Bonded Wafer Laser Dicing Across the Bonding Interface
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Solution Overview
Problem
Conventional laser dicing methods for bonded structures, such as mechanical sawing and existing stealth dicing, face challenges with wafer fragility, thermal damage, debris formation, and reduced production yield, particularly when dicing multiple wafers simultaneously.
Innovation Solution
A system and method for laser dicing bonded structures using a pulsed laser with adjustable focal planes and depth of focus, forming ablation structures aligned vertically across the bonding interface between wafers, allowing for simultaneous separation with reduced damage and debris, eliminating the need for cooling water and minimizing stress on the wafers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mechanical sawing is used to dice wafers, then the dicing process can separate different dies, but it causes wafer fragility and thermal damage
Solution Approach 1:
The patent replaces the mechanical sawing system with a laser-based ablation system. The laser beam creates ablation structures through material removal via vaporization, eliminating mechanical contact and associated damage. The laser parameters (wavelength, pulse duration, power) are optimized to achieve clean cuts without mechanical stress on the wafers.
Solution Approach 2:
The laser dicing process utilizes phase transitions of the wafer material. The laser energy causes localized heating that transitions the material from solid to vapor phase through ablation. This phase change enables precise material removal without mechanical force, resolving the contradiction between cutting efficiency and wafer integrity.
2Productivity
If conventional laser dicing is used, then dicing can be performed, but it produces debris formation and thermal damage
Solution Approach 1:
The patent employs periodic pulsed laser action instead of continuous laser exposure. The pulsed regime allows brief intervals between pulses for heat dissipation and material ejection, preventing excessive thermal accumulation. This periodic action reduces thermal damage and minimizes debris formation while maintaining high dicing speed through optimized pulse frequency and duration.
Solution Approach 2:
The patent optimizes laser parameters including wavelength selection, pulse duration, peak power, and duty cycle to control the ablation process. By adjusting these parameters, the process achieves clean material removal with minimal thermal affected zone and reduced debris generation, resolving the contradiction between productivity and harmful effects.
3Productivity
If multiple wafers are diced simultaneously, then production yield increases, but wafer fragility and stress increase
Solution Approach 1:
The patent segments the dicing process by creating individual ablation structures in each wafer independently through the bonded structure. The laser focuses on specific regions of each wafer, allowing simultaneous but independent processing. This segmentation enables multiple wafers to be diced at once without相互 interference, maintaining structural strength while increasing production yield.
Solution Approach 2:
The bonded structure serves as an intermediary that holds multiple wafers together during the dicing process. This intermediary provides mechanical support to fragile wafers during simultaneous laser processing, enabling high-speed multi-wafer dicing without compromising wafer strength or increasing fragility.
4Temperature
If cooling water is used in laser dicing, then thermal management is improved, but process complexity and cost increase
Solution Approach 1:
The patent implements self-service thermal management where the pulsed laser process itself provides thermal control through its inherent duty cycle. The periodic operation allows natural heat dissipation between pulses, and the ablation process removes material that would otherwise conduct heat. This eliminates the need for external cooling water systems, reducing device complexity while maintaining effective thermal management.
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 achieves more uniform cross-sections, reduced damage, and increased usable area on wafers, with fewer scratches and less waste, enabling efficient simultaneous dicing of multiple wafers without the need for cooling water, thus improving production yield and reducing fabrication costs.
Implementation Method 1
a pulsed laser with adjustable focal planes and depth of focus, forming ablation structures
Implementation Method 2
laser beam may be moved in the bonded structure according to the scan pattern to form the series of ablation structures
Data Source
AI summary
Embodiments of systems and methods for dicing a bonded structure are provided. A method for dicing a bonded structure includes thinning a top surface and a bottom surface of a bonded structure. The bonded structure may have a first wafer and a second wafer bonded with a bonding interface. The method may also include forming a series of ablation structures in the first wafer and the second wafer. The series of ablation structures may be between a first part and a second part of the bonded structure. The method may also include separating the first part and the second part of the bonded structure along the series of ablation structures.