Thin Oxide Growth via Nitride Conversion for High-Aspect Trenches
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Solution Overview
Problem
Conventional methods face challenges in forming a thin, high-quality oxide layer in high aspect ratio semiconductor structures due to high silicon consumption, defects, and non-uniform nitrogen incorporation, leading to reduced device reliability.
Innovation Solution
A method involving plasma-enhanced atomic layer deposition (PE ALD) to form a silicon nitride layer with a nitrogen concentration gradient, followed by a conversion process to oxidize the silicon nitride layer, forming a high-quality silicon oxide layer with controlled nitrogen distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermal oxidation growth is used to form an oxide layer, then the oxide layer can be formed, but high silicon consumption occurs and the oxide layer cannot be thin enough for high aspect ratio structures
Solution Approach 1:
The patent changes the formation method parameter from thermal oxidation to deposition process, enabling precise thickness control down to nanometer scale while minimizing silicon consumption. The deposition method allows forming thin oxide layers (e.g., 1-10 nm) that would be impossible to achieve with conventional thermal oxidation without excessive silicon consumption.
2Manufacturing precision
If deposition method is used to form an oxide layer, then thin layers can be formed, but the oxide layer quality is low with defects and traps reducing device reliability
Solution Approach 1:
The patent introduces a nitrogen-containing intermediate layer as a mediator between the substrate and the oxide layer. This intermediate layer acts as a buffer that improves the quality of the deposited oxide layer by reducing defects and traps, thereby enhancing device reliability while maintaining the ability to form thin oxide layers through deposition.
Solution Approach 2:
The patent creates a composite structure consisting of multiple layers including the oxide layer and nitrogen-containing intermediate layer. This composite material approach combines the advantages of deposition (thin layer formation) with the benefits of the intermediate layer (defect reduction), achieving both thinness and high reliability.
3Ease of manufacture
If conventional methods are used to form an oxide layer, then the process is simple, but nitrogen incorporation in the oxide layer is low and non-uniform
Solution Approach 1:
The patent performs preliminary action by forming a nitrogen-containing intermediate layer before depositing the oxide layer. This preliminary nitrogen incorporation ensures uniform nitrogen distribution throughout the final oxide layer structure, solving the non-uniformity problem while maintaining process simplicity through a straightforward sequential deposition approach.
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
Reduces silicon consumption, minimizes defects, and enables precise control over nitrogen incorporation, resulting in a reliable and uniform gate oxide layer.
Implementation Method 1
forming a silicon nitride layer on the protective interlayer oxide, by a plasma-enhanced atomic layer deposition (PE ALD) process utilizing nitrogen-containing process gas
Implementation Method 2
performing a conversion process to oxidize the formed silicon nitride layer to at least partially convert the formed silicon nitride layer to a silicon oxide layer
Data Source
AI summary
A method for forming an oxide layer includes forming a protective interlayer oxide on sidewalls of a trench formed on a substrate, forming a silicon nitride layer on the protective interlayer oxide, by a plasma-enhanced atomic layer deposition (PE ALD) process utilizing nitrogen-containing process gas, the silicon nitride layer having a concentration gradient of nitrogen varying from high concentration away from the protective interlayer oxide to low concentration near the protective interlayer oxide, and performing a conversion process to oxidize the formed silicon nitride layer to at least partially convert the formed silicon nitride layer to a silicon oxide layer.