SEMICONDUCTOR NONVOLATILE MEMORY

摘要

PURPOSE:To enable the plate-form injection of electrons into a floating gate electrode by forming an injection region in a level differential region on the surface of a semiconductor in the punch-through injection type semiconductor nonvolatile memory. CONSTITUTION:The P type semiconductor substrate 11 comprising a level difference is provided with the source region 12 as a carrier supply region and the drain region 13 as a carrier absorption region through the level difference. A floating gate electrode is formed over both of the level differential region and the drain region 13 through an oxide film 16. Writing of information, that is injection of electrons into the floating gate electrode 14 is performed by causing a punch-through between the source and drain regions. The voltage which causes a punch-through injection is required to be applied to the drain region 13. By applying an inverse bias to the drain region 13, a depletion layer 13a is formed in an injection region adjacent to the floating gate electrode 14. When the depletion layer 12a of the source region 12 and the depletion layer 13a of the injection region overlap on each other, a space charge region is formed in a space charge forming region between the source region 12 and the injection region to cause a punch-through.