IC Defect Localization Using Active Excitation Condition Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing excitation condition-based diagnosis techniques struggle to accurately distinguish between cell internal defects and interconnect defects in integrated circuits, particularly at advanced fabrication nodes like 90 nm and beyond, leading to inefficient and costly physical failure analysis processes.
Innovation Solution
The implementation of active excitation condition extraction techniques that heuristically determine true failing and passing excitation conditions from test patterns, allowing for the differentiation between cell internal defects and interconnect defects by correlating exercising conditions from failing and observable passing test patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional logic diagnosis is used to determine failure location, then the most likely location inside a failing die can be identified, but the diagnosis cannot distinguish whether the defect is on the interconnecting wire or inside the library cell
Solution Approach 1:
The patent segments the defect diagnosis process into two distinct stages: first identifying the failure location using conventional logic diagnosis, then determining whether the defect is cell-internal or interconnect-based by analyzing exercising conditions. This segmentation allows each stage to focus on its specific objective without compromising the other.
Solution Approach 2:
The patent introduces an intermediary analysis step that examines exercising conditions as a mediator between the failure location and defect type. By analyzing which input conditions excite the failure, the system can infer whether the defect lies within the cell or on interconnect wires without directly observing the physical defect location.
2Productivity
If advanced fabrication technology (90 nm and beyond) is used, then circuit functionality is improved, but the number of cell internal defects increases making defect localization more difficult
Solution Approach 1:
The patent applies dynamics by adaptively adjusting the diagnosis approach based on fabrication node characteristics. For 90 nm and beyond, the system recognizes the higher prevalence of cell-internal defects and uses exercising condition analysis to dynamically focus the investigation on cell inputs rather than exhaustively examining all interconnect layers.
Solution Approach 2:
The patent changes the diagnostic parameter from physical location only to include logical exercising conditions. By incorporating which input patterns excite the failure into the diagnosis, the system can differentiate between cell and interconnect defects even at advanced nodes where cell defects are more common.
3Measurement precision
If physical failure analysis is performed without cell internal diagnosis, then all metal layers must be examined, but the process time and cost increase significantly
Solution Approach 1:
The patent performs preliminary logical analysis of exercising conditions before initiating physical failure analysis. This preliminary action identifies cell-internal defects through logical deduction, allowing the physical analysis to be skipped for those cases and proceed directly to interconnect analysis only when necessary, thereby reducing overall PFA time.
Solution Approach 2:
The patent applies partial action by performing only the necessary portion of physical failure analysis. When exercising condition analysis conclusively identifies a cell-internal defect, the physical analysis is partially performed (only down to metal layer 1) rather than examining all metal layers, reducing time and cost while maintaining diagnostic accuracy.
4Measurement precision
If defect model-based diagnosis techniques are used, then cell internal defects can be identified, but the technique depends on a specific defect model which may not cover unknown defect types
Solution Approach 1:
The patent creates a universal diagnosis approach that works for all defect types regardless of their physical nature. By focusing on the logical exercising conditions that excite failures rather than the physical characteristics of defects, the method becomes applicable to both known and unknown defect types, including cell-internal and interconnect defects.
Solution Approach 2:
The patent extracts the essential diagnostic information (exercising conditions) from the complex defect model framework. Instead of relying on specific defect models, the system extracts and analyzes which input conditions cause failures, separating the diagnostic logic from any particular defect type assumptions.
Data Source
AI summary
Among the various embodiments described is a method of detecting defects in a cell of an integrated circuit that analyzes exercising conditions applied to an input of the cell during a capture phase of testing with failed test patterns that produce an indication of a fault and that analyzes the exercising conditions that are applied during a capture phase of testing with observable passing patterns that do not provide an indication of a fault. From the analysis, true failing excitation conditions and passing excitation conditions can be determined and used to identify whether a defect is in the cell or on an interconnect wire of the integrated circuit.