Illumination optical apparatus and exposure apparatus

An illumination optical apparatus, comprising in order along an optical axis:

• a) a light source capable of supplying a primary light beam having a first cross-section;
• b) a condenser optical system capable of condensing said light beam;
• c) a light pipe optical integrator having a most light-source-wise incident surface with an incident surface shape, and capable of forming, from said primary light beam, a plurality of secondary light sources and associated secondary light beams;
• d) an imaging optical system designed to converge said secondary light beams to illuminate the surface to be irradiated;
• and
• e) a light beam shaping apparatus designed to shape said light beam first cross-section to form a second light-beam cross-section having a shape substantially similar to said light pipe incident surface shape.

A method of uniformly illuminating a surface with an illumination optical apparatus having a light pipe optical integrator with an integrator cross-section, an incident surface and an exit surface, comprising the steps of:

• a) providing a primary light beam having a primary light beam cross-section;
• b) condensing said primary light beam and forming a convergence point at a position spaced apart from said incident surface;
• c) collecting light emanating from said convergence point at an angle α using said light pipe optical integrator;
• d) forming a plurality of secondary light sources and associated secondary light beams by multiply internally reflecting said light within said light pipe optical integrator;
• and
• e) converging said primary and secondary light beams emanating from said exit surface to uniformly illuminate the illumination surface.

A method of patterning a photosensitive substrate by uniformly illuminating a mask having a pattern thereon with an exposure apparatus including a light pipe optical integrator having an integrator cross-section, an incident surface and an exit surface, comprising the steps of:

• a) providing a primary light beam having a primary light beam cross-section;
• b) condensing said primary light beam and forming a convergence point at a position spaced apart from said incident surface;
• c) collecting light emanating from said convergence point at an angle α using said light pipe optical integrator;
• d) forming a plurality of secondary light sources and associated secondary light beams by multiply internally reflecting said light within said light pipe optical integrator;
• e) converging said primary and secondary light beams emanating from said exit surface to uniformly illuminate the mask;
• and
• f) projecting an image of the mask onto the photosensitive substrate so as to form a pattern thereon.