Apparatus for inspecting film on substrate by using optical interference and method thereof

A substrate inspection apparatus comprising:

• a light source configured to radiate laser light onto a region of a coated film that is spread on a substrate;
• a light detector configured to obtain optical interference data on an interference between reference light, that is generated by the laser light being reflected from a surface of the region of the coated film, and measurement light, that is generated by the laser light penetrating the region of the coated film and being scattered;
• a processor;
• and
• a component mover, controlled by the processor, configured to move the light source,
• wherein the processor is configured to:
• derive a reflectivity of the surface from an intensity of the reference light;
• determine whether the reflectivity is less than a predetermined reflectivity stored in a memory;
• upon the determination that the reflectivity is not less than the predetermined reflectivity, derive a thickness of the coated film corresponding to the region based on the optical interference data;
• and
• upon the determination that the reflectivity is less than the predetermined reflectivity, control the component mover to move the light source so as to radiate the laser light onto another region of the coated film on the substrate.