Abstract: Memory cells are disposed in plural array form. Select gate electrodes of the memory cells arranged in an X direction are connected to one another by select gate lines respectively. Memory gate electrodes are connected by memory gate lines respectively. The memory gate lines respectively connected to the memory gate electrodes of the memory cells adjacent to one another through source regions interposed therebetween are not electrically connected to one another. Each of the select gate lines has a first portion that extends in the X direction, and a second portion 9b of which one end is connected to the first portion and extends in a Y direction. The memory gate line is formed on its corresponding sidewall of the select gate line with an insulating film interposed therebetween.

Abstract: For enhancing the high performance of a non-volatile semiconductor memory device having an MONOS type transistor, a non-volatile semiconductor memory device is provided with MONOS type transistors having improved performance in which the memory cell of an MONOS non-volatile memory comprises a control transistor and a memory transistor. A control gate of the control transistor comprises an n-type polycrystal silicon film and is formed over a gate insulative film comprising a silicon oxide film. A memory gate of the memory transistor comprises an n-type polycrystal silicon film and is on one of the side walls of the control gate. The memory gate comprises a doped polycrystal silicon film with a sheet resistance lower than that of the control gate comprising a polycrystal silicon film formed by ion implantation of impurities to the undoped silicon film.