Substrate structure, photomask and preparation method of photomask

The invention relates to a substrate structure, a photomask and a preparation method of the photomask, and the substrate structure comprises a transparent substrate which is provided with a closed hollow cavity; the hollow cavity is filled with the transparent liquid; and the transparent liquid is used for transmitting light projected on the transparent substrate. The closed hollow cavity is formed in the transparent substrate, and the transparent liquid is arranged in the hollow cavity. Therefore, during photoetching, the light of the photoetching machine can penetrate through the transparent liquid in the transparent substrate, and compared with the traditional technology, the medium in the propagation path of the light of the photoetching machine is changed, so that the factor parameters in the photoetching process are improved, the photoetching resolution is further improved, and the purposes of improving the photoetching precision and resolution are achieved. 本申请涉及一种基板结构、光掩膜版及其制备方法，基板结构包括：透明基板，所述透明基板具有封闭