Semiconductor surface gratings can find applications in various areas, including optical communications, display, storage, and sensing. The diffraction effects of a surface grating can be used for the operations of various devices. Although semiconductor surface gratings can be fabricated with etching techniques, such a process requires the preparation of a mask and is usually quite complicated. Recently, because of the development of high-power laser, direct writing of surface grating with laser has become an important alternative [1 ,2]. Basically, writing grating with laser is a process of exposing the sample to laser interference fringes. The photons at the bright lines of the fringes interact with the sample material to form periodical corrugations. Because we can control the period of the interference fringe through the interferometer setup and the depth of corrugation through the laser power level, fabrication of surface grating with laser is more flexible than other techniques. In this paper, we investigate the interaction mechanisms between laser photons and semiconductor in fabricating silicon surface gratings with 266 nm laser.