EM Evaluation with Self-Heating Thermal Coupling Correction
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Solution Overview
Problem
Current electromigration (EM) evaluation methodologies in semiconductor devices do not accurately account for self-heating effects (SHE), leading to underestimated operating temperatures of conductive lines, which can result in premature failures due to increased EM-induced failures.
Innovation Solution
A self-heating aware EM evaluation methodology that uses equation-based device temperature calculations and pseudo-3D thermal modeling to adjust conductive line temperatures, considering FinFET, high-resistance, and conductive line self-heating effects, to provide more accurate EM analysis and reduce the risk of premature failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional EM evaluation methodologies are used, then the evaluation process is simple, but the operating temperature of conductive lines is underestimated leading to premature failures
Solution Approach 1:
The patent applies preliminary action by calculating self-heating temperature increases before conducting the EM evaluation. The methodology computes the temperature rise due to self-heating effects in advance, then uses this adjusted temperature as the basis for EM analysis, ensuring accurate temperature compensation is performed beforehand rather than during the evaluation process.
Solution Approach 2:
The patent introduces an intermediary approach by using a separate self-heating calculation model that acts as a mediator between the physical thermal effects and the EM evaluation process. This intermediary calculation provides the corrected temperature input needed for accurate EM assessment without directly modifying the EM evaluation methodology itself.
2Reliability
If self-heating effects are not considered, then the EM evaluation is faster, but the reliability of the evaluation results deteriorates
Solution Approach 1:
The patent performs preliminary calculation of self-heating temperature increases before the EM evaluation, so that when the EM analysis is conducted, the accurate temperature data is already available. This preliminary action ensures reliability without adding significant time during the critical evaluation phase.
Solution Approach 2:
The patent changes the temperature parameter used in EM evaluation from the nominal operating temperature to an adjusted temperature that accounts for self-heating effects. By modifying this key parameter, the reliability of the EM evaluation is improved while the additional computational overhead remains manageable.
3Measurement precision
If conventional EM evaluation is used, then the process is simpler, but the mean time to failure estimation becomes inaccurate
Solution Approach 1:
The patent calculates the self-heating temperature increase in advance before conducting the EM evaluation. This preliminary temperature adjustment ensures that the MTTF estimation is based on accurate operating temperatures, improving measurement precision without significantly complicating the overall evaluation process.
Solution Approach 2:
The patent incorporates feedback by using the calculated self-heating temperature increase to adjust the operating temperature input for the EM evaluation. This feedback loop ensures that the temperature parameter reflects actual operating conditions, leading to more accurate MTTF estimates.
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 enhances the accuracy of EM evaluations, reduces the risk of premature product failure, and optimizes semiconductor device performance by accounting for thermal effects, thereby improving the reliability and longevity of semiconductor devices.
Implementation Method 1
Current passing through conductive lines induces electromigration (EM), i.e., the movement of the metal atoms resulting from momentum transfer between the electrons passing through the conductive lines and the metal atoms of the conductive lines
Implementation Method 2
self-heating effects (SHE), leading to underestimated operating temperatures of conductive lines
Data Source
AI summary
A system for evaluating a heat sensitive structure of an integrated circuit design including a memory for retrieving and storing integrated circuit design layout data, thermal data, process data, and one or more operational parameters, a processor capable of accessing the memory and identifying a target region having a nominal temperature Tnom, first and second heat generating structures within a first impact range of the target region, calculating the temperature increases ΔTh1 and ΔTh2 in the target region as a result of thermal coupling between the target region and the first and second heat generating structures, and conducting one or more parametric evaluations of the target region at an adjusted evaluation temperature TE=Tnom+ΔTh1+ΔTh1 after which a network interface transmits the result(s) of the parametric evaluation(s) for use in a design review.