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US 6,636,295 B2Granted
Exposure apparatus and device manufacturing method
AssigneeCanon Kabushiki Kaisha
InventorTakahisa Shiozawa
Life of this patent
Estimating the term…
Abstract
An illumination system for lithography includes an optical system for projecting light from a laser onto a mask. The optical system includes a birefringent element being effective to dissolve polarization of light from the laser. The birefringent element is made of CaF2.
Claims14
An illumination system for lithography, comprising:
- an optical system for projecting light from a laser onto a mask, said optical system including a plurality of optical integrators, including first and second optical integrators,
- wherein light beams from said first optical integrator are superposed one upon another on said second optical integrator and said optical system includes a birefringent element being effective to dissolve polarization of light from the laser, and being made of CaF2, said birefringent element being disposed between the laser and said first optical integrator.
An exposure apparatus, comprising:
- an optical system for projecting light from a laser onto a mask, said optical system including (i) a plurality of optical integrators, including first and second optical integrators, wherein light beams from said first optical integrator are superposed one upon another on said second optical integrator and (ii) a birefringent element being effective to dissolve polarization of light from the laser, and being made of CaF2, said birefringent element being disposed between the laser and said first optical integrator;
- and
- a projection optical system for projecting a pattern of the illuminated mask, upon a substrate.
Dependencies are inferred from the claim text.