Radical Oxidation for Nonvolatile Charge Trap Memory Leakage
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Solution Overview
Problem
Conventional SONOS transistors suffer from poor data retention due to leakage current through the nitride or oxy-nitride layer, limiting the lifetime and application of semiconductor devices.
Innovation Solution
A method for fabricating nonvolatile charge trap memory devices using a radical oxidation process to form high-quality tunnel and blocking dielectric layers, which reduces leakage current and improves data retention by oxidizing a charge-trapping layer to create a blocking dielectric layer and forming a tunnel dielectric layer, resulting in denser, low-hydrogen-content films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a nitride or oxy-nitride layer is used as charge-trapping layer in conventional SONOS transistors, then the device can store charge, but leakage current through the layer causes poor data retention and limits device lifetime
Solution Approach 1:
The patent changes the chemical composition and physical state of the charge-trapping layer by oxidizing it to form silicon oxide. This parameter change transforms the layer from a nitride/oxy-nitride composition to an oxide composition, which has lower leakage current characteristics while maintaining charge-trapping capability, thereby resolving the contradiction between data retention and leakage current
Solution Approach 2:
The patent employs steam oxidation, a strong oxidation process, to convert the charge-trapping layer into silicon oxide. This accelerated oxidation using steam as the oxidant effectively transforms the layer composition and reduces leakage current, improving data retention without sacrificing charge-trapping function
2Manufacturing precision
If conventional oxidation processes are used to form dielectric layers, then the process is simple, but the resulting films have higher hydrogen content and lower quality
Solution Approach 1:
The patent uses steam oxidation, a strong oxidation process, to form high-quality silicon oxide dielectric layers. This process produces denser films with lower hydrogen content compared to conventional oxidation methods, thereby improving film quality and reducing unwanted hydrogen incorporation in the dielectric layers
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 method enhances data retention and extends the lifetime of semiconductor devices by reducing leakage current and maintaining capacitance, while being compatible with batch-processing tools and capable of high throughput.
Implementation Method 1
A portion of the charge-trapping layer is then oxidized to form a blocking dielectric layer above the charge-trapping layer
Implementation Method 2
by exposing the charge-trapping layer to a radical oxidation process
Data Source
AI summary
A method for fabricating a nonvolatile charge trap memory device and the device are described. In one embodiment, the method includes providing a substrate in an oxidation chamber, wherein the substrate comprises a first exposed crystal plane and a second exposed crystal plane, and wherein the crystal orientation of the first exposed crystal plane is different from the crystal orientation of the second exposed crystal plane. The substrate is then subjected to a radical oxidation process to form a first portion of a dielectric layer on the first exposed crystal plane and a second portion of the dielectric layer on the second exposed crystal plane, wherein the thickness of the first portion of the dielectric layer is approximately equal to the thickness of the second portion of the dielectric layer.