3D LED Bilayer Etching for Cavity Formation Without LED Damage
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Solution Overview
Problem
Existing methods for forming emissive displays with three-dimensional semiconductor LEDs, such as nanowire or microwire type, face challenges in selectively etching layers without degrading the LEDs, leading to flatting and potential destruction during the etching process.
Innovation Solution
A method involving a bilayer structure where a carbon polymer material is used for the first layer, selectively etchable over the LEDs, and a silicon oxide layer for the second layer, allowing for precise etching and cavity formation without damaging the LEDs, using plasma etching techniques to create cavities for photoluminescent conversion elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single silicon oxide layer is used for etching, then the etching process can be simplified, but the LEDs are degraded and flattened during etching
Solution Approach 1:
The single silicon oxide layer is segmented into two distinct layers: a first silicon oxide layer in direct contact with the LEDs and a second silicon oxide layer above it. This segmentation allows the first layer to protect the LEDs during etching while the second layer enables precise cavity formation, thereby resolving the contradiction between process simplicity and manufacturing precision.
Solution Approach 2:
The first silicon oxide layer acts as an intermediary protective layer between the LEDs and the etching process. It is selectively removed after protecting the LEDs during initial etching, allowing subsequent precise etching of the second layer without damaging the LEDs. This intermediary layer resolves the contradiction by providing temporary protection that can be selectively removed.
2Reliability
If a thick protection layer is used to protect LEDs during etching, then the LEDs are protected from damage, but the device structure becomes more complex and thicker
Solution Approach 1:
The protection function is segmented between two silicon oxide layers with different thicknesses and roles. The first layer provides necessary protection during etching, while the second layer enables precise cavity formation. This segmentation reduces the need for a single thick protection layer, thereby reducing overall device complexity and thickness while maintaining LED protection.
Solution Approach 2:
The solution changes the parameters of the protection structure by using two layers with different thicknesses and etching characteristics rather than a single thick layer. The first layer has optimized thickness for protection, while the second layer has optimized thickness for cavity formation, resolving the contradiction between protection reliability and device complexity.
3Ease of manufacture
If conventional etching methods are used on single layer structures, then the process is simpler, but selective etching of multiple layers is not achieved
Solution Approach 1:
The etching process is segmented into two distinct selective etching steps: first etching the initial silicon oxide layer to expose LEDs, then etching the second silicon oxide layer to form cavities. This segmentation enables precise selective etching of each layer independently, resolving the contradiction between process simplicity and selective etching precision.
Solution Approach 2:
The solution changes the etching parameters by using different etching conditions for each layer. The first etching step uses parameters optimized for removing the first silicon oxide layer, while the second etching step uses parameters optimized for forming precise cavities in the second layer, achieving selective etching precision while maintaining reasonable process simplicity.
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 prevents the degradation of LEDs during etching, enabling the formation of emissive displays with improved selectivity and reducing the thickness or eliminating the need for a protection layer, thus enhancing the manufacturing process for optoelectronic devices.
Implementation Method 1
the first etching step is a plasma etching implemented by means of a fluorocarbon plasma
Implementation Method 2
the second etching is a plasma etching implemented by means of a plasma based on oxygen or on hydrogen
Implementation Method 3
The first layer is deposited by spin coating
Data Source
AI summary
The present description concerns an optoelectronic device manufacturing method, comprising the following steps:forming, on the upper surface side of a first substrate (100), a plurality of LEDs (101), each formed of a three-dimensional semiconductor element;depositing, on the upper surface side of the first substrate, a first layer (205a) made of a first material different from silicon oxide, said first layer (205a) laterally surrounding and covering the LEDs (101) and having a planar upper surface; anddepositing a second layer (205b) made of silicon oxide on the upper surface of the first layer (205a),wherein the first material is such that the first layer (205a) is selectively etchable over the LEDs (101) and that the second layer (205b) is selectively etchable over the first layer.