A method for manufacturing an integrated electronic device (100;400;500) of the SOI type, the method comprising the steps of: providing an SOI substrate (105;505) comprising a semiconductor substrate (110;510), an insulating layer (115;515) on the semiconductor substrate, and a semiconductor starting layer (112;512) on the insulating layer, performing an epitaxial growing process, the epitaxial growing process being applied to the starting layer to obtain a thicker semiconductor active layer (142;542) embedding the starting layer on the insulating layer, forming at least one insulating trench (158;405;558) extending from an exposed surface of the active layer to the insulating layer, the at least one insulating trench partitioning the active layer into insulated regions (160;415;560) and a further insulated region (161;450;561), and integrating components (420;580) of the device in the insulated regions, the components being insulated from the semiconductor substrate by the insulating layer, characterized in that the method further comprises, before the step of performing the epitaxial growing process: forming at least one contact trench (120;520) extending from an exposed surface of the starting layer to the semiconductor substrate in correspondence of the further insulated region, wherein each contact trench clears a corresponding portion (130b,130s;530b,530s) of the starting layer, of the insulating layer and of the semiconductor substrate, and implanting impurities into at least part of the cleared portions (130b,130s;530b,530s), wherein the epitaxial growing process is further applied to the cleared portions thereby at least partially filling the at least one contact trench with semiconductor material, the impurities diffusing during the epitaxial growing process to form an interface region (145;545) enclosing the at least one contact trench. providing an SOI substrate (105;505) comprising a semiconductor substrate (110;510), an insulating layer (115;515) on the semiconductor substrate, and a semiconductor starting layer (112;512) on the insulating layer, performing an epitaxial growing process, the epitaxial growing process being applied to the starting layer to obtain a thicker semiconductor active layer (142;542) embedding the starting layer on the insulating layer, forming at least one insulating trench (158;405;558) extending from an exposed surface of the active layer to the insulating layer, the at least one insulating trench partitioning the active layer into insulated regions (160;415;560) and a further insulated region (161;450;561), and integrating components (420;580) of the device in the insulated regions, the components being insulated from the semiconductor substrate by the insulating layer, the method further comprises, before the step of performing the epitaxial growing process: forming at least one contact trench (120;520) extending from an exposed surface of the starting layer to the semiconductor substrate in correspondence of the further insulated region, wherein each contact trench clears a corresponding portion (130b,130s;530b,530s) of the starting layer, of the insulating layer and of the semiconductor substrate, and implanting impurities into at least part of the cleared portions (130b,130s;530b,530s), wherein the epitaxial growing process is further applied to the cleared portions thereby at least partially filling the at least one contact trench with semiconductor material, the impurities diffusing during the epitaxial growing process to form an interface region (145;545) enclosing the at least one contact trench. forming at least one contact trench (120;520) extending from an exposed surface of the starting layer to the semiconductor substrate in correspondence of the further insulated region, wherein each contact trench clears a corresponding portion (130b,130s;530b,530s) of the starting layer, of the insulating layer and of the semiconductor substrate, and implanting impurities into at least part of the cleared portions (130b,130s;530b,530s), wherein the epitaxial growing process is further applied to the cleared portions thereby at least partially filling the at least one contact trench with semiconductor material, the impurities diffusing during the epitaxial growing process to form an interface region (145;545) enclosing the at least one contact trench.