Patent ID: 7897299

Claim:
A method of forming a phase- shift mask (PSM), comprising: sequentially forming a phase-shift layer and a light-shielding layer on a transparent substrate, to thereby form a blank mask on the transparent substrate; forming a light-shielding pattern and a phase-shift pattern by consecutively and partially removing the phase-shift layer and the light-shielding layer, the light-shielding pattern including a first opening and the phase-shift pattern including a second opening that is connected to the first opening and partially exposes the transparent substrate; and forming a transmitting portion by partially removing the light-shielding pattern, the transmitting portion including at least one portion of the phase-shift pattern on which a transmittance controller is formed; wherein forming the transmitting portion includes: forming a mask layer on the light-shielding pattern to a sufficient thickness to fill up the first and second openings; forming a second mask pattern through which the light-shielding pattern is partially exposed; etching the exposed light-shielding pattern off of the phase-shift pattern using the second mask pattern as an etching mask simultaneously with the second mask pattern in the first opening, to thereby form a preliminary transmitting portion through which the phase-shift pattern and the second mask pattern in the second opening are exposed; forming a thin layer on the phase-shift pattern and second mask pattern exposed in the second opening of the preliminary transmitting portion; and diffusing a material of the thin layer into the phase-shift pattern.