Flash memory device and method of fabricating the same

A method of fabricating a semiconductor device, the method comprising:

• forming a trench mask pattern that includes a gate insulation pattern and a charge storage pattern on a semiconductor substrate;
• etching the semiconductor substrate, using the trench mask pattern as an etch mask, thereby forming trenches defining active regions;
• forming a lower device isolation pattern in the trench, the lower device isolation pattern having a discontinuous interface that is extended downwardly from a surface of the lower device isolation pattern toward a surface of the semiconductor substrate;
• forming an upper device isolation pattern that is free of discontinuous interfaces and that covers the discontinuous interface of the lower device isolation pattern;
• sequentially forming an intergate insulation film and a control gate film on the upper device isolation pattern;
• and
• patterning the control gate film, the intergate insulation film and the charge storage pattern to form gate lines crossing over the active regions.