A method of forming SOI-like finFETs, bulk finFETs and isolation structures, wherein the method comprises: patterning a bulk substrate to form a plurality of fin structures of a first dimension and a plurality of fin structures of a second dimension larger than the first dimension, wherein the first dimension is a width dimension in a range from 2 nm to 20 nm and the second dimension is a width dimension of at least 30 nm; forming oxide material in spaces formed between the plurality of fin structures of the first dimension and the plurality of fin structures of the second dimension; forming a capping material over sidewalls of selected ones of the plurality of fin structures of the first dimension and selected ones of the plurality of fin structures of the second dimension; recessing the oxide material to expose the bulk substrate on sidewalls below the capping material, wherein an exposed portion of the bulk substrate is formed; performing an oxidation process to form silicon on insulator, SOI, fin structures for the SOI-like finFETs from the selected ones of the plurality of fin structures of the first dimension, and bulk fin structures for the bulk finFETs from the selected ones of the plurality of fin structures of the second dimension; and forming a gate structure over the SOI fin structures and the bulk fin structures, wherein the oxidation process forms isolation structures from the plurality of fin structures of the first dimension located between the SOI fin structures and the bulk fin structures, wherein the isolation structures are oxide fins formed from the bulk substrate on any of the unselected ones of the plurality of fin structures of the first dimension where no capping material is present on the sidewalls thereof during the oxidation process, and wherein the first dimension is of a width that allows the oxidation process to completely oxidize the exposed portion of the bulk substrate on sidewalls below the capping material. patterning a bulk substrate to form a plurality of fin structures of a first dimension and a plurality of fin structures of a second dimension larger than the first dimension, wherein the first dimension is a width dimension in a range from 2 nm to 20 nm and the second dimension is a width dimension of at least 30 nm; forming oxide material in spaces formed between the plurality of fin structures of the first dimension and the plurality of fin structures of the second dimension; forming a capping material over sidewalls of selected ones of the plurality of fin structures of the first dimension and selected ones of the plurality of fin structures of the second dimension; recessing the oxide material to expose the bulk substrate on sidewalls below the capping material, wherein an exposed portion of the bulk substrate is formed; performing an oxidation process to form silicon on insulator, SOI, fin structures for the SOI-like finFETs from the selected ones of the plurality of fin structures of the first dimension, and bulk fin structures for the bulk finFETs from the selected ones of the plurality of fin structures of the second dimension; and forming a gate structure over the SOI fin structures and the bulk fin structures, wherein the oxidation process forms isolation structures from the plurality of fin structures of the first dimension located between the SOI fin structures and the bulk fin structures, wherein the isolation structures are oxide fins formed from the bulk substrate on any of the unselected ones of the plurality of fin structures of the first dimension where no capping material is present on the sidewalls thereof during the oxidation process, and wherein the first dimension is of a width that allows the oxidation process to completely oxidize the exposed portion of the bulk substrate on sidewalls below the capping material.