TSV Isolation Layer Structure Reducing Contact Resistance
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Solution Overview
Problem
Conventional through-silicon via (TSV) formation processes in 3DICs and stacked dies face challenges due to complex manufacturing steps, high contact resistance, and material differences leading to delamination, which increase RC delay and manufacturing costs.
Innovation Solution
A novel integrated circuit structure and method that eliminates redundant passivation layers by forming a continuous metal feature with a vertical and horizontal portion of an isolation layer, directly connecting a conductor to a top metal pad without intermediate passivation, reducing manufacturing complexity and improving electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional passivation layers and aluminum pads are used in TSV formation, then manufacturing processes can be inherited from legacy processes, but the resistance of aluminum pad and contact resistance cause increase in RC delay
Solution Approach 1:
The patent removes the aluminum pad and intermediate passivation layers from the conventional TSV structure. By extracting these problematic intermediate layers, the invention achieves direct connection between the TSV conductor and the top IMD, eliminating the source of high contact resistance and reducing RC delay while maintaining manufacturing feasibility through modified legacy processes
Solution Approach 2:
The patent transitions from a multi-layer vertical stack (passivation layers + aluminum pad + TSV) to a simplified direct-through structure. This dimensional simplification removes intermediate horizontal layers, creating a more direct electrical path through the substrate and significantly reducing the resistive interface layers that cause RC delay
2Reliability
If multiple passivation layers and insulation layers are stacked for TSV isolation, then TSV can be electrically connected to integrated circuits, but the structure involves more complicated manufacturing processes
Solution Approach 1:
The patent merges the isolation function and the electrical connection function into a single integrated structure. The TSV conductor directly penetrates through the substrate and connects to the top IMD, combining what were previously separate functions (isolation layers + aluminum pad + TSV connection) into a unified direct-through architecture, thereby simplifying manufacturing while maintaining electrical integrity
Solution Approach 2:
The top IMD serves multiple functions simultaneously: it acts as the interconnect dielectric, provides the electrical connection interface, and serves as the isolation barrier. This multi-functional design eliminates the need for separate dedicated isolation layers and aluminum pads, reducing manufacturing complexity while maintaining all necessary electrical and isolation functions
3Reliability
If aluminum pad and copper line interface is created for TSV connection, then electrical connection is achieved, but material difference at interface may cause delamination
Solution Approach 1:
The patent eliminates the heterogeneous aluminum-copper interface by removing the aluminum pad entirely. The TSV conductor (typically copper) connects directly to copper interconnect lines through the top IMD, creating a homogeneous copper-to-copper interface. This material homogeneity eliminates galvanic corrosion and delamination issues that arise from dissimilar metal interfaces, significantly improving interface stability
Data Source
AI summary
An integrated circuit structure includes a semiconductor substrate; an interconnect structure over the semiconductor substrate, wherein the interconnect structure comprises a top inter-metal dielectric (IMD); an opening penetrating the interconnect structure into the semiconductor substrate; a conductor in the opening; and an isolation layer having a vertical portion and a horizontal portion physically connected to each other. The vertical portion is on sidewalls of the opening. The horizontal portion is directly over the interconnect structure. The integrated circuit structure is free from passivation layers vertically between the top IMD and the horizontal portion of the isolation layer.