Spatial Light Modulator Boundary Region Control for Sub-Pixel Accuracy
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Solution Overview
Problem
Conventional spatial light modulators struggle to achieve position and shape accuracy finer than the width of their optical elements when forming patterns on substrates, particularly in forming line-and-space patterns with non-integral multiples of the optical element widths.
Innovation Solution
The method involves setting optical elements in a spatial light modulator into specific states to control the position of patterns, with elements in boundary regions being set at pitches over the resolution limit of the projection optical system, allowing for precise control of pattern formation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional spatial light modulators are used to form patterns, then the pattern formation process is simple, but the position accuracy and shape accuracy are limited to the width of the optical element images
Solution Approach 1:
The patent divides the spatial light modulator into multiple regions (first region, second region, and boundary region) with different control states. By segmenting the control strategy into distinct zones, the system achieves sub-pixel position accuracy through the boundary region while maintaining manageable complexity through region-based organization.
Solution Approach 2:
The patent applies different control states to different regions of the spatial light modulator. The boundary region uses a specific control state with pitch over the resolution limit to achieve high position accuracy, while the first and second regions use different states. This local differentiation enables fine position control without requiring the entire device to operate at maximum complexity.
2Adaptability or versatility
If optical elements are arranged at standard pitches, then the device structure is simple, but patterns with non-integral multiple pitches cannot be formed
Solution Approach 1:
The patent introduces a boundary region with dynamic control where optical elements can be set to different states based on the required pattern pitch. This dynamic arrangement in the boundary region allows the system to adapt to non-integral multiple pitches while maintaining a relatively simple overall structure, as the standard arrangement is preserved in the main regions.
3Manufacturing precision
If boundary regions are added to improve position accuracy, then pattern formation precision improves, but the number of optical element states increases
Solution Approach 1:
The patent applies a specialized control state only to the boundary region (partial action) rather than the entire array. By limiting the complex control to only where needed (the boundary between regions), the system achieves high position accuracy without requiring all optical elements to operate in maximum complexity mode.
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 approach enables the formation of patterns with position and shape accuracy finer than the width of the optical elements, effectively overcoming the limitations of conventional spatial light modulators.
Implementation Method 1
There are also the proposed spatial light modulators of a type having an array of many micromirrors a height of a reflective surface of each of which is controllable, in order to control a phase distribution of incident light
Implementation Method 2
the exposure apparatus of a one-shot exposure type such as steppers or the exposure apparatus of a scanning exposure type such as scanning steppers are used for forming a predetermined pattern in each shot area on a substrate such as a wafer or a glass plate through a projection optical system
Data Source
AI summary
A method for driving a spatial light modulator includes setting a plurality of mirror elements in a first region into a state of phase 0, setting a plurality of optical elements in a second region adjacent in a Y-direction to the first region into a state of phase π, and setting auxiliary pattern elements consisting of a plurality of mirror elements arranged at a pitch P over a resolution limit of a projection optical system in an X-direction in a boundary region extending in the X-direction between the first region and the second region, into the state of phase π. In projecting a pattern onto an object with use of the spatial light modulator having the array of optical elements, the pattern can be formed in position accuracy or shape accuracy finer than the width of images of the optical elements.