thickness above the 4H-SiC wafer, and greatly enhances the epitaxial growth rates. The growth rate increase ~2 times using the combination of high-speed wafer rotation and relatively high system pressure.

Study of Al Incorporation in Chemical Vapor Deposition of p-Doped SiC

Quasi-thermodynamic model of SiC doping with Al in CVD from C3H8, SiH4, and Al (CH3)3 on the Si-face is developed. The model is validated by quantitative agreement of calculated and experimental data on the Al concentration in SiC as a function of temperature, pressure, SiC growth rate, and TMAl flow rate. The model is shown to be consistent with the site competition mechanism of Al incorporation into SiC.