Integrated Capacitor Stack with Support Pillars for Void Formation

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Solution Overview

Problem

In the fabrication of capacitors peripheral to memory arrays, such as NAND memory arrays, there is a challenge in removing insulative materials without collapsing the remaining structure, which can lead to incomplete capacitive stacks due to the loss of support between insulative levels.

Innovation Solution

The method involves forming a stack of alternating insulative materials, partially removing the first insulative material to leave supporting pillars, and then depositing conductive material within the voids formed, which are later patterned into conductive plates, ensuring the integrity of the capacitive stack.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If insulative material is completely removed to form voids for conductive material deposition, then capacitor formation is enabled, but structural collapse occurs and capacitive stack integrity is lost

Engineering Contradiction:

Improvecapacitor formationVSAvoidstructural integrity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies preliminary action by forming sacrificial mandrels from the first insulative material before removing them. These mandrels are intentionally left in place during subsequent processing steps to provide structural support, and are only removed after conductive material is deposited around them. This preliminary placement of support structures prevents collapse during the void formation process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The first insulative material serves as an intermediary element - it is initially present to provide structural support, then selectively removed to create voids. During the intermediate stage, it acts as a sacrificial mandrel that enables the formation of conductive plates while maintaining structural integrity. The intermediary material is eventually removed after serving its dual purpose of support and template.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If all insulative material is removed to create voids, then conductive plates can be formed, but support between insulative levels is lost causing collapse

Engineering Contradiction:

Improvecapacitive stack formationVSAvoidsupport structure

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The patent applies local quality by selectively removing the first insulative material only in specific regions where conductive plates need to be formed, while leaving it intact in other regions where structural support is needed. This localized removal creates voids for capacitor formation in certain areas while maintaining support structures in adjacent areas, allowing both capacitor production and structural integrity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The first insulative material is segmented into different functional regions: portions are removed to create voids for conductive material deposition, while other portions are retained as support structures. This segmentation allows the same material to serve multiple functions - as a template for capacitor formation and as structural support - thereby enabling both high productivity and maintained strength.

Inventive Principle:

Principle #1Segmentation

3Reliability

If insulative pillars are retained to maintain structure, then structural integrity is preserved, but complete removal of first insulative material is prevented

Engineering Contradiction:

Improvestructural supportVSAvoidmaterial removal

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies partial action by removing only a portion of the first insulative material rather than all of it. Specifically, material is removed to the extent needed to create voids for conductive plate formation, but intentionally left intact in regions where it provides necessary structural support. This partial removal achieves the minimum necessary action for capacitor formation while preserving structural integrity.

Inventive Principle:

Principle #16Partial or excessive 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 allows for the successful formation of capacitors that maintain structural integrity and can be integrated into memory arrays using similar materials and processes as the memory cells, reducing fabrication costs and time.

Implementation Method 1

The second insulative material is exhumed with etchant provided in the slots to form voids within the second levels

Methodology Applied

Scientific EffectChemical etching:

Implementation Method 2

The voids are filled with conductive material, and the conductive material is formed into conductive plates within the second levels

Methodology Applied

Scientific EffectMaterial deposition: Deposition (physical)

Data Source

PatentUS11784058B2Integrated structures, capacitors and methods of forming capacitors

Publication Date: 2023.10.10 LODESTAR LICENSING GROUP LLC

AI summary

Some embodiments include an integrated structure having a semiconductor base and an insulative frame over the semiconductor base. The insulative frame has vertically-spaced sheets of first insulative material, and pillars of second insulative material between the vertically-spaced sheets. The first and second insulative materials are different from one another. Conductive plates are between the vertically-spaced sheets and are directly against the insulative pillars. Some embodiments include capacitors, and some embodiments include methods of forming capacitors.