SEMICONDUCTOR MEMORY DEVICE

摘要

PURPOSE:To effectively prevent a semiconductor memory device from malfunctioning by a method wherein an N-type semiconductor substrate is provided, a well onto which a potential lower than an outer input potential is applied is provided inside the semiconductor substrate, and a first diffusion layer to which an outer input potential is applied and a second diffusion layer to which a voltage of Vref is applied are formed in the well. CONSTITUTION:A semiconductor memory device is composed of the following: a P well 16 which is formed on an N-type semiconductor substrate 11 and to which the substrate potential (VBB) of the semiconductor substrate 11 is applied through the intermediary of a third terminal 17 and a P<+> diffusion layer 18; a first N<+> diffusion layer 12 which is formed inside the P well 16 and to which a voltage of VIN is applied through the intermediary of a second terminal 15; and a second N<+> diffusion layer 13 to which a voltage of Vref is applied. A potential applied to a P well is changed from a conventional VSS to a VBB, whereby minority carriers are prevented from moving to the P well 16 even if VIN is given a negative potential as far as VIN is larger than VBB, so that a semiconductor memory device is effectively prevented from malfunctioning due to the reduction of Vref caused by the inflow of minority carriers.