3D Memory Cell Strings With Etch-Stop Conductor Tier Coupling

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing memory array technologies face challenges in efficiently forming strings of memory cells with reliable electrical access, particularly in the formation of wordlines and the integration of peripheral control circuitry.

Innovation Solution

The method involves forming a conductor tier with etch-stop material spanning across locations where channel-material-string constructions will be formed, followed by etching channel openings through alternating insulative and conductive tiers to stop on the etch-stop material, thereby enabling direct electrical coupling of channel material to the conductor tier.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional memory array formation methods are used, then manufacturing process is simpler, but electrical access reliability to memory cells deteriorates

Engineering Contradiction:

Improveelectrical access reliabilityVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The etch-stop material is formed in the conductor tier before the channel openings are etched, establishing a predetermined stopping plane that ensures reliable electrical access. This preliminary placement of the etch-stop material guides subsequent etching operations and guarantees proper alignment without requiring complex real-time adjustments.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The etch-stop material acts as an intermediary layer between the conductor tier and the channel openings, providing a controlled interface that ensures precise electrical coupling. This intermediate structure mediates the connection between conductive elements and channel regions, achieving reliable electrical access while simplifying the overall manufacturing process.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If direct electrical coupling is achieved through etching channel openings, then electrical access reliability improves, but manufacturing precision requirements increase

Engineering Contradiction:

Improveelectrical access reliabilityVSAvoidetching precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The etch-stop material is designed to self-limit the etching process by providing a distinct compositional boundary that automatically stops the etch when reached. This self-service mechanism eliminates the need for complex external control systems to precisely control etch depth, as the etch-stop material inherently provides the stopping condition.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The etch-stop material is formed with a different composition from the surrounding conductor material, creating a distinct physical and chemical parameter boundary. This compositional change provides an easily identifiable etch-stop signal, allowing standard etching processes to achieve precise stopping without requiring ultra-precise depth control.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If etch-stop material is used to control channel opening depth, then manufacturing precision is reduced, but device complexity increases

Engineering Contradiction:

Improvechannel opening depth controlVSAvoidconductor tier structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The etch-stop material serves multiple functions simultaneously: it provides the etch-stop boundary for depth control, acts as a compositional marker for alignment, and maintains the structural integrity of the conductor tier. This multi-functionality reduces the need for separate dedicated structures, thereby limiting the increase in device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The etch-stop functionality is merged directly into the conductor tier structure by forming the etch-stop material as an integral part of the conductor tier. This consolidation eliminates the need for separate etch-stop layers or additional structural elements, minimizing the increase in device complexity while achieving precise depth control.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS12232317B2Memory arrays comprising strings of memory cells and methods used in forming a memory array comprising strings of memory cells

Publication Date: 2025.02.18 MICRON TECHNOLOGY INC

AI summary

A memory array comprises strings of memory cells. The memory array comprises laterally-spaced memory blocks individually comprising a vertical stack comprising alternating insulative tiers and conductive tiers above a conductor tier. Channel-material-string constructions of memory cells extend through the insulative tiers and the conductive tiers. The channel material of the channel-material-string constructions is directly electrically coupled to conductor material of the conductor tier. Substructure material is in the conductor tier and spans laterally-across and laterally-between bottoms of multiple of the channel-material-string constructions. The substructure material is of different composition from an upper portion of the conductor material. The substructure material comprises laterally-opposing sides that taper laterally-inward moving deeper into the conductor tier. Other embodiments, including method, are disclosed.