Flip-Chip LED Structure Without Bonding-Induced Yield Loss
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Solution Overview
Problem
The bonding process in conventional flip-chip light emitting diodes can damage the devices, leading to reduced production yield and efficiency due to the requirement for substrate removal and metallic bonding.
Innovation Solution
A flip-chip light emitting device with an epitaxial structure including a first-type and second-type semiconductor layer, where the second-type semiconductor layer has a cladding and window sublayer, and electrodes are formed for electrical connection, using an AlGaAs-based current spreading layer that improves growth efficiency and reduces production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the bonding process is used to connect the semiconductor structure to the substrate for substrate removal, then the growth substrate can be removed, but the LED may be damaged, reducing production yield
Solution Approach 1:
The patent extracts the growth substrate removal function from the bonding process. By using a loosening layer that enables non-bonding substrate removal, the harmful bonding step is eliminated while retaining the beneficial substrate removal capability. This resolves the contradiction by separating the substrate removal function from the bonding process that causes damage.
Solution Approach 2:
The patent introduces a loosening layer as an intermediary between the growth substrate and the semiconductor structure. This loosening layer enables the growth substrate to be removed without bonding, acting as a mediator that facilitates substrate removal while preventing the damage caused by bonding processes.
2Ease of manufacture
If conventional bonding processes are used for packaging, then electrical connection can be achieved, but the device may be damaged, reducing production efficiency
Solution Approach 1:
The patent extracts the electrical connection function from the bonding process. By forming electrodes directly on the semiconductor structure that extend to the front surface, the electrical connection is achieved without requiring subsequent bonding operations, thereby eliminating the damage risk and improving production efficiency.
Solution Approach 2:
The patent performs the electrical connection action in advance during the semiconductor structure formation process. The electrodes are formed and extended to the front surface before packaging, so that no additional bonding step is needed later, preventing damage and improving productivity.
3Reliability
If the AlGaAs-based current spreading layer is used, then light emitting efficiency and anti-electrostatic discharge performance are improved, but the device structure becomes more complex
Solution Approach 1:
The AlGaAs-based current spreading layer performs multiple functions simultaneously: it provides current spreading, enhances light emitting efficiency, and improves anti-electrostatic discharge performance. By making this single layer multi-functional, the patent reduces the need for additional separate layers, thereby managing device complexity while achieving multiple performance improvements.
Data Source
AI summary
A light emitting device includes an epitaxial structure and first and second electrodes on a side of the epitaxial structure. The epitaxial structure includes a first-type semiconductor layer, an active layer, and a second-type semiconductor layer. The active layer is disposed between the first-type semiconductor layer and the second-type semiconductor layer. The first electrode is disposed on the epitaxial structure to be electrically connected with the first-type semiconductor layer. The second electrode is disposed on the epitaxial structure to be electrically connected with the second-type semiconductor layer. The second electrode is in ohmic contact with a second-type window sublayer of the second-type semiconductor layer.