Dielectric Slot Structures for 3D NAND Source Corrosion Containment
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Solution Overview
Problem
The challenge in 3D NAND Flash memory device fabrication is corrosion of source and contact materials during the replacement gate process, leading to issues like tier lifting and arcing due to overetching during material removal, which affects memory device performance.
Innovation Solution
Incorporating corrosion containment features within the microelectronic device structure to isolate and contain corrosion to a specific area, using dielectric materials that are not removed during the replacement gate process, and forming bridges to connect adjacent source portions in the array region, thereby preventing corrosion from spreading and maintaining device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If material removal process is conducted to form slits in the tiers, then the nitride material is removed and replaced with conductive material, but overetch occurs extending slits into the source material and contact material causing corrosion
Solution Approach 1:
The source material is segmented into isolated portions by corrosion containment features (dielectric slots), preventing corrosion from propagating across the entire source region. This segmentation contains the harmful effect to localized areas while maintaining overall device functionality.
Solution Approach 2:
Corrosion containment features act as intermediary structures between the slits and the source material, preventing direct contact between corrosive etchants and the source. These dielectric slots serve as protective mediators that block corrosion pathways.
2Reliability
If corrosion containment features are added to prevent corrosion spread, then device reliability is improved, but device complexity increases
Solution Approach 1:
Rather than making the entire device more complex, corrosion containment features are strategically placed only where needed - adjacent to slits in the source material. This local application of protective structures provides maximum benefit with minimum added complexity.
Solution Approach 2:
The device structure becomes a composite of functional materials (source, contact, tiers) and protective materials (dielectric corrosion containment features). This composite approach integrates protection into the existing device architecture without requiring entirely new structures.
3Reliability
If bridges are formed to connect adjacent source portions, then electrical connectivity is maintained, but manufacturing process complexity increases
Solution Approach 1:
Bridges are formed preliminarily to connect adjacent source portions before corrosion occurs or as part of the source formation process. This preliminary connectivity ensures that even if corrosion isolates portions of the source, electrical pathways are already established.
Solution Approach 2:
The bridge formation process merges the connectivity function with the source structure. Rather than adding separate interconnect structures, the bridges are integrated directly into the source material, combining structural and electrical functions.
Data Source
AI summary
A microelectronic device comprising a stack structure comprising a non-staircase region, a staircase region, and an array region. Each of the non-staircase region, the staircase region, and the array region comprises tiers of alternating conductive materials and dielectric materials. One or more pillars are in the non-staircase region and in the array region, and one or more supports are in the staircase region. A conductive material is in each of the non-staircase region, the staircase region, and the array region and extends vertically into a source adjacent to the tiers. The source comprises corrosion containment features in each of the non-staircase region, the staircase region, and the array region, adjacent to the conductive material in the source. Additional microelectronic devices, electronic systems, and methods are also disclosed.