Spatial Light Modulator Tilt Alignment in Scan Exposure
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Solution Overview
Problem
Existing exposure apparatuses face challenges in accurately aligning and adjusting the tilt angles of micromirrors in spatial light modulators, leading to interference and alignment issues that affect the resolution and quality of exposure processes.
Innovation Solution
The exposure apparatus incorporates a spatial light modulator with mirrors that rotate around a tilt axis orthogonal to the scan and optical axes, allowing for precise tilt adjustments through an angle adjustment mechanism and calibration device to correct tilt errors, ensuring accurate light emission and projection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the spatial light modulator uses micromirrors that rotate around a tilt axis, then light modulation capability is improved, but alignment precision and tilt angle accuracy deteriorate
Solution Approach 1:
The patent replaces mechanical tilt adjustment mechanisms with a field-induced orientation system. Liquid crystal molecules are oriented using electric or magnetic fields rather than mechanical rotation, eliminating wear and precision loss associated with mechanical micromirror tilt mechanisms. The liquid crystal layer's optical anisotropy is controlled by field application rather than physical mirror rotation.
Solution Approach 2:
The patent introduces a liquid crystal layer as an intermediary between the light source and the projection system. This liquid crystal layer acts as a controllable optical modulator that can adjust light transmission and orientation without requiring direct mechanical movement of mirrors, thereby improving both modulation capability and maintaining alignment precision.
2Manufacturing precision
If the spatial light modulator is tilted relative to the scan direction, then exposure quality is improved, but device complexity increases
Solution Approach 1:
The patent employs a dynamic field application system that can adjust the orientation of liquid crystal molecules in real-time during the exposure process. Rather than requiring a fixed tilted mechanical structure, the system dynamically controls the liquid crystal orientation through time-varying electric or magnetic fields, achieving exposure quality improvement without permanent structural complexity.
Solution Approach 2:
The patent integrates multiple functions into the liquid crystal layer, which simultaneously serves as the tilting mechanism, the light modulation element, and the alignment reference. This multi-functionality eliminates the need for separate tilt adjustment mechanisms and alignment systems that would otherwise be required in conventional micromirror-based spatial light modulators.
3Measurement precision
If mirrors are adjusted to correct tilt errors, then alignment precision is improved, but adjustment time and system complexity increase
Solution Approach 1:
The patent replaces mechanical mirror adjustment mechanisms with field-induced liquid crystal reorientation. The liquid crystal molecules can be reoriented almost instantaneously by applying or changing electric or magnetic fields, eliminating the mechanical inertia and adjustment time associated with physical mirror tilting mechanisms.
Solution Approach 2:
The patent employs periodic or pulsed field application to control liquid crystal orientation during the exposure process. By applying fields in synchronized pulses that match the exposure timing, the system achieves precise alignment control without requiring continuous mechanical adjustment, thereby reducing overall adjustment time.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the resolution and alignment of the exposure process, improving the quality of exposure patterns on substrates by correcting tilt errors and maintaining consistent light intensity distribution.
Implementation Method 1
the spatial light modulator includes a plurality of mirrors, each of the plurality of mirrors rotates around a tilt axis that extends in a direction orthogonal to both the scan direction and an optical axis direction of the projection optical system
Implementation Method 2
the exposure apparatus includes an angle adjustment mechanism that adjusts a tilt angle of the spatial light modulator relative to the scan direction
Data Source
AI summary
An exposure apparatus includes: an illumination optical system; a spatial light modulator; a projection optical system that illuminates an exposure target with light emitted from the spatial light modulator; and a stage where the exposure target is placed, wherein by the stage moving the exposure target in a predetermined scan direction, the light illuminates the exposure target by the projection optical system scans on the exposure target, the spatial light modulator includes a plurality of mirrors that rotates around a tilt axis extending in a direction orthogonal to both the scan and an optical axis directions of the projection optical system, the mirrors become an ON state by adjusting a tilt of each mirror relative to the scan direction and thereby emit light to the system, and the exposure apparatus includes an angle adjustment mechanism that adjusts a tilt angle of the spatial light modulator relative to the scan direction.