LCD Exposure Method Using Reference Substrate Alignment
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Solution Overview
Problem
In large-size liquid crystal display manufacturing, the alignment precision between the TFT array substrate and the color filter substrate is compromised due to the stitching exposure region, leading to defects like light leakage, as the existing methods fail to accurately measure and correct for pattern deflection and deformation across the stitching area.
Innovation Solution
The method involves using at least two photo masks with active and inactive areas, including alignment precision marks, performing exposure on separate reference substrates to determine and adjust exposure parameters, and then combining these masks on the glass substrate with accurate parameters to ensure precise alignment and pattern formation, shielding the marks during the final exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple photo masks are used for stitching exposure on large-size glass substrates, then the area of the exposed pattern is improved, but the alignment precision between TFT array substrate and color filter substrate deteriorates
Solution Approach 1:
The exposure process is segmented into multiple operations using separate photo masks for different regions of the large-size substrate. Each photo mask covers a specific area and is exposed sequentially, allowing the total exposed area to exceed the size of a single photo mask while maintaining control over each segment's exposure parameters
Solution Approach 2:
Alignment precision measurement marks are incorporated into the photo mask design, and their positions are measured after exposure to detect deflection and deformation. This measurement feedback is used to calculate compensation values that are applied to subsequent exposure operations, creating a closed-loop control system that maintains alignment precision across multiple stitching exposures
2Measurement precision
If alignment precision measurement marks are placed in the active area, then the measurement of pattern deflection is enabled, but the stitching exposure region cannot be properly monitored due to mask coverage
Solution Approach 1:
The alignment precision measurement marks are positioned in the inactive area (marginal region) of the photo mask rather than in the active exposure area. This spatial repositioning allows the marks to be exposed and measured without being obscured by the photo mask body during subsequent stitching operations, preserving alignment information at the stitching regions
Solution Approach 2:
The inactive area of the photo mask serves as an intermediary zone that contains the alignment measurement marks. This marginal region acts as a buffer that is exposed during the exposure process but does not interfere with the active pattern formation, allowing simultaneous achievement of pattern exposure and alignment measurement
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 enhances alignment precision between the TFT array and color filter substrates, reduces defects, and increases the production yield of LCD panels by allowing for accurate monitoring and adjustment of exposure parameters.
Implementation Method 1
performing exposure with each the photo mask on a separate reference substrate at a corresponding position
Data Source
AI summary
An exposure method for an LCD glass substrate is revealed and includes: providing at least two photo masks, wherein each the photo mask includes active and inactive area with alignment-precision measurement-and-check marks disposed around the active area; performing exposure with each the photo mask on a separate reference substrate at a corresponding position, performing measurement of the alignment-precision measurement-and-check marks formed on the reference substrate, determining whether to modify a parameter of the exposure based on the measurement result, and obtaining accurate exposure parameter of each the photo mask; and combining the accurate exposure parameter of each the photo mask, using the combined exposure parameter to perform exposure sequentially with the at least two photo masks on the same substrate at corresponding positions, thereby obtaining an exposed pattern. Accordingly, the alignment precision between the TFT array and color filter substrates is enhanced and the LCD-panel production yield is increased.