Semiconductor Light Emitting Device ALD Light Reflection Layer
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Solution Overview
Problem
Existing semiconductor light emitting devices face challenges in achieving even thickness of the light reflection layer, particularly when formed using sputtering methods, which results in uneven light reflection and reduced performance.
Innovation Solution
The use of atomic layer deposition (ALD) to form a light reflection layer that continuously covers the surfaces of the substrate and semiconductor layer structure, ensuring a substantially even thickness and improved light reflection performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sputtering method is used to form light reflection layer, then formation process is simple, but layer thickness becomes uneven across the light emitting element surface
Solution Approach 1:
The patent changes the deposition method parameter from sputtering to atomic layer deposition (ALD). ALD uses sequential chemical reactions with self-limiting surface reactions to deposit conformal thin films, achieving uniform thickness across complex 3D structures including vertical sidewalls, whereas sputtering produces thickness gradients due to line-of-sight deposition geometry
Solution Approach 2:
The patent replaces the physical sputtering process (mechanical/physical vapor deposition) with a chemical vapor deposition process. ALD uses precursor gases that undergo surface-mediated chemical reactions, allowing conformal coating through diffusion and self-limiting surface chemistry rather than physical particle bombardment
2Productivity
If light reflection layer is formed by sputtering, then deposition is faster, but thickness control precision deteriorates
Solution Approach 1:
The patent employs periodic pulsed deposition cycles characteristic of ALD, where precursor gas is introduced, reacts and saturates the surface, then is purged, followed by a second precursor or co-reactor step. This periodic action with self-limiting surface reactions enables precise thickness control at the nanometer and sub-nanometer scale, unlike continuous sputtering which lacks inherent self-regulation
Solution Approach 2:
The patent utilizes the self-limiting nature of ALD surface reactions as an inherent feedback mechanism. When the surface is saturated with adsorbed precursor species, further precursor introduction does not increase deposition rate, automatically limiting the thickness increment per cycle. This self-regulating feedback enables precise thickness control without requiring complex real-time monitoring
3Ease of manufacture
If DBR layer thickness is not precisely adjusted, then manufacturing is easier, but light reflection performance deteriorates
Solution Approach 1:
The patent changes the deposition methodology to ALD, which provides atomic-layer precision thickness control through programmable pulse cycles. Each ALD cycle deposits a precise thickness determined by the number of cycles and precursor dosing, enabling accurate control of DBR quarter-wave layer thicknesses (λ/4) required for high reflectivity at specific wavelengths, whereas sputtering lacks this precision
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
This approach allows for precise adjustment of the light reflection layer thickness, enhancing light extraction efficiency and maintaining consistent performance across the light emitting surface, reducing chromaticity and luminance unevenness.
Implementation Method 1
Surfaces of the substrate, and the semiconductor layer structure, and a side of the connecting member with a light reflection layer are coated using atomic layer deposition
Data Source
AI summary
A method for producing a semiconductor light emitting device includes providing a light emitting element that includes a semiconductor layer structure on a side of a lower surface of a substrate. The light emitting element is placed on a supporting member via a connecting member so that the semiconductor layer structure of the light emitting element faces the supporting member. Surfaces of the substrate, and the semiconductor layer structure, and a side of the connecting member with a light reflection layer are coated using atomic layer deposition so as to expose at least a part of at least one of an upper surface and a side surface of the substrate as a light-extracting region after the light emitting element is placed on the supporting member.