Display Test Element Structure for Contact Resistance Detection
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Solution Overview
Problem
Existing display devices, particularly those with inorganic light-emitting elements, face challenges in measuring electrical characteristics and detecting defects during the fabrication process, which affects reliability and efficiency.
Innovation Solution
A test element is developed with a specific structure comprising a base layer, bank, first and second layers, and a photoresist layer, allowing for the measurement of contact resistance between layers to assess the reliability of micro-LEDs and detect defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fabrication methods are used for display devices, then the manufacturing process can be completed, but electrical characteristics cannot be measured and defects cannot be detected, resulting in unreliable products
Solution Approach 1:
The fabrication process is segmented into two distinct parts: a test element fabrication process that includes measurement structures, and a conventional display device fabrication process. The test element includes a test electrode, test insulation layer, and test contact structure that are fabricated separately from the main display device, allowing electrical characteristic measurements to be performed without complicating the overall manufacturing process.
Solution Approach 2:
Measurement structures (test elements) are fabricated in advance during the manufacturing process, before the final product completion. The test contact structure is formed with preliminary alignment marks and positioning features that enable subsequent electrical measurements to be performed easily, ensuring reliability is built-in rather than added later.
2Measurement precision
If measurement structures are added to the display device, then electrical characteristics can be measured, but the device complexity increases
Solution Approach 1:
The measurement function is extracted from the main display device structure and implemented as a separate test element. The test contact structure includes a test electrode and test insulation layer that are distinct from the display device's functional layers, allowing electrical measurements to be performed without adding complexity to the core display structure.
Solution Approach 2:
The test insulation layer acts as an intermediary element between the test electrode and the underlying structures. It provides electrical isolation and structural support, enabling precise electrical measurements while maintaining a clean separation between measurement functions and display device functions, thus avoiding direct complexity in the main device.
3Reliability
If defect detection capabilities are implemented, then reliability can be improved, but the manufacturing process becomes more complex and time-consuming
Solution Approach 1:
The test element fabrication is merged with the existing display device manufacturing process flow. The test contact structure is formed using the same deposition, etching, and insulation layer formation steps already required for the display device, allowing defect detection capabilities to be built-in without requiring separate manufacturing steps that would reduce productivity.
Data Source
AI summary
A test element may include a base layer, a bank on a portion of the base layer, a first layer on the base layer and on the bank, a photoresist layer on the first layer, the photoresist layer including a patterned area; and a second layer positioned on the photoresist layer. A height of a first area of the first layer on the bank may be greater than a height of a second area of the first layer on the base layer.