Nonvolatile semiconductor memory

Abstract

A semiconductor memory capable of increasing the coupling ratio between a diffusion layer and a floating gate by reducing the coupling ratio between the floating gate and a control gate thereby easily performing high-speed writing with a low diffusion layer voltage is provided. This semiconductor memory comprises the floating gate, a first diffusion layer capacitively coupled with the floating gate for controlling the potential of the floating gate and the control gate arranged oppositely to the floating gate. In an erase operation, the control gate feeds a tunnel current to the floating gate in a direction substantially parallel to the main surface of a semiconductor substrate. Thus, the tunnel current can be fed by extracting carriers from the floating gate also when the control gate has no region overlapping with the upper portion of the floating gate.