Patent ID: 6335532
Filing Date: 2002-01-01
Classification: G01N,H01J

Abstract:
A convergent charged particle beam apparatus comprising:an electron beam source; electron optical system which converges and focuses an electron beam emitted from said electron beam source; a vacuum chamber having an evacuated interior; a stage arranged in the interior of said vacuum chamber so as to mount a specimen under inspection thereon and to move said specimen in at least one plane; an electron beam image observation arrangement which observes an electron beam image of a surface of said specimen mounted on said stage when the electron beam converged by said electron optical system is irradiated and scanned over the surface of said specimen and secondary charged particles produced from said specimen are detected so as to provide electron image data of the surface of said specimen; a height detector which optically detects a surface height of said specimen in a region irradiated with the electron beam scanned by said electron optical system and provides an output indicative thereof; a controller which controls a focal point of the electron beam converged and focused by said electron optical system and a height position of said specimen in accordance with the output from said height detector; and a defect detector which detects a defect on said specimen by processing the electron image data of the surface of said specimen observed by said electron beam image observation arrangement when the focal point of the electron beam irradiating the surface of said specimen and the height position of said specimen are controlled by said controller; wherein said height detector comprises a light beam projecting part for projecting a slit-shaped or spot-shaped light beam onto said specimen, a light receiving part for receiving a light beam which is projected by said light beam projecting part and then reflected from the surface of said specimen, and a height calculator which calculates a surface height of said specimen in a focus direction of the electron beam according to position data attained through said light receiving part by receiving the light beam reflected from said specimen, and wherein said light beam projecting part and said light receiving part are disposed outside said vacuum chamber, said light projecting part projects the light beam onto said specimen mounted on said stage means through a first optically transparent window having first characteristics, said first optically transparent window being provided in a portion of said vacuum chamber, and said light receiving part receives the light beam reflected from said specimen through a second optically transparent window which is provided in a portion of said vacuum chamber.