PURPOSE: To obtain a phase shift mask having self-aligning spacers of a phase shift material adjacent to the edges of opaque mask patterns and its production.

CONSTITUTION: A blanket layer of the adequate phase shift material is adhered onto a transparent mask substrate 11 having patterned opaque layers 13. The phase shift layer is then subjected to anisotropic blanket etching within a reactive ion etching(RIE) chamber by using the opaque layers 13 and the substrate 11 as etch stoppers. The phase shift materials remaining after the etching form spacer patterns 15 of nearly a quarter cylindrical shape. The spacer patterns are self-aligned to the edges of the opaque mask patterns 13. The phase shift material having such thickness and refractive index which bring about a phase shift of 0.67π radian (120°) to π radian (180°) of the range of the phase shift verified to be effective with the finished mask is selected.