Patent ID: 7109483

Claim:
A substrate inspection method comprising: emitting a primary charged particle beam from a charged particle beam source, wherein said charged particle beam source is actuated in a space charge limited region, wherein a shot noise reduction factor is smaller than 1 and said charge particle beam source has a pointed cathode; focusing said emitting charged particle beams into a fine beam; irradiating and scanning said fine charged particle beam onto a substrate through a primary optical system; introducing a secondary charged particle beam into a secondary charge particle beam detector, said secondary charged particle beam being emitted from said substrate by said irradiation of said primary charged particle beam; detecting said secondary charged particle beam having been introduced into said secondary charge particle beam detector and converting said detected secondary charged particle beam into an electric signal; and processing said electric signal to evaluate said substrate, wherein said shot noise reduction factor is defined by the following equation, S/N=n 1/2 /(Γ*2 1/2 ) where, S/N is signal to noise ratio, Γ is shot noise reduction factor, and n is the number of detected secondary electrons per pixel.