| 摘要 |
PROBLEM TO BE SOLVED: To further increase a working speed of a semiconductor device having a photodiode and a transistor loaded mixedly on the same semiconductor substrate and to make improvement in a response delay of a pulse in the photodiode. SOLUTION: The semiconductor device has the semiconductor substrate of a first conductivity type, an epitaxial layer of the first conductivity type formed on the semiconductor substrate, an epitaxial layer of a second conductivity type formed on the epitaxial layer of the first conductivity type, the transistor having a collector region of the second conductivity type formed in the epitaxial layer of the first conductivity type, and the photodiode constituted by forming a semiconductor region of the second conductivity type on the epitaxial layer of the first conductivity type. Herein the impurity concentration of the surface of the semiconductor substrate under the collector region is made to be of such a degree that the lower end of a depletion layer brought about by the junction of the collector region with the epitaxial layer of the first conductivity type reaches the semiconductor substrate, and thereby a trap level is formed in the semiconductor substrate under the photodiode. COPYRIGHT: (C)2009,JPO&INPIT
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