Effect of UV light irradiation on SiC dry etch rates

• Inductively Coupled Plasma etching of 4H-SiC under ultraviolet illumination was examined for SF6/Ar and Cl-2/Ar chemistries. Etch rate enhancements up to a factor of 8 were observed with UV light irradiation during Cl-2/Ar etching. The enhancement mechanism is related to photodesorption of SiClx and CClx species. Surface morphologies were unchanged as a result of the UV enhancement with Cl-2/Ar discharges. By contrast, there was no effect of UV irradiation on the SiC etch rates in SF6/Ar plasmas, but the surfaces were typically smoother than those obtained without the ultraviolet illumination. In the SF6/Ar chemistry the rate-limiting steps are either Si-C bond-breaking or supply of fluorine radicals to the surface, and not desorption of the SiFx and CFx etch products.

Nyckelord

plasma etching

inductively coupled plasma

4H-SiC

ultraviolet illumination

via holes

inductively-coupled plasma

power devices

nf3

chemistries

semiconductor

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