PURPOSE: To reduce a semiconductor storage device in soft error and to enable word lines to be easily connected by a method wherein a connection hole is provided between the word lines in a self-aligned manner overlapping a positional relation between a non-selection part and a selection part and a selection part and a non-selection part.

CONSTITUTION: A poly Si word line is formed on a P-type Si substrate 1 isolated by a field insulating film 2 through the intermediary of a gate insulating film 3, and Wa and Wb denote a non-selection part and a selection part respectively. Wa1 and Wb2 are located in the same layer and Wa2 and Wb1 are provided to the same layer as they are arranged close to each other partially overlapping, a cutout is provided respectively to provide connection holes 10 and 15 of very small size between the word lines on small diffusion layers 7 and 8 in a self-aligned manner. Therefore, that electrons induced by α-rays are trapped by the diffusion layers 7 and 8 is small in probability, so that soft errors can be lessened. The overlap of the word line Wa1 with the word line Wa2 is insulated by providing an oxide film to the surface of a lower Si layer, a capacitor composed of a dielectric film 12 and an upper and a lower electrode, 13 and 11, is provided, and an Al bit line 16 is provided through the intermediary of an insulating film 14 to constitute a storage device.