Crossbar Switch Resistance Change Element Contact Area

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing resistance change elements face variations in program voltage and leak current in the high-resistive state due to inaccuracies in the contact area between copper interconnects and resistance change films, which are not adequately addressed by current manufacturing techniques.

Innovation Solution

A metal deposition type resistance change element is designed with symmetrically exposed end portions of copper electrodes and resistance change films, ensuring equivalent surface areas and reducing variations in program voltage and leak current, achieved through precise lithography and specific material configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional manufacturing techniques are used to form copper interconnects and resistance change films, then the manufacturing process is simple, but the contact area between copper interconnects and resistance change films varies, causing variations in program voltage and leak current

Engineering Contradiction:

Improvecontact area uniformityVSAvoidmanufacturing process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The copper interconnect end portions are exposed from the insulating film before forming the resistance change films. This preliminary exposure ensures that when resistance change films are subsequently formed, they automatically contact the copper interconnects at predetermined positions with consistent contact areas, eliminating variations in program voltage and leak current without complicating the manufacturing process

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The manufacturing process is segmented into distinct steps: first exposing copper interconnect end portions, then forming resistance change films on exposed surfaces. This segmentation allows precise control of the contact interface between copper interconnects and resistance change films, ensuring uniform contact areas while maintaining manufacturing simplicity

Inventive Principle:

Principle #1Segmentation

2Reliability

If the contact area between copper interconnects and resistance change films is increased to reduce program voltage variations, then program voltage stability improves, but the chip area increases

Engineering Contradiction:

Improveprogram voltage stabilityVSAvoidchip area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The resistance change films are formed to cover only the exposed end portions of copper interconnects, creating a localized contact area at the interface. This localized approach ensures sufficient contact area for stable program voltage while minimizing the overall chip area occupied by the resistance change element structure

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If asymmetric exposure of copper electrodes is used in conventional manufacturing, then the manufacturing process is simpler, but variations in surface area lead to variations in program voltage and leak current

Engineering Contradiction:

Improvesurface area equivalenceVSAvoidmanufacturing process ease

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention intentionally creates asymmetric exposure patterns in the insulating film to achieve symmetric contact areas. By controlling which copper interconnect end portions are exposed and to what extent, the method ensures equivalent surface areas for contact while maintaining manufacturing simplicity through standardized photomask processes

Inventive Principle:

Principle #4Asymmetry

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 reduces variations in program voltage and leak current in the high-resistive state while minimizing the program voltage, enhancing the reliability and efficiency of the resistance change element.

Implementation Method 1

A resistance change element using metal ion transfer and electrochemical reaction in a resistance change film includes three layers of a copper electrode, a resistance change film, and an inert electrode

Methodology Applied

Scientific EffectElectrochemical reaction: Redox Reactions

Implementation Method 2

the metal ion in the resistance change film is precipitated as a metal in the resistance change film and the precipitated metal forms a metal-bridge

Methodology Applied

Scientific EffectMetal deposition: Deposition (physical)

Data Source

PatentUS10490743B2Crossbar switch and method of manufacturing the same and semiconductor device

Publication Date: 2019.11.26 NANOBRIDGE SEMICON INC

AI summary

A crossbar switch comprising: a first interconnect, a second interconnect, and a resistance change element. The resistance change element includes: a first electrode connected to the first interconnect and a second electrode connected to the second interconnect which are embedded in a first insulating film on a substrate having a transistor; a second insulating film covering the first insulating film and the first and second electrodes; first and second opening portions exposing parts of an upper surface including end portions of the first and second electrodes from the second insulating film with translational symmetry; first and second resistance change films covering the first and second opening portions and connecting to the first and second electrodes at the opening portions; third and fourth electrodes connecting to the first and second resistance change films; a fifth electrode connecting to the third and fourth electrodes and to a diffusion layer of the transistor.