Stacked Semiconductor Dicing With Laser Grooves and Substrate Cutting
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Solution Overview
Problem
Conventional dicing methods for stacked semiconductor devices, such as mechanical and laser dicing, lead to silicon peeling and silicon debris contamination, which cause device damage and yield loss due to thermal and mechanical stress, and high-energy laser irradiation.
Innovation Solution
A hybrid dicing process combining laser grooving before bonding and mechanical dicing, where laser grooving is limited to device layers to minimize silicon debris and mechanical dicing is restricted to the substrate to prevent micro-cracks, thereby reducing device damage and improving yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mechanical dicing is used to cut stacked semiconductor devices, then the device can be divided into individual dies, but thermal and mechanical stress during dicing causes substrate lattice distortion and creates cracks into layers containing circuits (silicon peeling)
Solution Approach 1:
The patent segments the dicing process into two distinct stages: laser grooving (creating initial cuts in device layers) and mechanical dicing (completing the cut in substrate). This segmentation allows each process to operate on optimized parameters - laser for precise device layer cutting without mechanical contact, and mechanical dicing for efficient substrate separation - thereby resolving the contradiction between productivity and device integrity.
Solution Approach 2:
The patent applies preliminary laser grooving to create cuts in device layers before performing mechanical dicing on the substrate. This preliminary action removes the harmful thermal and mechanical stress from the device layers by using non-contact laser energy, while the subsequent mechanical dicing efficiently completes the separation in the substrate, thus protecting device integrity while maintaining productivity.
2Reliability
If laser dicing is used to cut stacked semiconductor devices, then dicing can be performed without mechanical contact, but laser irradiation creates silicon debris causing contamination to sidewalls of dice
Solution Approach 1:
The patent segments the dicing process to apply laser grooving only to device layers rather than the entire stack including substrate. This segmentation limits laser-induced silicon debris generation to the device layer region, preventing debris contamination of dice sidewalls while still achieving the benefit of non-contact cutting for device integrity.
Solution Approach 2:
The patent extracts the laser grooving step to apply it selectively only to device layers, separating it from the substrate dicing operation. This extraction allows the laser process to be optimized for device layer cutting without generating harmful debris in the substrate region, thereby eliminating silicon debris contamination while preserving device integrity.
3Manufacturing precision
If laser grooving is applied to the substrate during dicing, then complete cuts can be achieved, but excessive thermal stress and silicon debris are generated causing device damage
Solution Approach 1:
The patent segments the dicing process into laser grooving for device layers and mechanical dicing for substrate. This segmentation achieves complete cuts through the entire stack by combining two methods, each optimized for its specific layer, thereby obtaining manufacturing precision without subjecting the substrate to excessive thermal stress and silicon debris generation.
Solution Approach 2:
The patent applies different cutting methods to different regions: laser grooving is applied locally to device layers where thermal stress and debris are problematic, while mechanical dicing is applied to the substrate where complete cutting is needed without thermal concerns. This local quality approach achieves complete cuts while minimizing harmful effects in each specific region.
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 hybrid dicing process effectively alleviates micro-cracking and silicon debris re-deposition issues, reducing dicing-related device damage and enhancing product yield by limiting thermal and mechanical stress to the substrate.
Implementation Method 1
A laser beam is used to form a groove in a device layer of a wafer
Implementation Method 2
A blade is used to cut through the groove, the wafer, and the groove to divide the wafer into individual dice
Data Source
AI summary
A semiconductor structure includes a first device and a second device bonded on the first device. The first device has a first sidewall distal to the second device and a second sidewall proximal to the second device. A surface roughness of the second sidewall is larger than a surface roughness of the first sidewall.