Plasma Oxidation of Silicon-Rich SiON for Memory Blocking Layers
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Solution Overview
Problem
Conventional non-volatile charge trap memory devices face challenges in data retention and sensing due to the poor quality of the oxide blocking layer, which leads to carrier back streaming and reduced transistor performance, especially as devices are scaled down.
Innovation Solution
The formation of a blocking layer through consumptive plasma oxidation of a charge trapping layer, such as a silicon-rich silicon oxynitride layer, instead of conventional deposition methods, results in a higher quality oxide with improved uniformity and reduced micro-roughness, enhancing the barrier against charge leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional high temperature oxide deposition is used to form the blocking layer, then the process is simple and suitable for thick layers, but the oxide quality is poor with high roughness and low uniformity
Solution Approach 1:
The patent changes the deposition parameters by using plasma-enhanced chemical vapor deposition (PECVD) instead of conventional thermal deposition, operating at lower temperatures (300-450°C) with controlled plasma power and gas flow rates to achieve high-quality oxide films with improved uniformity and reduced roughness
Solution Approach 2:
The patent replaces the conventional thermal field-based deposition with a plasma field-based process, using electromagnetic field (plasma) to enhance the deposition mechanism and achieve better film quality at lower temperatures
2Length of moving object
If the blocking layer thickness is reduced to enable device scaling, then device density increases, but carrier back streaming increases and data retention deteriorates
Solution Approach 1:
The patent changes the material composition parameters by forming an oxide-nitride-oxide (ONO) stack where the nitride layer provides enhanced barrier properties, allowing thinner overall blocking structures while maintaining or improving carrier blocking capability and data retention
Solution Approach 2:
The patent uses a composite oxide-nitride-oxide structure where the nitride layer (Si3N4 or SiOxNy) is embedded between oxide layers to create a multi-functional barrier that provides both electrical isolation and carrier blocking, enabling scaled device dimensions with improved reliability
3Productivity
If batch processing equipment is used for oxide deposition, then throughput is high, but wafer-to-wafer thickness non-uniformity increases
Solution Approach 1:
The patent replaces conventional batch thermal deposition with plasma-enhanced deposition, using electromagnetic field (plasma) to achieve more uniform reaction conditions across the wafer surface, resulting in improved wafer-to-wafer thickness uniformity while maintaining batch processing capability
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 leads to improved uniformity and quality of the blocking layer, enabling better performance and reliability in scaled non-volatile charge trap memory devices with reduced wafer-to-wafer and substrate-to-substrate thickness variations, and lower Vt variation across devices.
Implementation Method 1
consumptive plasma oxidation of a charge trapping layer, such as a silicon-rich silicon oxynitride layer
Data Source
AI summary
A blocking layer of a non-volatile charge trap memory device is formed by oxidizing a portion of a charge trapping layer of the memory device. In one embodiment, the blocking layer is grown by a radical oxidation process at temperature below 500° C. In accordance with one implementation, the radical oxidation process involves flowing hydrogen (H2) and oxygen (O2) gas mixture into a process chamber and exposing the substrate to a plasma. In a preferred embodiment, a high density plasma (HDP) chamber is employed to oxidize a portion of the charge trapping layer. In further embodiments, a portion of a silicon-rich silicon oxynitride charge trapping layer is consumptively oxidized to form the blocking layer and provide an increased memory window relative to oxidation of a nitrogen-rich silicon oxynitride layer.