Nonvolatile memory

Abstract

Abstract PURPOSE:To construct the titled device in such a manner that charge outflow from a floating gate electrode hardly occur even when voltage is impressed on the drain region, by a method wherein the neighborhood of the surface of a readout region surperposing on the floating gate electrode via insulation film is formed of a low-concentration impurity region of the second conductively type. CONSTITUTION:A source region 2 and a drain region 3 are both formed of an N type impurity region of high concentration, but an N type impurity region 35 of low concentration is formed in the drain region 3 at the part under the floating gate electrode 5. Except for this region 35, this device is the same as a nonvolatile memory of normal channel type. Since this nonvolatile memory is provided with the low-concentration impurity region 35 in the drain region 3 at the part under the floating gate electrode 5, the voltage between the drain region 3 and the floating gate electrode 5 in a state that this electrode 5 is electrified negatively, and that a positive voltage is impressed on the drain region 3 is absorbed to a depletion layer in the surface part of the region 35; accordingly, the voltage impressed directly on the insulation film 7 is alleviated.

Inventors

• 👤 Yutaka Hayashi
• 👤 豊 林
• 👤 Masaaki Kamiya
• 👤 昌明 神谷
• 👤 Yoshikazu Kojima
• 👤 芳和 小島

Bibliographic Details