Defects at the Si/SiO2 interface: Their nature and behaviour in technological processes and stress

The electronic properties of silicon surfaces and interfaces are characterized by charges and gap states whose densities and distributions can be strongly influenced by preparation conditions and technological treatments. A defect model for the Si/SiO2 interface considers stretched silicon—silicon bonds and silicon dangling-bond centres with different back bond configurations connecting each kind of these defects with a specific energetically distributed group of interface states. The defect model was proved to be appropriate also for real silicon surfaces investigating their state distributions depending on cleaning procedures and during native oxide growth. The state density of real and oxide-passivated silicon surfaces can be drastically reduced by saturation of silicon dangling bonds with hydrogen. Interfacial Si-H bonds and weak Si-Si bonds give rise to instability phenomena in connection with stress treatments including radiation effects.