Conductive Redistribution for Hexagonal DRAM Capacitor Packing
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Solution Overview
Problem
The challenge in integrated memory fabrication is the limited packing density of capacitors due to the rectangular pattern of capacitor connections, which restricts the tight packing of storage elements in DRAM arrays.
Innovation Solution
The implementation of conductive redistribution structures that convert a rectangular pattern of interconnection regions to a hexagonal-close-packed pattern, allowing for the redistribution of capacitor connections and enabling tighter arrangement of capacitors across active regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a rectangular pattern of capacitor connections is used, then the fabrication process is simple, but the packing density of capacitors is limited
Solution Approach 1:
The invention divides the capacitor interconnection structure into two distinct parts: (1) a rectangular array of capacitor contact regions that maintains simple fabrication, and (2) a separate conductive redistribution layer that creates the hexagonal-close-packed pattern. This segmentation allows each layer to optimize for its specific function without compromising the other.
Solution Approach 2:
The invention transitions from a two-dimensional rectangular grid to a three-dimensional structure by adding a conductive redistribution layer above the capacitor contact regions. This vertical dimensionality change enables the formation of hexagonal-close-packed patterns that maximize horizontal packing density while maintaining the simple rectangular footprint below.
2Productivity
If capacitors are tightly packed, then integration level increases, but the rectangular connection pattern restricts further packing optimization
Solution Approach 1:
The conductive redistribution layer acts as an intermediary between the rectangular capacitor contact regions and the ultimately formed capacitors. This intermediate structure enables flexible hexagonal arrangement of capacitors while the underlying rectangular contact pattern maintains compatibility with standard fabrication processes.
3Quantity of substance
If a hexagonal-close-packed pattern is implemented, then capacitor packing density is maximized, but the fabrication complexity increases
Solution Approach 1:
The fabrication process is segmented into two independent stages: first forming the simple rectangular capacitor contact regions using standard processes, then adding the conductive redistribution layer to create the hexagonal pattern. This segmentation isolates the complexity to a single added layer while maintaining simplicity in the base structure.
Data Source
AI summary
Some embodiments include an integrated assembly. The integrated assembly includes active regions which each have a digit-line-contact-region between a pair of capacitor-contact-regions. The capacitor-contact-regions are arranged in a pattern such that six adjacent capacitor-contact-regions form a substantially rectangular configuration. Conductive redistribution material is coupled with the capacitor-contact-regions and extends upwardly and laterally outwardly from the capacitor-contact-regions. Upper surfaces of the conductive redistribution material are arranged in a pattern such that seven adjacent of the upper surfaces form a unit of a substantially hexagonal-close-packed configuration. Capacitors are coupled with the upper surfaces of the conductive redistribution material.