Pyrometry Filter Reflective Coating Thermal Chamber
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Solution Overview
Problem
In thermal processing of semiconductor substrates, existing pyrometry systems face challenges in accurately measuring substrate temperatures due to interference from radiation from the heating source, especially at lower temperatures, leading to inaccurate readings and loss of weak thermal emission signals.
Innovation Solution
A pyrometry filter is introduced for the thermal process chamber, utilizing a reflective coating on the window to block radiation from the heating source within the pyrometer's bandwidth, ensuring that only substrate radiation is measured, thereby minimizing interference and improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pyrometer is used to measure substrate temperature in a thermal processing chamber, then temperature measurement capability is provided, but measurement precision deteriorates due to interference from heating source radiation
Solution Approach 1:
A filter is introduced as an intermediary component between the pyrometer and the substrate. This filter selectively transmits thermal radiation from the substrate while blocking radiation from the heating source, thereby mediating the interaction between the measurement device and the processed object to eliminate harmful interference.
Solution Approach 2:
The filter is designed with specific spectral properties that are optimized for the particular wavelength range of interest. By tailoring the filter's transmission characteristics to match the substrate's thermal emission spectrum while blocking the heating source's radiation spectrum, local quality enhancement achieves precise temperature measurement capability.
2Temperature
If the substrate is maintained at lower temperatures (less than 400°C), then process requirements are met, but measurement precision deteriorates due to weak thermal emission signals
Solution Approach 1:
The filter's spectral transmission characteristics are specifically designed to enhance the signal strength in the wavelength range where low-temperature substrates emit their peak thermal radiation. By changing the optical parameters of the measurement system through the filter, the weak thermal emission signals from cold substrates are amplified relative to the background noise.
Solution Approach 2:
The filter converts the challenge of weak thermal emission at low temperatures into an advantage by selectively enhancing those very weak signals while simultaneously suppressing the stronger but unwanted heating source radiation. What was previously a limiting factor (weak signal) becomes the focused measurement target with improved signal-to-noise ratio.
3Measurement precision
If the pyrometer bandwidth includes wavelengths from the heating source, then measurement capability is provided, but measurement precision deteriorates due to detected heating source radiation
Solution Approach 1:
The spectral bandwidth of the pyrometer system is segmented into different wavelength ranges. The filter isolates the specific wavelength range that corresponds to substrate thermal emission, separating it from the broader spectrum that includes heating source radiation. This segmentation allows selective measurement of substrate signal while excluding interfering radiation.
Solution Approach 2:
The harmful heating source radiation is extracted or removed from the pyrometer's detected signal by the filter. By taking out the unwanted wavelength components from the overall radiation spectrum, only the desired substrate thermal emission information reaches the pyrometer, preventing signal contamination.
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 solution effectively reduces interference from heating source radiation, allowing for more accurate temperature measurements across a wider range of substrate temperatures, including those below 400°C, by reflecting unwanted radiation back to the source and ensuring that the pyrometer detects primarily the substrate's thermal emission.
Implementation Method 1
A pyrometry filter is introduced for the thermal process chamber, utilizing a reflective coating on the window to block radiation from the heating source within the pyrometer's bandwidth
Implementation Method 2
radiation that is within the radiation pyrometer bandwidth, and that originates from the heating source, can interfere with the interpretation of the pyrometer signal
Data Source
AI summary
Embodiments of the invention generally relate to pyrometry during thermal processing of semiconductor substrates. More specifically, embodiments of the invention relate to a pyrometry filter for a thermal process chamber. In certain embodiments, the pyrometry filter selectively filters selected wavelengths of energy to improve a pyrometer measurement. The pyrometry filter may have various geometries which may affect the functionality of the pyrometry filter.