Laser Severing Brittle Flat Materials via Thermal Shock
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for dicing brittle flat materials, such as wafers, are inefficient and prone to errors due to the need for deep notches and mechanical stress, leading to contamination and reduced yield.
Innovation Solution
A method that uses shallow notches or material modifications produced by lasers or etching techniques, followed by thermally-induced mechanical stresses to separate the material, allowing for faster and more precise separation with reduced contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If deep notches are produced by laser ablation to ensure complete separation, then separation reliability is improved, but processing time increases and material contamination occurs
Solution Approach 1:
The method creates shallow notches in advance that serve as stress concentration points, preparing the material for subsequent fracture without requiring deep removal. These preliminary shallow notches (depth 1-10 μm) are sufficient to initiate cracks when thermal stress is applied, eliminating the need for deep notching while ensuring complete separation.
Solution Approach 2:
The invention replaces mechanical fracture methods with thermally-induced mechanical stresses. Instead of applying direct mechanical force to propagate cracks from deep notches, the method uses controlled thermal expansion and contraction to generate tensile stresses that propagate cracks from shallow notches, reducing processing time and contamination.
2Reliability
If deep notches are produced by laser ablation, then separation reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The invention changes the critical parameter from notch depth to stress application method. Instead of increasing notch depth (which requires complex laser systems and long processing times), the method maintains shallow notches (1-10 μm depth) and achieves separation through controlled thermal stress application, simplifying the overall system while maintaining reliability.
3Productivity
If mechanical forces are applied to propagate cracks from notches, then separation is achieved, but fracture flaws and contamination occur
Solution Approach 1:
The invention replaces direct mechanical force application with thermally-induced stresses. By using controlled heating and cooling cycles to generate tensile stresses that propagate cracks from shallow notches, the method achieves clean separations without the fracture flaws and particle contamination associated with mechanical fracture methods.
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 method enables efficient and high-quality separation of wafers into chips with minimized particle release and fracture flaws, improving time efficiency and edge quality.
Implementation Method 1
traces are produced which extend along intended dividing lines... by material removal or by material modification... The traces can be produced either by material removal or by material modification of the flat material
Implementation Method 2
The traces can be produced either by material removal or by material modification of the flat material
Implementation Method 3
the traces are produced... followed by a second laser radiation or beam 7, which produces thermally-induced mechanical stresses that lead to the production of separation cracks from the traces
Implementation Method 4
followed by a second laser radiation or beam 7, which produces thermally-induced mechanical stresses
Data Source
AI summary
The invention relates to a method for severing brittle flat materials, for example made of glass, ceramic, silicon, gallium arsenide or sapphire. The method includes the step of heating the flat material along desired dividing lines below its melting temperature by means of a laser alone desired separating lines. Then the material is shocked by a coolant jet so that a thermally-induced mechanical stress difference brings about a material separation. Traces are formed in the flat material in advance along the separation lines, so that the flat material has a lower breaking stress along the traces than in the unworked flat material, and the separation with the laser takes place along these traces.