Wafer Radiation Thermometry With Ambient Light Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing temperature measurement methods for semiconductor wafers during flash lamp annealing are inaccurate due to ambient light interference from quartz structures, leading to errors in temperature readings.
Innovation Solution
A method involving measuring the reflectivity of the substrate and calculating the intensity of ambient light based on synchrotron radiation from quartz windows, allowing for accurate subtraction from the radiation thermometer readings to determine the substrate's temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a radiation thermometer measures the temperature of a semiconductor wafer, then the temperature can be obtained, but measurement precision deteriorates due to ambient light interference from quartz structures
Solution Approach 1:
The patent extracts and separates the harmful ambient light component from the total radiation received by the thermometer. By measuring the ambient light intensity separately (when the wafer is absent or at known temperature) and subtracting it from the total radiation measurement, the method isolates the wafer's emitted radiation for accurate temperature calculation.
Solution Approach 2:
The patent implements a feedback mechanism where the measured ambient light intensity is used to correct the temperature measurement. The system continuously monitors ambient light conditions and adjusts the temperature calculation by compensating for the reflected ambient light component, creating a closed-loop correction process.
2Temperature
If the halogen lamp is turned on to preheat the semiconductor wafer, then the wafer temperature increases, but the temperature of the quartz window constantly varies causing ambient light intensity to change
Solution Approach 1:
The patent performs preliminary measurement of the ambient light intensity from the quartz window before or during the heating process. By characterizing the ambient light conditions in advance and establishing the relationship between quartz window temperature and light intensity, the system can predict and compensate for ambient light variations during subsequent temperature measurements.
Solution Approach 2:
The system continuously monitors the quartz window temperature and uses this feedback to adjust the ambient light compensation. As the quartz window temperature changes during preheating, the system updates the ambient light intensity calculation accordingly, maintaining accurate temperature measurements throughout the dynamic heating process.
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 enables precise temperature measurement of the substrate by accounting for ambient light variations, resulting in high-precision temperature calculations.
Implementation Method 1
a non-contact radiation thermometer measures the temperature of a semiconductor wafer during the heat treatment. Since the radiation thermometer receives not only infrared light radiated from the semiconductor wafer
Implementation Method 2
calculating an intensity of ambient light received by a radiation thermometer, based on the reflectivity measured in step (a) and an intensity of synchrotron radiation radiated from a quartz window included in the chamber
Implementation Method 3
since the front surface and the back surface of a semiconductor wafer are mirror-finished surfaces, a ratio of a component of an ambient light reflected by the front surface or the back surface of the semiconductor wafer is relatively higher
Data Source
AI summary
An edge radiation thermometer performs measurements before a semiconductor wafer is transported into a chamber. The edge radiation thermometer performs the measurements while the semiconductor wafer is supported by lift pins and while the semiconductor wafer is placed on a susceptor, after the semiconductor wafer is transported into the chamber. A controller calculates a reflectivity of the semiconductor wafer based on these measurement values. Then, the controller calculates an intensity of an ambient light receive by the edge radiation thermometer, based on the reflectivity and an intensity of synchrotron radiation radiated from a quartz window. Subsequently, the controller subtracts the intensity of the ambient light from an intensity of light received by of the edge radiation thermometer during heat treatment on the semiconductor wafer to calculate the temperature of the semiconductor wafer.