Reliability of ultra-thin buried oxides for multi-VT FDSOI technology

• Adapt reliability methods to evaluate the degradation of UTBOX.
• Study the carrier trapping and defects generation for breakdown in SOI technology.
• Evaluate the quality and lifetime of buried oxides for back-bias applications.

This paper investigates the intrinsic reliability of ultra-thin buried oxides (UTBOX) integrated in the last generation of FDSOI wafers obtained by the Smart Cut™ technology. In term of breakdown reliability, these state-of-the-art UTBOX oxides exhibit comparable performances with thermally-grown SiO2 references. In “the worst case condition”, the voltage for a 10 years lifetime of 25 nm thick BOX, is estimated to 14 V, which largely exceeds the maximum operating conditions for back-bias [+3 V, –3 V] in advanced FDSOI integrated circuits. This makes UTBOX family of engineered substrates fully compatible and suitable for multi-VT applications.