| 摘要 |
PURPOSE:To shorten data reading and writing times and to obtain large-capacity, high-speed bipolar memories, by enlarging the thickness of an epitaxial layer, in which a memory-cell peripheral circuit is formed, and securing the effective thickness of the (p) epitaxial layer to some extent even after impurities from an n<+> embedded layer rise up. CONSTITUTION:An impurity introduced mask is formed on one main surface of a p<-> type semiconductor substrate 3. Ions of boron and arsenic As are selectively implanted in the p<-> type semiconductor substrate 3. Then an epitaxial layer 6 is formed on the main surface of the semiconductor substrate 3. The impurities introduced in the semiconductor substrate 3 are diffused by heat applied at this time, and a p<+> layer 5 and an n<+> embedded layer 4 are formed. A surface oxide film 14 and a part of the epitaxial layer 6 are selectively etched. Then a groove is formed in an isolation forming region. This part is selectively oxidized, and a thick oxide film 7 is formed. The isolation region is formed by the oxide film 7 and the p<+> diffused layer 5. Thereafter, impurity diffused layers 8-13 are selectively formed on the main surface of the epitaxial layer 6 by using ordinary technology. |
