| 摘要 |
PURPOSE:To cause th entire face of a trench capacitor to function as a capacitance without reducing writing voltage, by forming the trench of the trench capacitor for storing information charges in a closed loop shape and by forming an impurity-implanted region with a conductive type opposite to the semiconductor substrate, on the face of the substrate contacting to the bottom face of the trench capacitor. CONSTITUTION:A trench of a trench capacitor for storing information charges is formed in a closed loop shape. On the face of p type substrate 21 contacting to the bottom 29c of the trench, an n type region 33 having n type made slightly is formed selectively by implanting arsenic ions vertically to the substrate surface from the above of the trench, in order to prevent maximum writable voltage of the trench bottom 29c from decreasing. Thus threshold voltage of the trench bottom 29c in the trench capacitor 30 is considerably reduced, so that maximum writable voltage of the trench bottom 29c rises more than another regions and therefore an inverting layer formed along the trench can not be disconnected between the outer peripheral wall face 29a and the inner peripheral wall face 29b. |
