Abstract: A process including the steps of: carrying out a directional etching in a semiconductor material body to form trenches having a first width; carrying out an isotropic etching of the semiconductor material body under the trenches to form cavities having a width larger than the trenches; covering the walls of the cavities with dielectric material; depositing non-conducting material different from thermal oxide to fill the cavities at least partially, so as to form a single-crystal island separated from the rest of the semiconductor material body. The isotropic etching permits the formation of at least two adjacent cavities separated by a support region of semiconductor material, which is oxidized together with the walls of the cavities to provide a support to the island prior to filling with non-conducting material.

Abstract: A method for eliminating the bird's beak from selective oxidations of semiconductor electronic devices having a semiconductor substrate (1) which is covered by a pad oxide layer (2) covered, in turn, by a first layer (3) of nitride, and wherein at least one vertical-walled pit (11) is defined for growing an isolation region, comprises the sequential steps of: selectively etching the oxide layer (2) within the pit (11) to define peripheral recesses (6,8) between the substrate (1) and the nitride; filling the recesses (6,8) with nitride; and growing oxide in the pit (11) so as to form the isolation region contrasting the nitride portions (9,10) which occlude the recesses (6,8).