| 摘要 |
PURPOSE:To independently form a high voltage transistor (Tr) element and a low voltage Tr element one substrate by forming a thick film epitaxial layer in a semiconductor substrate and further forming a thin film epitaxial layer on the whole substrate. CONSTITUTION:An opening is formed at a position to be formed with a high voltage Tr on an Si substrate 1, and an N-type buried region 5 and an N-type epitaxial layer 6 are grown. Then, an N-type buried region 7 and a P-type buried region 8 are respectively formed at positions to be formed with low voltage Trs, and a thin N-type epitaxial layer 9 is formed on the whole substrate. Then, a P-type element insulation isolating region 10, P-type base regions 11, 12, and N<+> type emitter regions 15, 16 are respectively formed. Thus, independently formed high and low voltage type N-P-N type bipolar Trs are obtained in coexistent shape on one substrate 1.
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