Highly-Strained Silicon-On-Insulator Development

Abstract

Bi-axially highly-strained Silicon-On-Insulator (sSOI) substrates with a tensile stress up to 2.5 GPa have been obtained by Smart CutTM technology. Thin strained silicon (sSi) layers epitaxially grown on relaxed Si0.6Ge0.4 virtual substrates (VS) were used as starting materials. The threading dislocation density in those sSi layers was in the low 105 cm-2. Some stacking faults were also present in those highly strained Si films. The evolution of this linear defect density was characterized as a function of the sSi thickness by Secco etch. 2.5 GPa sSOI wafers have been demonstrated in 200 mm diameter. Stress uniformity σ equal to 1.14% and 2 nm thickness range has been obtained for 8 nm thick sSi layers.