Method and apparatus for inspecting a surface state

A method for inspecting foreign particles on a pellicle, the method comprising the steps of:

• directing a light beam to be obliquely incident upon a pattern surface of a reticle through the pellicle stretched on a pellicle frame, which is placed on the pattern surface;
• moving the obliquely incident light beam and the reticle relative to each other;
• and
• detecting, by a detector, a scattered light from the pellicle traveling along a detection optical axis to inspect foreign particles on the pellicle,
• wherein a first angle formed between the detection optical axis of the detector and a pellicle surface is smaller than a second angle formed between a specularly reflected light of the obliquely incident light beam reflected by the pellicle surface and the pellicle surface, both the first and the second angles being measured from a side of the pellicle surface closest to the specularly reflected light, such that when the light beam is reflected by the pellicle frame and irradiates the pattern surface, a scattered light caused at the pattern surface is thereby prevented from entering the detector.