| 摘要 |
PROBLEM TO BE SOLVED: To increase the amount of charges handled by a transfer register, without deteriorating transfer efficiency of signal charges. SOLUTION: In a vertical transfer register 130, a region which serves as an accumulation portion 132 is additionally doped with an N-type impurity. By utilizing the potential well generated by this doping, the potential of the accumulation portion 132 is made deeper to generate a potential difference between the accumulation portion 132 and a transfer portion 134. Since the N-type impurity has less heat diffusion than that of a P-type impurity, diffusion of the impurity added to generate the potential difference under an electrode having a difference phase can be prevented. As a result, not potential barrier is formed, and the accumulation portion can be doped with the N-type impurity at a high concentration. Since the potential difference between the accumulation portion 132 and the transfer portion 134 can be increased, amount of charges handled can be increased without deteriorating the transfer efficiency.
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