Self-Aligned RRAM Thermal Isolation Cell Design
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Solution Overview
Problem
Manufacturing non-volatile memory devices with small dimensions and low reset currents is challenging due to variations in process specifications, especially in integrating small RRAM elements with peripheral circuits on the same integrated circuit, requiring a structure and method that minimizes reset current magnitude and maintains tight process control.
Innovation Solution
A self-aligned RRAM memory device with a funnel-shaped central cavity and thermal isolation cell, where the RRAM element is positioned between electrodes, and a spandrel element creates a thermal isolation cell, reducing the reset current needed by concentrating high current densities in a small area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the RRAM material element size and electrode contact area are reduced to achieve low reset currents, then the reset current magnitude is reduced, but manufacturing precision and process control become more difficult to maintain tight specifications
Solution Approach 1:
The patent applies local quality by creating a non-uniform RRAM material element geometry with a narrow neck region and larger base area. This localized geometric variation concentrates the current density specifically in the narrow region during reset operations, enabling low overall reset currents while maintaining manufacturable dimensions. The localized structure allows process variations to be tolerated because the critical function is achieved in a specific region rather than requiring uniform precision across the entire element.
Solution Approach 2:
The patent changes the geometric parameters of the RRAM material element, specifically creating a tapered or necked geometry where the cross-sectional area varies along the length. This parameter change enables the element to achieve high current density in the narrow region with lower overall current, resolving the contradiction between low reset current and manufacturable dimensions.
2Loss of energy
If the RRAM material element size is reduced to achieve low reset currents, then the reset current magnitude is reduced, but device complexity increases due to integration challenges with peripheral circuits
Solution Approach 1:
By concentrating the functional change in a localized narrow region of the RRAM element, the patent enables small effective switching area without requiring the entire device structure to be miniaturized. This allows integration with peripheral circuits at larger dimensions, reducing overall device complexity while achieving low reset currents through the localized high current density in the narrow neck region.
3Loss of energy
If small pores are used to reduce RRAM material quantity and reset current, then the reset current is reduced, but manufacturing variations increase making it difficult to meet tight specifications
Solution Approach 1:
The patent changes from using small uniform pores to using a larger RRAM material element with a necked or tapered geometry. This parameter change in the element shape allows the critical current concentration to occur in the narrow region, achieving low reset currents while using larger overall dimensions that are less sensitive to manufacturing variations, thereby improving reliability and process control.
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 solution effectively reduces the reset current required for transitioning the RRAM material from a crystalline to an amorphous state, enabling the production of memory devices with small dimensions and tight process control, compatible with large-scale manufacturing and integration with peripheral circuits.
Implementation Method 1
a spandrel element positioned between the sidewall spacer element and the lower electrode, having an inner surface defining a thermal isolation cell
Implementation Method 2
The change from the amorphous to the crystalline state... The change from crystalline to amorphous, referred to as reset herein
Implementation Method 3
a short high current density pulse to melt or breakdown the crystalline structure
Data Source
AI summary
A non-volatile memory with a self-aligned RRAM element includes a lower electrode element, generally planar in form, having an inner contact surface; an upper electrode element, spaced from the lower electrode element; a containment structure extends between the upper electrode element and the lower electrode element, with a sidewall spacer element having a generally funnel-shaped central cavity with a central aperture; and a spandrel element positioned between the sidewall spacer element and the lower electrode. A RRAM element extends between the lower electrode element and the upper electrode, occupying at least a portion of the sidewall spacer element central cavity and projecting from the sidewall spacer terminal edge toward and making contact with the lower electrode. In this manner, the spandrel element inner surface is spaced from the RRAM element to define a thermal isolation cell adjacent the RRAM element.