DEVELOPMENT OF NANOVOIDS AT HYDROPHILIC, HYDRO-PHOBIC AND UHV BONDED SILICON INTERFACES

摘要

Czochralski-grown silicon wafers were bonded hydrophilicly, hydro-phobicly or in ultra high vacuum (UHV) at room temperature. Wafers bonded hydrophilicly and hydrophobicly adhere to each other by low bonding forces whereas UHV bonded adhere by strong covalent bonds. Annealing the hydrophilicly and hydrophobicly bonded wafer pairs at different temperatures increases the initially low bonding energy. UHV bonded wafer pairs were also annealed to compare the results. TEM investigations at cross section and plan-view samples show nanovoids at the interface of hydrophobicly and hydrophilicly bonded wafer pairs. The nanovoid size and density depends on the initial bonding strength. The shape, coverage and density of the voids change significantly during annealing. No nanovoids are observed at UHV bonded wafer pairs, but there additional dislocation loops are observed after annealing.