Laser-Cut LED Wafer Cleaning with Acid Etching
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Solution Overview
Problem
Current methods for manufacturing nitride semiconductor light-emitting devices face challenges in efficiently removing by-products from laser beam cutting, leading to reduced light extraction efficiency and increased manufacturing costs due to high sapphire or SiC substrate hardness and waste material absorption.
Innovation Solution
A method involving laser beam cutting followed by cleaning with an acid solution, specifically a mixture of phosphoric acid and sulfuric acid at elevated temperatures, to effectively remove by-products and enhance light-emitting efficiency, while minimizing wafer breakage and improving product yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a high energy density laser beam is used to scribe the wafer, then the cutting speed is improved, but waste material is built up along the scribing lines which absorbs light and reduces light extraction efficiency
Solution Approach 1:
The patent extracts and removes the harmful waste material (slag) from the scribing lines using chemical etching processes. The waste material is separated from the substrate surface through selective chemical reactions, allowing the light-emitting device to function without the harmful light-absorbing byproducts.
Solution Approach 2:
The patent converts the harmful waste material into a beneficial process by using chemical etching to selectively remove the slag. The etching process transforms the problematic light-absorbing material into soluble compounds that can be washed away, turning a harmful byproduct into part of the cleaning solution's function.
2Manufacturing precision
If mechanical scribing with diamond scribe is used to separate the wafer, then the cutting precision is improved, but the manufacturing time is increased and diamond consumption is high
Solution Approach 1:
The patent replaces the mechanical scribing process with a chemical etching process. Instead of using a diamond scribe to mechanically cut through the hard sapphire or SiC substrate, the invention uses chemical reactions to selectively remove material along predetermined scribing lines, achieving similar precision without the mechanical wear and time constraints.
Solution Approach 2:
The patent changes the fundamental parameter of the cutting process from mechanical force to chemical reactivity. By controlling the etching solution's chemical properties and exposure time, the process achieves precise cutting without the mechanical limitations of diamond scribing, thereby improving manufacturing efficiency.
3Object-generated harmful factors
If dry etching method is used to remove by-products, then the light extraction efficiency is improved, but the device is damaged and product yield is reduced
Solution Approach 1:
The patent changes the etching method from physical (dry etching) to chemical (wet etching). The chemical etching process uses liquid solutions that selectively dissolve waste material without the high-energy particle bombardment that damages the device structure, thereby maintaining product yield while still removing by-products effectively.
Solution Approach 2:
The patent introduces a chemical intermediary (etching solution) that mediates between the waste material and the removal process. The solution selectively reacts with the slag and by-products, dissolving them without directly impacting the delicate device structures, thus protecting device integrity while achieving effective cleaning.
4Object-generated harmful factors
If KOH cleaning solution is used to remove by-products, then some debris is removed, but the slag cannot be removed completely and efficiently
Solution Approach 1:
The patent uses a composite cleaning approach combining multiple chemical agents and processes. Instead of relying on a single KOH solution, the invention employs sequential or combined etching solutions with different chemical properties that target various types of contaminants, achieving complete slag removal while maintaining high cleaning efficiency.
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
The acid solution cleaning method significantly enhances light extraction efficiency, reduces cleaning time, and prevents wafer breakage, thereby increasing product yield and reducing manufacturing costs.
Implementation Method 1
Another separation method involves scribing the wafer by a high energy density laser beam ablating the bonds between atoms of the substrate
Implementation Method 2
cleaning the light-emitting wafer by an acid solution to remove by-products resulted from the laser beam cutting
Data Source
AI summary
A method for manufacturing a light-emitting device comprising the steps of cutting a light-emitting unit by a laser beam, and cleaning the light-emitting unit by an acid solution to remove by-products resulted from the laser cutting.