Spatial Light Modulator Phase Control for Gap Region Errors
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Solution Overview
Problem
Conventional spatial light modulators with arrays of micromirrors face issues with pattern errors due to low reflectance in gap regions between micromirrors, leading to thermal deformation and shape errors in projected patterns, and high reflectance causing random light mixing and pattern distortions.
Innovation Solution
A spatial light modulator with optical elements that can be controlled into multiple states, including phases that allow incident light to pass with specific phase changes, and boundary portions that change the phase differently, reducing errors even with high light incidence in gap regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the gap region between adjacent micromirrors has low reflectance, then the micromirrors can be driven independently, but the spatial light modulator absorbs excessive energy causing thermal deformation
Solution Approach 1:
The patent applies local quality by giving different optical properties to different regions of the spatial light modulator. Specifically, the gap regions between micromirrors are equipped with phase control capability, allowing them to have different phase shift characteristics compared to the micromirror regions. This enables the gap regions to manage light energy locally, reducing excessive absorption and thermal deformation while maintaining independent micromirror operation.
2Temperature
If the reflectance of the gap region is increased, then thermal deformation is reduced, but reflected light from the gap region mixes with reflected light from micromirrors causing pattern errors
Solution Approach 1:
The patent introduces phase control as an intermediary mechanism to manage the optical behavior of gap regions. By controlling the phase of light reflected from gap regions, the system can distinguish between light from micromirrors and light from gap regions, preventing unwanted mixing and pattern errors while maintaining appropriate reflectance levels to avoid thermal deformation.
Solution Approach 2:
The patent changes the optical parameter (phase) of light in the gap regions to differentiate it from light reflected by micromirrors. By controlling the phase shift in gap regions to be different from that of micromirrors, the system can maintain higher reflectance in gap regions without causing pattern errors, as the phase-differentiated light can be distinguished or suppressed in the projection system.
3Ease of operation
If a larger gap region is provided between micromirrors, then micromirrors can be driven more independently, but light energy is lost and pattern accuracy decreases
Solution Approach 1:
The patent changes the optical parameter (phase) of light in the gap regions to utilize the gap regions constructively. By controlling the phase shift in gap regions, the system can prevent light energy loss and pattern accuracy degradation, as the phase-controlled light from gap regions can be managed to complement rather than interfere with the micromirror light, thereby maintaining pattern accuracy even with larger gap regions for independent micromirror operation.
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
The solution effectively reduces pattern errors and maintains high light utilization efficiency by controlling the phase changes across the spatial light modulator, ensuring accurate pattern projection on substrates.
Implementation Method 1
each of the optical elements is controllable into a plurality of states including a first state in which the optical element allows incident light to pass without any change in a phase thereof or with a change in the phase by a first phase and a second state in which the optical element allows the incident light to pass with a change in the phase thereof by a second phase 180° different from the first phase
Data Source
AI summary
A spatial light modulator includes a first reflective surface which reflects incident light and is movable between a first position and a second position, the first and the second positions being located along a first axis, a second reflective surface which reflects the incident light, is arranged at a position where the second reflective surface is adjacent to the first reflective surface in a direction along a second axis crossing the first axis, and is movable between a third position and a fourth position, the third and the fourth positions being located along a direction parallel to the first axis, and a reflective part which reflects the incident light and is arranged between the first reflective surface and the second reflective surface in the direction along the second axis, wherein a distance between the first position and the reflective part, defined in the direction parallel to the first axis, is configured to attenuate light reflected at the reflective part by using light reflected at the first reflective surface, and a distance between the second position and the reflective part, defined in the direction parallel to the first axis, is configured to attenuate the light reflected at the reflective part by using the light reflected at the first reflective surface.