Stair Step Memory Stack Contacts for Collapse-Resistant Density

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional vertical memory arrays face issues with stack collapse during processing and reduced reliability due to decreased margin between conductive contact structures, making it difficult to increase memory density.

Innovation Solution

A method is introduced where first openings are formed through the dielectric material overlying the stair step structure before forming pillar structures, allowing for the creation of conductive contact structures that maintain electrical connections without pillar fall-off, thereby enhancing memory cell density.

Engineering Contradictions & Design Principles

VSEngineering 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

Engineering Contradiction:

Improvememory densityVSAvoidstack stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The method forms openings through the dielectric material overlying the stair step structure before forming the pillar structures. This preliminary action allows conductive contact structures to be positioned in predetermined locations, providing early structural support and electrical connections that prevent stack collapse during subsequent processing steps

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The conductive contact structures serve as intermediary elements that provide both structural support and electrical connections. By positioning these contact structures in openings formed before pillar formation, the invention creates a stable framework that mediates between the need for high memory density and the requirement for stack stability

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Engineering Contradiction:

Improvememory densityVSAvoidstructural margin

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

By forming openings through the dielectric material before creating pillar structures, the method establishes precise locations for conductive contact structures in advance. This preliminary positioning ensures adequate margins between contact structures and other components, even as vertical memory string density increases

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The stair step structure is divided into multiple tiers with individual steps, allowing conductive contact structures to be positioned at specific locations on different tiers. This segmentation enables independent optimization of contact structure placement, maintaining necessary margins while increasing overall memory density

Inventive Principle:

Principle #1Segmentation

3Quantity of substance

If replacement gate processing is performed on tall stacks, then memory density is improved, but tier collapse occurs during or after removal of portions to be replaced

Engineering Contradiction:

Improvememory densityVSAvoidvertical memory string reliability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The conductive contact structures are formed in predetermined locations before the replacement gate processing and tier removal steps. This preliminary formation of stable electrical connections ensures that even if tier collapse occurs during processing, the fundamental reliability of the vertical memory strings is preserved

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

By establishing conductive contact structures in advance, the invention creates a cushioning effect that protects against reliability degradation. These pre-formed structures provide a stable foundation that compensates for potential damage or collapse that may occur during subsequent replacement gate processing

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS20260082892A1Microelectronic devices including stair step structures, and related memory devices

Publication Date: 2026.03.19 MICRON TECHNOLOGY INC

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.