Laser Dicing Semiconductor Substrates Reducing Recast Damage
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Solution Overview
Problem
Conventional methods for dicing thin semiconductor substrates, such as mechanical blade saws and laser dicing, result in significant structural damage and yield loss due to cracks and heat damage, making them unsuitable for mass production.
Innovation Solution
A laser dicing method using a specialized apparatus with multiple laser beams and heat processing to reduce recast material, employing a V-shaped or X-shaped beam configuration to minimize heat impact and enhance die strength, while also allowing for simultaneous dicing and recast material processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional laser dicing is used to singulate thin semiconductor substrates, then the substrates can be separated into individual devices, but heat damage occurs to the sides of the singulated integrated devices resulting in significant reduction of die strength
Solution Approach 1:
The laser beam is divided into multiple segments (first laser beam for dicing, second laser beam for heat processing) that operate at different stages. The first laser beam performs the primary cutting function, while the second laser beam subsequently removes recast material and reduces heat damage. This segmentation allows each laser beam to be optimized for its specific function, resolving the contradiction between productivity and die strength.
Solution Approach 2:
Heat processing is performed as a preliminary or immediate follow-up action to the dicing process. By applying controlled heat treatment right after laser dicing, the recast material is removed and heat-affected zones are minimized before the device is fully singulated. This preliminary heat processing prevents the accumulation of harmful heat damage while maintaining high dicing efficiency.
2Manufacturing precision
If high laser energy level is applied to achieve melting and evaporation of substrate material, then dicing can be performed, but heat damages the sides of the singulated integrated device
Solution Approach 1:
The harmful recast material and excess heat-affected zones are selectively removed using a second laser beam configured for heat processing. This extraction process eliminates the damaging byproducts of high-energy dicing while preserving the precision-cut edges. The second laser beam targets and removes only the recast material without affecting the freshly cut surfaces, thus resolving the contradiction between cutting precision and heat damage.
Solution Approach 2:
The recast material and heat-affected zones, which are harmful byproducts of high-energy laser dicing, are converted into a controlled heat treatment process. The second laser beam uses controlled heating to remove recast material and strengthen the cut edges through controlled thermal effects. This transforms the harmful heat damage into a beneficial heat treatment that improves die strength while maintaining cutting precision.
3Productivity
If mechanical blade saw is used to dice thin semiconductor substrates, then substrates can be separated, but cracks and breakage occur resulting in yield loss of more than 30%
Solution Approach 1:
The mechanical blade saw system is replaced with a laser-based dicing system that uses optical energy instead of mechanical force. The laser beams melt and vaporize the substrate material along the cut lines without applying mechanical stress to the thin substrate. This substitution eliminates the cracks and breakage that occur with mechanical cutting, dramatically improving yield rate while maintaining mass production capability through high-speed laser 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
This approach reduces structural damage and increases die strength, improving yield and productivity by minimizing recast material and heat damage during the dicing process.
Implementation Method 1
laser beam is projected onto a surface of the semiconductor substrate. This results in ablation of the material of the semiconductor substrate through melting and evaporation
Implementation Method 2
ablation of the material of the semiconductor substrate through melting and evaporation
Implementation Method 3
ablation of the material of the semiconductor substrate through melting and evaporation
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
A method of dicing a plurality of integrated devices included in a semiconductor substrate using laser energy comprises the steps of directing a first laser beam onto a cutting line along the substrate to ablate a portion of the substrate located along the cutting line to be diced, the portion of the substrate that is ablated forming a recast material adjacent to the cutting line of the substrate that has been diced. A second laser beam is directed onto another portion of the substrate adjacent to the cutting line to conduct heat processing of the recast material formed adjacent to the cutting line.