Method and lens arrangement to improve imaging performance of microlithography exposure tool
AssigneeIntel Corporation
InventorsYan Borodovsky, Christof Krautschik
Life of this patent
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Abstract
A technique for introducing variable phase delay across portions of a spatially coherent light beam, such as a laser, without changing the focal length of the portions of the beam. A fly's-eye lens array is utilized to distribute the light for a more uniform illumination, but different length air gaps are introduced in the lens elements to provide a variable delay of portions of the beam. In a second scheme, a set of prisms is positioned in the path of the laser beam, in which the shape of the prism introduces variable phase delay across the cross-section of the beam.
Claims19
An apparatus for providing improved illumination uniformity by reducing spatial coherence of transmitted light to remove speckle comprising:
- a light source for generating a coherent beam of light to provide the transmitted light;
- and
- a set of fly's eye lens elements arranged to receive the transmitted light and disperse the transmitted light into a number of beamlets for projection onto a target, having the same focal length for imaging onto the target and, said lens elements having a plurality of lens media and a second medium disposed within at least one of said lens media, each said lens medium having a first light transition time, said second medium having a second light transition time different than said first light transition time.
In a microlithography tool which is used to pattern images onto a semiconductor wafer, an apparatus for providing improved illumination uniformity by reducing spatial coherence of transmitted light to remove speckle comprising:
- a coherent laser light source for generating a coherent beam of light to provide the transmitted light;
- and
- a set of fly's eye lens elements arranged to receive the transmitted light and disperse the transmitted light into a number of beamlets for projection onto the wafer, and having the same focal length for imaging onto the wafer, said lens elements having a plurality of lens media and a second medium disposed within at least one of said lens media, each said lens medium having a first light transition time, said second medium having a second light transition time different than said first light transition time.
An apparatus for providing improved illumination uniformity by reducing spatial coherence of transmitted light to remove speckle comprising:
- a light source for generating a coherent beam of light to provide the transmitted light;
- a set of fly's eye lens elements arranged to receive the transmitted light and disperse the transmitted light into a number of beamlets for projection onto a target, said lens elements having the same focal length for imaging onto a target;
- and
- a delay element disposed between said light source and lens elements to introduce a continuously variable delay within a single optical path, said continuously variable delay applied across the field of the transmitted light to reduce the spatial coherence of the transmitted light.
In a microlithography tool which is used to pattern images onto a semiconductor wafer, an apparatus for providing improved illumination uniformity by reducing spatial coherence of transmitted light to remove speckle comprising:
- a light source for generating a coherent beam of light to provide the transmitted light;
- a set of fly's eye lens elements arranged to receive the transmitted light and disperse the transmitted light into a number of beamlets for projection onto the wafer, said lens elements having the same focal length for imaging onto the wafer;
- and
- a delay element disposed between said light source and lens elements to introduce a continuously variable delay within a single optical path said continuously variable delay applied across the field of the transmitted light to reduce the spatial coherence of the transmitted light.
A method of improving illumination uniformity by reducing spatial coherence of transmitted light to remove speckle, comprising the steps of:
- generating a coherent beam of light to provide the transmitted light;
- arranging a set of fly's eye lens elements to receive the transmitted light and disperse the transmitted light into a number of beamlets for projection onto a target, and having the same focal length for imaging onto the target, said lens elements having a plurality of lens media and a second medium disposed within at least one of said lens media, each said lens medium having a first light transition time, said second medium having a second light transition time different than said first light transition time.
A method of improving illumination uniformity by reducing spatial coherence of transmitted light to remove speckle, comprising the steps of:
- generating a coherent beam of light to provide the transmitted light;
- arranging a set of fly's eye lens elements to receive the transmitted light and disperse the transmitted light into a number of beamlets for projection onto a target, the lens elements having the same focal length for imaging onto a target;
- and
- inserting a delay element across the field of the transmitted light prior to the lens elements to introduce a continuously variable delay within a single optical path to reduce the spatial coherence of the transmitted light.
Dependencies are inferred from the claim text.