A method for separating a semiconductor from a substrate is disclosed. The method comprises the following steps: forming a plurality of columns on a substrate; epitaxially growing a semiconductor on the plurality of columns; and injecting etching liquid into the void among the plurality of columns so as to separate the semiconductor from the substrate. The method of this invention can enhance the etching efficiency of separating the semiconductor from the substrate and reduce the fabrication cost because the etching area is increased due to the void among the plurality of columns. In addition, the method will not confine the material of the above-mentioned substrate.