3D Memory Array Strings With Direct Conductor-Tier Coupling

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Solution Overview

Problem

The existing methods for forming memory arrays with strings of memory cells face challenges in ensuring reliable direct electrical connections between channel-material-string constructions and conductor tiers, which affects the overall reliability and efficiency of the memory array.

Innovation Solution

The method involves forming a conductor tier with sacrificial plugs, etching channel openings through alternating tiers, removing the plugs to form channel-material strings that directly couple with the conductor tier, and using isotropic etching to expose and remove sacrificial material, followed by forming conductive material to electrically couple the channel-material strings with the conductor tier, thereby creating a stable and efficient memory array structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional methods are used to form memory arrays, then the basic structure can be created, but reliable direct electrical connections between channel-material-string constructions and conductor tiers cannot be ensured

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Sacrificial plugs are formed in the conductor tier before etching channel openings, preparing the structure in advance to enable direct electrical connections. This preliminary placement of sacrificial material facilitates subsequent formation of channel-material strings that will directly contact the conductor tier, ensuring reliable electrical connections while maintaining manufacturability through staged processing.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Sacrificial plugs serve as intermediary elements during fabrication, temporarily occupying spaces where direct electrical connections will eventually form. These plugs are removed after channel openings are etched, leaving behind direct contact regions between channel-material strings and conductor tier, thus enabling reliable electrical connections without permanent interference in the final structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If direct electrical connections are ensured between channel-material strings and conductor tier, then reliability improves, but the manufacturing process becomes more complex

Engineering Contradiction:

Improveelectrical connection stabilityVSAvoidprocess complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The conductor tier is segmented by forming sacrificial plugs at specific locations where channel-material strings will be positioned. This segmentation creates discrete connection regions, allowing precise control over where direct electrical connections form between channel-material strings and conductor tier, thereby ensuring reliability while managing process complexity through localized structuring.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sacrificial plugs are formed in advance before channel openings are etched and channel-material strings are deposited. This preliminary action pre-establishes the geometric framework for direct electrical connections, simplifying subsequent processing steps and ensuring that reliable connections form automatically when channel-material strings are placed in their final positions.

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enhances the reliability of the direct electrical connection between channel-material strings and the conductor tier, improving the overall performance and efficiency of the memory array by ensuring a stable and efficient electrical pathway.

Implementation Method 1

isotropic etching to expose and remove sacrificial material

Methodology Applied

Scientific EffectIsotropic etching:

Implementation Method 2

forming conductive material to electrically couple the channel-material strings with the conductor tier, thereby creating a stable and efficient electrical pathway

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS20230380159A1Memory Arrays Comprising Strings Of Memory Cells And Methods Used In Forming A Memory Array Comprising Strings Of Memory Cells

Publication Date: 2023.11.23 MICRON TECHNOLOGY INC

AI summary

A memory array comprises strings of memory cells. The memory array comprises laterally-spaced memory blocks that individually comprise a vertical stack comprising alternating insulative tiers and conductive tiers directly above a conductor tier. Channel-material strings of memory cells extend through the insulative tiers and the conductive tiers. The channel material of the channel-material strings directly electrically couples to conductor material of the conductor tier. Individual ones of the channel-material strings in a vertical cross-section comprise an external jog surface that is above the conductor tier and an internal jog surface that is in the conductor tier. Other aspects, including methods, are disclosed.