| 摘要 |
PURPOSE:To enable to detect the memory cell of defective operation of temperature dependancy at room temperature, by normal and virtual write-in to the memory cell of selective state. CONSTITUTION:At the memory device test, the level of Wc1, Wc0 is enabled for selection of two types of levels such as normal level and holding voltage defective test level, and the memory content ''1'' is written in the all cells at normal level. Next, after selecting Wc1, Wc0 are selected to the hold voltage test level, the content written in the normal level and the inverse content are written in the virtual write-in mode and the cell memory content is read out as to all the cells with normal readout level of Wc1, Wc0. Then, in the memory device having normal hold voltage, the memory content written in the normal level is not inverted for the memory device of normal hold voltage, and the memory content of defective cells is inverted to the memory unit including defective cells for hold voltage. Thus, the memory device including defective cells can be detected and removed. |
