Bonded Wafer Measurement Pattern for Accurate Overlay Shift Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for monitoring wafer bonding in 3DIC structures rely on visual inspection, which is inaccurate and time-consuming, hindering productivity and overlay shifting control in semiconductor processes.
Innovation Solution
A method using an automatic optical inspection device with a measurement pattern on bonded wafers, where specific formulas for searching distances and target distances ensure accurate measurement of overlay shifts, replacing manual visual inspection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visual inspection by naked eye is used to monitor wafer bonding, 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 automatic optical inspection device that uses light to detect overlay shifts. The optical device captures images of measurement patterns on bonded wafers and automatically calculates shift amounts, eliminating the need for manual visual inspection while significantly improving measurement precision.
Solution Approach 2:
The patent uses measurement patterns that create optical copies or representations of the wafer alignment state. By capturing images of these patterns and analyzing their relative positions, the system indirectly measures overlay shifts without requiring direct physical measurement, thereby improving both accuracy and automation.
2Productivity
If visual inspection by naked eye is used to monitor wafer bonding, then the equipment requirement is low, but the productivity is slow and time-consuming
Solution Approach 1:
The automatic optical inspection device performs measurements rapidly by capturing images and automatically processing them, eliminating the time-consuming manual visual inspection process. This substitution enables high-throughput measurement capable of keeping pace with fast wafer bonding processes.
Solution Approach 2:
The patent enables continuous inspection by automating the measurement process. The optical device can continuously capture images and calculate overlay shifts without interruption, maintaining continuous productive action rather than the intermittent nature of manual inspection.
3Measurement precision
If visual inspection by naked eye is used to monitor wafer bonding, then the cost is low, but the measurement accuracy is rough leading to misjudgment
Solution Approach 1:
The patent replaces manual visual inspection with an automated optical inspection system that uses light-based measurement and automatic image processing. This substitution eliminates human error and subjectivity in judgment while providing consistent, precise measurements through automated calculation of overlay shifts from captured images.
Solution Approach 2:
The patent implements an automated feedback system where the optical device continuously monitors overlay shifts and provides quantitative measurement results. This feedback mechanism enables real-time detection and correction of alignment issues, improving measurement precision through systematic automated analysis rather than subjective visual assessment.
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 measurement accuracy and productivity by automating the detection of overlay shifts, allowing for high-throughput quality control and preventing manual misjudgment, thus improving the efficiency of semiconductor processes.
Implementation Method 1
an automatic optical inspection device is used to measure a distance between a first portion of the top wafer pattern and a first part of the bottom wafer pattern
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.