ETCHING METHOD FOR WORK HAVING SI SURFACE

PURPOSE:To form a pattern conforming exactly to the pattern of a mask layer by immersing a work into a fluorine ion-contg. soln., then processing the same at the time of processing the work formed with the mask layers consisting of an org. high-polymer material. CONSTITUTION:The mask layer C' is formed from the mask material layer 6C of a semiconductor substrate body 10 formed thereon with the mask material layers 6A, 6B, 6C by a lithographic method, and the mask layer 6B' is formed from the mask material layer 6B by an etching treatment. The mask layer 6C' is removed and deposit 7 of silicon oxide is formed on the side faces of the mask layers 6B', 6A' when the mask layer 6A' is formed from the mask material layer 6A by a dry etching treatment. Such substrate body 10 is immersed together with the mask layers 6B', 6A' in the fluorine ion-contg. soln. to remove the deposit 7 and the mask layer 6B'. Further, a patterned semiconductor layer 5' is formed from a semiconductor layer 5 and the mask layer 6A' is removed by the etching treatment. The patterned semiconductor layer 5' conforming exactly to the mask layer 6C' is thereby formed on the semiconductor substrate 1.