Micro-LED Groove Electrode Structure for High-Yield Transfer
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Solution Overview
Problem
The challenge of achieving high-yield transfer of micro-LEDs is hindered by the fragility of the semiconductor layer sequence after substrate removal, leading to structural instability and potential damage during mass transfer processes.
Innovation Solution
A micro-LED design featuring a semiconductor layer sequence with a groove and metal electrodes, where the first-type semiconductor layer acts as a support layer, and a dielectric passivation layer is used to reinforce the structure, along with a specific metal electrode configuration to enhance holding strength and reduce stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the substrate is removed and the semiconductor layer sequence is thinned to improve light emission and reduce weight, then the brightness and energy efficiency are improved, but the structural strength and reliability deteriorate, making the micro-LED fragile and difficult to transfer
Solution Approach 1:
The invention divides the semiconductor layer sequence into distinct segments: a first semiconductor layer with a groove formed therein, and a second semiconductor layer. This segmentation allows the groove to be positioned strategically to reduce stress concentration while maintaining light emission pathways, thus resolving the contradiction between brightness and structural strength.
Solution Approach 2:
The invention employs a composite structure combining semiconductor materials with metal electrodes and dielectric passivation layers. The metal electrodes provide mechanical reinforcement and electrical connection, while the dielectric passivation layer offers protection and insulation. This composite approach maintains structural integrity even when the semiconductor layer is thinned for improved light emission.
2Use of energy by moving object
If the semiconductor layer sequence is thinned or substrate is removed to improve light extraction and reduce power consumption, then the energy efficiency is improved, but the micro-LED becomes very fragile and transfer yield decreases
Solution Approach 1:
The groove is formed in the first semiconductor layer before final device assembly and transfer operations. This preliminary structural preparation creates a stress-relief feature that prevents fracture during subsequent thinning, substrate removal, and transfer processes, thereby maintaining reliability while enabling energy efficiency improvements.
Solution Approach 2:
The metal electrodes and dielectric passivation layer act as intermediary elements between the thinned semiconductor layers. These intermediaries provide mechanical support and protection during transfer operations, allowing the device to maintain structural integrity even when the active semiconductor region is minimized for energy efficiency.
3Stability of the object's composition
If metal electrodes are added to reinforce the structure and improve holding strength, then the structural stability is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The invention merges multiple functions into the metal electrodes: they provide structural reinforcement to prevent fracture, serve as electrical contacts for current injection, and act as anchoring points for dielectric passivation layers. This consolidation reduces the need for separate components, thereby limiting the increase in device complexity while achieving structural stability.
Solution Approach 2:
The metal electrodes are designed to perform multiple functions simultaneously: mechanical support, electrical conduction, and stress distribution. This multi-functionality approach allows a single structural element to address multiple requirements, avoiding the need for additional specialized components and keeping manufacturing complexity manageable.
Data Source
AI summary
A micro light-emitting diode is provided, which includes a semiconductor layer sequence. A back side of the semiconductor layer sequence is provided with a first metal electrode and a second metal electrode. The back side includes a first mesa in a groove, a second mesa, and a groove sidewall between them. A first metal electrode is disposed on the first mesa. A first-type semiconductor layer in the semiconductor layer sequence acts as a support layer. A distance from a bottom surface of the groove to a front side of the semiconductor layer sequence is not greater than 4 micrometers. On a horizontal projection plane of a longer side of the support layer, the semiconductor layer sequence is at least partially penetrated by the groove. The first metal electrode extends along the longer side of the support layer, and specifically extends from the groove sidewall to the second mesa.