Martin Pölzl

Ultra-thick gate oxides: charge generation and its impact on reliability

Abstract In this work, degradation and breakdown characteristics of ultra-thick gate oxides ( T ox : 50–150 nm) used in power MOS devices is investigated. Measurements indicate, that in addition to charge generation via Fowler–Nordheim tunneling, a second mechanism becomes dominant in ultra-thick gate oxides even at moderate electrical fields (i.e. 7–8 MV/cm). The results suggest, that impact ionization and related electron–hole pair creation by energetic electrons is responsible for the experimental observations. The impact of these results on the interpretation of lifetime extrapolations from accelerated tests will be discussed.

95% DC-DC conversion efficiency by novel trench power MOSFET with dual channel structure to cut body diode losses

A novel 25V silicon trench power MOSFET optimized for fast and high efficient switching with record Ron*Qg and Ron*Qoss figure-of-merits is reported. A dual channel structure with two different gate oxide thicknesses allows reducing the body diode conduction losses by up to 50% and enables 95% DC-DC conversion efficiency.

Reliability issues of ultra-thick gate oxides

In this work, degradation and breakdown characteristics of ultra-thick gate oxides (Tox: 50 nm-120 nm) used in power MOS devices is investigated. Measurements indicate, that the established thin-oxide models for lifetime extrapolations from accelerated tests may not be appropriate for ultra-thick oxides and lead to erroneous results.