III-Nitride Microdevice Etching With AlN Layer Selectivity Control
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Solution Overview
Problem
The complexity of conventional photoresist strippers used in micro LED fabrication poses challenges in the etching process, particularly in achieving precise control over the etch selectivity between the photoresist layer and the III-nitride epitaxial structure, which affects the formation of micro devices with desired dimensions.
Innovation Solution
A method involving a III-nitride epitaxial structure with specific layer configurations, including a p-type, n-type, AlxIII_others1-xN, and undoped III-nitride layers, where a photoresist layer is patterned and subjected to sequential plasma etching processes to form trenches and micro devices, with the AlxIII_others1-xN layer contributing to amplifying trench effects and reducing photoresist thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional photoresist strippers with complex chemical compositions (4-6 substances) are used, then the photoresist removal process can be performed, but the etch selectivity control between photoresist layer and III-nitride epitaxial structure becomes difficult to achieve
Solution Approach 1:
The patent changes the chemical composition parameters of the photoresist stripper from complex mixtures (4-6 substances) to simplified formulations with specific chemical compositions. This parameter change enables better etch selectivity control while maintaining effective photoresist removal, directly resolving the contradiction between reliability and device complexity.
2Manufacturing precision
If the photoresist layer thickness is reduced to enable precise micro device formation, then the manufacturing precision improves, but the etching process becomes more sensitive and difficult to control
Solution Approach 1:
The patent modifies the chemical parameters of the etching process by using photoresist strippers with specific compositions that provide controlled etching rates. This allows thin photoresist layers to be removed precisely while maintaining ease of process control through optimized chemical reactions, resolving the contradiction between manufacturing precision and ease of operation.
3Manufacturing precision
If sequential plasma etching processes are used to form trenches and micro devices, then the manufacturing precision and etch selectivity improve, but the process time and complexity increase
Solution Approach 1:
The patent segments the etching process into two distinct plasma etching steps: first forming trenches through the photoresist layer, then forming micro devices within those trenches. This segmentation enables precise control over each feature formation stage, achieving high manufacturing precision while managing process time through efficient step-by-step execution.
Solution Approach 2:
The patent optimizes plasma etching parameters (power, pressure, gas flow, temperature) for each sequential step to maximize etching efficiency and precision. By carefully controlling these parameters, the process achieves high manufacturing precision without excessive time loss, resolving the contradiction between precision and time.
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 effectively reduces the photoresist thickness and enhances etch selectivity, allowing for the precise formation of micro devices with lateral lengths less than 100 μm, thereby improving the manufacturing process for micro LEDs.
Implementation Method 1
performing a first plasma etching process to the III-nitride epitaxial structure through the patterned photoresist layer to form a trench
Data Source
AI summary
A method of manufacturing micro devices includes: preparing a III-nitride epitaxial structure including a p-type III-nitride layer, an n-type III-nitride layer on the p-type III-nitride layer, a AlxIII_others1-xN layer on the n-type III-nitride layer, and an undoped III-nitride layer on the AlxIII_others1-xN layer; forming a photoresist layer on the III-nitride epitaxial structure to contact the undoped III-nitride layer; patterning the photoresist layer; performing a first plasma etching process to the III-nitride epitaxial structure through the patterned photoresist layer to form a trench in the etched III-nitride epitaxial structure, in which the trench extends from the etched photoresist layer at least to the AlxIII_others1-xN layer; and performing a second plasma etching process to the etched III-nitride epitaxial structure until the etched III-nitride epitaxial structure is cut into a plurality of micro devices and a top surface of the etched AlxIII_others1-xN layer is exposed.