IO Cell Interconnect Layout for Lower Parasitic Capacitance
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Solution Overview
Problem
The increasing miniaturization of semiconductor integrated circuit devices leads to higher parasitic capacitance between interconnects, which hinders speedup and efficiency in signal exchange.
Innovation Solution
A layout structure for IO cells is introduced, featuring multiple interconnect layers with specific configurations to reduce parasitic capacitance at signal terminals. This includes arranging transistors in rows with non-overlapping interconnects to minimize capacitance between layers and within layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of metal interconnect layers is increased to support miniaturization, then the integration density is improved, but the parasitic capacitance between interconnects increases
Solution Approach 1:
The patent utilizes three-dimensional stacking of interconnect layers to achieve higher integration density. By arranging interconnects in multiple layers (M1, M2, M3, etc.) vertically stacked, the design transitions from two-dimensional planar布局 to three-dimensional spatial arrangement, allowing more interconnects to coexist without increasing in-plane parasitic capacitance significantly.
Solution Approach 2:
The patent segments the interconnect structure into multiple independent layers with distinct functions. Each metal layer (M1, M2, M3, M4, M5, M6) is segmented to carry specific signals (gate signals, drain signals, power supplies, etc.), reducing unwanted capacitive coupling between different signal types by separating them in the vertical dimension.
2Length of moving object
If the distance between interconnect layers is reduced for miniaturization, then the device size is reduced, but the parasitic capacitance between different interconnect layers increases
Solution Approach 1:
The patent introduces intermediate structures such as insulating layers and spacing elements between adjacent metal interconnect layers. These intermediary structures act as dielectric barriers that reduce parasitic capacitance coupling between layers while maintaining the compact vertical stacking arrangement necessary for miniaturization.
Solution Approach 2:
The patent applies different spacing and insulation strategies to different regions of the interconnect structure. In regions where high capacitance would be problematic (such as between gate and drain interconnects), increased spacing or additional insulating layers are applied locally, while in other regions compact routing is maintained to minimize overall device size.
3Area of stationary object
If the distance between interconnects in the same layer is reduced, then the area is reduced, but the parasitic capacitance between interconnects in the same layer increases
Solution Approach 1:
The patent resolves same-layer parasitic capacitance issues by moving interconnects to different vertical layers. Instead of routing all interconnects in a single plane, the design distributes them across multiple stacked layers (M1 through M6), allowing closer in-plane spacing while maintaining electrical isolation through vertical separation where needed.
Data Source
AI summary
In an output circuit included in an IO cell, between transistor rows of an output transistor, placed is a first interconnect connected to the gates of the transistors. Second interconnects connected to the drains of the transistors are placed for the transistor rows. The first interconnect is located between the second interconnects separated from each other in planar view. That is, the second interconnects connected to the drains of the transistors do not overlap the first interconnect connected to the gates of the transistors in planar view.