SEMICONDUCTOR DEVICE HAVING INSULATED WORD LINE AND MANUFACTURING METHOD THEREOF

摘要

PURPOSE: A semiconductor device and manufacturing a method thereof are provided to prevent erroneous writing of information by insulating a word line from a semiconductor substrate. CONSTITUTION: A memory cell array(MA) includes a plurality of memory cells(MU) arranged in a matrix formation. Each of the memory cells has a float electrode on a semiconductor substrate(1). An element isolation region(3) includes the first trench(30) and a isolation material(31). The first trench is arranged to a depth direction from the surface of the semiconductor substrate between adjacent memory cells. The isolation material seals the inner portion of the first trench. The second trench is arranged to the depth direction from the surface of the element isolation region between the float electrode of memory cells adjacent to each other in gate width direction. The width of the second trench is wider in upper portion than in lower portion.