3D Memory Staircase Trench Fill for Precise Etch Stops

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Solution Overview

Problem

Conventional methods for forming vertical memory arrays in microelectronic devices result in undesirable defects due to increased feature packing densities and reduced fabrication margins, affecting memory device performance, reliability, and durability.

Innovation Solution

A method involving a preliminary stack structure with alternating insulative and sacrificial materials, forming stadium structures with opposing staircase structures, and using dielectric liners and fill materials to create etch stop structures and protect against conductive material replacement, ensuring precise etching and reduced defect formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If feature packing density is increased to improve memory device integration, then memory density is improved, but fabrication precision deteriorates due to reduced margins for formation errors

Engineering Contradiction:

Improvememory densityVSAvoidfabrication precision

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

Dielectric liner structures are formed in advance before conductive material deposition and replacement gate processing. These pre-formed liners create defined etch stop boundaries that prevent conductive material from replacing stack structure materials, ensuring precise feature formation even at high packing densities where fabrication margins are reduced.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Dielectric liner structures serve as intermediary layers between the stack structure and conductive contact structures. These liners act as etch stop barriers that mediate the interaction between etching processes and the stack structure, preventing unwanted material replacement while enabling precise conductive material placement at high density.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If conventional fabrication methods are used to simplify manufacturing, then ease of manufacture is improved, but device reliability deteriorates due to undesirable defects

Engineering Contradiction:

Improveease of manufactureVSAvoiddevice reliability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

Dielectric liner structures function as intermediary protective layers that prevent direct contact between conductive materials and stack structure materials during replacement gate processing. This intermediary approach maintains manufacturing simplicity while eliminating defects that would compromise device reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Dielectric liner structures are formed in advance to counteract the potential harmful effect of conductive material replacing stack structure materials during etching processes. This preliminary protective action prevents reliability-critical defects before they can occur, while maintaining conventional fabrication simplicity.

Inventive Principle:

Principle #9Preliminary anti-action

3Area of moving object

If feature dimensions are reduced to improve integration, then area is reduced, but manufacturing precision deteriorates due to smaller tolerances

Engineering Contradiction:

Improvefeature areaVSAvoidmanufacturing precision

Core Design Contradiction:

Area of moving objectVSManufacturing precision

Solution Approach 1:

Dielectric liner structures serve as intermediary etch stop barriers that enable precise definition of conductive contact structure boundaries even when feature dimensions are reduced. The liners provide clear etching boundaries that maintain manufacturing precision despite smaller feature sizes and tighter tolerances.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Dielectric liner structures are formed beforehand to establish precise geometric boundaries before conductive material deposition. This preliminary structuring ensures that even reduced-dimension features maintain accurate dimensions and positioning, overcoming the precision challenges of miniaturization.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS20240071919A1Methods of forming microelectronic devices, and related microelectronic devices, memory devices, and electronic systems

Publication Date: 2024.02.29 MICRON TECHNOLOGY INC

AI summary

A microelectronic device includes a stack structure comprising blocks separated from one another by dielectric slot structures and each including a vertically alternating sequence of conductive structures and insulative structures arranged in tiers. At least one of the blocks comprising a stadium structure comprising opposing staircase structures each having steps comprising edges of the tiers; and a filled trench vertically overlying and within horizontal boundaries of the stadium structure of the at least one of the blocks. The filled trench includes a dielectric liner material on the opposing staircase structures of the stadium structure and on inner sidewalls of the two bridge regions and at least one dielectric structure doped with one or more of carbon and boron on the dielectric liner material, the at least one dielectric structure horizontally overlapping the steps of the stadium structure.