Hybrid Laser-Plasma Dicing for Thin Substrates
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Solution Overview
Problem
Conventional dicing techniques for thin semiconductor substrates face challenges such as microcrack formation, delamination, and kerf width control issues, and plasma dicing is hindered by high implementation costs and masking complexities.
Innovation Solution
A hybrid dicing method combining laser scribing and plasma etching, where a femtosecond laser ablates a patterned mask to create trenches in the substrate, followed by plasma etching to singulate ICs, allowing for precise control of kerf width and minimizing thermal damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional scribing or sawing is used for thin substrate dicing, then the substrate can be separated into individual devices, but microcrack formation and delamination occur
Solution Approach 1:
The patent replaces mechanical scribing and sawing systems with a laser-based system that uses optical energy to ablate material. The laser beam delivers controlled energy to the substrate surface, vaporizing material through ablation rather than mechanical contact, thereby eliminating microcracks and delamination caused by mechanical stress while maintaining high dicing productivity
Solution Approach 2:
The patent utilizes controlled variation of laser parameters including pulse duration (femtosecond scale), wavelength, and power density to achieve precise ablation. By adjusting these parameters, the laser selectively removes material at the dicing lines without transmitting excessive energy that could cause substrate damage, thus maintaining both productivity and substrate integrity
2Reliability
If plasma dicing is implemented, then dicing can be performed without mechanical contact, but implementation cost increases due to lithography requirements
Solution Approach 1:
The patent extracts and removes the lithography step from the plasma dicing process. Instead of using patterned masks requiring lithography, the laser directly writes the dicing pattern through ablation. This eliminates the need for expensive lithography equipment and mask fabrication while maintaining contactless processing benefits
Solution Approach 2:
The patent introduces laser ablation as an intermediary step before plasma dicing. The laser first creates precise ablation patterns and trenches in the substrate, which then serve as guides for the subsequent plasma etching process. This intermediary step eliminates the need for lithography-based patterning while maintaining the precision and contactless nature of plasma processing
3Reliability
If plasma dicing is used, then contactless processing is achieved, but masking complexities arise
Solution Approach 1:
The patent removes the masking step entirely from the plasma dicing process. The laser directly ablates the dicing pattern into the substrate without requiring any masks. This eliminates masking complexities related to mask fabrication, alignment, and handling while preserving the contactless processing advantage
Solution Approach 2:
The patent performs preliminary laser ablation to create the dicing pattern before plasma etching. The laser pre-defines the exact locations where material removal is needed, creating trenches and modifying the substrate surface in advance. This preliminary action eliminates the need for masks during plasma processing, simplifying the overall device complexity
4Ease of manufacture
If single irradiance laser scribing is used, then processing is simple, but kerf width control and thermal damage are problematic
Solution Approach 1:
The patent employs periodic pulsed laser irradiation where the laser delivers energy in discrete femtosecond pulses rather than continuous illumination. This periodic action allows heat to dissipate between pulses, preventing thermal accumulation and damage. The pulse frequency and duty cycle are controlled to achieve precise kerf width while maintaining simple processing
Solution Approach 2:
The patent dynamically adjusts laser parameters including pulse duration, power, and scanning speed during the scribing process. By varying these parameters in real-time, the system optimizes kerf width control for different materials and depths while maintaining processing simplicity. The dynamic control allows adaptation to different substrate conditions without complex fixed-parameter systems
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 effectively singulates ICs with reduced microcrack formation and delamination, achieving precise kerf width control and eliminating the need for costly lithography, while maintaining high manufacturing throughput.
Implementation Method 1
The masked substrate is ablated along streets between the ICs with a point on the substrate exposed to increasing irradiance. At least a portion of the mask thickness in the street is ablated through exposure to electromagnetic radiation of first irradiance (optical intensity)
Implementation Method 2
A plasma etch is performed in a plasma etch chamber to additionally remove substrate material below the removed film layer stack to singulate individual ICs out of the single substrate
Data Source
AI summary
Methods of dicing substrates by both laser scribing and plasma etching. A method includes laser ablating material layers, the ablating leading with a first irradiance and following with a second irradiance, different than the first. An asymmetrically shaped beam having an asymmetrical spatial profile along the direction of travel, multiple passes of a beam adjusted to have different irradiance levels, and multiple laser beams having various irradiance levels may be utilized to ablate at least a mask with the first irradiance and expose the substrate with the second irradiance.