Method and apparatus for optical inspection of substrates

Inspection apparatus for inspecting surface features of a substrate comprising:

• memory means for storing the desired features of the surface of the substrate;
• illumination means for substantially uniformly illuminating a region of the surface of the substrate to be inspected;
• TDI sensor means for imaging the region of the substrate illuminated by the illumination means;
• and
• comparison means responsive to the memory and sensor means for comparing the imaged region of the substrate with the stored desired features of the substrate.

A method for inspecting surface features of a substrate, said method comprising the steps of:

• a. storing the desired features of the surface of the substrate;
• b. substantially uniformly illuminating a region of the surface of the substrate to be inspected with focussed quasi-Lambertian illumination;
• c. imaging the region of the substrate illuminated by the illumination means;
• and
• d. comparing the imaged region of the substrate with the stored desired features of the substrate.

A method for inspecting surface features of a substrate, said method comprising the steps of:

• a. storing the desired features of the surface of the substrate;
• b. substantially uniformly illuminating a region of the surface of the substrate to be inspected;
• c. imaging the region of the substrate illuminated by the illumination means with TDI sensor means;
• and
• d. comparing the imaged region of the substrate with the stored desired features of the substrate.

Illumination apparatus for substantial uniform focussed illumination along a narrow linear region comprising:

• first and second reflector means elliptically cylindrical segments in shape, each with its long axis substantially parallel to the long axes of the other, and each being spaced-apart from the other along their closest edges to define a path through which the illuminated linear region can be viewed from above through said illumination apparatus;
• third and fourth reflector means each being flat and mounted parallel to the other and at opposite ends of each of said first and second reflector means and substantially perpendicular to the long axis of each of said first and second reflector means;
• and
• first and second linear light source means each mounted parallel to a corresponding one of said first and second reflector means to direct light onto substantially the entire surface of the corresponding reflector means with the illuminated linear region at one focus of each of the first and second reflector means.