Noncontact determination of interface trap density for semiconductor-dielectric interface structures

Abstract

Embodiments of the subject method and apparatus relate to a sequence of noncontact Corona-Kelvin Metrology, C-KM, that allows the determination and monitoring of interface properties in dielectric/wide band gap semiconductor structures. The technique involves the incremental application of precise and measured quantities of corona charge, Q, onto the dielectric surface followed by determination of the contact potential difference, V, as the material structure response. The V-Q characteristics obtained are used to extract the surface barrier, V, response related to the applied corona charge. The metrology method presented determines an intersection of the V-Qcharacteristic obtained in the dark with the V-Qcharacteristic representing the dielectric response. The specific V-Qdependence surrounding the reference Vvalue is obtained from this method and allows the noncontact determination of the dielectric interface trap density and its spectrum. Application of embodiments of the subject metrology method to thermal oxide on n-type 4H—SiC demonstrates the modification of the Ddistribution by Fowler-Nordheim stress. In addition, an ability to quantify and separate trapped charge components is provided.