MxSiOy Ferroelectric Capacitor Electrodes for Stable Memory Reads

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Solution Overview

Problem

Ferroelectric capacitors in memory cells face challenges where the act of reading the memory state can reverse the polarization, necessitating immediate rewriting of the cell, which is undesirable and affects the stability of non-volatile data storage.

Innovation Solution

The use of ferroelectric capacitors with electrodes comprising MxSiOy, where M is at least one of Ru, Ti, Ta, Co, Pt, Ir, Os, Mo, V, W, Sr, Re, Rh, Pd, La, Zn, In, Sn, and Nb, and the formation method involves sequential processes such as forming metal oxides, contacting with metal-organic precursors, and oxidizing to create stoichiometrically metal-rich layers, enhancing the capacitor's performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional ferroelectric capacitors are used for non-volatile memory storage, then data retention is achieved, but reading the memory state reverses the polarization requiring immediate rewriting

Engineering Contradiction:

Improvememory state stabilityVSAvoidreading operation efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes the material composition parameter of the capacitor electrode from conventional materials to MxSiOy (where M is a metal such as Ru, Ti, Ta, Co, Pt, Ir, Os, Mo, V, W, Sr, Re, Rh, Pd, La, Zn, In, Sn, or Nb). This material parameter change modifies the electrical characteristics of the capacitor, enabling it to maintain stable polarization states during read operations without reversal, thus resolving the contradiction between reliability and productivity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material structure by combining metal oxide (MxSiOy) with ferroelectric material in the capacitor construction. This composite approach creates a system where the metal oxide electrode interacts specifically with the ferroelectric material to prevent polarization reversal during reading, thereby maintaining both data retention reliability and reading operation efficiency.

Inventive Principle:

Principle #40Composite materials

2Duration of action of stationary object

If ferroelectric material with high stability is used to ensure non-volatile storage, then data retention time increases, but the reading process still causes polarization reversal

Engineering Contradiction:

Improvedata retention timeVSAvoidpolarization reversal during reading

Core Design Contradiction:

Duration of action of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The patent modifies the electrode material composition parameter to MxSiOy, which changes the electrical field distribution and interaction characteristics at the electrode-ferroelectric interface. This parameter change suppresses the harmful polarization reversal effect during reading operations while preserving the long-term data retention capability of the ferroelectric material.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The MxSiOy metal oxide layer acts as an intermediary between the external read signal and the ferroelectric material. This intermediary layer modifies the electric field applied during reading, preventing direct polarization reversal in the ferroelectric material while still enabling successful read operations, thus eliminating the harmful effect while maintaining data retention.

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 improves the ferroelectric capacitor's stability and retention of memory states, reducing the need for immediate rewriting after reading, thereby enhancing the reliability of non-volatile memory storage.

Implementation Method 1

Ferroelectric materials are characterized by having two stable polarized states and thereby can comprise programmable material of a capacitor and/or memory cell. The polarization state of the ferroelectric material can be changed by application of suitable programming voltages and remains after removal of the programming voltage

Methodology Applied

Scientific EffectFerroelectric effect:

Implementation Method 2

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

Methodology Applied

Scientific EffectElectrostatic energy storage: Capacitance

Implementation Method 3

contacting the first solid reaction product with an oxygen-containing precursor to form a second non-solid and non-liquid reaction product and remaining metal oxide on the substrate that is stoichiometrically metal-rich

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentUS11825662B2Ferroelectric capacitor, a ferroelectric memory cell, an array of ferroelectric memory cells, and a method of forming a ferroelectric capacitor

Publication Date: 2023.11.21 MICRON TECHNOLOGY INC

AI summary

A ferroelectric capacitor comprises two conductive capacitor electrodes having ferroelectric material there-between. At least one of the capacitor electrodes comprise MxSiOy, where “M” is at least one of Ru, Ti, Ta, Co, Pt, Ir, Os, Mo, V, W, Sr, Re, Rh, Pd, La, Zn, In, Sig, and Nb, Other aspects, including method, are disclosed.