Stair Step Memory Stack Contacts for Collapse-Resistant Scaling
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Solution Overview
Problem
Conventional vertical memory arrays face issues with stack collapse during processing and reduced margin between conductive contact structures, affecting memory cell reliability and density as the height of stacks increases.
Innovation Solution
A method involving the formation of first openings through a dielectric material over a stair step structure before forming pillar structures, followed by the creation of sacrificial structures and conductive contact structures, ensuring precise electrical connections without pillar fall-off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the height of stacks increases to facilitate additional memory cells, then memory density is improved, but the stack becomes prone to toppling or collapse during processing
Solution Approach 1:
The method forms first openings through the dielectric material over the stair step structure before forming the pillar structures. This preliminary action allows for precise positioning and support structures to be in place before the tall stack is fully constructed, preventing collapse during subsequent processing steps.
Solution Approach 2:
The patent introduces sacrificial structures as intermediary elements that are formed between the pillar structures and the final conductive contact structures. These sacrificial structures provide temporary support and spacing during manufacturing, ensuring the tall stack maintains its integrity throughout the fabrication process.
2Quantity of substance
If the density of vertical memory strings increases, then memory density is improved, but the margin between conductive contact structures and other structures decreases
Solution Approach 1:
The first openings are formed through the dielectric material before the pillar structures are created. This preliminary positioning establishes precise locations for the conductive contact structures, ensuring adequate margins are maintained even as the density of vertical memory strings increases.
Solution Approach 2:
The stair step structure serves as a template or copy that defines the precise locations and spacing of the conductive contact structures. By replicating the stair step pattern through the opening formation process, the patent ensures consistent spacing and margins are maintained across high-density configurations.
Data Source
AI summary
A microelectronic device comprises a stack structure comprising a vertically alternating sequence of conductive structures and insulative structures arranged in tiers, a stair step structure within the stack structure and having steps comprising lateral edges of the tiers, pillar structures extending through the stack structure and the stair step structure and in contact with a source tier vertically underlying the stack structure, and conductive contact structures in contact with the steps of the staircase structure, the conductive contact structures individually comprising a first portion and a second portion vertically overlying the first portion, the second portion vertically above the pillar structures and having a greater lateral dimension than the first portion. Related microelectronic devices, memory devices, and electronic systems are also described.