Semiconductor Wafer Division via Internal Laser Fissuring
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Solution Overview
Problem
Existing methods for dividing semiconductor wafers using pulsed laser beams face challenges in controlling the direction of cracks, leading to inaccurate division and energy wastage due to focusing precision issues and substrate irregularities.
Innovation Solution
A method involving laser irradiation with a pulsed laser beam focused inside a sapphire substrate, creating processed portions and fissures that link adjacent portions, with specific energy and frequency settings, and a controlled distance between focal points and substrate surface, to accurately divide the wafer along intended lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a pulsed laser beam is used to form modification regions inside the substrate, then discoloration is avoided and brightness is maintained, but the direction of cracks cannot be controlled and division accuracy decreases
Solution Approach 1:
The patent divides the substrate into multiple processing regions by forming separate modification regions at different locations. By segmenting the laser processing into multiple focal points arranged in specific patterns, the crack propagation direction can be controlled while maintaining the benefits of pulsed laser processing throughout the substrate.
Solution Approach 2:
The patent transitions from two-dimensional surface processing to three-dimensional internal processing by focusing the laser beam inside the substrate at controlled depths. This dimensional change allows modification regions to be formed within the substrate volume, enabling precise crack direction control while avoiding surface discoloration.
2Manufacturing precision
If the focal point is positioned inside the substrate, then processing precision is improved, but energy is wasted due to plasma generation when focusing is imprecise
Solution Approach 1:
The patent performs preliminary positioning and focusing adjustments before actual processing begins. By pre-establishing the correct focal point location inside the substrate and verifying the focusing accuracy, the system ensures that subsequent laser processing occurs at the optimal depth, preventing plasma generation and energy waste.
Solution Approach 2:
The patent incorporates feedback mechanisms to monitor and adjust the laser focusing in real-time. By detecting the actual focal point position and comparing it with the target position, the system can make corrective adjustments to maintain precise focusing inside the substrate, thereby avoiding energy loss from plasma generation.
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 precise and accurate splitting of semiconductor wafers by controlling the direction of cracks and minimizing energy loss, ensuring consistent and efficient division.
Implementation Method 1
a method in which a pulsed laser beam with a short pulse width is used to work the wafer. Using a pulsed laser beam with a short pulse width allows working to be performed that is free of discoloration because it involves multiphoton absorption rather than melting
Implementation Method 2
a laser irradiation step of focusing a pulsed laser beam inside of a sapphire substrate constituting a wafer
Implementation Method 3
focusing a pulsed laser beam inside of a sapphire substrate constituting a wafer, wherein the pulsed laser beam has a pulse width of 300 to 50000 fs, an amount of energy of 0.8 to 5 μJ per pulse
Data Source
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AI summary
A method for manufacturing a semiconductor element of the present invention, has: a laser irradiation step of focusing a pulsed laser beam inside of a substrate constituting a wafer, thereby forming a plurality of isolated processed portions along an intended dividing line inside of the substrate, and creating a fissure that runs from the processed portions at least to the surface of the substrate and links adjacent processed portions; and a wafer division step of dividing the wafer along the intended dividing line.