Full-chip TDDB Assessment via Pattern Matching
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Solution Overview
Problem
Current methods fail to accurately assess and mitigate time-dependent dielectric breakdown (TDDB) in copper/low-k interconnects within integrated circuits, leading to unreliable predictions and conservative results due to the complexity of electric field distribution and varying geometries, which affects the kinetics of current conduction paths and leakage current density.
Innovation Solution
A full-chip assessment technique that analyzes layout designs to identify patterns susceptible to TDDB by using a pre-calculated pattern database with time-to-failure characteristic values based on electric current path generation models, calibrated with experimental data, and modifies the layout to address these vulnerabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional TDDB assessment methods are used, then the assessment process is simple, but the prediction accuracy is low and results are overly conservative
Solution Approach 1:
The patent segments the continuous electric field distribution into discrete stress zones based on voltage division across interconnect lines. Each zone is assigned a specific stress level (e.g., 0-0.5V, 0.5-1.0V, 1.0-1.5V) and evaluated independently using pattern matching, enabling accurate yet computationally efficient TDDB assessment without requiring complex full-chip simulation.
Solution Approach 2:
The patent pre-calculates time-to-failure (TTF) characteristic values for representative patterns and stores them in a database before actual TDDB assessment. This preliminary action allows the system to quickly retrieve and apply pre-computed reliability data during layout evaluation, avoiding repeated complex simulations while maintaining high prediction accuracy.
2Reliability
If full-chip analysis is performed, then comprehensive TDDB assessment is achieved, but computational time and resources increase significantly
Solution Approach 1:
The patent creates representative patterns that copy the essential characteristics of recurring interconnect structures across the chip. Instead of analyzing every unique geometry, the system identifies matching patterns from a limited set of representatives and applies their pre-computed TTF values to multiple instances, dramatically reducing computational time while maintaining comprehensive chip-level assessment.
Solution Approach 2:
The patent develops a universal pattern matching framework that can evaluate different interconnect geometries, materials, and voltage conditions using the same core methodology. The system universally applies stress zone identification, pattern matching, and TTF retrieval across diverse interconnect structures, enabling full-chip assessment with consistent accuracy without requiring separate analysis procedures for each case.
3Measurement precision
If detailed electric field distribution is considered, then TDDB prediction accuracy improves, but the complexity of modeling increases
Solution Approach 1:
The patent changes the modeling approach from continuous electric field distribution to discrete voltage-based stress zones. By parameterizing the electric field into distinct levels (0-0.5V, 0.5-1.0V, 1.0-1.5V) and associating each with specific TTF characteristic values, the system maintains accurate field distribution effects while significantly simplifying the underlying model and enabling efficient pattern matching.
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 provides a robust method for evaluating TDDB-induced interconnect lifetime by accurately determining time-to-failure and modifying layouts to prevent breakdown, improving the reliability of copper/low-k dielectric structures by accounting for varying geometries and electric attributes.
Implementation Method 1
The break-down is caused by formation of a conducting path through the IMD oxide between metal lines due to electron tunneling current
Implementation Method 2
The E-model describes weak bond breakage due to thermochemical heating
Implementation Method 3
The √E-model, first proposed for metal-SiN-metal capacitors, has been employed for the low-k TDDB, assuming that the copper ions play a major role in dielectric breakdown
Data Source
AI summary
Aspects of the disclosed technology relate to techniques of full-chip assessment of time-dependent dielectric breakdown. A layout design is analyzed to identify matching patterns that match a pre-calculated pattern in a pattern database. Each of pre-calculated patterns in the pattern database has a time-to-failure characteristic value pre-computed based on a model of electric current path generation and evolution. Time-to-failure characteristic values are then determined for the matching patterns based on the pre-computed time-to-failure characteristic values and electric attributes of geometric elements in each of the matching patterns. Based on the time-to-failure characteristic values, matching patterns most susceptible to time-dependent dielectric breakdown are identified and fixed.