Bonded Wafer Overlay Measurement Pattern for AOI Shift Detection
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Solution Overview
Problem
Current methods for monitoring wafer bonding in 3DIC structures rely on visual inspection, which is inaccurate and time-consuming, hindering productivity.
Innovation Solution
A method using automatic optical inspection (AOI) to measure overlay shift in bonded wafers by aligning patterns on top and bottom wafers, setting target distances, and performing searches based on specific formulas to determine actual shifting amounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visual inspection from naked-eye is used to judge bonding accuracy, then the method is simple and easy to operate, but the measurement accuracy is rough and productivity is slow
Solution Approach 1:
The patent replaces the mechanical visual inspection system with an optical measurement system. Specifically, it uses optical micrographs and automated image processing to measure overlay shift, substituting human eyes and manual judgment with optical instruments and computational algorithms, thereby achieving both high precision and high productivity
Solution Approach 2:
The patent creates optical copies (micrographs) of the wafer patterns and performs measurements on these copies rather than directly on the physical wafers. This allows multiple measurements to be performed rapidly from static images, improving productivity while maintaining measurement precision through automated image analysis
2Measurement precision
If visual inspection from naked-eye is used to judge bonding accuracy, then the equipment complexity is low, but the measurement accuracy is rough
Solution Approach 1:
The patent replaces simple visual inspection with an optical measurement system that captures micrographs and uses automated image processing. This substitution introduces optical instruments and computational methods, increasing device complexity but enabling precise quantitative measurement of overlay shift that cannot be achieved through visual inspection alone
3Productivity
If visual inspection from naked-eye is used to judge bonding accuracy, then the method is easy to operate, but productivity may be slow
Solution Approach 1:
The patent creates optical copies (micrographs) of the wafer patterns and performs measurements on these copies. This allows the measurement process to be automated through image processing algorithms, significantly improving productivity. The automation reduces manual operation requirements, and while the setup requires technical knowledge, the actual measurement process becomes rapid and consistent
Solution Approach 2:
The patent replaces manual visual inspection with an automated optical measurement system that processes images computationally. This substitution automates the measurement process, improving productivity through rapid image analysis while reducing reliance on human operators, though it requires expertise in operating and interpreting the automated system
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
Enables precise and efficient measurement of overlay shift, improving productivity and accuracy by automating the process and reducing manual errors.
Implementation Method 1
an automatic optical inspection device is used to measure a measurement pattern on the bonded wafers
Data Source
AI summary
A measurement pattern for monitoring overlay shift of bonded wafers includes a top wafer pattern and a bottom wafer pattern. The top wafer pattern includes a first portion with a width Wx1 measured along a first axis. The bottom wafer pattern includes a first part with a width Wx2 measured along the first axis, wherein the first portion of the top wafer pattern and the first part of the bottom wafer pattern are separated by a target distance Dx, and wherein the measurement pattern satisfies the following measurement formulas:Tx>Dx-Sx;Tx<Dx-Sx+Wx2;Tx>Sx;Tx<Dx-Sx+Wx1;wherein, Tx represents a searching distance for finding an end-point of the first portion or an end-point of the first part; and Sx represents an actual shifting amount of the first portion.