Mask blank substrate processing device, mask blank substrate processing method, mask blank substrate fabrication method, mask blank fabrication method, and transfer mask fabrication method

A fabrication method of a substrate with a multilayer reflective film, comprising:

• conducting a Catalyst Referred Etching, including supplying and contacting a first processing fluid to a principal surface of the substrate, and with a catalytic face of a catalytic surface plate in contact with the principal surface or in contact with the first processing fluid on the principal surface, causing the substrate and the catalytic face to move relative to each other so as to subject the principal surface to Catalyst Referred Etching;
• and
• after the Catalyst Referred Etching, conducting a physical cleaning for removing foreign matters attached to the principal surface using a physical action,
• wherein the substrate is a glass substrate,
• wherein the physical cleaning is at least one cleaning selected from the group consisting of megasonic cleaning and brush cleaning,
• wherein the physical cleaning is conducted by supplying a second processing fluid to the principal surface, and
• wherein the second processing fluid for the megasonic cleaning and the brush cleaning contains at least one selected from the group consisting of ozone water, hydrogen water, and neutral detergent;
• and
• forming a multilayer reflective film including a first layer with a first refractive index and a second layer with a second refractive index lower than the first refractive index laminated alternately on a principal surface of the mask blank substrate,
• wherein the multilayer reflective film is formed by an ion beam sputtering using a target of a first material for the first refractive index and a second material for the second refractive index by allowing sputter particles of the first material and the second material to enter at an incident angle between 0 and 30 degrees, both inclusive, with respect to a normal line of the principal surface.