Bonded Wafer Contact Pad Layout for Pre-Bond Probe Testing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional bonded wafer structures, such as Wafer-on-Wafer (WoW) structures, do not allow for comprehensive testing of individual wafers before stacking and bonding, leading to potential defects in the entire structure and increased costs due to discarded defective wafers.
Innovation Solution
Forming an array of contact pads in the interconnect level of each wafer prior to stacking, enabling circuit probe testing and early detection of defects, allowing for improved yield and reduced costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wafer stacking and bonding is performed without prior comprehensive testing, then manufacturing process speed is improved, but reliability deteriorates due to potential defects in the entire structure
Solution Approach 1:
The patent applies preliminary action by forming an array of contact pads in the interconnect level of each wafer before stacking and bonding. This allows circuit probe testing to be performed on individual wafers prior to assembly, enabling early detection of defects. By conducting testing actions before the final bonding operation, defective wafers can be identified and discarded individually rather than requiring disposal of entire bonded structures, thus maintaining reliability while preserving manufacturing efficiency
2Reliability
If individual wafer testing is performed before bonding, then reliability is improved by detecting defects early, but device complexity increases due to additional testing structures
Solution Approach 1:
The patent applies universality by designing the array of contact pads to serve multiple functions: they are integral to the interconnect structure for normal device operation and simultaneously serve as test access points for circuit probe testing. This multi-functionality allows testing capability to be added without requiring separate dedicated test structures, thereby improving reliability while minimizing the increase in device complexity
3Loss of substance
If defective wafers are detected early through testing, then loss of substance is reduced by discarding only defective wafers, but manufacturing precision requirements increase to ensure proper contact pad formation
Solution Approach 1:
The patent applies segmentation by forming the array of contact pads as discrete, localized features within the interconnect level rather than requiring comprehensive high-precision processing of entire wafer surfaces. The contact pads are segmented elements that can be formed using standard photolithography and deposition processes, reducing overall manufacturing precision requirements while still enabling effective testing. This segmentation allows defective wafers to be identified and discarded individually, minimizing material waste
Data Source
AI summary
Bonded wafer device structures, such as a wafer-on-wafer (WoW) structures, and methods of fabricating bonded wafer device structures, including an array of contact pads formed in an interconnect level of at least one wafer of the bonded wafer device structure. The array of contact pads formed in an interconnect level of at least one wafer may have an array pattern that corresponds to an array pattern of contact pads that is subsequently formed over a surface of the bonded wafer structure. The array of contact pads formed in an interconnect level of at least one wafer of the bonded wafer device structure may enable improved testing of individual wafers, including circuit probe testing, prior to the wafer being stacked and bonded to one or more additional wafers to form a bonded wafer structure.