Sapphire Substrate Removal via Grinding and Plasma Etching
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Solution Overview
Problem
The conventional laser lift-off method for removing growth substrates in LED manufacturing is inefficient for large LED dies, leading to non-uniformity, damage, and increased manufacturing time and cost, as it requires high power density and is not suitable for advanced applications.
Innovation Solution
A method involving grinding and dry or wet etching to remove the growth substrate, where the sapphire substrate is first ground to a specified thickness and then further reduced using inductively coupled plasma or wet etching, eliminating the need for laser beams and allowing for larger LED die sizes without damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser lift-off method is used to remove growth substrate, then substrate removal is achieved, but manufacturing efficiency decreases and damage occurs for large LED dies
Solution Approach 1:
The patent replaces the laser-based thermal field system with a chemical etching system using inductively coupled plasma. This substitution eliminates the need for high power density laser beams that cause damage to large LED dies, while achieving uniform substrate removal through controlled chemical reactions with the sapphire substrate.
Solution Approach 2:
The patent changes the fundamental parameter of substrate removal from thermal ablation (laser) to chemical etching (plasma). By using inductively coupled plasma to generate reactive species that chemically react with the sapphire substrate, the process achieves uniform removal without the localized high energy density that causes damage in laser methods.
2Reliability
If laser lift-off method is used, then substrate removal is achieved, but manufacturing cost and time increase
Solution Approach 1:
The patent replaces the sequential laser heating and mechanical peeling process with a direct chemical etching process using inductively coupled plasma. This substitution eliminates the time-consuming laser heating phase and enables more efficient substrate removal through controlled chemical reactions that proceed at optimized rates.
Solution Approach 2:
The inductively coupled plasma etching process maintains continuous useful action by sustaining a stable plasma environment that continuously generates reactive species for substrate removal. This continuous chemical reaction process is more efficient than the pulsed laser heating followed by mechanical separation, reducing overall manufacturing cycle time.
3Ease of manufacture
If high power density laser is used for substrate removal, then lift-off is achieved, but LED die damage occurs
Solution Approach 1:
The patent replaces the high power density laser system with an inductively coupled plasma system that uses chemical etching instead of thermal ablation. This substitution eliminates the harmful localized heating and mechanical stress that cause LED die damage, while maintaining substrate removal feasibility through controlled chemical reactions with the sapphire substrate.
Solution Approach 2:
The patent introduces an intermediary plasma environment that mediates the substrate removal process. The inductively coupled plasma generates reactive species that chemically interact with the sapphire substrate, providing a gentle and controlled removal mechanism that avoids the direct high energy density impact of laser beams on the LED die structure.
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 enables efficient and uniform removal of growth substrates, reducing manufacturing time and cost, and is suitable for high-power LED applications by avoiding the limitations of the laser lift-off process.
Implementation Method 1
the sapphire substrate is first ground to a specified thickness and then further reduced using inductively coupled plasma or wet etching
Implementation Method 2
the sapphire substrate is first ground to a specified thickness
Data Source
AI summary
A Light-Emitting Diode (LED) is formed on a sapphire substrate that is removed from the LED by grinding and then etching the sapphire substrate. The sapphire substrate is ground first to a first specified thickness using a single abrasive or multiple abrasives. The remaining sapphire substrate is removed by dry etching or wet etching.