To enable the formation of a surface structure with an atomically smooth surface and atomically uniform heights and pitches by introducing an defect onto the crystalline surface of a substrate and forming a spiral structure on the crystalline surface by etching the crystal.

A gold coating is formed on a mica substrate or a glass substrate by vacuum evaporation. Next, the probe tip of a scanning tunnel microscope(STM) is brought into contact with the above-formed close-packed crystalline plane of gold and is vertically forced in to introduce a defect into the crystal. Then, the gold crystal on which a flaw is priorly made by the STM is immersed in a treatment solution formed by dissolving iodine or bromine in alcohols or water to form a spiral pattern 1 formed of a monoatomic step with the defect as an origin on the surface of the crystal. By this, it is possible to improve the smoothness of the crystal substantially and to obtain an optimal substrate for STM observation.