Micro-LED Electrode Layout With Inverted Tapered Structure
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Solution Overview
Problem
The transfer process of LED elements from a semiconductor substrate to a display device substrate is inefficient and prone to defects such as misalignment and flipping, leading to increased production costs and defective pixels due to the high cost of semiconductor substrates and difficulties in precise placement.
Innovation Solution
A light-emitting device with an inverted tapered structure between the n-type and p-type semiconductor layers, minimizing defects during electrode connection and improving processing stability, thereby reducing defective connections and enhancing productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LED elements are transferred from semiconductor substrate to display device substrate, then light-emitting function is achieved, but misalignment and flipping defects occur leading to increased production costs
Solution Approach 1:
The inverted tapered structure is formed on the semiconductor substrate before LED element transfer. This preliminary structural preparation ensures that when LED elements are later transferred and connected to electrodes, the tapered structure guides proper alignment and prevents misalignment defects, thereby improving both reliability and manufacturing precision
Solution Approach 2:
The inverted tapered structure acts as an intermediary element between the LED element and the electrode. It provides a geometric guide that facilitates proper positioning and connection, preventing both misalignment and flipping defects during the transfer process while maintaining connection stability
2Reliability
If semiconductor substrate is used for LED element growth, then high quality LED elements are produced, but high substrate cost increases production cost
Solution Approach 1:
The inverted tapered structure is extracted or formed separately on the semiconductor substrate, allowing the substrate to be reused or replaced more easily. This separation enables the use of cost-effective substrates while maintaining the quality benefits of controlled LED element growth
Solution Approach 2:
The semiconductor substrate with the inverted tapered structure can be designed as a disposable or single-use component. After LED elements are transferred to the display device substrate, the semiconductor substrate can be discarded, reducing the need for expensive substrate reuse or recovery processes
3Productivity
If transfer process is performed to move LED elements, then display device assembly is completed, but flipping defects occur reducing productivity
Solution Approach 1:
The inverted tapered structure introduces asymmetry to the otherwise symmetric LED element and electrode interface. This asymmetric geometry provides a preferred orientation that prevents flipping during transfer, ensuring that LED elements can only be connected in the correct orientation, thereby improving both reliability and productivity
Data Source
AI summary
A display device includes a substrate; a thin-film transistor including an active area, a source electrode, and a drain electrode disposed on the substrate; a passivation layer disposed on the thin-film transistor; a light-emitting device disposed on the passivation layer and including a first electrode, a second electrode, and a structure disposed between the first electrode and the second electrode; a planarization layer disposed on the passivation layer to cover a side surface of the light-emitting device; a pixel electrode electrically connected to the drain electrode of the thin-film transistor through a first contact hole in the passivation layer and the planarization layer, and electrically connected to the first electrode through a second contact hole in the planarization layer; and a common electrode electrically connected to the second electrode through the second contact hole in the planarization layer.