Formation and elimination mechanism of thermal blistering in Al2O3/Si system

The local delamination of dielectric oxides, manifesting as blistering, is always a puzzle preventing films from practical applications. In this work, an elaborate study on thermal blistering in Al2O3/Si system is reported. Blisters are proved to originate from the excess H impurities remaining in the deposition process. A thermal-dynamic H-diffusion model is proposed to explain the competitions between lateral gas effusion and longitudinal impurity trapping. Blister distribution is discovered to be related with interfacial imperfections. Oxygenous Si surfaces can ease the reliable risks of thermal blistering by decreasing Si–H bond amount and accelerating H-diffusion. Two derived CMOS-compatible methods, wet chemical oxidation and interlayer deposition, are demonstrated to eliminate blisters via interface modification. A thin film scheme is also effective to avoid blistering. Modified Al2O3/Si systems show an improved thermal stability, and are appropriate for high-performance MOSFETs with a high-permittivity (high- $$\kappa$$ ) dielectric. Notably, our work presents a detailed physical insight into thermal blistering in Al2O3/Si system, which may promote the practical applications of oxide dielectrics in many domains.