Semiconductor Wafer Laser Grooving for High Die Strength
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Solution Overview
Problem
Conventional laser processing methods for semiconductor wafers result in devices with low die strength, leading to degradation in the quality of electrical equipment, with a die strength of 400 MPa compared to 800 MPa achieved using dicing apparatus.
Innovation Solution
A laser processing method that applies a pulsed laser beam with a pulse width of 2 ns or less and a peak energy density between 5 to 200 GW/cm2, along with an overlap rate of 16/20 to 19/20 for adjacent laser beam spots, to form grooves on semiconductor wafers, enhancing die strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional laser processing method is used, then laser processing can be performed, but die strength is low (400 MPa)
Solution Approach 1:
The patent applies parameter changes by optimizing the pulse width to 2 ns or less and setting the peak energy density in the range of 5 to 200 GW/cm². These specific parameter adjustments transform the laser processing conditions to achieve die strength of 800 MPa or more, directly resolving the contradiction between laser processing capability and die strength requirement.
Solution Approach 2:
The patent employs periodic action through pulsed laser beam application with specific pulse width control (2 ns or less). The pulsed nature of the laser processing, with controlled repetition and timing, enables repeated high-energy density applications that progressively strengthen the die structure while maintaining processing efficiency.
2Strength
If dicing apparatus is used, then die strength is high (800 MPa), but mechanical cutting complexity increases
Solution Approach 1:
The patent replaces the mechanical cutting blade system with a laser-based processing system. By substituting mechanical contact cutting with optical field processing, the invention eliminates the complexity of cutting blades, rotation mechanisms, and mechanical feed systems while achieving comparable or superior die strength through controlled laser parameter application.
3Strength
If pulse width is reduced to 2 ns or less, then die strength improves, but energy control precision requirements increase
Solution Approach 1:
The patent addresses the precision challenge by establishing a specific parameter range: peak energy density between 5 to 200 GW/cm². This defined range provides clear manufacturing targets and control boundaries, transforming the abstract requirement of 'high precision' into actionable parameter specifications that guide the laser processing system.
Solution Approach 2:
The patent implements feedback control through monitoring and adjusting the pulse energy and repetition rate to maintain peak energy density within the specified range. By continuously measuring processing outcomes and adjusting laser parameters accordingly, the system achieves consistent die strength results while managing the inherent precision challenges of ultra-short pulse processing.
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 significantly improves the die strength of semiconductor devices to 800 MPa or more, surpassing the strength achieved with conventional methods.
Implementation Method 1
applying a pulsed laser beam having an absorption wavelength to the semiconductor wafer along a division line formed on the semiconductor wafer to thereby form a laser processed groove along the division line
Implementation Method 2
pulsed laser beam having an absorption wavelength to the semiconductor wafer
Data Source
AI summary
A laser processing method for a semiconductor wafer including a groove forming step of applying a pulsed laser beam having an absorption wavelength to the semiconductor wafer along a division line formed on the semiconductor wafer to thereby form a laser processed groove along the division lines on the semiconductor wafer, wherein the pulse width of the pulsed laser beam to be applied in the groove forming step is set to 2 ns or less, and the peak energy density is set in the range of 5 to 200 GW/cm2.