We studied the feasibility of micromachining of silicon wafer using 200 W fiber laser of 1090 nm in wavelength. Irradiated area was observed and analyzed using scanning electron microscope and surface profiler. It was found that micromachining of silicon could not be carried out efficiently. Careful analyses revealed possible causes for the poor machinability: first, very weak plasma formed during the fiber laser-material interaction, leading to low evaporation or melt ejection; second, formation of large amounts of SiO2 resulted in expansion of volume. It is further demonstrated that the surface oxidation can be made use of for the purpose of surface texturing.