Measurement apparatus, exposure apparatus, and device fabrication method

A measurement apparatus which measures a wavefront aberration of an optical system to be measured, the apparatus comprising:

• a measurement mask which is inserted on an object plane of the optical system to be measured, and includes a plurality of reflection units configured to generate spherical waves by reflecting light;
• a diffractive optical element configured to diffract the light having passed through said measurement mask and the optical system to be measured;
• and
• a detection unit configured to detect an interference pattern formed by interference of the light diffracted by said diffractive optical element,
• said measurement mask including:
• a reflection layer configured to reflect the light,
• a first layer which is stacked on said reflection layer, has a plurality of openings, and is made of a first substance, and
• a second layer which is stacked on said first layer, has a window configured to expose a region in which said plurality of openings are arrayed, and is made of a second substance different from said first substance,
• wherein said plurality of reflection units are formed by portions of said reflection layer, which are exposed through said plurality of openings.