SEMICONDUCTOR DEVICE AND ITS MANUFACTURING METHOD

PROBLEM TO BE SOLVED: To provide a semiconductor device comprising a dynamic type memory cell superior in memory holding characteristics, and to provide a method for manufacturing it. SOLUTION: The semiconductor device has a first conductive semiconductor substrate 11; a trench capacitor 12 having a charge storage region; a gate electrode 15 provided through a gate insulating film 13 on the semiconductor substrate 11; a second conductive drain region 16 and a source region 17; an element separation region 18 so provided on the semiconductor substrate 11 as to adjoin the trench capacitor 12 and cover the top surface of the charge storage region; a second conductive buried strap region 19 so that the upper part of the charge storage region is electrically connected to the source region 17; and a first conductive well region 20 which exists under a part of the drain region 16 and the gate electrode 15, is provided in the semiconductor substrate 11 upper than the deepest bottom (a) of the element separation region 18, and has carrier concentration higher than that of the semiconductor substrate 11. COPYRIGHT: (C)2006,JPO&NCIPI