| 摘要 |
PURPOSE:To enhance the sensitivity of a sensor without sacrifice of the withstand voltage of a bipolar element. CONSTITUTION:A mask of BSG film is formed on a P-type silicon substrate and an N-type buried layer 105. A P-type buried layer 104 is also formed at that time by heat treatment. When an N-type epitaxial layer 102 and a P-type isolation layer 106 are formed subsequently, boron is diffused upward from the P-type buried layer 104 into the N-type epitaxial layer 102 by heat treatment and thereby the N-type epitaxial layer 102 in the sensor region becomes thinner than that in the bipolar region. Consequently, the sensitivity of a semiconductor acceleration sensor is enhanced without sacrifice of the withstand voltage between the collector 113 and the base 112. |
