GaN LED Micro-cone Formation via Recess-guided Etching
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Solution Overview
Problem
Conventional methods for forming micro-cones on semiconductor films result in irregular sizes, pitches, and arrangements, leading to reduced light extraction efficiency and increased yield loss due to deformation and through-hole formation during the manufacturing process of light emitting diodes.
Innovation Solution
A manufacturing method involving the formation of recesses with specific arrangements and shapes on the semiconductor film surface, which act as etching control points to produce micro-cones of consistent size and closest packed arrangement, preventing deformation and enhancing light extraction efficiency while maintaining yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional chemical etching is performed on the semiconductor film surface, then light extraction efficiency is improved by forming micro-cones, but the sizes, pitches, and arrangements of micro-cones become irregular leading to deformation and through-hole formation
Solution Approach 1:
The patent applies preliminary action by forming recesses on the semiconductor film surface before performing chemical etching. These pre-formed recesses serve as etching control points that guide the subsequent etching process, ensuring that micro-cones form with uniform sizes, pitches, and arrangements. The recesses are created through a first etching process that defines the positions where micro-cones will later form, preventing irregular growth and deformation during the second etching process.
2Illumination intensity
If etching time is increased to enlarge micro-cone size for better light extraction, then light extraction efficiency improves, but through-holes are formed in the semiconductor film reducing yield
Solution Approach 1:
The patent uses preliminary action by pre-defining the maximum depth and position of micro-cones through the first etching process that creates recesses. This preliminary structure acts as a physical stop that prevents over-etching during the second etching process, ensuring micro-cones reach optimal size for light extraction without penetrating through the semiconductor film. This resolves the contradiction by providing a built-in depth control mechanism.
Solution Approach 2:
The patent applies parameter changes by using a two-stage etching process with different etching conditions. The first etching process uses specific parameters to form shallow recesses, while the second etching process uses different parameters to form micro-cones within the recesses. This separation of etching parameters allows precise control over micro-cone depth and size, preventing through-hole formation while achieving optimal light extraction efficiency.
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
The method achieves improved light extraction efficiency by forming micro-cones of consistent size and arrangement, preventing through-hole formation and ensuring a high production yield by controlling the etching process effectively.
Implementation Method 1
by performing wet etching with an alkali solution on the C-plane of a GaN-based semiconductor film
Implementation Method 2
When a plurality of micro-cones are formed in a surface of a semiconductor film by conventional chemical etching
Data Source
Figure 1
Figure 2A~2D
Figure 3A~3D
AI summary
An optical semiconductor element and a manufacturing method thereof that can improve the light extraction efficiency with maintaining the yield. The manufacturing method includes forming a plurality of recesses (60) arranged at equal intervals along a crystal axis of a semiconductor film (20) in a surface of the semiconductor film (20); and performing an etching process on the surface of the semiconductor film (20), thereby forming a plurality of protrusions (22a) arranged according to the arrangement form of the plurality of recesses (60) and deriving from the crystal structure of the semiconductor film (20) in the surface of the semiconductor film (20).