Laser Frangible Layer for Crack-Free Semiconductor Chip Division
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Solution Overview
Problem
Mechanical sawing of semiconductor wafers can induce cracks in semiconductor chips, leading to breakage during transfer and handling.
Innovation Solution
A method involving the formation of a frangible layer in a semiconductor substrate using a laser beam, followed by back-side polishing to fracture the substrate into chips, minimizing crack formation and improving chip strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mechanical sawing is used to cut the semiconductor wafer, then the wafer can be divided into individual chips, but cracks are induced in the chips leading to breakage during transfer
Solution Approach 1:
The patent replaces the mechanical sawing system with a laser-based system. A laser beam is used to form a frangible layer within the wafer substrate, and then mechanical pressure is applied to cause controlled fracture along this layer. This substitution eliminates the direct mechanical contact and cutting forces that cause cracks, while still achieving efficient chip division.
Solution Approach 2:
The patent applies preliminary action by first forming a frangible layer through laser irradiation before applying the mechanical pressure to divide the wafer. This pre-prepared weak layer guides the fracture path and ensures clean separation without inducing random cracks in the chip structures.
2Reliability
If laser beam irradiation is used to form a frangible layer, then chip strength is improved, but additional process steps are required
Solution Approach 1:
The patent merges two functions into a coordinated sequence: the laser forms the frangible layer and the subsequent mechanical pressure divides the wafer along this layer. This combination achieves both chip division and strength improvement in an integrated process flow, where the frangible layer formation enables controlled fracture without requiring complex additional equipment.
3Manufacturing precision
If back-side polishing is used to remove the frangible layer, then chip quality is enhanced, but processing time increases
Solution Approach 1:
The patent applies local quality by selectively removing material only from the back side of the wafer where the frangible layer is located. The polishing process is targeted to remove the frangible layer and expose clean fracture surfaces, while leaving the front side chip structures untouched. This localized approach enhances chip quality without requiring complete wafer reprocessing.
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 method produces semiconductor chips with enhanced back-side and front-side strengths, reducing the likelihood of breakage during transfer and handling, and allows for more efficient division of the substrate into higher-quality chips.
Implementation Method 1
irradiating the semiconductor substrate with a laser beam to form a frangible layer in the semiconductor substrate
Implementation Method 2
stressing the frangible layer to the point at which the semiconductor substrate fractures by polishing the semiconductor substrate
Data Source
AI summary
A method of manufacturing semiconductor chips includes providing a semiconductor substrate including circuit regions, irradiating the semiconductor substrate with a laser beam onto to form a frangible layer, and polishing the semiconductor substrate to separate the circuit regions of the semiconductor substrate from one another into semiconductor chips. The frangible layer may be removed completely during the polishing of the semiconductor substrate.