Semiconductor Wafer Temperature Detection via Bandedge Standardization
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Solution Overview
Problem
Conventional methods for detecting the temperature of semiconductor wafers during processing face challenges such as instability and reduced accuracy due to the dependence on light intensity and spectrum conditions, requiring calibration for each wafer type and heating condition, and lack consideration for appropriate wavelength ranges, leading to reduced processing efficiency and yield.
Innovation Solution
A temperature detection system that includes a light source, spectroscope, and photodetector, with a controller performing standardization and bandedge determination processing to accurately detect the temperature of semiconductor wafers by defining local minimum and maximum wavelengths and comparing them to correlation data, allowing for robust temperature measurement across different wafer types and conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bandedge evaluation technology is used to detect temperature at 500°C or lower, then measurement precision is improved, but device complexity increases due to the need for spectroscope and complex signal processing
Solution Approach 1:
The patent combines the light source, spectroscope, and photodetector into an integrated temperature detection system. The spectroscope and photodetector are positioned to receive light transmitted through or reflected from the wafer surface, merging multiple functional components into a unified detection apparatus that reduces spatial complexity while maintaining measurement precision.
Solution Approach 2:
The detection system is designed to measure the absorption edge wavelength of semiconductor wafers across a broad temperature range (room temperature to 500°C or higher). By using the same bandedge evaluation methodology for both lower temperatures (where radiation thermometers fail) and higher temperatures, the system achieves universal applicability without requiring multiple specialized devices.
2Measurement precision
If calibration is performed for each wafer type and heating condition to ensure accuracy, then measurement precision is improved, but productivity decreases due to extensive calibration requirements
Solution Approach 1:
The patent measures the absorption edge wavelength, which changes with temperature according to the relationship λg = hc/Eg. By monitoring the shift in absorption edge wavelength rather than requiring full spectral calibration for each condition, the system achieves accurate temperature measurement across different wafer types and heating conditions without extensive recalibration.
Solution Approach 2:
The system performs preliminary measurement of the absorption edge wavelength and uses this information to directly determine temperature through the known relationship between bandgap energy and temperature. This preliminary measurement approach eliminates the need for repeated calibration procedures for each wafer type and heating condition, significantly improving processing efficiency.
3Device complexity
If radiation thermometer is used for temperature detection, then device complexity is reduced, but measurement precision deteriorates at temperatures of 500°C or lower
Solution Approach 1:
The patent replaces contact-based or simple radiation thermometer methods with optical spectroscopy-based bandedge evaluation. By measuring the absorption edge wavelength of the semiconductor wafer and using the relationship between bandgap energy and temperature, the system achieves accurate temperature measurement at lower temperatures (500°C or lower) where radiation thermometers are insufficient, while maintaining reasonable device complexity through the use of standard optical components.
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
Enables high-accuracy temperature detection of semiconductor wafers, improving processing efficiency and reducing the need for extensive calibration, thereby enhancing the stability and flexibility of semiconductor processing operations.
Implementation Method 1
a spectroscope disperses transmitted light or scattered reflection light generated from the semiconductor wafer according to irradiation of the light
Implementation Method 2
a photodetector measures an intensity of the light dispersed by the spectroscope
Implementation Method 3
bandedge evaluation technology, which stably detects temperature by using temperature dependence of a frequency of a region edge in a frequency (wavelength) range of an electromagnetic wave absorbed by the semiconductor
Data Source
AI summary
A temperature detector capable of detecting temperature of a semiconductor wafer with high accuracy is provided. In standardizing a spectrum of light measured by a photodetector, a controller uses as a local minimum wavelength a wavelength corresponding to bandgap energy of a semiconductor at absolute zero to set as a local minimum value a minimum value of a light intensity in a wavelength region shorter than the local minimum wavelength, uses as a first maximum wavelength a wavelength corresponding to a difference between bandgap energy and thermal energy of a semiconductor at the highest temperature assumed as a temperature measurement range to set as a local maximum value a value obtained by taking a difference with a local minimum value from the maximum value of the light intensity in a wavelength region shorter than the first maximum wavelength, and performs a difference processing with the local minimum value with respect to the spectrum of the measured light to divide it by the local maximum value, thereby standardizing it.