| 摘要 |
PURPOSE:To avoid the reduction of logical level or inversion of informations stored in a memory device, by constructing the memory device with an information charge storage region, bit wire and sense amplifier and making these regions entrap the carriers formed by an irradiation of gamma ray. CONSTITUTION:An n<+>-type layer is formed by an epitaxial growth method on a p- type Si substrate 10, and a p-type layer 12 is formed thereon. A thick SiO2 field film 13 is formed along the periphery of the layer 12 while the central area of the layer 12 surrounded by the field film 13 is covered with a thin gate SiO2 film 14. Then, a fixed voltage line 15 consisting of a low resistance poly-crystal Si is deposited between the surface of the film 13 and an intermediate portion of the layer 14. Only the surface of this line is changed into an SiO2 film 16. A poly-crystal Si layer 17 constituting a gate electrode or a word line is formed to extend over the SiO2 film 16 and the layer 14. A window is formed in the film 14 contacting the other film 13, for forming in the region 12 an n<+>-type region 18 which serves as a source region or a bit line. In this arrangement, a depletion region 19 and a depletion layer DP are formed in the layer 12, so that the carriers produced as a result or irradiation by gamma rat is entrapped by the layer 11. |
