| 摘要 |
PURPOSE:To make a depletion layer extending under a capacitance element thin, and improve maintaining characteristics of data, by providing a high concentration semiconductor region of the same conductivity as a substrate, under a semiconductor region being an electrode of one side of a capacitance element. CONSTITUTION:Under the N<+> type semiconductor region 9 of a capacitor element, a P-type semiconductor region 10 is formed by using a process to form a P-type base 6. As a result, the P-type semiconductor region 10 has the same impurity concentration and concentration distribution as the P-type base 6. Since the P-type semiconductor region 10 exsists, a depletion layer extending in a substrate 1 from an N<+> type semiconductor region 9 becomes thin, and minority carrier generating in the depletion layer decreases. When minority carrier generating under the P-type semiconductor region 10 permeates into the N<+> type semiconductor 9, the region 10 acts as a barrier. Therefore the potential fluctuation of the capacitor element caused by alpha-ray is prevented, and the destruction of data written in a memory cell can be avoided. |
