Photomask Line Width Correction for Scanning Exposure
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Solution Overview
Problem
The scanning exposure type photomask technology faces issues with line width abnormalities in forming colored pixels, black matrices, and micro-lenses due to connecting portions in the projection lens assembly, resulting in uneven line widths when using negative or positive resists.
Innovation Solution
A photomask design that corrects line widths by introducing stepwise changes in the scanning direction, including a correction component based on random numbers, to ensure uniformity in pattern formation across the substrate, addressing the line width abnormalities caused by connecting portions in the projection lens assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If scanning exposure method is used to reduce photomask cost and complexity, then ease of manufacture is improved, but line width uniformity deteriorates due to connecting portions in projection lens assembly
Solution Approach 1:
The patent applies local quality by introducing position-dependent line width corrections in the photomask pattern. Different regions of the photomask receive different correction amounts based on their spatial location, particularly addressing the connecting portions where line width abnormalities occur. This allows the photomask to compensate for projection lens aberrations locally rather than uniformly, achieving improved line width uniformity while maintaining the scanning exposure method's manufacturing advantages.
Solution Approach 2:
The patent changes the geometric parameters of the photomask pattern by adjusting line widths according to position. Specifically, the line widths of light transmitting parts are modified based on their coordinates, with greater corrections applied to regions corresponding to connecting portions in the projection lens assembly. This parameter adjustment compensates for the optical aberrations and achieves uniform line widths in the final pattern.
2Productivity
If one-shot exposure method is used to increase productivity, then productivity is improved, but device complexity and cost increase due to larger photomask size requirements
Solution Approach 1:
The patent applies segmentation by using a small photomask with a limited scanning range rather than a large one-shot exposure photomask. The photomask pattern is scanned across the substrate in a systematic manner, dividing the exposure process into multiple smaller exposure steps. This segmentation approach maintains high productivity while using a simpler, smaller photomask device, avoiding the complexity and cost of large photomask manufacturing.
3Manufacturing precision
If line width correction is applied to compensate for connecting portions, then manufacturing precision is improved, but device complexity increases due to correction calculations and random number components
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-storing line width correction values in the photomask design data before the actual exposure process. The correction amounts, including those based on random numbers for additional uniformity, are determined in advance and embedded in the photomask pattern definition. During exposure, these pre-computed corrections are simply applied without real-time complex calculations, maintaining high precision while minimizing operational complexity.
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 corrects line width abnormalities, achieving uniformity in the formation of colored pixels, black matrices, and micro-lenses, thereby improving the quality and consistency of color filter substrates and solid-state image sensors.
Implementation Method 1
a black matrix, colored pixels such as a red filter, a green filter, a blue filter and the like, and spacers and the like are patterned such as by pattern exposure and development, using a photomask
Data Source
AI summary
A photomask is used for scanning type projection exposure provided with a projection lens assembly composed of a lens assembly. A line width in a plurality of patterns of the photomask in a region to be transferred by performing scanning exposure including connecting portions of the lens assembly are corrected with respect to a line width of patterns which are the same as the patterns of the photomask present in a region to be transferred by performing scanning exposure but do not include the connecting portions.