Laser Dicing Pulse Picker Synchronization for Linear Crack Formation
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Solution Overview
Problem
Conventional laser dicing methods using pulse laser beams often result in zig-zag shaped cuts with poor linearity, affecting semiconductor device performance and reducing the number of devices that can be formed on a substrate, due to inadequate control over the formation of altered regions and dicing line widths.
Innovation Solution
A laser dicing method that synchronizes a pulse laser beam with a clock signal, uses a pulse picker to control irradiation and non-irradiation in light pulse units, and increases light pulse density at the intersection of dicing lines to form continuous, linear cracks, optimizing irradiation energy and process point depth for improved cutting performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional pulse laser beam parameters are used for dicing, then the cutting process can be completed, but the cut portions form zig-zag shapes with poor linearity, affecting device performance
Solution Approach 1:
The patent applies periodic action by using pulsed laser irradiation with optimized pulse intervals instead of continuous irradiation. The laser beam is irradiated in periodic pulses with specific time intervals, allowing the material to cool between pulses and preventing thermal accumulation that causes zig-zag cutting. This periodic irradiation pattern enables linear crack propagation while maintaining cut quality and device performance.
Solution Approach 2:
The patent employs parameter changes by optimizing multiple laser irradiation parameters including pulse width, pulse interval, irradiation energy, and spot diameter. By carefully adjusting these parameters, the method achieves linear crack propagation without zig-zag formation. The parameter optimization ensures that each pulse creates a controlled altered region that guides crack propagation in a straight line, improving both linearity and device reliability.
2Reliability
If wider dicing lines are secured to prevent device damage, then device performance is protected, but the number of devices that can be formed on a substrate decreases
Solution Approach 1:
The periodic pulsed laser irradiation creates narrow, precise dicing lines with excellent linearity, eliminating the need for wide safety margins. The controlled pulse intervals ensure that cracks propagate cleanly without deviating, allowing narrower dicing widths that maximize device packing density while maintaining device integrity and performance.
Solution Approach 2:
By optimizing laser parameters including reducing spot diameter and adjusting pulse energy, the method achieves precise crack control with minimal dicing width. This parameter optimization allows narrower cuts that increase the number of devices per substrate while maintaining sufficient separation to protect device performance.
3Ease of manufacture
If the pulse laser beam irradiation is continuous, then the cutting process is simple, but the altered regions form irregularly and crack linearity deteriorates
Solution Approach 1:
The patent replaces continuous irradiation with periodic pulsed irradiation, where the laser operates in discrete pulses with optimized intervals. This approach maintains process simplicity while dramatically improving crack linearity. The periodic nature of the pulses creates uniformly spaced altered regions that guide crack propagation in a straight line, eliminating irregularities caused by continuous irradiation.
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 achieves good cutting performance with high linearity, low cutting force, and increased packing density of diced devices, particularly on hard substrates like sapphire, by preventing zig-zag shapes and allowing for narrower dicing widths, thus enhancing device performance and manufacturing efficiency.
Implementation Method 1
forms an altered region inside a work piece by means of an optical damage produced by a pulse laser beam
Data Source
AI summary
A laser dicing method is a laser dicing method which includes: switching irradiation and non-irradiation of the pulse laser beam on the work piece in light pulse units by controlling passing and blocking of the pulse laser beam using a pulse picker in synchronization with the clock signal; and forming a crack reaching a substrate surface of the work piece to be continuous in the substrate surface of the work piece, and which includes: a first crack forming step of irradiating the pulse laser beam on the work piece along a first line; and a second crack forming step of irradiating the pulse laser beam on the work piece along a second line orthogonal to the first line, and in which, in an area in which the first line and the second line cross, a light pulse density of the pulse laser beam is increased in the first crack forming step or the second crack forming step.