Semiconductor Light Emitting Device Pad Electrode Stopper
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Solution Overview
Problem
Semiconductor light emitting devices face issues with reduced light output and productivity due to pad electrode placement, which absorbs light and causes damage during electrical/optical property inspection, leading to reduced yield and light emission efficiency.
Innovation Solution
Incorporating a stopper member with a semicircular arc shape around the pad electrode to securely hold probe needles during inspection, preventing protection film damage and allowing for smaller pad electrode diameters without compromising bonding strength or light emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the pad electrode is arranged on the surface of the substrate to supply current to semiconductor layers, then current conduction is achieved, but light absorption increases and light output decreases
Solution Approach 1:
The pad electrode is moved from the front surface (light emission side) to the back surface of the substrate. This spatial repositioning in another dimension allows current supply functionality to be maintained while eliminating the harmful light absorption effect on the light emission path.
2Reliability
If the pad electrode is arranged on the substrate surface, then electrical connection is established, but the area for semiconductor layers is reduced
Solution Approach 1:
By relocating the pad electrode to the back surface of the substrate, the front surface area is fully available for semiconductor layer formation, maximizing the light emitting area while maintaining electrical connection functionality through the back surface arrangement.
3Productivity
If the pad electrode diameter is reduced to suppress light absorption, then light emission efficiency improves, but probe needle alignment during inspection becomes difficult
Solution Approach 1:
The pad electrode structure is segmented into two distinct parts: a small-diameter electrode portion for optimal light emission efficiency and a larger stopper member portion for probe needle alignment during inspection. This segmentation allows each part to fulfill its specific function without compromise.
Solution Approach 2:
The stopper member acts as an intermediary element between the small pad electrode and the probe needle. It provides a larger target area for accurate probe needle positioning while the small electrode portion maintains high light emission efficiency, effectively mediating between the two conflicting requirements.
4Device complexity
If the pad electrode is arranged on the same side as the light emitting portion, then device structure is simplified, but yield is reduced due to protection film damage during inspection
Solution Approach 1:
The pad electrode and stopper member are positioned on the back surface of the substrate, opposite to the light emitting portion. This spatial separation in another dimension prevents probe needle-induced damage to the protection film during inspection while maintaining structural simplicity.
Data Source
AI summary
The object of the invention is to improve the visual inspection yield of a semiconductor light emitting device. To achieve the object, a semiconductor light emitting device includes a semiconductor layer, a pad electrode on the layer, and a protection film covering at least the layer. The device includes at least one stopper arranged on a peripheral part of the pad electrode surface away from the film. The stopper has a semicircular arc shape opening toward the center of the pad electrode. In electrical/optical property inspection, if sliding on the pad electrode, a probe needle can be guided into the concave surface of the semicircular arc shape. The stopper can reliably hold the needle. It is avoidable that the needle contacts the film. It is preferable that each of positive/negative electrodes have the pad electrode, and a pair of stoppers be arranged in positions on the electrodes facing each other.