Nitrogen-plasma surface treatment in a direct bonding method

摘要

Two plates, each comprising a thin layer of silicon or silicon oxide at a surface thereof, are bonded by subjecting the thin layer of at least one of the plates to a surface treatment step forming a silicon oxynitride superficial thin film with a thickness of less than 5nm. The thin film is performed with a nitrogen-based plasma generated by an inductively coupled plasma source. Furthermore, a potential difference applied between the plasma and a substrate holder supporting said plate during the surface treatment step is less than 50 V, advantageously less than 15 V and preferably zero. This enables a defect-free bonding interface to be obtained irrespective of a temperature of any heat treatment carried out after a contacting step between the respective thin layers of the two plates.