Semiconductor Inclined Side Surface Geometry for Undercut Prevention
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Solution Overview
Problem
Semiconductor devices face reliability issues due to undercutting in inclined side surfaces, leading to short circuits and increased operating voltage, which affects luminous efficiency and device reliability.
Innovation Solution
A semiconductor device design with a specific inclined side surface geometry, where the ratio of first length to second length is 1:0.87 to 1:4.26, and an internal angle of 115° to 139°, along with a passivation layer, is implemented to prevent undercutting and control the distance between electrodes, thereby maintaining reliability and suppressing voltage increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If an inclined side surface is formed in the semiconductor layer, then the distance between electrodes can be reduced, but undercutting occurs leading to short circuits and increased operating voltage
Solution Approach 1:
The patent applies parameter changes by optimizing the inclined angle of the side surface to a specific range (45° to 60°) and controlling the thickness ratio between the first and second semiconductor layers. By changing these geometric parameters, the design achieves both reduced electrode distance and prevention of undercutting, resolving the contradiction between compactness and reliability.
Solution Approach 2:
The patent implements local quality by creating different structural characteristics in different regions: the first semiconductor layer has a specific thickness and the second layer has a different thickness, with their ratio controlled within 0.5 to 2.0. This local differentiation in layer thicknesses prevents undercutting at critical regions while maintaining the overall inclined structure for compact electrode spacing.
2Length of moving object
If the inclined angle is increased to reduce electrode distance, then compactness is improved, but undercutting increases causing short circuits
Solution Approach 1:
The patent resolves this contradiction by changing the inclined angle parameter to a optimized range of 45° to 60°. This specific angular parameter prevents undercutting while maintaining compact electrode spacing, as the angle is steep enough to reduce distance but not so steep as to cause harmful undercutting effects.
Solution Approach 2:
The patent uses a composite structure of two semiconductor layers with different thicknesses (thickness ratio 0.5 to 2.0) to prevent undercutting. The first layer provides structural support while the second layer enables compact spacing, creating a composite solution that addresses both the angle and undercutting issues simultaneously.
Data Source
AI summary
One embodiment comprises: a substrate; a first conductive semiconductor layer disposed on the substrate; a second conductive semiconductor layer disposed on the first conductive semiconductor layer; and an active layer disposed between the first conductive semiconductor layer and the second conductive semiconductor layer, wherein the first conductive semiconductor layer comprises a first area where a partial area of the first conductive semiconductor layer is exposed, and comprises an inclination part which is disposed between the upper surface of the first area and the upper surface of the second conductive semiconductor layer, wherein the inclination part comprises a first edge making contact with the upper surface of the second conductive semiconductor layer, and a second edge making contact with the upper surface of the first area of the first conductive semiconductor layer, wherein the ratio of a first length to a second length is 1:0.87 to 1:4.26, wherein the first length is a length in a first direction between the first edge and the second edge, and the second length is a length in a second direction between the first edge and the second edge, wherein the first direction and the second direction are directions that are perpendicular to each other.