| 摘要 |
PURPOSE:To selectively etch so that a silica film and an SiO2 layer formed on the film remain only on a region on which a buried diffused layer is formed thereby to improve the yield and the safety of a bipolar semiconductor integrated circuit by coating a substrate with the film which contains an N-type impurity and then forming the SiO2 layer. CONSTITUTION:A substrate 11 is coated with a silica film layer 12 which contains an N-type impurity, such as As or Sb, and an SiO2 layer 13 is formed thereon. Then, after the layers 12 and 13 are selectively removed except an element forming region, an N<+>-type buried diffused layer 14 is formed by a buried diffusion. After an N<-> type epitaxial layer 16 is then formed, a P<+>-type separately diffused layer 17 is selectively diffused with a thermal oxide film 15 as a mask to complete the separation of the element region. Similar selective diffusion is repeated to form electrode leading diffused layers 20 of a P<+>-type base layer 18, an N<+>-type emitter layer 19 and an N<+>-type collector layer.
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