Double Encapsulation Ring for Wafer Alignment
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Solution Overview
Problem
The fabrication of electronic devices with stacked assemblies of base wafers, integrated circuit chips, and protection wafers is challenging due to difficulties in aligning the front face of the encapsulation block with the protection wafer, leading to inefficiencies in the collective fabrication process.
Innovation Solution
A process involving the formation of stacked assemblies with channels between them, followed by the deposition and hardening of a first encapsulation ring with protruding beading, and a second encapsulation ring filling the grooves created by the first ring, allowing for precise encapsulation and dicing of individual electronic devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single encapsulation block is formed around stacked assemblies, then the front face of the encapsulation block can be aligned with the protection wafer, but fabrication difficulties arise that prevent proper alignment
Solution Approach 1:
The encapsulation block is divided into multiple separate encapsulation rings, each independently formable around individual stacked assemblies. This segmentation allows each ring to be precisely positioned and formed without the fabrication difficulties associated with creating a single large encapsulation block, while still achieving the desired alignment precision with protection wafers.
2Productivity
If stacked assemblies are formed with channels between them, then collective fabrication is enabled, but the encapsulation structure becomes more complex
Solution Approach 1:
The encapsulation structure is segmented into multiple rings corresponding to the channels between stacked assemblies. This allows collective fabrication processes to treat multiple assemblies simultaneously while maintaining the ability to precisely encapsulate each individual assembly, balancing productivity gains with manageable structural complexity.
Solution Approach 2:
The encapsulation rings serve multiple functions: they provide mechanical support, enable collective fabrication handling, define cutting paths for dicing operations, and protect the stacked assemblies. This multi-functionality reduces the need for additional separate structures, managing overall device complexity.
3Volume of moving object
If the protection wafer is placed close to the chip, then the device size is reduced, but stress on the stacked assembly increases
Solution Approach 1:
The encapsulation rings provide localized mechanical support and stress distribution at critical interfaces between the protection wafer and chip. This allows the protection wafer to be positioned closer to the chip for compact device size while the encapsulation structure locally manages the stress, preventing excessive stress on the stacked assembly.
4Stress or pressure
If a deformable material is used for the first encapsulation ring, then stress is minimized during dicing, but the material selection becomes more constrained
Solution Approach 1:
The first encapsulation ring is formed from a deformable material whose mechanical properties can be adjusted through parameter changes such as cross-linking density, filler content, or curing conditions. This allows optimization of the material's deformability to minimize stress during dicing operations while maintaining other required properties like adhesion and structural support.
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 enables efficient collective fabrication of electronic devices with precise encapsulation, minimizing stress on the stacked assemblies and allowing for the preservation of a free space between the chip and protection wafer, facilitating the integration of sensors and maintaining the structural integrity of the device.
Implementation Method 1
depositing a first coating material within the channels and hardening this first coating material so as to form a first encapsulation ring
Implementation Method 2
injecting a second coating material into the recessed grooves and hardening this second coating material so as to form a second encapsulation ring
Data Source
AI summary
An integrated circuit chip is mounted on top of a base wafer, and a protection wafer is mounted on top of the integrated circuit chip. An encapsulation block is formed around the integrated circuit chip and the protection wafer and on a peripheral part of the front face of the base wafer. The encapsulation block includes a first encapsulation ring arranged around the integrated circuit chip and the protection wafer, having an annular beading protruding with respect to the front face of the protection wafer and forming a peripheral groove (24) recessed with respect to this protruding annular beading. A second encapsulation ring of the encapsulation block fills the peripheral groove of the first encapsulation ring.