Semiconductor Memory Gate Line Insulation via Separation Structure
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Solution Overview
Problem
The integration of semiconductor memory devices is limited by the area occupied by a unit memory cell, and existing three-dimensional structures face challenges in improving operation and reliability due to issues with gate line thickness variations and seam formation during manufacturing.
Innovation Solution
A semiconductor memory device structure featuring alternately stacked first and second gate structures with a separation insulating structure, where the second dummy gate line has a greater width than the first dummy gate line, and a sacrificial layer is used as a polishing stop to reduce seam formation and enhance insulation between gate lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If gate lines are formed with uniform thickness in three-dimensional stacked structures, then manufacturing precision is improved, but seam formation and insulation issues worsen due to the complexity of maintaining uniformity in stacked architectures
Solution Approach 1:
A separation insulating structure is introduced as an intermediary element between adjacent gate structures. This separation insulating layer fills the gaps and prevents direct contact between gate lines from different stacks, thereby ensuring reliable insulation without requiring perfect thickness uniformity in the gate lines themselves.
Solution Approach 2:
The gate structures are divided into multiple independent stacks, each with its own separation insulating structure. This segmentation allows each gate line to be formed and insulated independently, reducing the cumulative effect of thickness variations and preventing seam formation between adjacent gate structures.
2Productivity
If three-dimensional stacked memory structures are implemented to improve integration density, then productivity is improved, but device complexity increases due to multiple stacking layers and associated manufacturing challenges
Solution Approach 1:
Multiple gate structures are stacked vertically in a nested configuration, with each layer containing complete gate structures that include separation insulating elements. This nesting approach maximizes vertical space utilization for higher integration density while keeping each individual layer's complexity manageable through modular design.
Solution Approach 2:
The separation insulating structures are strategically placed only where needed between adjacent gate lines, rather than uniformly throughout the entire device. This localized approach provides necessary insulation and seam prevention only at critical interfaces, reducing overall material usage and manufacturing complexity while maintaining reliability.
3Reliability
If separation insulating structures are added between gate structures, then insulation and reliability are improved, but device complexity and manufacturing steps increase
Solution Approach 1:
The separation insulating structure formation is merged with the existing gate structure fabrication process. The same sacrificial layers and etching steps used to create gate structures are also utilized to form the separation insulating regions, thereby adding necessary insulation functionality without proportionally increasing manufacturing complexity or process steps.
Data Source
AI summary
A semiconductor memory device may include first gate structures each including first real gate lines and first insulating layers that are alternately stacked. The device may also include first dummy gate lines located on the first gate structures, a separation insulating structure configured to extend between the first dummy gate lines and between the first gate structures, and a second gate structure located on the first gate structures and the separation insulating structure and comprising a second dummy gate line having a greater width than each of the first dummy gate lines.