A method for the formation of buried cavities within a semiconductor body envisages the steps of: providing a wafer having a bulk region made of semiconductor material; digging, in the bulk region, trenches delimiting between them walls of semiconductor material; forming a closing layer for closing the trenches in the presence of a deoxidizing atmosphere so as to englobe the deoxidizing atmosphere within the trenches; and carrying out a thermal treatment such as to cause migration of the semiconductor material of the walls and to form a buried cavity. Furthermore, before the thermal treatment is carried out, a barrier layer that is substantially impermeable to hydrogen is formed on the closing layer on top of the trenches.