SEMICONDUCTOR MEMORY DEVICE AND METHOD FOR MANUFACTURING THE SAME

摘要

A semiconductor memory device is provided to improve yield by forming a shallow trench groove in a memory cell region, and to increase isolation voltage tolerance by forming a deep trench groove in a high voltage transistor region of a peripheral circuit part. A plurality of memory cell transistors are formed in the first region by using the first gate insulation layer composed of a stack structure including at least a charge accumulation insulation layer. A plurality of transistors are formed in the second region by using the second gate insulation layer different from the charge accumulation insulation layer. An isolation trench formed in the first region has a shallower depth from the surface of the semiconductor substrate than an isolation trench formed in the second region.