Germanium Oxynitride Charge Trapping Layer for V-NAND
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Solution Overview
Problem
Current charge trapping layers in V-NAND devices, such as silicon nitride, face challenges with scaling due to lower electron affinity, leading to reduced conduction band offset and retention issues, and existing alternatives like tantalum and titanium oxides can crystallize, causing charge migration.
Innovation Solution
Forming a germanium oxynitride film through atomic layer deposition, which offers a higher electron affinity, thermal stability, and low intermixing with surrounding layers, using a process that includes alternating cycles of germanium and nitrogen precursors to achieve desired thickness and stoichiometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon nitride is used as charge trapping layer, then the device structure is simple and manufacturing is easy, but the electron affinity is low leading to reduced conduction band offset and retention issues
Solution Approach 1:
The patent uses germanium oxynitride, a composite material combining germanium, oxygen, and nitrogen elements, to form the charge trapping layer. This composite material provides higher electron affinity and conduction band offset compared to silicon nitride, while maintaining compatibility with existing V-NAND device structures and manufacturing processes.
Solution Approach 2:
The patent changes the material composition parameters by introducing germanium into the oxynitride layer, which increases the electron affinity and conduction band offset. The specific composition is controlled through atomic layer deposition processes thatpreciseley regulate the ratios of germanium, oxygen, and nitrogen precursors.
2Reliability
If tantalum oxide or titanium oxide is used as charge trapping layer, then the conduction band offset is improved, but the material can crystallize causing charge migration
Solution Approach 1:
The patent optimizes the composition parameters of germanium oxynitride to achieve the desired conduction band offset while maintaining thermal stability. By controlling the germanium content and oxynitride ratio, the material provides high electron affinity without crystallizing at typical V-NAND processing temperatures.
Solution Approach 2:
The patent uses a material composition that remains stable and amorphous under processing conditions, avoiding the need for additional stabilization layers or complex processing steps required for other high-k materials.
3Productivity
If the charge trapping layer is scaled down for advanced V-NAND nodes, then the device density is improved, but the retention performance deteriorates due to lower conduction band offset
Solution Approach 1:
The patent changes the material parameters by using germanium oxynitride with higher electron affinity, which maintains adequate conduction band offset even as the layer thickness is reduced for scaling. This enables continued scaling to higher density V-NAND nodes while preserving retention characteristics.
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 germanium oxynitride film provides improved retention and charging capabilities with enhanced thermal stability and conformal deposition, suitable for scaled V-NAND devices and other applications like integrated circuits.
Implementation Method 1
performing an atomic layer deposition cycle of a nitride onto the substrate; performing an atomic layer deposition cycle of an oxide onto the substrate
Data Source
AI summary
A method for forming layers suitable for a V-NAND stack is disclosed. Specifically, the method may include multiple cycles for forming an oxide and a nitride in order to form an oxynitride layer.