LCD Fabrication: In-Chamber Passivation to Reduce Leakage
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Solution Overview
Problem
The reliability of liquid crystal display (LCD) devices is compromised due to contamination of the channel portion during the fabrication process, leading to leakage current and abnormal transistor operation, which affects image clarity and overall device reliability.
Innovation Solution
The method involves forming a passivation layer in a dry-etching chamber to cover the channel portion of the active layer, using sulfur hexafluoride to etch the ohmic contact layer and subsequently forming a silicon nitride or silicon oxide passivation layer to prevent contamination by external particles, thereby minimizing leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the channel portion is exposed during the fabrication process to allow for proper layer formation, then the manufacturing process can be completed, but the channel portion becomes contaminated by external particles causing leakage current
Solution Approach 1:
The patent applies the inert atmosphere principle by performing both the etching of the ohmic contact layer and the formation of the passivation layer within the same vacuum chamber of the dry-etching device. This continuous vacuum environment prevents external particles from contaminating the exposed channel portion, thereby maintaining device reliability while completing the necessary fabrication steps.
Solution Approach 2:
The patent applies preliminary action by forming the passivation layer immediately after etching the ohmic contact layer, while the substrate remains in the vacuum chamber. This sequence ensures the channel portion is protected from contamination before it is exposed to external environment, preventing leakage current issues.
2Productivity
If the substrate is removed from the chamber after layer formation to proceed with other processes, then subsequent fabrication steps can be performed, but the channel portion is exposed to external contamination
Solution Approach 1:
The patent merges two separate fabrication steps (etching the ohmic contact layer and forming the passivation layer) into a single continuous process within the same vacuum chamber. This eliminates the need to break vacuum and expose the channel portion to external particles, thereby preventing contamination while maintaining fabrication efficiency.
Solution Approach 2:
By maintaining the vacuum chamber environment throughout both etching and passivation layer formation, the patent ensures the channel portion remains protected from external particle contamination, addressing the harmful factor while allowing continuous production.
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 the reliability of the LCD device by reducing leakage current and ensuring the channel portion remains uncontaminated, leading to improved image clarity and increased reliability.
Implementation Method 1
a portion of the ohmic contact layer between the source and drain electrodes is etched in a chamber of a dry-etching device
Implementation Method 2
forming a passivation layer on the first substrate which remains in the chamber, the passivation layer covering the portion of the active layer
Data Source
AI summary
A method of fabricating a liquid crystal display device includes the steps of forming a gate electrode and a gate line on a first substrate, forming a gate insulating layer on the gate electrode, forming an active layer on the gate insulating layer and an ohmic contact layer on the active layer, forming source and drain electrodes spaced apart from each other and on the ohmic contact layer, forming a data line that crosses the gate line, etching a portion of the ohmic contact layer between the source and drain electrodes in a chamber of a dry-etching device to expose a portion of the active layer, forming a passivation layer on the first substrate which remains in the chamber, the passivation layer covering the portion of the active layer, forming a pixel electrode connected to the drain electrode, and interposing a liquid crystal layer between the pixel electrode and a second substrate.