To fabricate a two-dimensional array structure which has potential application to a nano-devices array, we formed imbricate step/terrace structures on precisely-controlled vicinal Si substrates. From STM observation, it was found that on Si(1 0 0) surfaces offsetting towards (0 1 0) direction by 4 degrees, a rectangular-imbricate structure, where only a 2 x 1 structure is formed and dimers on neighboring terraces are at right angles to each other, was obtained after annealing of the Si wafers in ultra-high vacuum. Furthermore, formation of a larger-scale rectangular imbricate step/terrace structure, using anisotropic etching of Si substrate, was observed by AFM. This is expected to be a novel technique for fabricating ultra small capacitance arrays on Si wafers for nano-scale array circuits.