Method for forming photomask and photolithography method

A method for forming a photomask, comprising:

• forming a light-absorbing layer over a reflective substrate;
• forming a mask layer over the light-absorbing layer, wherein the mask layer covers a first portion of the light-absorbing layer, and the first portion is over a second portion of the reflective substrate;
• removing the light-absorbing layer, which is not covered by the mask layer;
• removing the mask layer, wherein the first portion of the light-absorbing layer is removed during removing the mask layer;
• removing the second portion of the reflective substrate to form a recess in the reflective substrate;
• and
• forming a light-absorbing structure in the recess.

A photolithography method, comprising:

• providing a photomask over a photoresist layer, wherein the photomask comprises:
• a transparent substrate having a surface;
• a first light blocking structure over the surface;
• and
• a second light blocking structure in the transparent substrate;
• and
• irradiating the photomask by a light, wherein the light passes through the transparent substrate and irradiates a first portion of the photoresist layer.