Relaxed SiGe Layers with High Ge Content by Compliant Substrates

摘要

Relaxed, high Ge content SiGe layers have been realized using stress balance on a compliant borophosphorosilicate glass (BPSG). A 30-nm fully-strained Si_(0.7)Ge_(0.3) layer was transferred onto a 1 μm BPSG film by wafer-bonding and Smart-cut~(~R) processes, after which the continuous Si_(0.7)Ge_(0.3) film was patterned into small islands to allow for lateral expansion. After the strain in Si_(0.7)Ge_(0.3) islands was released by the lateral expansion resulting from the flow of the BPSG, a Si_(0.4)Ge_(0.6) layer was commensurately deposited under compression. Upon equilibrium after an annealing, stress balance was formed between the SiGe films, resulting in a larger in-plane lattice constant than that of relaxed Si_(0.7)Ge_(0.3). With a thiner (6 nm) Si_(0.7)Ge_(0.3) starting film, an in-plane lattice constant equivalent to fully-relaxed Si_(0.45)Ge_(0.55) has been obtained.