Dynamic Peak Current Density Specification for IC Conductor Lines
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Solution Overview
Problem
Conventional peak current density specifications for integrated circuits are overly conservative for short current waveforms, limiting circuit speed and density, while being too aggressive for long waveforms, risking melting failures.
Innovation Solution
A method to compute a peak current density specification that accounts for the on-time of the current waveform and thermal time constant, allowing for dynamic adjustment of conductor line dimensions based on waveform width, using equations that model Joule heating effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional constant peak current density specification is used, then reliability is improved for long waveforms, but circuit speed and density are limited for short waveforms
Solution Approach 1:
The patent applies dynamics by transitioning from a static, constant peak current density specification to a dynamic specification that varies with waveform duration. The jpeak spec is adjusted based on the ratio of waveform duration to thermal time constant, allowing higher current densities for short waveforms and lower densities for long waveforms, thus optimizing both reliability and circuit performance across different operating conditions
Solution Approach 2:
The patent changes the parameter of peak current density specification from a fixed constant value to a variable value that depends on waveform characteristics. By introducing the waveform duration parameter and its relationship with thermal time constant, the specification adapts to different pulse widths, enabling higher speeds for short pulses while maintaining reliability for long-duration operations
2Reliability
If a conventional constant peak current density specification is used, then reliability is improved for long waveforms, but interconnect density is limited for short waveforms
Solution Approach 1:
The dynamic jpeak specification enables the interconnect structure to adapt its current-carrying capacity based on the temporal characteristics of the signal. For short waveforms, the relaxed specification allows higher current densities that can be sustained without thermal damage, effectively increasing the functional density of interconnect resources available for high-speed signaling
Solution Approach 2:
By changing the peak current density parameter from constant to waveform-duration-dependent, the patent enables more efficient utilization of interconnect resources. Shorter waveforms can exploit higher current densities, increasing the number of functional interconnects available for high-speed operations while long waveforms automatically operate at safer density levels
3Reliability
If conductor line widths are increased to reduce peak current density, then melting failure is prevented, but circuit density is reduced
Solution Approach 1:
Instead of uniformly increasing conductor line widths for all waveforms, the patent changes the current density specification parameter to account for waveform duration. This allows standard-width conductors to safely carry higher currents for short pulses without melting, eliminating the need for width increases and preserving circuit density while maintaining reliability
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 enables more reliable and efficient design of integrated circuits by optimizing conductor line dimensions for varying waveform widths, balancing speed and reliability, and preventing unwanted melting failures.
Implementation Method 1
Thermal effects are an inherent aspect of electrical power distribution and signal transmission through the interconnects due to self-heating (or Joule heating) caused by resistance to the flow of electrical current
Implementation Method 2
the adjacent layers (e.g., dielectric layers) to the electrical conductor line which determines the thermal resistance reflected in a thermal time constant (τ) associated with the conductor line
Data Source
AI summary
A method of computing a peak current density specification (jpeakspec) for an electrical conductor line of an integrated circuit (IC) resulting from conducting pulsed electrical current represented as a current waveform. An on-time (ton) is identified for the current waveform based on a current density being greater than or equal to (≧) a predetermined current density level. The jpeakspec is computed for the electrical conductor line using a jpeakspec modeling equation which includes the ton for the current waveform and a thermal time constant (τ) for the electrical conductor line.