Pitch Division Patterning for Lithographic Feature Isolation
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Solution Overview
Problem
Lithographic techniques face limitations in forming features below a minimum pitch due to optics and wavelength constraints, leading to feature collapse and shorting issues in pitch quad lines, especially when feature sizes are reduced below 15 nm, as prior art methods lack sufficient spatial isolation and structural robustness.
Innovation Solution
The proposed solution involves a double 'pitch double' process using two hard mask layers and additional spacer layers to create pitch quad lines with increased spatial isolation and structural robustness, employing photo-resist pads and negative spacers to ensure stability, and optimizing the aspect ratio of depth to width for enhanced physical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If pitch division techniques are used to reduce feature size below lithographic minimum pitch, then feature density and circuit capacity are improved, but feature physical strength deteriorates leading to collapse and shorting
Solution Approach 1:
The patent introduces a vertical dimension by forming trenches beneath the pitch-divided lines and filling them with support material. This third-dimensional support structure reinforces the fragile nanoscale lines without affecting their lateral dimensions or electrical function, directly addressing the strength deterioration caused by pitch division.
Solution Approach 2:
The patent uses an intermediary support material filled into trenches that acts as a mechanical reinforcement between the substrate and the fragile pitch-divided lines. This intermediary structure provides physical strength to prevent collapse while maintaining the electrical isolation and functionality of the conductive lines.
2Quantity of substance
If feature size is reduced below 15 nm to increase circuit density, then manufacturing capacity is improved, but feature stability deteriorates due to capillary forces and processing environment susceptibility
Solution Approach 1:
The patent applies beforehand cushioning by pre-forming trenches and filling them with support material before subsequent processing steps. This preventive measure cushions the fragile sub-15nm features against capillary forces and processing stresses that would otherwise cause collapse or deformation during manufacturing.
Solution Approach 2:
By adding vertical support structures through trench formation and filling, the patent provides three-dimensional reinforcement that stabilizes the nanoscale features against environmental factors and processing stresses without interfering with their electrical function or reducing circuit density.
3Quantity of substance
If pitch is quartered to extend lithographic capabilities, then feature density is improved, but spatial isolation deteriorates leading to shorting problems
Solution Approach 1:
The patent uses vertical trenches filled with dielectric support material to provide spatial isolation between pitch-divided lines. This third-dimensional isolation structure prevents lateral migration or merging of conductive lines while maintaining the high density achieved through pitch quartering, directly addressing the shorting risk.
Data Source
AI summary
Embodiments of the invention comprise pitch division techniques to extend the capabilities of lithographic techniques beyond their minimum pitch. The pitch division techniques described herein employ additional processing to ensure pitch divided lines have the spatial isolation necessary to prevent shorting problems. The pitch division techniques described herein further employ processing acts to increase the structural robustness of high aspect ratio features.