| 摘要 |
A solid state image sensing device, comprises: an n-type semiconductor substrate (11), a p-type well (12) formed on a surface of the semiconductor substrate, and a p+-type diffusion layer (13, 21) having an impurity concentration higher than that of the well. In particular, the P+-type diffusion layer (13) is formed so as to cover at least a part of circumference of an n-type diffusion layer (17) of a load transistor (N3) formed in the well (12) as a source follower circuit. Instead, the P+-type diffusion layer (21) is formed between the n-type diffusion layer (17) of the load transistor (N3) and the semiconductor substrate (11). In both the cases, since the n-type diffusion layer (17) of the load transistor (N3) of the source follower circuit is covered with the second conductivity diffusion layer (13, 21) higher in impurity concentration than that of the well, even when a pulse is applied to the semiconductor substrate during electronic shutter operation, the p-type well (12) is not depleted, so that it is possible to prevent punch through current (I) from flowing from the n-type diffusion layer (17) of the load transistor (N3) to the n-type substrate (11).
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