Alignment mark and alignment method using the same for photolithography to eliminating process bias error

[0025] Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings.

[0026] For solving the problems encountered by the prior arts, i.e. the alignment bias error produced by the asymmetrical profile of a thin film formed on alignment marks, the present invention provides an alignment mark and a photolithography alignment method using the same for eliminating process bias error.

[0027] A partial enlarged top view of an alignment mark according to a preferred embodiment of the present invention is shown in FIG. 3. In FIG. 3, a trench 310 is formed on a substrate 300 to be an alignment mark. A film is subsequently formed on the substrate 300, and a trench 320 is simultaneously formed in the trench 310. An asymmetrical profile of the thin film in the trench 310 can be produced by various process bias errors. Hence, the centerline 325 of the trench 320 and the centerline 315 of the trench 310 are n