Ge-Te-Li Resistance Memory Element Crystalline State High Resistance
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Solution Overview
Problem
Conventional memory devices using phase change memory elements do not achieve excellent resistance change characteristics, as they typically exhibit low resistance in a crystalline state and high resistance in an amorphous state, which is the opposite of the desired high resistance in crystalline and low resistance in amorphous states.
Innovation Solution
A memory device with a resistance change memory element comprising a first and second electrode and an intermediate layer made of a compound material containing germanium (Ge), tellurium (Te), and at least one element selected from lithium (Li) or sodium (Na), which can exhibit both crystalline and amorphous states, allowing for a high resistance state in crystalline and low resistance state in amorphous conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional phase change memory elements are used, then the memory device can store data, but the resistance ratio between crystalline and amorphous states is insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the intermediate layer by incorporating specific elements (Ge, Te, In, Sn, Sb) in controlled ratios. This compositional parameter change enables the material to exhibit the desired resistance characteristics where crystalline state shows high resistance and amorphous state shows low resistance, directly resolving the insufficient resistance ratio problem.
Solution Approach 2:
The patent employs a composite intermediate layer material combining multiple elements (Ge-Te-In, Ge-Te-Sn, Ge-Te-Sb, or Ge-Te-In-Sb) rather than using a single element or simple compound. This composite material approach creates synergistic effects that achieve the target resistance ratio between crystalline and amorphous states, solving the reliability issue.
2Reliability
If the intermediate layer composition is optimized for resistance ratio, then memory characteristics improve, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by creating distinct regions with different compositions within the intermediate layer. The intermediate layer contains specific elements (Ge, Te, In, Sn, Sb) distributed in controlled local concentrations, allowing different parts of the layer to contribute differently to the overall resistance characteristics, thus achieving good memory properties while managing manufacturing precision requirements.
Solution Approach 2:
The patent defines specific parameter ranges for element compositions (e.g., In: 1-20 at%, Sn: 1-20 at%, Sb: 1-20 at%) to optimize memory characteristics. By establishing these parameter windows, the patent balances achieving excellent memory properties with practical manufacturing precision capabilities, allowing production within controlled tolerances.
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 configuration enables a resistance change memory element with a large resistance ratio, allowing for effective storage of binary data by selectively switching between high and low resistance states, thereby achieving excellent memory device characteristics.
Implementation Method 1
an intermediate layer provided between the first electrode and the second electrode, containing germanium (Ge), tellurium (Te) and at least one element selected from lithium (Li) and sodium (Na), and at least a part of which being capable of exhibiting a crystalline state
Data Source
AI summary
According to one embodiment, a memory device includes a resistance change memory element including a first electrode, a second electrode, and an intermediate layer provided between the first electrode and the second electrode, containing germanium (Ge), tellurium (Te) and at least one element selected from lithium (Li) and sodium (Na), and at least a part of which being capable of exhibiting a crystalline state.