Mandrel-Pull-First Interconnect Patterning Without Line Bridges
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Solution Overview
Problem
Modern semiconductor devices face challenges in accurately forming sub-wavelength features due to spacer pinch-off issues in self-aligned double patterning, leading to non-mandrel line bridges and mandrel line bridges, which affect product yield.
Innovation Solution
A mandrel-pull-first interconnect patterning technique involving sequential deposition and etching of organic planarization layers and spin-on glass to form metal traces without line bridges, utilizing mandrel pulling and precise alignment of cuts to avoid spacer pinch-off artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional SADP process is used with photolithography to form metal traces, then sub-wavelength features can be formed, but spacer pinch-off occurs leading to line bridges and reduced manufacturing precision
Solution Approach 1:
The patent extracts and removes the problematic mandrels after the spacers have been formed. By pulling the mandrels out of the structure, the spacers are released from the constraint of surrounding mandrels, eliminating the pinch-off effect that causes line bridges. This allows the spacers to maintain their intended dimensions without deformation.
Solution Approach 2:
The mandrels are pulled out at an intermediate stage before the final metal deposition. This preliminary action prevents the pinch-off problem from occurring in the first place, allowing subsequent processing steps to proceed without the harmful effects of spacer deformation.
2Manufacturing precision
If gap widths are increased to prevent non-mandrel line bridges, then spacer pinch-off is reduced, but mandrel line bridges occur when gaps are too narrow
Solution Approach 1:
By removing the mandrels entirely from the structure before final processing, the patent eliminates the source of both non-mandrel line bridges (from spacer pinch-off) and mandrel line bridges. The spacers are formed around mandrels temporarily, then the mandrels are extracted, leaving clean spacer structures without pinch-off artifacts.
3Manufacturing precision
If process variations occur across the wafer, then critical dimensions cannot be replicated consistently, but traditional SADP requires tight dimensional control
Solution Approach 1:
The spacers serve a dual function: they define the final feature dimensions and simultaneously protect the underlying areas from metal deposition. This self-service mechanism ensures that even with process variations, the spacer-defined regions maintain their intended dimensions and the metal filling process automatically respects these boundaries.
Solution Approach 2:
The spacers are formed in advance to establish the final feature dimensions before any metal deposition occurs. This preliminary dimensioning action ensures that all subsequent processing steps work within the correctly defined boundaries, making the process tolerant to variations in later steps.
4Manufacturing precision
If EUV photolithography is used to form sub-wavelength features, then minimum feature sizes can be achieved, but the features are still larger than desired
Solution Approach 1:
The patent uses spacer deposition to create features that are approximately half the size of what can be directly patterned by photolithography. The mandrel defines one boundary, the spacer defines the other boundary, effectively segmenting the feature formation into two separate dimensional contributions that combine to achieve the final sub-wavelength dimension.
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
Enables self-aligned double patterning of interconnect layers without line bridges, improving product yield and reliability by avoiding spacer pinch-off defects.
Implementation Method 1
depositing a first organic planarization layer (OPL) onto the first structure
Implementation Method 2
filling the second non-mandrel cut and the mandrel cut with spin-on glass
Implementation Method 3
ashing the first OPL
Data Source
AI summary
A semiconductor structure includes a substrate; a spacer protruding from the substrate and surrounding a cavity; and spin-on glass filling a portion of the cavity.