Bistable Resistive Memory Kernel for Heat Dissipation Reduction
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Solution Overview
Problem
Conventional phase change memory devices face challenges with high reset currents due to heat sink effects from metallic electrodes and manufacturing complexities in small dimensions, particularly in achieving low heat conductivity and tight process variations for large-scale memory devices.
Innovation Solution
The design confines the heating region within a kernel of programmable resistive memory material between upper and lower programmable resistive members, with sides aligning with electrodes to reduce heat dissipation, using a dielectric spacer or via to minimize heat transfer from conductive materials, and incorporating programmable resistive memory material with low thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metallic electrodes of the same size as the phase change member are used, then electrical contact is achieved, but heat dissipation increases requiring higher current
Solution Approach 1:
The patent applies local quality by making the electrodes smaller than the phase change member, concentrating the heating effect locally at the phase change material contact region while reducing the heat sink effect. The electrodes are designed with dimensions specifically optimized to minimize heat dissipation while maintaining sufficient electrical contact with the phase change member.
Solution Approach 2:
The patent extracts the harmful heat sink effect by removing excess electrode material beyond what is necessary for electrical contact. By taking out the unnecessary portions of the electrodes, the design reduces the heat dissipation path while preserving the essential electrical connection function.
2Loss of energy
If the size of phase change material element and contact area are reduced, then reset current magnitude is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent changes the dimensional parameters of the phase change material element and electrodes to optimized values that reduce reset current while remaining manufacturable. Specifically, the phase change member is sized at about 0.5 micrometers and electrodes are made smaller than conventional designs, representing parameter changes that balance performance improvement with manufacturing capability.
Solution Approach 2:
The patent introduces a dielectric layer as an intermediary between the electrodes and the phase change member. This dielectric intermediary allows for precise control of the heating region and improves manufacturing precision by providing a stable, planar interface that is easier to fabricate with tight dimensional control than direct metal-to-phase-change-contact.
3Reliability
If conventional metallic electrodes are used on both sides of the phase change member, then electrical connection is established, but heat conductivity increases requiring higher programming current
Solution Approach 1:
The patent applies local quality by using smaller electrodes only where necessary for electrical contact with the phase change member, rather than extending electrodes across the entire phase change member surface. This localized electrode design maintains essential electrical connection while minimizing the heat conductivity effect that would require higher programming current.
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 the programming current and heat dissipation, enabling smaller, more efficient memory cells with improved manufacturing compatibility for large-scale production.
Implementation Method 1
Phase change based memory materials are widely used in read-write optical disks. These materials have at least two solid phases, including for example a generally amorphous solid phase and a generally crystalline solid phase.
Implementation Method 2
The change from the amorphous to the crystalline state is generally a lower current operation. The change from crystalline to amorphous, referred to as reset herein, is generally a higher current operation, which includes a short high current density pulse to melt or breakdown the crystalline structure
Implementation Method 3
using a dielectric spacer or via to minimize heat transfer from conductive materials
Data Source
AI summary
Structures and methods to form a bistable resistive random access memory for reducing the amount of heat dissipation from electrodes by confining a heating region in the memory cell device are described. The heating region is confined in a kernel comprising a programmable resistive memory material that is in contact with an upper programmable resistive memory member and a lower programmable resistive memory member. The lower programmable resistive member has sides that align with sides of a bottom electrode comprising a tungsten plug. The lower programmable resistive member and the bottom electrode function a first conductor so that the amount of heat dissipation from the first conductor is reduced. The upper programmable resistive memory material and a top electrode function as a second conductor so that the amount of heat dissipation from the second conductor is reduced.