IC Layout with FIB-Ready Access Nodes for Debug Probing
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Solution Overview
Problem
The complexity of modern integrated circuits makes debugging challenging, especially with advanced process technologies, as unsuitable layouts significantly decrease the percentage of nets observable through Focused Ion Beam (FIB) probing, necessitating improved methods for internal signal observation and manipulation.
Innovation Solution
The integration of a network of Basic FIB elements (BFEs) and routing circuitry in the IC design, with metal pads and supply-path circuits, allows for easy FIB access and manipulation of functional nodes, enabling efficient FIB editing and analysis by ensuring that any node is within a predefined distance from a BFE, thereby simplifying the debugging process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If FIB probing is used for debugging advanced process technologies, then internal signals can be observed, but unsuitable layouts significantly decrease the percentage of nets observable through FIB probing
Solution Approach 1:
The patent applies preliminary action by pre-placing Basic FIB elements (BFEs) with metal pads at predetermined locations within the IC layout during the design phase. These BFEs are positioned in advance to ensure coverage of all functional nodes, so that when FIB debugging is needed, the probes can immediately connect to pre-positioned access points without requiring complex layout modifications or extensive probing searches.
2Productivity
If the IC layout is optimized for standard design, then manufacturing efficiency is improved, but accessibility of functional nodes for FIB probing is reduced
Solution Approach 1:
The patent applies segmentation by dividing the IC into multiple regions, each containing at least one Basic FIB element (BFE) with a metal pad. This segmentation allows the bulk of the IC layout to maintain standard manufacturing optimization while specific localized regions are modified to include FIB access points. The BFEs are distributed throughout the IC to provide localized access to functional nodes without requiring global layout changes.
3Loss of time
If BFEs are distributed across the IC to reduce maximum FIB distance, then FIB probing efficiency is improved, but device area increases
Solution Approach 1:
The patent applies local quality by making the Basic FIB elements (BFEs) compact in structure while strategically positioning them to provide localized access to functional nodes. Each BFE contains a metal pad and associated circuitry that is optimized to occupy minimal area while still providing effective FIB probing capability. The distribution density of BFEs is adjusted based on the local functional density of the IC, placing more BFEs in regions with higher node density and fewer BFEs in regions with lower node density.
Data Source
AI summary
An Integrated Circuit (IC), designed for debugging by Focused Ion Beam (FIB) editing, includes functional circuitry, a network of Basic FIB elements (BFEs), and routing circuitry. The functional circuitry includes functional nodes. Each of the BFEs includes a respective metal pad configured to be connected to one of the functional nodes using FIB editing. The routing circuitry is configured to route one or more selected BFEs for analysis.