Resistive Memory Device With Segmented Electrode

Solution Overview

Problem

Current resistive memory devices face limitations in switching characteristics due to a large contacting area between the bottom electrode and the resistive layer, making it difficult to uniformly control filamentary current paths and requiring high reset currents, which is exacerbated by the challenges of reducing contact plug dimensions in advanced fabrication processes.

Innovation Solution

A resistive memory device is fabricated using a damascene process to form a resistive layer with a hole structure having positive slope sidewalls and a bottom width equal to or smaller than the bottom electrode, reducing the contacting area and facilitating the formation of a smaller switching region, thereby improving switching characteristics and reducing reset current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the bottom electrode dimensions are made larger to ensure sufficient contacting area, then the contacting area between bottom electrode and resistive layer increases, but the switching characteristic deteriorates and reset current increases

Engineering Contradiction:

Improvecontacting areaVSAvoidswitching characteristic

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The patent segments the bottom electrode into two distinct functional regions: a large-area contact electrode for reliable electrical contact and a small-area switching electrode for precise filamentary current path control. This segmentation allows the contacting area to be sufficiently large while the switching region remains small, resolving the contradiction between contacting area and switching characteristic.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by creating a bottom electrode with non-uniform dimensions - the contact electrode has a larger area for reliable contact, while the switching electrode has a smaller area for precise switching control. This local differentiation allows each region to optimize its function, improving switching characteristic while maintaining sufficient contacting area.

Inventive Principle:

Principle #3Local quality

2Reliability

If the bottom electrode dimensions are reduced to improve switching characteristic, then the contacting area decreases, but the manufacturing precision becomes more difficult to achieve

Engineering Contradiction:

Improveswitching characteristicVSAvoidcontact plug dimension control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The segmentation of the bottom electrode into contact electrode and switching electrode allows the contact electrode to maintain larger dimensions that are easier to manufacture with precise control, while the switching electrode can be smaller without compromising overall manufacturing precision. The contact electrode serves as a robust foundation that is less sensitive to dimensional variations.

Inventive Principle:

Principle #1Segmentation

3Stability of the object's composition

If the whole resistive layer becomes a switching region, then the resistance change is more uniform, but the reset current becomes too high and filamentary current paths cannot be uniformly controlled

Engineering Contradiction:

Improveresistance state uniformityVSAvoidreset current control

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent applies local quality by creating a bottom electrode with non-uniform dimensions - the contact electrode has a larger area for reliable contact, while the switching electrode has a smaller area for precise switching control. This local differentiation allows each region to optimize its function, improving switching characteristic while maintaining sufficient contacting area.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the bottom electrode into two distinct functional regions: a large-area contact electrode for reliable electrical contact and a small-area switching electrode for precise filamentary current path control. This segmentation allows the contacting area to be sufficiently large while the switching region remains small, resolving the contradiction between contacting area and switching characteristic.

Inventive Principle:

Principle #1Segmentation

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

The approach enhances the switching characteristic and operation speed of the resistive memory device by decreasing the number and distribution of filamentary current paths and reducing the reset current, while also simplifying the fabrication process.

Implementation Method 1

According to the applied bias, filamentary current paths are formed in the resistive layer 14 to have the low resistance state or the existing filamentary current paths are destroyed to allow the resistive layer to have the high resistance state.

Methodology Applied

Scientific EffectFilamentary current path formation:

Data Source

PatentUS8345463B2Resistive memory device and method for fabricating the same

Publication Date: 2013.01.01 SK HYNIX INC

AI summary

A resistive memory device includes: a bottom electrode formed over a substrate; and an insulation layer having a hole structure formed over the substrate structure. Herein, the hole structure exposes the bottom electrode, has sidewalls of positive slope, and has a bottom width equal to or smaller than a width of the bottom electrode; a resistive layer formed over the hole structure; and an upper electrode formed over the resistive layer.