Monolithic Stacked ICs with Redundant Layer for Defect Repair
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Solution Overview
Problem
Monolithic stacked integrated circuits face challenges such as low yield due to manufacturing defects, heat dissipation issues, and electromagnetic interference (EMI) as more layers are added, particularly in advanced process nodes like 28 nm and below.
Innovation Solution
Incorporating redundant layers and circuits in the IC design that can be used to repair defects and mitigate heat dissipation and EMI issues through a method that involves forming redundant layers over functional layers, using inter-layer vias for connectivity, and employing direct-writing lithography to form interconnect structures in the redundant layers for defect correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If more layers are added to increase functional complexity, then the number of semiconductor building blocks per unit area increases, but manufacturing defects compound and yield decreases
Solution Approach 1:
A redundant layer is formed over the functional layers before final assembly, containing spare circuit elements that can be activated if defects are detected in the functional layers. This preliminary preparation allows for post-fabrication repair without requiring re-manufacturing of the entire stacked IC.
Solution Approach 2:
The patent changes the structural parameter by adding an additional redundant layer to the stacked IC architecture. This modifies the yield calculation from the product of functional layer yields to include the redundant layer, effectively increasing overall yield by providing backup pathways when defects occur in functional layers.
2Adaptability or versatility
If more layers are stacked to increase density, then functional complexity increases, but heat dissipation becomes more difficult
Solution Approach 1:
The stacked IC is segmented into functional layers and a separate redundant layer. The redundant layer can be configured to provide thermal management functions, such as acting as a heat spreader or containing thermal vias, while the functional layers maintain their computational functions. This segmentation allows independent optimization of thermal characteristics.
3Adaptability or versatility
If more layers are stacked to increase density, then functional complexity increases, but electromagnetic interference increases
Solution Approach 1:
The redundant layer acts as an intermediary between functional layers, providing shielding and isolation. It can contain ground planes, shielding structures, or filtering circuits that reduce electromagnetic interference between adjacent functional layers while maintaining signal integrity for redundant repair pathways.
4Reliability
If redundant layers are added to repair defects, then manufacturing yield increases, but device complexity increases
Solution Approach 1:
The redundant layer is essentially a copy of the functional layer structure, containing duplicate circuit elements and interconnect patterns. This copying approach allows for straightforward repair by switching to the redundant copy when defects are detected, without requiring complex repair logic or additional control circuitry beyond standard multiplexing.
Data Source
AI summary
Provided is a monolithic stacked integrated circuit (IC). The IC includes a first layer over a substrate and a second layer over the first layer. The first layer includes first circuit elements where a first portion of the first circuit elements has a defect. The second layer includes second circuit elements. The IC further includes interconnect elements coupling the first portion to a second portion of the second circuit elements for mitigating the defect.