Display Test Pad Structure for ESD-Safe Layer Deposition
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Solution Overview
Problem
During the deposition process of materials for layers in display devices, electrostatic discharge (ESD) can occur, posing a challenge.
Innovation Solution
A display device design that includes a substrate with a display area and non-display area, featuring a signal line, test pad, and connection line, with a photoresist layer having a positive taper cross-section, and layers in contact, to mitigate ESD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional deposition process is used for manufacturing display device layers, then manufacturing process is simple, but electrostatic discharge (ESD) occurs causing reliability issues
Solution Approach 1:
A photoresist layer with a positive taper cross-section is introduced as an intermediary structure between conductive layers. This photoresist layer acts as a mediator to dissipate electrostatic charge gradually, preventing sudden ESD events while maintaining the overall functionality of the display device structure.
Solution Approach 2:
The photoresist layer is designed with a specific positive taper cross-section geometry, where the width of the photoresist layer decreases from the bottom to the top surface. This geometric parameter change creates a controlled charge dissipation path that reduces ESD effectiveness while managing the structural complexity.
2Reliability
If photoresist layer with positive taper cross-section is added to reduce ESD, then reliability improves, but manufacturing process complexity increases
Solution Approach 1:
The photoresist layer is formed and patterned before the deposition of upper conductive layers. This preliminary action ensures that the ESD protection structure is already in place to protect subsequent layers from electrostatic damage during the manufacturing process, while the taper geometry is established in advance to control charge dissipation.
Solution Approach 2:
The photoresist layer is selectively applied in specific regions where ESD protection is most needed, such as near test pads and connection lines. The positive taper cross-section provides localized charge dissipation capability without requiring the entire device structure to be modified, thus balancing reliability improvement with manufacturing feasibility.
Data Source
AI summary
The present disclosure provides a display device and a method of manufacturing a display device. A display device according to one embodiment of the present specification may include a substrate including a display area and a non-display area around the display area, a signal line located in the display area, a test pad located in the non-display area, and a connection line located in the non-display area and configured to electrically connect the test pad and the signal line. The test pad may include a bank, a first layer, which is the connection line, disposed on the bank, a photoresist layer disposed on the first layer and including a pattern area, and a second layer disposed on the photoresist layer. The pattern area may have a positive taper cross-section, and the first layer and the second layer are in contact with each other in the pattern area.