3D Semiconductor Bonding Layout for Misalignment and RC Delay
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Solution Overview
Problem
In three-dimensional semiconductor structure technology, misalignment of contact holes during etching leads to ineffective electrical connections between wafers, and the small distance between contact holes results in high parasitic capacitance, causing delays in RC circuits.
Innovation Solution
A semiconductor structure and method where two semiconductor layers are bonded with redistribution lines of different projection lengths on their bonding surface, allowing for electrical connection through metal pads, which increases the distance between bonding points and reduces parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact holes are used to connect wafers, then electrical connection between wafers is achieved, but misalignment occurs during etching leading to connection failures
Solution Approach 1:
The invention divides the electrical connection path into multiple segments: redistribution lines on the first wafer, bonding interfaces, and redistribution lines on the second wafer. This segmentation allows each component to be optimized independently, with redistribution lines providing flexible routing to compensate for alignment variations during bonding.
Solution Approach 2:
The invention transitions from vertical through-hole connections to a combination of planar redistribution lines and bonding interfaces. By adding the dimension of planar metal line routing on wafer surfaces, the system gains flexibility in achieving electrical connection without relying solely on precise vertical hole alignment.
2Productivity
If contact holes are used with small distance between them, then wafer connection is achieved, but parasitic capacitance increases causing RC circuit delay
Solution Approach 1:
The invention extracts the electrical connection function from the vertical through-hole structure and relocates it to planar redistribution lines on the wafer surfaces. This separation allows the bonding interface to focus on mechanical and electrical contact while the routing function is handled by the redistributed metal lines, reducing parasitic capacitance at the bonding interface.
3Manufacturing precision
If different projection lengths of redistribution lines are used, then misalignment tolerance is improved, but manufacturing complexity increases
Solution Approach 1:
The invention applies different projection lengths to different redistribution lines based on their specific positioning requirements. Rather than using a uniform structure, each redistribution line is locally optimized with its projection length tailored to compensate for expected alignment variations in its specific region, achieving overall high precision without excessive global complexity.
Data Source
AI summary
A semiconductor structure includes a first semiconductor layer and a second semiconductor layer bonded to each other. The first semiconductor layer includes a first redistribution line, and the first redistribution line has a first projection length on a bonding surface of the first semiconductor layer and the second semiconductor layer. The second semiconductor layer includes a second redistribution line, and the second redistribution line has a second projection length on the bonding surface. The first projection length is different from the second projection length. The first redistribution line is electrically connected to the second redistribution line. A method for forming the same is also provided.