Apparatus for producing a hologram mask

An apparatus for producing a hologram mask approximating the exposure produced by a non-holographic phase shifting photomask comprising:

• a first object light at least partially transmittable through a first original mask having a light transmitting screening pattern;
• a first reference light wherein a first phase difference exists between the first object light and the first reference light;
• a hologram recording material operatively positioned to receive both the transmitted first object light and the first reference light;
• a second object light at least partially transmittable through a second original mask having a light transmitting screening pattern;
• a second reference light wherein the hologram recording material is operatively positioned to receive both the transmitted second object light and the second reference light, wherein a second phase difference exists between the second object light and the second reference light, and the second phase difference is not the same as the first phase difference, and
• wherein the first and second original mask images recorded in the hologram recording material can be simultaneously replayed to produce an exposed pattern approximating an exposed pattern of a non-holographic phase shifting photomask.