3D Chip Stacking with Wall-Block Alignment and Cone Bumps
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Solution Overview
Problem
Current methods for manufacturing 3D integrated circuits face challenges in achieving high precision position-alignment between stacked IC chips, with existing self-alignment techniques based on surface tension limiting accuracy to about one micrometer and complicating the jointing process.
Innovation Solution
The use of wall-block patterns and cone bumps with specific geometric configurations on the IC chips, combined with a hydrophobic film pattern, allows for precise alignment and jointing through surface tension-assisted self-alignment, achieving alignment accuracy of 0.2 micrometers or less and simplifying the jointing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical positioning is used to stack upper and lower level IC chips, then the stacking process can be performed, but the alignment accuracy is limited to about one micrometer
Solution Approach 1:
The liquid droplet system performs self-alignment through surface tension forces. The droplet automatically adjusts its position to minimize surface energy, causing the upper chip to align precisely with the lower chip without external positioning mechanisms. This self-service mechanism achieves sub-micrometer alignment accuracy naturally.
Solution Approach 2:
The patent replaces mechanical positioning systems with a surface tension-based liquid droplet system. Instead of using complex mechanical stages, clamps, or alignment fixtures, the invention uses the physical properties of liquid surface tension to achieve precise alignment and bonding of chips.
2Manufacturing precision
If self-alignment based on surface tension of liquid only is used, then alignment can be achieved, but the accuracy is limited and the jointing process becomes complex
Solution Approach 1:
The invention segments the alignment and jointing functions into distinct phases. First, the liquid droplet provides surface tension-based alignment. Second, the inclined plane structure provides mechanical guidance and constraint during bonding. This segmentation allows each mechanism to optimize its specific function without interfering with the other.
Solution Approach 2:
The liquid droplet acts as an intermediary medium between the upper and lower chips. It provides both alignment through surface tension and facilitates the bonding process. The inclined plane structure serves as a mechanical intermediary that guides the chips into proper alignment and maintains contact during jointing.
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 enables high precision position-alignment and straightforward jointing of IC chips, significantly improving the accuracy and ease of the stacking process in 3D integrated circuit manufacturing.
Implementation Method 1
a step of floating a plurality of IC chips on the plurality of droplets, which are separated for each of temporally to-be-jointed areas, and using the surface tension of the liquid, position-aligning each of the chips in each of the temporally to-be-jointed areas
Implementation Method 2
a step of vaporizing the droplets of the liquid, which are inserted between each of the IC chips and the temporally to-be-jointed areas, respectively, and temporally jointing each of the IC chips to the temporally to-be-jointed areas
Data Source
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AI summary
A stacked device encompasses a lower chip including a plurality of wiring lands and a plurality of wall-block patterns, each of the wall-block patterns is allocated at a position except locations where the wiring lands are disposed, each of the wall-block patterns has a inclined plane, a height of each of the wall-block patterns measured from a reference plane of the array of the wiring lands is higher than the wiring lands, and an upper chip including a plurality of wiring bumps assigned correspondingly to the positions of the wiring lands, respectively, and a plurality of cone bumps assigned correspondingly to the positions of the wall-block patterns, respectively.