Rapid Thermal Annealing Temperature Uniformity via STI Density Mapping
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Solution Overview
Problem
The rapid thermal annealing process in semiconductor manufacturing experiences temperature non-uniformity due to varying semiconductor structure densities, which affects the electrical performance of integrated circuits by influencing parameters like threshold voltage and saturation current.
Innovation Solution
A method is introduced to establish a ternary correspondence relationship between device electrical parameters, annealing temperature, and STI distribution density, allowing for the addition of virtual structures to achieve a target STI distribution density and subsequently determining a target annealing temperature to ensure uniformity and consistent electrical performance across the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If rapid thermal annealing is performed on a wafer with varying semiconductor structure densities, then the annealing process can be completed quickly at high temperature, but temperature non-uniformity occurs across different areas of the wafer
Solution Approach 1:
The patent applies local quality by adjusting the light source intensity distribution to match the specific density characteristics of different areas on the wafer. Areas with higher semiconductor structure density receive lower light intensity, while areas with lower density receive higher light intensity, ensuring uniform temperature distribution across the entire wafer surface during rapid thermal annealing.
Solution Approach 2:
The patent implements dynamics by making the light source intensity distribution adjustable and controllable. The system can dynamically modify the intensity profile of the light source based on the wafer's structure density map, allowing the annealing process to adapt to varying local conditions while maintaining high processing speed and temperature uniformity.
2Temperature
If dummy structures are added to balance reflective indices in different areas, then temperature uniformity may be improved, but the device complexity and manufacturing process become more complicated
Solution Approach 1:
The patent replaces the mechanical approach of adding physical dummy structures with an optical control approach. Instead of modifying the wafer structure to balance reflectivity, the system uses a controllable light source to dynamically adjust intensity distribution, achieving temperature uniformity through optical modulation rather than structural modification.
Solution Approach 2:
The patent applies parameter changes by modifying the light source intensity distribution parameters rather than changing the physical structure of the semiconductor device. The system adjusts the intensity parameters of the light source to compensate for density variations, achieving the desired temperature uniformity without adding complex manufacturing steps or altering device architecture.
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 ensures uniform actual RTA process temperatures and achieves uniform target electrical parameters by adjusting STI distribution densities and adding virtual structures, thereby improving the consistency of semiconductor device performance.
Implementation Method 1
a wafer is placed onto a quartz stand within a process cavity and heated using a light source with high intensity
Implementation Method 2
The phenomenon of temperature non-uniformity of a rapid thermal annealing process may influence directly the electrical performance
Data Source
AI summary
The present invention discloses a rapid thermal annealing method for a semiconductor device, which includes the steps of: establishing a ternary correspondence relationship among a device electrical parameter, an annealing temperature, and an STI distribution density; deriving an STI distribution density in a specific area of the semiconductor device and a target STI distribution density; determining whether the STI distribution density in the specific area is larger than the target STI distribution density; if the STI distribution density in the specific area is larger than the target STI distribution density, adding a virtual structure in the specific area to make the STI distribution density in the specific area equal to the target STI distribution density; and deriving from the ternary correspondence relationship a target annealing temperature corresponding to the target STI distribution density and performing an annealing process with the annealing temperature on the semiconductor device to achieve a target electrical parameter. The method can alleviate the phenomenon of temperature non-uniformity of a rapid thermal annealing process so as to avoid any influence thereof upon the electrical performance of the semiconductor device.