Patent ID: 6512578
Filing Date: 2003-01-28
Classification: G01N

Abstract:
A surface inspection apparatus comprising:an illumination apparatus which is fixed in a position facing an object at a first predetermined angle with respect to the object and which irradiates an illuminating light beam toward an inspection region of the object, wherein a wavelength of the illuminating light beam can be varied; an image pickup device which is fixed in a position facing the object at a second predetermined angle with respect to the object and which receives diffracted light or scattered light generated from the illumination of the object by the illuminating light beam and creates an image of the object; and an image processing apparatus which takes an image signal obtained by the image pickup device and performs a macro inspection of the inspection region by carrying out image processing; wherein the illumination apparatus is capable of altering or selecting at least two wavelengths including a first wavelength and a second wavelength, if the first predetermined angle is represented by an angle of &thgr;i with respect to a line perpendicular to the surface of the object and the second predetermined angle is represented by an angle of &thgr;d with respect to the line perpendicular to the surface of the object, then the first wavelength is a wavelength ), which is set so as to satisfy the following formula: (sin&thgr;iâˆ’sin&thgr;d)=nÂ·&lgr;1/p (n: order of diffracted light undergoing image projection, p: pattern pitch of the surface of the object), and the second wavelength is a wavelength &lgr;2 which is set such that an angle &thgr;dâ€² which is determined by the following formula: (sin&thgr;iâˆ’sin&thgr;dâ€²)=nÂ·&lgr;2/p (n: order of diffracted light generated from the illuminating light beam, p: pattern pitch of the surface of the object), and an angle &thgr;dâ€³ which is determined by the following formula: (sin&thgr;iâˆ’sin&thgr;dâ€³)=(n+1)Â·&lgr;2/p â€ƒsatisfy the requirement that &thgr;dâ€²