IC Layout Tool Electromigration Analysis
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Solution Overview
Problem
As integrated circuit device dimensions shrink, the increased density of conductive metal lines and contacts leads to challenges in predicting and preventing electromigration, which can cause degradation or failure of these structures, necessitating lengthy and costly testing to ensure reliability.
Innovation Solution
An integrated circuit design system that includes a layout design tool connected to a computer system, which creates interconnect structures that meet electromigration criteria by manipulating a design database to adjust dimensions based on current density and length, using equations to determine critical dimensions that prevent void formation and ensuring the interconnect structure's integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If device dimensions are reduced to increase packing density, then more transistors and memory cells can be located on the same substrate space, but the conductive metal lines and contacts become smaller and more closely packed, increasing resistance and susceptibility to electromigration
Solution Approach 1:
The system performs preliminary electromigration analysis during the design phase to predict potential failures before manufacturing. By calculating current density and comparing it against empirical thresholds, the system identifies at-risk interconnects in advance, allowing designers to modify dimensions or materials proactively rather than reacting after failures occur during testing.
Solution Approach 2:
The system modifies key parameters of the interconnect structure, specifically the cross-sectional area (width and thickness) of metal lines and contacts. By increasing these dimensions in critical areas, the system reduces current density and electromigration susceptibility while maintaining the overall high-density packing of the device.
2Reliability
If extensive testing is performed to verify electromigration resistance, then reliability can be confirmed, but development time and costs increase significantly
Solution Approach 1:
The patent replaces physical electromigration testing with a computational analysis system. Instead of subjecting devices to lengthy stress tests at elevated temperatures and voltages, the system uses mathematical models to calculate current density distributions and predict electromigration risks, substituting mechanical/physical testing with computational methodology.
Solution Approach 2:
The system creates a virtual model of the interconnect structure within the design database, allowing repeated analysis without physical testing. This digital copy can be simulated multiple times under different conditions to verify electromigration resistance, replacing the need for repeated physical stress testing.
3Reliability
If the cross-sectional area of metal lines is increased to maintain resistance, then electromigration effects are reduced, but the packing density and device integration density decrease
Solution Approach 1:
Instead of uniformly increasing the cross-sectional area of all metal lines, the system applies local quality by increasing dimensions only in specific areas where electromigration risk is highest. The layout design tool identifies critical interconnects based on current density calculations and applies dimensional adjustments selectively to those locations, maintaining high overall device density while ensuring reliability where needed.
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 allows for the prediction and prevention of electromigration failures, reducing the need for extensive testing and ensuring reliable integrated circuit performance by designing interconnect structures that meet electromigration life requirements, thereby shortening verification time and reducing costs.
Implementation Method 1
a phenomenon known as electromigration can adversely impact conductive metal lines in an integrated circuit product. In general, electromigration is a process whereby a conductive structure, such as a metal line, contact or via tends to degrade or become damaged, thereby resulting in a change in the physical characteristics, e.g., shape, size, etc., of the conductive structure.
Data Source
AI summary
The present invention provides an integrated circuit design system, comprising providing a design system in a computer system, providing a layout design tool coupled to the design system, wherein the layout design tool creates an interconnect structure to satisfy electromigration criteria, and manipulating a design database within the design system.