IC Conductive Line Thermal Zoning for Accurate Electromigration Checks
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Solution Overview
Problem
Existing electromigration evaluation methodologies fail to accurately account for self-heating effects in conductive lines, leading to underestimated operating temperatures and increased risk of premature IC device failures due to electromigration-induced failures.
Innovation Solution
An electromigration evaluation method that considers thermal coupling and self-heating effects by using thermal models to estimate conductive line temperatures, incorporating thermal affected zones and rating factors to assess temperature rises in neighboring conductive lines, and performing electromigration confirmation checks at estimated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional electromigration evaluation methodologies are used, then the evaluation process is simple and fast, but the accuracy of temperature estimation is insufficient leading to underestimated operating temperatures
Solution Approach 1:
The IC design is divided into thermal zones based on proximity to self-heating structures. Conductive lines are segmented and assigned to different thermal zones, with each zone having its own temperature estimation. This segmentation allows accurate temperature estimation without requiring a single complex global thermal model.
Solution Approach 2:
Thermal zones are pre-defined and rating factors are pre-calculated based on distance from self-heating structures before the actual electromigration evaluation. This preliminary action prepares the temperature estimation framework in advance, making the subsequent EM evaluation faster and simpler while maintaining accuracy.
2Reliability
If self-heating effects are ignored in electromigration evaluation, then the evaluation methodology is simpler, but the reliability of IC devices is compromised due to premature failures
Solution Approach 1:
Rating factors serve as an intermediary that quantifies the thermal influence of self-heating structures on conductive lines. Instead of directly simulating complex thermal coupling, the rating factors mediate the relationship between self-heating structures and conductive lines, providing a simplified yet accurate way to account for self-heating effects in EM evaluation.
Solution Approach 2:
The evaluation methodology changes the temperature parameter from a single nominal value to zone-specific estimated temperatures that account for self-heating. By modifying the temperature parameter to reflect actual operating conditions in different thermal zones, the reliability of EM evaluation is improved without requiring full thermal simulation complexity.
3Measurement precision
If thermal coupling between neighboring conductive lines is not considered, then the evaluation process is faster, but the accuracy of electromigration assessment is reduced
Solution Approach 1:
The IC design is divided into thermal zones based on proximity to self-heating structures. Conductive lines are segmented and assigned to different thermal zones, with each zone having its own temperature estimation. This segmentation allows accurate temperature estimation without requiring a single complex global thermal model.
Solution Approach 2:
Thermal zones are pre-defined and rating factors are pre-calculated based on distance from self-heating structures before the actual electromigration evaluation. This preliminary action prepares the temperature estimation framework in advance, making the subsequent EM evaluation faster and simpler while maintaining accuracy.
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
Improves the accuracy of electromigration evaluations by compensating for self-heating effects, reducing the risk of premature IC device failures and enhancing the reliability of conductive lines in advanced IC designs.
Implementation Method 1
IC devices such as semiconductor devices tend to increase in temperature during operation as a result of self-heating effects (SHE)
Implementation Method 2
modeling an operating temperature of the structure of interest based on the highest temperature and the rating factor
Data Source
AI summary
A method includes identifying a structure of interest in an IC design; assigning a thermal affected zone to a region of the IC design encompassing at least a portion of the structure of interest; identifying a plurality of structures that are, in whole or in part, in the thermal affected zone and that correspond to IC device elements that self-heat during operation of an IC device that is based on the IC design; modeling a corresponding plurality of operating temperatures for the plurality of structures and identifying, among the plurality of operating temperatures, a highest temperature; identifying, among the plurality of structures, a structure having the highest temperature as a first neighboring structure; assigning a rating factor based on a distance between the structure of interest and the first neighboring structure; and modeling an operating temperature of the structure of interest based on the highest temperature and the rating factor.