Sb-rich GST Phase Change Memory with Dielectric Doping
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Solution Overview
Problem
Phase change memory materials like Ge2Sb2Te5 (GST-225) have limitations in high temperature tolerance, requiring high reset currents and experiencing undesired phase transformations, which hinder their use in storage class memory, embedded memory, and automotive applications due to poor data retention and endurance.
Innovation Solution
Development of dielectric-doped, antimony-rich GST family materials with specific Ge, Sb, and Te compositions and dielectric additives, increasing crystallization transition temperature and resistivity, enabling lower reset currents and improved endurance and data retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If GST-225 material is used for phase change memory, then good performance in terms of speed and switching characteristics is achieved, but high reset current is required and data retention at elevated temperatures deteriorates
Solution Approach 1:
The patent modifies the chemical composition parameters of the GST material by adjusting the ratio of Ge, Sb, and Te elements, and by adding dielectric elements (Si, O, N) to create a new material system GexSbyTez-dielectric that achieves both fast switching and high temperature stability
Solution Approach 2:
The patent creates a composite phase change material by combining GST alloy with dielectric additives (silicon, oxygen, nitrogen), forming a new composite material system that integrates the fast switching properties of GST with the thermal stability of dielectric materials
2Speed
If GST-225 material is used, then fast phase transition is achieved, but undesired transformation from amorphous to crystalline phase occurs at elevated temperatures
Solution Approach 1:
The patent raises the crystallization transition temperature TX above 160°C (preferably above 170°C or 190°C) by modifying the material composition, thereby preventing undesired phase transformation at operating temperatures while preserving fast switching capability
Solution Approach 2:
The dielectric additives (Si, O, N) act as intermediaries that modify the phase transformation behavior of the GST material, raising the crystallization temperature and stabilizing the amorphous phase at elevated temperatures
3Speed
If GST-225 is used for storage class memory applications, then good speed characteristics are achieved, but endurance and data retention requirements are not met
Solution Approach 1:
The patent optimizes the material composition parameters to achieve TX > 160°C and appropriate resistivity ratios, enabling the material to simultaneously satisfy storage class memory requirements for endurance (>10^7 cycles), speed (hundreds of nanoseconds), and data retention
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 dielectric-doped, Sb-rich GST-225 family materials provide suitable speed, retention, and endurance characteristics for integrated circuit memory, enabling effective data storage with lower power operation and enhanced thermal stability, suitable for storage class and automotive applications.
Implementation Method 1
Phase change based memory materials, like chalcogenide based materials and similar materials, can be caused to change solid phase between an amorphous phase and a crystalline phase by application of electrical current
Implementation Method 2
application of electrical current at levels suitable for implementation in integrated circuits
Implementation Method 3
dielectric-doped, antimony-rich GST family materials which are antimony rich relative to GST-225... provide a crystallization transition temperature greater than to 160° C.
Data Source
AI summary
Phase change memory materials in a dielectric-doped, antimony-rich GST family of materials which are antimony rich relative to GST-225, are described that have speed, retention and endurance characteristics suitable for storage class data storage A memory device includes an array of memory cells, where each memory cell includes a first electrode and a second electrode coupled to a memory element. The memory element comprises a body of phase change memory material that comprises a combination of Ge, Sb, and Te with a dielectric additive in amounts effective to provide a crystallization transition temperature greater than to 160° C., greater that 170° C. in some effective examples and greater than 190° C. in other effective examples. A controller is coupled to the array, and configured to execute set operations and reset operations for memory cells in the array.