Nitride Semiconductor Electrode Recognition and Thermal Management
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Solution Overview
Problem
The challenge lies in mounting nitride semiconductor light-emitting elements on GaN substrates with hexagonal crystals, which have irregular corners and are transparent, making automatic recognition and high-yield production difficult, especially when operating at high temperatures and requiring high output powers, due to insufficient heat dissipation and electrode recognition issues.
Innovation Solution
A nitride semiconductor device with a p-side electrode structure that includes a first p-side electrode layer exposed under a second p-side electrode layer, allowing for easier recognition and mounting, and an insulating film with striped openings to enhance visibility and heat dissipation, facilitating the use of a junction-up mounting technique for improved yield and reduced manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If conventional mass-mounting machines sense the four corners of chips for automatic mounting, then mounting automation is achieved, but yield decreases due to irregular hexagonal chip corners and GaN wafer transparency
Solution Approach 1:
The patent applies color/reflectivity changes by making the uppermost layer of the first p-side electrode layer have different hue, saturation, and/or lightness from the second p-side electrode layer. This creates optical contrast that enables automatic recognition systems to distinguish chip features despite the transparency of GaN wafers and irregular hexagonal corners, thereby maintaining high mounting yield while achieving automation
Solution Approach 2:
The patent employs asymmetry by creating an asymmetric electrode structure where the first p-side electrode layer is partially exposed under the second p-side electrode layer. This asymmetric configuration provides distinctive recognition features that help automatic mounting systems identify and position chips accurately, overcoming the symmetry issue of regular rectangular patterns and the irregularity of hexagonal corners
2Power
If light-emitting devices operate at high temperatures to provide high output power, then output power increases, but heat dissipation becomes insufficient causing end facet deterioration
Solution Approach 1:
The patent applies segmentation by dividing the p-side electrode into two distinct layers: the first p-side electrode layer that contacts the p-type region and the second p-side electrode layer stacked on top. This segmented structure increases the surface area for heat dissipation and allows better thermal management, enabling the device to operate at high temperatures without end facet deterioration while maintaining high output power
Solution Approach 2:
The patent utilizes dimensionality change by stacking the second p-side electrode layer on top of the first layer, creating a vertical thermal conduction path. This three-dimensional electrode structure provides additional heat dissipation pathways in the vertical dimension, complementing the horizontal heat dissipation and enabling effective thermal management at high operating temperatures
Data Source
AI summary
A nitride semiconductor device according to the present invention includes a n-GaN substrate 10 and a semiconductor multilayer structure arranged on the principal surface of the n-GaN substrate 10 and including a p-type region, an n-type region and an active layer between them. An SiO2 layer 30 with an opening and a p-side electrode, which makes contact with a portion of the p-type region of the semiconductor multilayer structure, are arranged on the upper surface of the semiconductor multilayer structure. An n-side electrode 36 is arranged on the back surface of the substrate 10. The p-side electrode includes a p-side contact electrode 32 that contacts with the portion of the p-type region and a p-side interconnect electrode 34 that covers the p-side contact electrode 2 and the SiO2 layer 30. Part of the p-side contact electrode 32 is exposed under the p-side interconnect electrode 34.