Photomask Edge Test Pattern Layout for Shifted Exposure Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
During the manufacturing of large-sized display devices, misalignment of photomasks can occur when using smaller masks, leading to wires being formed at boundaries between exposure regions with shapes different from their original design.
Innovation Solution
A photomask with test patterns of varying shapes along its edges, allowing for the detection of alignment errors through a series of exposure processes, enabling correction and ensuring wires are formed as originally designed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a photomask smaller than the display device is used and shifted for multiple exposures, then the photomask can be used for large-sized display devices, but misalignment occurs leading to wires positioned at boundaries with shapes different from design
Solution Approach 1:
The patent applies preliminary action by pre-defining test patterns with nested shapes (first test pattern with first outer shape and first inner shape, second test pattern with second outer shape) at specific locations on the photomask. These patterns are prepared in advance to detect alignment errors before actual wire formation, allowing correction of misalignment issues that occur during multi-exposure processes.
Solution Approach 2:
The patent implements feedback by using the test patterns to detect alignment errors and providing this information back to the exposure process. The nested structure of test patterns (where second outer shape is larger than first inner shape but smaller than first outer shape) creates observable interference patterns or overlapping regions that indicate misalignment, enabling real-time correction to maintain wire position accuracy.
2Area of stationary object
If multiple exposure processes are performed by shifting the photomask, then large-sized display devices can be manufactured, but alignment errors cause wires to be formed at incorrect positions
Solution Approach 1:
The test patterns are prepared in advance on the photomask at specific locations to enable preliminary detection of alignment errors before actual manufacturing. The first test pattern and second test pattern with their nested shapes are positioned to be exposed during the multi-exposure process, allowing alignment verification before wire formation.
Solution Approach 2:
The test patterns serve as an intermediary element between the photomask positioning system and the final wire formation. By exposing these intermediate test patterns first, alignment can be measured and corrected without directly affecting the critical wire patterns, thus maintaining measurement precision during large-area manufacturing.
3Manufacturing precision
If test patterns with nested shapes are disposed on the photomask, then alignment errors can be detected and corrected, but the photomask design becomes more complex
Solution Approach 1:
The patent applies segmentation by dividing the test pattern into distinct nested components (first test pattern with outer and inner shapes, second test pattern with outer shape). This segmented nested structure allows each component to serve a specific detection function while maintaining overall simplicity. The segmentation enables clear identification of alignment errors through the relationship between nested shapes without requiring complex overall pattern design.
Solution Approach 2:
The test patterns are placed locally at specific positions on the photomask rather than distributing complexity across the entire mask. The first test pattern and second test pattern are positioned strategically to detect alignment errors in critical areas, allowing the majority of the photomask to remain simple while providing sufficient alignment detection capability where needed.
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 proposed solution allows for accurate alignment and formation of wires with their intended shape by detecting and correcting misalignment errors during the exposure process, improving the manufacturing precision of display devices.
Implementation Method 1
A photo process includes an exposure process and a development process, and a photomask may be used during the exposure process. Light may not pass through a portion of the photomask in which a predetermined pattern is formed while light may pass through a portion on which the predetermined pattern is not formed.
Data Source
AI summary
A photomask according to an exemplary embodiment includes: a mask substrate; and a first test pattern and a second test pattern disposed along a first edge of the mask substrate, wherein the first test pattern has a first outer shape and a first inner shape, the second test pattern has a second outer shape, and the second outer shape of the second test pattern is larger than the first inner shape of the first test pattern and smaller than the first outer shape of the first test pattern.