Semiconductors
Our products can be used in semiconductor illumination systems in various capacities such as
- Laser beam shaping
- Pupil defining – resolution enhancement element
- Field-angle defining element
The laser beam shaper is used to alter the cross-section profile of a laser beam, for instance, from Gaussian intensity profile to flat top. In this case a mild Engineered Diffuser™ or diffractive element can be used and possibly incorporated into the laser itself. This particular application generally requires high grade material due to the high energy densities involved. Examples include KrF and ArF grade fused silica or calcium fluoride.
The pupil-defining element serves to enhance resolution and determines the illumination pattern at the pupil plane. This particular component produces small angle output and is generally implemented in the form of a diffractive element that produces a pattern such as dipoles, quadrupoles, or any appropriate pupil pattern.
The field-defining element diffuses the laser beam to certain field angles that match the field of view of the stepper lens. In this application exceptional angular uniformity is required with wider divergence angles up to about 30 degrees. A common approach is to use fly’s eye assemblies which require several layers of microlens arrays. An Engineered Diffuser™ can replace the fly’s eye assembly with a single-surface diffuser that eliminates the diffraction effects caused by the periodic nature of the fly’s eye lenses.
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