Fine Pattern Formation on Semiconductor Light Emitting Devices
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Solution Overview
Problem
Current etching processes, such as dry etching, damage semiconductor surfaces like p-type GaN, leading to conductivity type conversion and defects in nitride semiconductor light emitting devices, while wet etching struggles with precise patterning and etching specific planes, limiting light-extraction efficiency.
Innovation Solution
A method combining dry and wet etching to form fine patterns on c-plane hexagonal semiconductor crystals, where dry etching is followed by horizontal wet etching to minimize damage and expand patterns, resulting in unique crystal plane sidewalls and bottom surfaces, enhancing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dry etching is used to form fine patterns, then precise and reproducible patterns can be obtained, but the semiconductor surface suffers damage and conductivity type conversion occurs
Solution Approach 1:
A thin film (intermediary layer) is deposited on the p-type GaN layer before dry etching. This intermediary layer absorbs the physical bombardment damage from ions and neutral atoms during dry etching, preventing direct damage to the p-type GaN surface. After etching, the thin film is removed, leaving the p-type GaN layer intact without conductivity type conversion.
Solution Approach 2:
The thin film is deposited in advance (preliminary action) before the dry etching process. This preliminary protective layer is specifically designed to withstand the etching conditions and protect the underlying p-type GaN from damage during the subsequent etching step.
2Object-affected harmful factors
If wet etching is used to avoid surface damage, then the semiconductor surface remains intact, but precise patterning and etching of specific planes become difficult
Solution Approach 1:
The invention merges two previously separate processes: first, dry etching is used to achieve precise patterning through the mask, and second, wet etching is used to selectively remove the thin film from exposed areas. This combination allows both precise patterning and avoidance of surface damage, as each process contributes its strength to the overall solution.
3Manufacturing precision
If excessive etching depth is applied, then fine patterns can be formed, but the photoresist mask is separated and pattern integrity is lost
Solution Approach 1:
The thin film serves as an intermediary sacrificial layer that allows deeper etching without compromising mask integrity. The mask remains on the surface protecting the p-type GaN, while the thin film can be completely removed through wet etching, enabling sufficient pattern depth to be achieved.
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 reduces damaged areas, improves electrical properties, and increases light extraction efficiency by forming precise, stable fine patterns that attenuate total reflection, enhancing the performance of semiconductor light emitting devices.
Implementation Method 1
the dry etching has limitations in that properties of a semiconductor surface easily deteriorate due to a physical bombardment with ions or neutral atoms during the dry etching
Implementation Method 2
wet-etching the semiconductor crystal including the first fine pattern to expand the first fine pattern in a horizontal direction to form a second fine pattern
Data Source
AI summary
A method of forming a fine pattern begins with providing a c-plane hexagonal semiconductor crystal. A mask having a predetermined pattern is formed on the semiconductor crystal. The semiconductor crystal is dry-etched by using the mask to form a first fine pattern on the semiconductor crystal. The semiconductor crystal including the first fine pattern is wet-etched to expand the first fine pattern in a horizontal direction to form a second fine pattern. The second fine pattern obtained in the wet-etching the semiconductor crystal has a bottom surface and a sidewall that have unique crystal planes, respectively. The present fine-pattern forming process can be advantageously applied to a semiconductor light emitting device, particularly, to a phonic crystal structure required to have fine patterns or a structure using a surface plasmon resonance principle.