Visible Alignment Markers for CAD-to-Silicon Backside Image Alignment
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Solution Overview
Problem
In 10 nm and smaller IC technology, the increasing density and decreasing feature sizes lead to challenges in CAD-to-image alignment during LVP measurement due to the limitations of current EFI tools, making it difficult to distinguish features and ensuring accurate probing of standard cells or signals.
Innovation Solution
Incorporating modified standard cells and tie cell devices with extended inactive regions that serve as visible alignment markers, these markers are designed to be highly reflective of electromagnetic radiation, allowing for precise local alignment by creating unique patterns that facilitate accurate CAD alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If feature sizes are decreased to increase IC density, then IC density is improved, but CAD-to-image alignment precision deteriorates
Solution Approach 1:
The patent applies reflective alignment markers that appear as bright spots or distinct patterns in laser scanning microscope images. These markers have different reflectivity properties compared to surrounding circuit features, creating visual contrast that enables precise identification and alignment at 10 nm and smaller technology nodes where standard features become indistinguishable
Solution Approach 2:
The patent introduces alignment markers as intermediary reference elements between the CAD design data and the physical silicon image. These markers serve as mediators that provide a common reference framework, allowing the alignment system to accurately map between digital design coordinates and physical probe positions despite the reduced feature size
2Quantity of substance
If feature sizes are decreased to increase IC density, then IC density is improved, but feature distinguishability deteriorates
Solution Approach 1:
The alignment markers are designed to reflect electromagnetic radiation differently than surrounding circuit features, creating distinct visual signatures in the laser scanning microscope image. This differential reflectivity allows markers to stand out as bright spots or unique patterns, making them easily distinguishable from the dense 10 nm circuit features
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
The use of modified standard cells and tie cell devices with extended inactive regions significantly enhances CAD-to-image alignment accuracy and efficiency, enabling accurate orientation and probing in 10 nm and smaller IC technologies by providing distinct fiducials within the field of view.
Implementation Method 1
these markers are designed to be highly reflective of electromagnetic radiation, allowing for precise local alignment
Data Source
AI summary
A MOS IC includes a first standard cell including first and second power rails, first and second active regions, and a plurality of metal interconnects. The first power rail extends in a first direction and provides a first voltage to the first standard cell. The second power rail extends in the first direction and provides a second voltage to the first standard cell. The first active region is between the first and second power rails on a first side of the first standard cell. The second active region is between the first and second power rails on a second side of the first standard cell. The second active region is separated from the first active region. The plurality of metal interconnects extend in a second direction between the first and second active regions and between the first and second power rails. The second direction is orthogonal to the first direction.