Charge trapping in SOI materials and devices

Commercially prepared Separation-by-IMplantation-of-OXygen (SIMOX) wafers having buried-oxide (BOX) thickness ranging from 0 to 400 nm were exposed to various doses of 10 keV x-rays. The net positive charge trapped in the buried-oxides during radiation was determined by dual capacitance-voltage (C-V) and point-contact current voltage (I-V) measurements. An inflection point has been observed in the plot of voltage shift versus buried oxide thickness. As a result, the radiation-induced voltage shifts for thin buried-oxides are greater than what could be expected from a simple square-law relationship. These results can be explained by the location and magnitude of the radiation induced oxide charge centroid and its relationship to the BOX thickness. The location of the centroid is dependent on the radiation-induced hole motion and electron trapped-hole recombination due to space charge effects.; In addition, Photo-injection was used to study the charge trapping properties of high temperature oxidation (HITOX) SIMOX buried oxides (BOX), provided by two independent vendors. After electron injection the electron trapping per area for both HITOX material sources was found to be larger than their respective standard (control) SIMOX structures. This increase has been attributed to the HITOX's process influence on the formation of the HITOX/BOX oxide.