Flash Lamp Annealing Temperature Correction Using Quantum IR Sensing
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Solution Overview
Problem
Radiation thermometers using quantum infrared sensors face challenges in accurately measuring the temperature of semiconductor wafers irradiated with flash light due to variations in output voltage over time, leading to precision issues in flash lamp annealing processes.
Innovation Solution
A heat treatment apparatus equipped with a quantum infrared sensor that calculates a correction coefficient based on reference and shift temperatures to correct temperature measurements, ensuring precise temperature control during flash lamp annealing, and includes an alarm unit to detect excessive differences in temperature thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a quantum infrared sensor is used to measure temperature during flash lamp annealing, then the response speed is improved, but the measurement precision deteriorates due to output voltage variations over time
Solution Approach 1:
The patent implements a feedback mechanism where the quantum infrared sensor continuously monitors the temperature during flash lamp annealing, and the measured temperature values are fed back to a control system. The control system compares the measured temperature with the target temperature and adjusts the flash lamp irradiation parameters accordingly, ensuring precise temperature control despite sensor output variations.
Solution Approach 2:
The patent changes the measurement parameters by measuring not only the absolute temperature but also the rate of temperature change. By monitoring both the temperature value and its temporal derivative, the system can more accurately track the rapid temperature changes during flash lamp annealing and compensate for sensor drift through differential measurement techniques.
2Reliability
If the flash lamp irradiation time is extended to ensure complete impurity activation, then the activation effectiveness is improved, but the impurity diffusion depth increases beyond the required junction depth
Solution Approach 1:
The patent employs periodic or pulsed irradiation with the flash lamp instead of continuous irradiation. By delivering the required energy in multiple short pulses with appropriate intervals, the system achieves complete impurity activation while limiting the total time at high temperature, thus preventing excessive diffusion and maintaining precise junction depth control.
Solution Approach 2:
The patent performs preliminary heating of the semiconductor wafer before flash lamp irradiation to reach an optimal starting temperature. This preliminary action ensures that when the flash lamp irradiation begins, the wafer is already at the ideal temperature range for rapid impurity activation, allowing the process to achieve complete activation with minimal irradiation time and thus minimal diffusion.
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 enables accurate temperature measurement and correction of semiconductor wafers during flash lamp annealing, even with changing output voltages, ensuring consistent and precise processing results.
Implementation Method 1
a radiation thermometer using a quantum infrared sensor
Implementation Method 2
irradiating a front-surface of a semiconductor wafer with a flash of light using a xenon flash lamp raises the temperature of only the front-surface
Data Source
AI summary
Even a radiation thermometer using a quantum infrared sensor appropriately measures the temperature of a substrate irradiated with a flash of light. A heat treatment apparatus includes a quantum infrared sensor configured to measure a temperature of the first substrate and a temperature of the second substrate. The heat treatment apparatus further includes a temperature correction unit configured to correct, using a correction coefficient calculated based on the reference temperature and the shift temperature, a temperature of the second substrate on which second heat treatment having irradiation with the flash of light is performed, the temperature being measured by the quantum infrared sensor.