SEMICONDUCTOR DEVICE HAVING LIGHT RECEIVING ELEMENT

PROBLEM TO BE SOLVED: To mixedly mount a high-speed, high-sensitivity, and low-noise light receiving element on the same semiconductor substrate with a high-speed bipolar element. SOLUTION: The light receiving element is constituted having a 1st semiconductor layer 21 of a 1st conductivity type formed of a high-density semiconductor layer that a semiconductor substrate 1 having low impurity density is filmed with, a 2nd semiconductor layer 22 of the 1st conductivity type which is formed on the 1st semiconductor layer 21 and has lower impurity density than the 1st semiconductor layer, a 3rd semiconductor layer 23 of a 2nd conductivity type which is formed on the 2nd semiconductor layer 21 and has higher impurity density than the 2nd semiconductor layer, and a 4th semiconductor region 25 which is formed on the 3rd semiconductor layer and has higher impurity density than the 3rd semiconductor region 24. COPYRIGHT: (C)2005,JPO&NCIPI