Surface form measuring apparatus and stress measuring apparatus and surface form measuring method and stress measuring method

A stress measuring apparatus for measuring a stress in a film formed on an object, comprising;

• a light source for emitting a light;
• an optical system for directing said light emitted from said light source to an irradiation region on an object through an objective lens and directing a reflected light reflected on said irradiation region to a predetermined position through said objective lens;
• a light shielding pattern positioned at a position almost optically conjugate to an aperture stop position on an optical path from said light source to said irradiation region;
• an imaging part for acquiring an image of said light shielding pattern formed on said predetermined position;
• a gradient vector calculation part for obtaining a gradient vector indicating a normal direction of said irradiation region on the basis of an output of said imaging part;
• a moving mechanism for moving said irradiation region relatively to said object;
• a surface form calculation part for obtaining surface form of said object on the basis of gradient vectors in a plurality of areas on said object, said gradient vectors being obtained by said gradient vector calculation part;
• a curvature radius calculation part for obtaining a radius of curvature of a stress measurement area on said object on the basis of said surface form obtained by said surface form calculation part;
• a film thickness measuring part for optically measuring a thickness of a film formed on said object;
• and
• a stress calculation part for obtaining a stress in said film of said stress measurement area on the basis of said radius of curvature and said thickness of said film in said stress measurement area which are obtained by said curvature radius calculation part and said film thickness measuring part.

A surface form measuring method of measuring surface form of an object, comprising the steps of:

• a) applying a light emitted from a light source to an irradiation region on an object through an optical system having an objective lens;
• b) directing a reflected light of said light reflected on said irradiation region to a predetermined position through said objective lens, to form an image of a light shielding pattern on said predetermined position and acquire said image by an imaging part, said light shielding pattern being positioned at a position almost optically conjugate to an aperture stop position on an optical path from said light source to said irradiation region;
• c) repeating said steps a) and b) while moving said irradiation region relatively to said object to obtain gradient vectors indicating a normal direction of a plurality of areas on said object on the basis of outputs of said imaging part;
• and
• d) obtaining surface form of said object on the basis of said gradient vectors in said plurality of areas.

A stress measuring method of measuring a stress in a film formed on an object, comprising the steps of;

• a) applying a light emitted from a light source to an irradiation region on an object through an optical system having an objective lens;
• b) directing a reflected light of said light reflected on said irradiation region to a predetermined position through said objective lens, to form an image of a light shielding pattern on said predetermined position and acquire said image by an imaging part, said light shielding pattern being positioned at a position almost optically conjugate to an aperture stop position on an optical path from said light source to said irradiation region;
• c) repeating said steps a) and b) while moving said irradiation region relatively to said object to obtain gradient vectors indicating a normal direction of a plurality of areas on said object on the basis of outputs of said imaging part;
• d) obtaining surface form of said object on the basis of said gradient vectors in said plurality of areas;
• e) obtaining a radius of curvature of a stress measurement area on said object on the basis of said surface form;
• f) optically measuring a thickness of a film in said stress measurement area;
• and
• g) obtaining a stress in said film of said stress measurement area on the basis of said radius of curvature and said thickness of said film in said stress measurement area.