A new Volcano pattern which has five different zones: hole, regular periodic ridges, fractals, microcolums, and fringes grows on silicon (100) surface by 308 nm excimer laser irradiation. The volcano pattern is disappeared under 1.5 J/cm2, and the period of the regular ridges relates to laser pulse number, which is can be calculated by laser-heat equations and Rayleigh-Taylor instability.
