Mark detection method, optical system and mark position detector

A mark detector which detects an alignment mark formed on a substrate, the alignment mark having a recess in which an insulator is embedded and being covered with a film which transmits substantially no visible light comprising:

• an irradiating system which irradiates the alignment mark with a coherent light beam in an infrared wavelength band through the film;
• and
• a receiving system which receives diffracted light produced from the alignment mark by the irradiation with the coherent beam,
• wherein positional information about the alignment mark is detected on the basis of the diffracted light.

A method of producing an exposure apparatus which exposes a substrate with a predetermined pattern, comprising:

• providing an irradiating system which irradiates, with a coherent light beam in an infrared wavelength band through a film which transmits substantially no visible light, an alignment mark formed on a substrate and covered with the film, the alignment mark having a recess in which an insulator is embedded;
• providing a receiving system which receives diffracted light produced from the alignment mark by the irradiation with the coherent beam;
• providing a detecting system which detects positional information about the alignment mark on the basis of the diffracted light;
• and
• providing an aligning system which aligns the substrate with the predetermined pattern on the basis of the positional information about the alignment mark.