FIB Open Via Analysis and Repair
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Solution Overview
Problem
Current failure analysis methods for integrated circuits, particularly for locating and characterizing resistive defects in vias and contacts, are ineffective as they often destroy the structure or circuit and cannot accurately identify multiple defects without destructive cross-sectioning.
Innovation Solution
The use of dynamic active voltage contrast (DAVC) with a non-DC applied voltage and pseudo-cross sectioning techniques via Focused Ion Beam (FIB) to localize and characterize resistive faults without destroying the structure, enabling precise identification and potential repair of defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If destructive cross-sectioning is used to locate and characterize defects, then measurement precision is improved, but the structure is destroyed and multiple defects cannot be identified
Solution Approach 1:
The patent replaces destructive mechanical cross-sectioning with non-destructive electrical measurement techniques. Specifically, it uses voltage contrast imaging and resistance measurements through probe contacts to locate and characterize defects in vias and contacts, eliminating the need to physically section the device structure.
Solution Approach 2:
The patent introduces probe contacts as intermediaries to access and measure electrical properties of vias and contacts. By making electrical contact through the structure rather than physically sectioning it, the method enables defect characterization while preserving the original device architecture.
2Ease of operation
If FIB is used for fault isolation, then ease of operation is improved, but the structure may be damaged and repair capability is limited
Solution Approach 1:
The patent enables the device structure itself to serve as the measurement probe. By using the existing vias, contacts, and interconnects as electrical pathways and making contacts through the structure, the method eliminates the need for external FIB milling to access internal nodes, thereby avoiding FIB-induced damage while maintaining ease of operation.
3Measurement precision
If passive voltage contrast is used for defect location, then measurement precision is improved, but resistive defects cannot be accurately identified
Solution Approach 1:
The patent transitions from observing passive voltage contrast (which only shows potential differences) to actively measuring resistance values. By applying known currents and measuring voltage drops, or vice versa, the method can quantify resistance values and distinguish between open circuits, short circuits, and resistive defects with different resistance levels, thereby expanding defect detection capability.
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
DAVC enhances defect localization and characterization, particularly for resistive defects, allowing for non-destructive analysis and potential in-situ repair, improving the efficiency and accuracy of failure analysis and reducing the need for destructive cross-sectioning.
Implementation Method 1
a focused ion beam (FIB) system to scan the ion beam over the contact/via to remove via material
Implementation Method 2
deposit conductive material into the removed via to repair the defect
Implementation Method 3
Passive Voltage Contrast (PVC), i.e., voltage contrast where no voltage is applied to the device, is a phenomenon seen while inspecting a semiconductor device with a charged particle beam tool such as a scanning electron microscope (SEM) or a FIB, where an image is seen according to secondary electrons emitted from the sample upon exposure to the beam
Data Source
AI summary
An improved method, apparatus, and control/guiding software for localizing, characterizing, and correcting defects in integrated circuits, particularly open or resistive contact/via defects and metal bridging defects, using FIB technology. An apparatus for identifying an abnormal discontinuity in a contact/via in an integrated circuit comprising a focused ion beam system to scan the ion beam over the contact/via to do remove or deposit via material, a detector to collect a secondary particle signal from the contact/via material that gets removed, a sub-system for storing the secondary particle signal from the contact/via in time as well as x-y scan position, a sub-system for correlating secondary particle signals and identifying discontinuities in the correlated secondary particle signals, a sub-system for optimizing the display of the abnormal discontinuity; and a computer to implement software aspects of the system.