| 摘要 |
PROBLEM TO BE SOLVED: To suppress deterioration in pause time (charge holding time in a capacitor). SOLUTION: The inner wall of a trench 7 formed in a p-type silicon substrate 1 is covered by an insulating film 8 except for a part having a desired depth X from the surface of the silicon substrate 1, and the trench 7 is filled with a part of an accumulation electrode 9, so that the region in which the accumulation electrode 9 is in contact with the silicon substrate 1 is limited to an inner wall part having the depth X of the trench 7, on which the insulating film 8 is not formed and an n-type diffusion layer 10 formed by diffusion impurities from the accumulation electrode 9 is formed only in a region around the trench 7. By controlling the depth X of the part which is not covered by the insulating film 8, the size of the n-type diffusion layer 10 is reduced and the p-n junction area is reduced. A distance between the n-type diffusion layer 10 and a channel stopper layer 6 is increased, so that a p-n junction leak current can be reduced. A capacitor is formed by the accumulation electrode 9, and the silicon substrate 1 over the insulating film 8 and the charge holding capacity can be increased. Thus, deterioration in pause time can be suppressed. |
