Silicon Oxynitride Nitrogen Profile via Ultra-Low Pressure Annealing
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Solution Overview
Problem
Current methods for incorporating nitrogen into silicon dioxide films to form ultra-thin silicon oxynitride gate dielectrics are ineffective for advanced technology nodes beyond 0.1 μm, leading to inadequate boron blocking, increased gate leakage, and mobility degradation due to inappropriate nitrogen concentration profiles and contamination issues.
Innovation Solution
A rapid thermal annealing process at ultra-low pressure (≤10 Torr) using ammonia (NH3) is employed to incorporate nitrogen into silicon dioxide films, optimizing the nitrogen concentration profile with a high concentration at the surface and minimal concentration at the substrate interface, thereby forming a silicon oxynitride film suitable for advanced technology nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional thermal processes are carried out in furnaces at atmospheric or slightly below atmospheric pressure, then multiple wafers can be processed at once, but the nitrogen concentration profile becomes inappropriate with insufficient nitrogen incorporation
Solution Approach 1:
The patent changes the pressure parameter from atmospheric/slightly below atmospheric pressure to ultra-low pressure (≤10 Torr) to enable sufficient nitrogen incorporation into the dielectric film while maintaining process efficiency through rapid thermal annealing
2Reliability
If nitrogen is incorporated into ultra-thin SiO2 films to form SiON, then boron blocking is improved, but gate leakage increases and mobility degrades due to inappropriate nitrogen concentration profiles
Solution Approach 1:
The patent creates a non-uniform nitrogen concentration profile where nitrogen concentration varies through the film thickness, with higher concentration near the top surface and lower concentration near the substrate interface, optimizing both boron blocking and electrical properties
Solution Approach 2:
The patent uses rapid thermal annealing to dynamically control nitrogen incorporation during the process, achieving the desired nitrogen concentration profile through time-dependent temperature and pressure conditions
3Speed
If dielectric thickness is decreased to increase gate capacitance, then transistor speed increases, but gate reliability deteriorates due to increased tunneling current and boron penetration
Solution Approach 1:
The patent creates a composite structure by incorporating nitrogen into SiO2 to form SiON (silicon oxynitride), which combines the benefits of thin dielectric for high speed with improved reliability through enhanced boron blocking and reduced tunneling current
4Speed
If higher k gate dielectric materials are used to increase gate capacitance, then transistor speed increases, but material compatibility and contamination issues arise
Solution Approach 1:
The patent changes the dielectric properties by incorporating nitrogen into SiO2, increasing the dielectric constant from 3.9 to higher values while maintaining compatibility with existing Si substrate and polysilicon gate electrode materials and avoiding contamination issues associated with rare-earth oxides
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 results in improved boron blocking, reduced gate leakage, and enhanced mobility, enabling the scaling of silicon oxynitride films for high-performance transistors with optimized nitrogen distribution and reduced contamination risks.
Implementation Method 1
A rapid thermal annealing process at ultra-low pressure (≤10 Torr) using ammonia (NH3) is employed to incorporate nitrogen into silicon dioxide films
Implementation Method 2
incorporating nitrogen into the dielectric film blocks boron as well as increases the dielectric constant of the gate dielectric
Data Source
AI summary
A method of forming a dielectric film that includes nitrogen. The method includes incorporating nitrogen into a dielectric film using a nitridation gas and a rapid thermal annealing process, wherein an ultra-low pressure of equal to or less than about 10 Torr is used for the rapid thermal annealing process.