Nitrogen Distribution in Gate Dielectric Layers
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Solution Overview
Problem
Conventional methods for introducing nitrogen into gate dielectrics result in non-uniform nitrogen profiles, leading to reliability issues, particularly in thicker gate dielectrics used in high voltage devices, causing increased leakage current.
Innovation Solution
A method involving a first plasma nitridation process to incorporate a nitrogen region in a silicon substrate, followed by growing a dielectric material layer using a nitrogen and oxygen containing fluid, and a second plasma nitridation process to form a nitrided dielectric layer, ensuring uniform nitrogen distribution across the gate dielectric layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional plasma nitridation is used to introduce nitrogen into gate dielectrics, then leakage current is suppressed, but nitrogen distribution becomes non-uniform leading to reduced reliability
Solution Approach 1:
The nitrogen introduction process is divided into multiple sequential plasma nitridation steps rather than a single step. Each step introduces nitrogen at different depths and concentrations, creating a graded nitrogen profile that ensures uniform distribution throughout the gate dielectric layer, thereby resolving the non-uniformity issue while maintaining leakage suppression
Solution Approach 2:
The patent varies plasma process parameters (such as power, pressure, gas composition, and treatment duration) across different nitridation steps to control nitrogen incorporation depth and concentration. By dynamically adjusting these parameters, the process achieves uniform nitrogen distribution throughout the dielectric layer while effectively suppressing leakage current
2Adaptability or versatility
If gate dielectric thickness is increased for high voltage devices, then voltage compatibility is improved, but leakage current increases
Solution Approach 1:
The patent applies nitrogen treatment with spatially varying characteristics - different nitrogen concentrations and profiles are introduced at different depths and regions of the gate dielectric. This localized nitrogen incorporation suppresses leakage current specifically where needed in thick dielectrics used for high voltage devices, while maintaining voltage compatibility across different device regions
3Manufacturing precision
If multiple plasma nitridation steps are performed, then nitrogen distribution uniformity is improved, but process complexity increases
Solution Approach 1:
Multiple plasma nitridation steps are combined into an integrated process sequence that can be performed in-situ without breaking vacuum or requiring separate equipment. The process merges nitrogen introduction with gate dielectric formation steps, achieving uniform nitrogen distribution while minimizing additional process complexity through consolidation
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 achieves a significantly reduced non-uniformity in nitrogen concentration, with an average uniform nitrogen concentration above 9 atomic percent, enhancing the reliability of gate dielectric layers and reducing leakage currents in both high and low voltage devices.
Implementation Method 1
subjecting the silicon substrate to a first plasma nitridation process to incorporate a nitrogen region therein
Implementation Method 2
subjecting the dielectric material layer to a second plasma nitridation process, thereby forming a nitrided dielectric material layer
Implementation Method 3
growing a dielectric material layer over the nitrogen region using a nitrogen and oxygen containing fluid
Data Source
AI summary
Provided is a method for manufacturing a gate dielectric. This method, without limitation, includes subjecting a silicon substrate to a first plasma nitridation process to incorporate a nitrogen region therein. This method further includes growing a dielectric material layer over the nitrogen region using a nitrogen containing oxidizer gas, and subjecting the dielectric material layer to a second plasma nitridation process, thereby forming a nitrided dielectric material layer over the nitrogen region.