oxide film using the photoresist pattern as an etch mask thus exposing the silicon substrate of the isolation region implementing an electrochemical etch process to form porous silicon in the silicon substrate of the exposed isolation region removing the photoresist pattern and implementing a thermal oxidization process to oxidize porous silicon thereby forming an oxide film in the isolation region application_number US 62880303 A description reference will now be made in detail to the preferred embodiments of the present invention examples of which are illustrated in the accompanying drawings in which like reference numerals are used to identify the same or similar parts the present invention relates to a method of forming porosities through an electrochemical etch process to form an isolation film the isolation film may be formed by forming porous silicon at a portion to be insulated using the electrochemical etch process and oxidizing porous silicon using a thermal oxidation process 0020 fig1 illustrates a work cell for performing an electrochemical etch process according to a preferred embodiment of the present invention fig2 u02dc fig5 illustrate semiconductor devices for explaining a method of forming porous silicon through electrochemical etch and then thermally oxidizing porous silicon to form an isolation film according to a preferred embodiment of the present invention fig6 is a sem scanning electron microscope photograph showing porosities formed in the silicon substrate through electrochemical etch which shows u2018 a u2019 portion in fig4 referring to fig1 a work cell 120 for performing the electrochemical etch process in order to form porosities is designed to apply a voltage v to the back of a wafer w to be used as a work electrode a counterpart electrode 130 and a reference electrode 140 are designed so that they are immersed into.