Nonvolatile Memory Cell Leakage Reduction via Plasma Oxynitride
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Solution Overview
Problem
Nonvolatile memory devices fabricated on glass substrates with polysilicon layers experience increased current leakage due to surface roughness and non-uniformity, affecting their normal operation during storage and erasing operations.
Innovation Solution
A nonvolatile memory cell is fabricated using a low temperature process involving a silicon oxynitride layer formed by nitrous oxide plasma, with silicon nanocrystals created in a nitride film through ion implantation and heat treatment, reducing surface roughness and current leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a polysilicon layer is formed by laser irradiation of amorphous polysilicon, then the nonvolatile memory cell can be fabricated on glass substrate, but the surface becomes rough and non-uniform causing increased current leakage
Solution Approach 1:
The patent changes the formation method parameter from laser irradiation to plasma treatment, which modifies the surface characteristics of the polysilicon layer to be smoother and more uniform, thereby reducing current leakage while maintaining the ability to fabricate on glass substrate
Solution Approach 2:
The patent replaces the mechanical/thermal process of laser irradiation with a plasma-based chemical process, substituting the high-energy laser field with plasma species that gently modify the polysilicon surface without causing roughness
2Stability of the object's composition
If laser irradiation is used to crystallize amorphous polysilicon, then polysilicon layer formation is achieved, but surface uniformity deteriorates leading to abnormal memory operation
Solution Approach 1:
The patent substitutes laser irradiation with plasma treatment, replacing a high-energy thermal field with a chemically active plasma environment that achieves polysilicon formation while maintaining surface smoothness and uniformity
Solution Approach 2:
The patent changes the processing parameter from laser energy input to plasma exposure conditions, which fundamentally alters the mechanism of polysilicon formation to preserve surface uniformity while achieving the desired crystalline structure
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 approach effectively reduces current leakage and enhances charge storage capacity, improving the operational reliability of nonvolatile memory cells on glass substrates.
Implementation Method 1
forming a first oxide film, including a silicon oxynitride (SiOxNy) layer, by using a nitrous oxide (N2O) plasma
Implementation Method 2
The silicon nanocrystals can be formed from silicon ions implanted in the nitride film by an ion implantation method
Data Source
AI summary
A nonvolatile memory cell is capable of reducing an excessive current leakage due to a rough surface of a polysilicon and of performing even at a low temperature process by forming the first oxide film including a silicon oxynitride (SiOxNy) layer using nitrous oxide plasma and by forming a plurality of silicon nanocrystals in a nitride film by implanting a silicon nanocrystal on the nitride film by an ion implantation method, and a fabricating method thereof and a memory apparatus including the nonvolatile memory cell.