Comb-Electrode Semiconductor Light Emitter With Separate Bonding Pads
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Solution Overview
Problem
The existing semiconductor light-emitting devices with comb tooth-shaped electrodes face challenges in securing a large bonding area, making the packaging process difficult and affecting the uniformity of light emission distribution.
Innovation Solution
The semiconductor light-emitting device is designed with an n-type AlGaN-based semiconductor layer, an active layer with a comb tooth shape, and p-type and n-type contact electrodes, along with a protective dielectric layer, to enhance light emission distribution and simplify packaging by forming pad electrodes and openings with a comb tooth shape, improving current uniformity and bonding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the electrodes are formed in a comb tooth shape to suppress unevenness in luminescence, then the light emission distribution is improved, but the bonding area on the electrodes becomes small making packaging difficult
Solution Approach 1:
The device is divided into two distinct electrode systems: comb tooth-shaped contact electrodes for current injection and large-area pad electrodes for bonding. The contact electrodes are segmented into multiple fingers that extend toward the active layer, while the pad electrodes provide consolidated large-area bonding surfaces. This segmentation allows each component to fulfill its specific function without compromise.
Solution Approach 2:
The solution transitions from a two-dimensional planar electrode structure to a three-dimensional multi-layer structure. Contact electrodes are formed in the lower layer extending toward the active layer, while pad electrodes are formed in the upper layer on the protective layer. This vertical dimensionality change allows both small contact areas and large bonding areas to coexist without spatial conflict.
2Manufacturing precision
If the contact electrodes are formed in a comb tooth shape to improve light emission uniformity, then the luminescence evenness is improved, but the packaging process becomes more difficult
Solution Approach 1:
The contact electrodes are segmented into multiple comb fingers that provide uniform current distribution across the active layer, improving luminescence evenness. Simultaneously, separate pad electrodes are provided as consolidated bonding surfaces, simplifying the packaging process by providing adequate bonding area despite the segmented contact electrode structure.
Solution Approach 2:
The protective layer acts as an intermediary between the comb tooth-shaped contact electrodes and the pad electrodes. It provides a planar bonding surface for the pad electrodes while allowing the underlying contact electrodes to maintain their comb tooth configuration for uniform current injection. This intermediary layer decouples the conflicting structural requirements.
3Manufacturing precision
If the pad openings are formed in a comb tooth shape to match the contact electrodes, then the current uniformity is enhanced, but the bonding area is reduced
Solution Approach 1:
The pad openings in the protective layer are segmented into multiple regions corresponding to the comb fingers, allowing current to enter each finger uniformly. This segmentation enhances current distribution evenness while the pad electrodes themselves maintain large continuous bonding areas on the protective layer surface, resolving the conflict between opening shape and bonding area.
Data Source
AI summary
A device includes: an active layer provided in a first comb tooth region on an n-type semiconductor layer; a p-type semiconductor layer provided on the active layer; an n-side contact electrode provided in a second comb tooth region on the n-type semiconductor layer; a p-side contact electrode provided in a third comb tooth region on the p-type semiconductor layer; a protective layer having a p-side pad opening provided in a fourth comb tooth region on the p-side contact electrode, having an n-side pad opening provided in a fifth comb tooth region on the n-side contact electrode, and made of a dielectric material; a p-side pad electrode connected to the p-side contact electrode in the p-side pad opening; and an n-side pad electrode connected to the n-side contact electrode in the n-side pad opening.