Stealth Laser Dicing With Backgrinding to Minimize Circuit Splash
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Solution Overview
Problem
Conventional laser dicing methods often result in splash damage to circuitry during the separation of semiconductor dies, which can lead to inefficiencies and damage to the substrate.
Innovation Solution
A method involving a single stealth laser dicing pass that focuses a laser beam within the semiconductor substrate to create a modified region and a crack orthogonal to the surface, followed by backgrinding to extend the crack and thin the substrate, thereby minimizing splash and allowing precise die separation without damaging the circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional laser dicing is used to separate semiconductor dies, then die separation is achieved, but splash damage occurs to the circuitry
Solution Approach 1:
The laser dicing process is divided into two distinct stages: a first laser pass that creates an initial crack without completing the cut, and a second laser pass that completes the separation. This segmentation allows the first pass to create a controlled fracture path while the second pass cleanly separates the dies without causing splash damage to the circuitry.
Solution Approach 2:
The first laser pass performs a preliminary action by creating an initial crack and modifying the substrate structure before the actual die separation. This preliminary cracking modifies the stress distribution in the substrate, allowing the second laser pass to complete the cut without generating harmful splashes that would damage the circuitry.
2Manufacturing precision
If laser beam is focused within the substrate to form modified region, then crack control is improved, but process complexity increases
Solution Approach 1:
The laser dicing process is divided into two distinct stages: a first laser pass that creates an initial crack without completing the cut, and a second laser pass that completes the separation. This segmentation allows the first pass to create a controlled fracture path while the second pass cleanly separates the dies without causing splash damage to the circuitry.
Solution Approach 2:
The laser processing parameters (such as power, pulse duration, and focal depth) are changed between the first and second passes. The first pass uses parameters optimized for creating controlled cracks within the substrate, while the second pass uses parameters optimized for clean separation, thereby achieving precise crack control through parameter optimization.
3Loss of time
If single laser pass is used for dicing, then processing time is reduced, but splash damage occurs
Solution Approach 1:
The laser dicing process is divided into two distinct stages: a first laser pass that creates an initial crack without completing the cut, and a second laser pass that completes the separation. This segmentation allows the first pass to create a controlled fracture path while the second pass cleanly separates the dies without causing splash damage to the circuitry.
Solution Approach 2:
The two laser passes are performed in continuous sequence without interrupting the overall dicing workflow. The first pass prepares the substrate by creating controlled cracks, and the second pass immediately follows to complete the separation, maintaining continuous useful action while preventing splash damage through the controlled two-stage process.
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 effectively prevents splash damage to the circuitry, enables precise control over crack formation, and facilitates efficient die separation with reduced risk of premature substrate breakage, enhancing the semiconductor fabrication process.
Implementation Method 1
The laser beam is focused within the substrate to form a modified region and a crack extending from the modified region
Implementation Method 2
The laser beam is focused within the substrate to form a modified region and a crack extending from the modified region
Implementation Method 3
backgrinding to reduce a thickness of the substrate from the second side surface
Data Source
AI summary
One example provides a method that includes directing a laser beam at a first side surface of a semiconductor substrate at an entry point along a respective scribe street thereof. The substrate includes a plurality of dies having circuitry at the first side surface and separated from one another by respective scribe streets. The laser beam is focused within the substrate to form a modified region and a crack extending from the modified region towards at least one of the first and second side surfaces. The modified region is closer to the first side surface than a second side surface that is opposite the first side surface. The method also includes applying tape on the first side surface after directing the laser beam, and backgrinding to reduce a thickness of the substrate from the second side surface and provide a thinned second side surface that intersects an extension of the crack.