Display Transistor Capacitor Layout for Threshold Voltage Stability
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Solution Overview
Problem
Display devices face challenges in maintaining a stable threshold voltage of transistors due to variations in parasitic capacitance, which can be exacerbated by misalignment of components.
Innovation Solution
The display device incorporates a compensation pattern on the active layer to maintain a constant parasitic capacitance around the first transistor, ensuring stable threshold voltage through a specific electrode configuration and capacitor design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transistor is designed with standard electrode configuration, then the device complexity is reduced, but the threshold voltage stability deteriorates due to parasitic capacitance variations
Solution Approach 1:
The gate electrode is divided into multiple segments (first gate electrode and second gate electrode) positioned at different locations relative to the semiconductor region. This segmentation allows independent control of parasitic capacitance at different locations, enabling compensation for threshold voltage variations while maintaining a manageable structural complexity through modular design.
Solution Approach 2:
A compensation electrode is introduced as an intermediary element between the gate electrode and the semiconductor region. This compensation electrode acts as a mediator to adjust and compensate for parasitic capacitance effects, thereby stabilizing the threshold voltage without requiring complete redesign of the fundamental transistor structure.
2Reliability
If misalignment of components occurs during manufacturing, then the manufacturing precision is reduced, but the threshold voltage stability should be maintained
Solution Approach 1:
The gate electrode and compensation electrode are pre-positioned at specific locations that anticipate potential misalignment issues. By establishing the electrode configuration before final assembly, the design inherently compensates for alignment variations that may occur during manufacturing, ensuring threshold voltage stability without requiring ultra-precise alignment.
Solution Approach 2:
The electrode configuration parameters (such as electrode width, spacing, and position) are optimized to be tolerant of manufacturing variations. By designing with parameter ranges that accommodate expected misalignment, the system maintains threshold voltage stability even when component alignment precision is reduced.
Data Source
AI summary
A display device includes: a first metal layer on a substrate; an active layer on the first metal layer; a second metal layer on the active layer; a third metal layer on the second metal layer; a first transistor including: a semiconductor region at the active layer; a drain electrode on a first side of the semiconductor region; a source electrode on a second side of the semiconductor region; and a gate electrode at the second metal layer; a first capacitor including: a first capacitor electrode at the first metal layer, and electrically connected to the gate electrode of the first transistor; and a second capacitor electrode integral with the source electrode of the first transistor, and on a third side of the semiconductor region of the first transistor; and a compensation pattern at the active layer, and on a fourth side of the semiconductor region of the first transistor.