Stacked Gate Electrode Structure for Display Transistor Reliability
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Solution Overview
Problem
Current display apparatuses face challenges in providing high-quality images, particularly with the integration of thin-film transistors and gate electrodes, where the etch rates and material combinations affect the reliability and performance of the display elements.
Innovation Solution
The display apparatus incorporates a substrate with a first thin-film transistor having a silicon semiconductor layer and a second thin-film transistor with an oxide semiconductor layer, featuring a gate electrode structure with stacked layers of different materials, where the upper layer has a higher etch rate than the lower layer, and a specific separation distance configuration to enhance the reliability and performance of the transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layer gate electrode structure is used, then the manufacturing process is simpler, but the etch rate control and material compatibility are insufficient for high-performance display applications
Solution Approach 1:
The gate electrode is divided into multiple layers (first gate electrode layer and second gate electrode layer) with different materials. The first layer uses a material with a first etch rate, while the second layer uses a material with a second etch rate that is different from the first. This segmentation allows each layer to be optimized for specific functions, improving both manufacturing control and device reliability.
Solution Approach 2:
The gate electrode structure employs composite materials by stacking different metallic layers. Each layer is selected for its specific etch rate characteristics, creating a composite structure that achieves optimal performance. The lower layer may provide structural stability while the upper layer enables precise patterning, resolving the contradiction between manufacturing simplicity and performance reliability.
2Area of stationary object
If gate electrode layers are closely stacked without separation distance, then the device area is minimized, but the etching process control and layer differentiation become difficult
Solution Approach 1:
A separation distance is introduced locally between the first gate electrode layer and the second gate electrode layer. This local separation is not uniform across the entire structure but is strategically positioned to enable differential etching control. The separation distance allows the etching process to selectively remove material from specific layers while preserving others, achieving manufacturing precision without significantly increasing the overall device area.
Data Source
AI summary
A display apparatus includes a substrate, a first thin-film transistor arranged on the substrate and including a first semiconductor layer and a first gate electrode, the first semiconductor layer including silicon, and the first gate electrode overlapping the first semiconductor layer, a second thin-film transistor arranged on the substrate and including a second semiconductor layer and a second gate electrode, the second semiconductor layer including an oxide semiconductor, and the second gate electrode overlapping the second semiconductor layer, and a display element electrically connected to the first thin-film transistor, wherein the second gate electrode has a structure in which a lower layer and an upper layer are stacked, the upper layer including a material different from that of the lower layer, and an end of an upper surface of the lower layer is apart by a first separation distance from an end of a lower surface of the upper layer.