Ferroelectric Capacitor Array Segmentation for Non-Destructive Memory Reads

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing memory technologies using ferroelectric capacitors face challenges in maintaining the polarization state during reading operations, often requiring immediate rewriting of memory cells after reading due to the reversible nature of polarization.

Innovation Solution

The formation of an array of capacitors and memory cells involves creating horizontally-spaced groups of lower capacitor electrodes with a ferroelectric capacitor insulator and a common upper capacitor electrode, where the upper capacitor electrode material is partially removed to disconnect adjacent groups, allowing for a horizontally-elongated conductive line to be formed atop, facilitating efficient data storage and retrieval without reversing polarization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If ferroelectric capacitors are used in memory cells, then non-volatile data storage is achieved, but the polarization state reverses during read operations requiring immediate rewriting

Engineering Contradiction:

Improvedata retentionVSAvoidtime for rewriting after reading

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The capacitor array is divided into multiple independently controllable groups with separate read paths. By segmenting the array, only the specific group containing the addressed memory cell is activated during read operations, preventing polarization reversal in other groups and eliminating the need for widespread rewriting.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the capacitor array are equipped with different functionality - some groups have full read capability while others serve as reference. This local differentiation allows certain groups to maintain polarization states during reading while others can be refreshed, reducing overall rewriting requirements.

Inventive Principle:

Principle #3Local quality

2Device complexity

If conventional capacitor arrays are used, then simple structure is maintained, but polarization state cannot be maintained during read operations

Engineering Contradiction:

Improvecapacitor array structureVSAvoidpolarization state maintenance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Reference capacitors are introduced as intermediary elements that store reference charge states. These reference capacitors enable differential reading operations where the actual read process compares stored data against reference values, allowing polarization state maintenance while enabling reliable data retrieval.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 configuration enhances the non-volatile nature of memory cells by maintaining the polarization state during read operations without immediate rewriting, improving data retention and stability in memory arrays.

Implementation Method 1

One type of non-volatile capacitor is a ferroelectric capacitor which has ferroelectric material as at least part of the insulating material. Ferroelectric materials are characterized by having two stable polarized states and thereby can comprise programmable material of a capacitor and/or memory cell.

Methodology Applied

Scientific EffectFerroelectricity:

Implementation Method 2

A capacitor has two electrical conductors separated by electrically insulating material. Energy as an electric field may be electrostatically stored within such material.

Methodology Applied

Scientific EffectElectrostatic energy storage: Capacitance

Implementation Method 3

The digitlines may conductively interconnect memory cells along columns of the array, and the access lines may conductively interconnect memory cells along rows of the array.

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS12150312B2Array of capacitors, array of memory cells, methods of forming an array of capacitors, and methods of forming an array of memory cells

Publication Date: 2024.11.19 MICRON TECHNOLOGY INC

AI summary

A method of forming an array of capacitors comprises forming a plurality of horizontally-spaced groups that individually comprise a plurality of horizontally-spaced lower capacitor electrodes having a capacitor insulator thereover. Adjacent of the groups are horizontally spaced farther apart than are adjacent of the lower capacitor electrodes within the groups. A void space is between the adjacent groups. An upper capacitor electrode material is formed in the void space and in the groups over the capacitor insulator and the lower capacitor electrodes. The upper capacitor electrode material in the void space connects the upper capacitor electrode material that is in the adjacent groups relative to one another. The upper capacitor electrode material less-than-fills the void space. At least a portion of the upper capacitor electrode material is removed from the void space to disconnect the upper capacitor electrode material in the adjacent groups from being connected relative to one another. A horizontally-elongated conductive line is formed atop and is directly electrically coupled to the upper capacitor electrode material in individual of the groups. Other methods, including structure independent of method of manufacture, are disclosed.