LED Reflective Layer and Bonding Pad Structure for Smaller Chips
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Solution Overview
Problem
Current semiconductor light emitting devices face challenges in improving optical characteristics and productivity, particularly in reducing size and increasing the number of light emitting structures per substrate, which affects their efficiency and cost-effectiveness.
Innovation Solution
The semiconductor light emitting device incorporates a structure with a first and second conductivity type semiconductor layer, an active layer, a reflective layer, and an insulating spacer, where the reflective layer is made of materials like chrome, nickel, or noble metals that are not etched by aqueous solutions, and bonding pads with a shell shape, allowing for reduced size and increased production efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the size of the light emitting device is reduced, then the number of devices per substrate increases, but the manufacturing complexity increases
Solution Approach 1:
The device is divided into multiple functional layers (semiconductor layers, active layer, electrode layer, reflective layer, insulating layer) that can be independently formed and optimized. This segmentation allows each layer to be processed separately using standard semiconductor fabrication techniques, enabling scaling to higher device densities without proportionally increasing overall manufacturing complexity
Solution Approach 2:
The patent transitions from planar two-dimensional structures to three-dimensional vertical stacking of multiple layers. By arranging functional components in the vertical dimension rather than only in the horizontal plane, the device achieves higher integration density while maintaining compatibility with existing fabrication processes that work in multiple dimensions
2Ease of manufacture
If conventional etching solutions are used, then the manufacturing process is simple, but the reflective layer is damaged
Solution Approach 1:
The etching process parameters are changed by selecting an etching solution with different chemical properties (aqueous ammonia instead of conventional solutions). This parameter change allows the etching to proceed effectively on semiconductor and insulating materials while being selective and non-damaging to the reflective layer, thus maintaining both manufacturing simplicity and layer integrity
Solution Approach 2:
The aqueous ammonia etching solution acts as a selective intermediary that differentially etches various materials in the device structure. It selectively removes unwanted materials while leaving the reflective layer intact, enabling precise pattern formation without damaging sensitive components
3Ease of manufacture
If the bonding pad width is uniform, then the manufacturing process is simple, but the electrical performance deteriorates
Solution Approach 1:
The bonding pad structure implements local quality variations with different widths at different locations. The pad has a wider region for mechanical bonding and a narrower region for electrical connection, optimizing both mechanical strength and electrical performance. This local differentiation is achieved through controlled etching and deposition processes that can accommodate varying dimensions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances optical characteristics, reduces the size of the light emitting device, and increases the number of devices that can be produced from a single substrate, thereby improving productivity and cost-effectiveness.
Implementation Method 1
a reflective layer formed on a part of a top surface of the electrode layer
Data Source
AI summary
A semiconductor light emitting device includes a first conductivity type semiconductor layer, a second conductivity type semiconductor layer arranged on the first conductivity type semiconductor layer, an active layer, an electrode layer formed on a top surface of the second conductivity type semiconductor layer, a reflective layer formed on a part of a top surface of the electrode layer, a bonding pad formed on a top surface of the reflective layer, an insulating layer formed on another part of the top surface of the electrode layer, and an insulating spacer conformally formed along a surface of the substrate. The reflective layer includes a material that is not etched by an aqueous solution including one of tetramethyl ammonium hydroxide (TMAH), KOH, NaOH, and NH4OH and the bonding pad has a shell shape including a part of which the width gradually decreases as the part distances from the reflective layer.