Image Pickup Chip Wafer Bonding Dummy Chips Yield
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Solution Overview
Problem
Conventional wafer-level chip size package (WL-CSP) technologies face high production costs and low productivity due to low yield rates of image pickup chips, equipment compatibility issues with large semiconductor wafers, and non-uniform machining challenges, leading to increased costs and reduced efficiency.
Innovation Solution
A method involving bonding image pickup chips to a transparent support substrate with dummy chips in the peripheral regions, filling a sealing member, machining the joined wafer to thin the thickness, forming external connection electrodes, and cutting the wafer to produce image pickup apparatuses, allowing for efficient use of existing equipment and reducing defective chip production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional WL-CSP technology is used to collectively fabricate multiple image pickup apparatuses, then production efficiency is improved, but production cost increases due to low yield rates and equipment compatibility issues
Solution Approach 1:
The patent applies preliminary action by bonding dummy chips to the peripheral regions of the support substrate before the actual image pickup chips. This preliminary arrangement ensures that during subsequent machining processes, the support substrate maintains uniform thickness and structural integrity, preventing defects in the actual image pickup chips and thereby improving yield rate while maintaining collective fabrication efficiency
Solution Approach 2:
The patent changes the structural parameters of the wafer by introducing dummy chips in peripheral regions, which modifies the thickness distribution and mechanical properties of the support substrate. This parameter change enables uniform machining across the entire wafer surface, reducing variability and improving both productivity and manufacturing cost-effectiveness
2Productivity
If semiconductor wafers with large diameters are used to increase production capacity, then productivity is improved, but equipment investment increases and production cost rises
Solution Approach 1:
The patent segments the support substrate into a central region for actual image pickup chips and peripheral regions for dummy chips. This segmentation allows the use of standard-sized wafers that are compatible with existing equipment, while still achieving high production capacity through optimized chip arrangement and reduced waste, thereby avoiding the need for expensive large-diameter wafer equipment
3Speed
If machining is performed on joined wafers with non-uniform thickness, then processing speed is improved, but machining uniformity deteriorates and yield rate decreases
Solution Approach 1:
The patent performs preliminary action by bonding dummy chips to peripheral regions before machining, which pre-establishes uniform thickness distribution across the entire support substrate. This preliminary structural preparation enables subsequent high-speed machining to proceed uniformly across the wafer surface, simultaneously achieving fast processing speed and high machining uniformity without compromising yield rate
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 enhances yield rates, reduces production costs, and improves productivity by utilizing non-defective chips and existing equipment, while ensuring uniform thickness and preventing cracking, resulting in a high-quality and cost-effective image pickup apparatus.
Implementation Method 1
bonding the first main face of each of the image pickup chips to a transparent support substrate via a transparent adhesive layer
Implementation Method 2
filling a sealing member between the image pickup chips and the dummy chips that are bonded to the joined wafer
Implementation Method 3
machining the joined wafer from a second main face side to thin a thickness
Data Source
AI summary
A method for producing an image pickup apparatus includes processes of: cutting an image pickup chip substrate to fabricate a plurality of image pickup chips; bonding the image pickup chips to a glass wafer via a transparent adhesive layer as well as bonding dummy chips to an outer peripheral region of the glass wafer where the image pickup chips are not bonded to fabricate a joined wafer; filling a sealing member between the image pickup chips and the dummy chips; machining the joined wafer to thin a thickness; and cutting the joined wafer.