Backside Wiring Layout for Optical Inspection of Integrated Circuits
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Solution Overview
Problem
The inspection of integrated circuits with backside wiring is challenging due to the blocking of optical fault isolation techniques by backside patterns, making it difficult to detect defects and ensuring proper functionality and lifespan.
Innovation Solution
The integration of backside wiring patterns that are removed or excluded from inspection regions allows for easy detection of defects by enabling unobstructed laser access to the junctions of transistors, while maintaining the functionality and performance of the integrated circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If backside wiring patterns are included in inspection regions, then the integrated circuit maintains complete wiring functionality, but optical fault isolation inspection becomes blocked and defect detection becomes difficult
Solution Approach 1:
The inspection region is segmented into multiple sub-regions, with certain areas excluded from containing backside wiring patterns. This allows the inspection region to be divided into wiring functional areas and inspection-friendly areas, enabling both complete wiring functionality and unobstructed optical inspection access.
Solution Approach 2:
Different regions within the inspection area have different properties: some regions contain backside wiring patterns for electrical connectivity, while other regions are cleared of patterns to allow optical inspection. This local differentiation enables simultaneous satisfaction of wiring functionality and inspection accessibility requirements.
2Difficulty of detecting and measuring
If backside patterns are removed from inspection regions, then laser access for inspection is enabled, but wiring continuity may be compromised
Solution Approach 1:
The backside wiring layer is segmented into continuous wiring segments and inspection region exclusions. Wiring patterns are continued across multiple cells except where inspection regions require pattern removal, maintaining wiring continuity in functional areas while enabling inspection access where needed.
Solution Approach 2:
The design uses inspection regions as intermediary zones that deliberately exclude backside wiring patterns to serve as access points for optical inspection tools, while maintaining the overall wiring architecture through careful placement of vias and conductive patterns in non-inspection areas.
3Reliability
If complete backside wiring coverage is implemented, then electrical connectivity is maximized, but inspection and defect detection become more difficult
Solution Approach 1:
The backside wiring layer is segmented to exclude patterns from inspection regions while maintaining connectivity through via holes and conductive patterns in non-inspection areas. This segmentation allows the inspection process to access underlying structures without being blocked by continuous backside wiring patterns.
Solution Approach 2:
Different local regions have different wiring densities: high-density wiring in functional areas for maximum electrical connectivity, and pattern-free inspection regions for ease of manufacturing and defect detection. This local quality differentiation resolves the contradiction between connectivity and inspectability.
Data Source
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AI summary
An example integrated circuit includes a plurality of cells positioned in a plurality of rows extending in a first horizontal direction. The plurality of cells include a first cell disposed in a first row. The first cell comprises a first active pattern extending in the first horizontal direction and a first backside pattern overlapping the first active pattern in a vertical direction and extending in the first horizontal direction in a first backside wiring layer below the first active pattern. The first backside pattern is removed from a first inspection region that overlaps the first active pattern and extends in a second horizontal direction.