Flash Wafer Heating Temperature Profiling With Variable Sampling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In flash heating of semiconductor wafers, creating an accurate temperature profile is challenging due to varying surface temperature histories caused by different flash lamp waveforms, leading to incomplete or inaccurate measurement of maximum temperatures and heat input, especially when using radiation thermometers with fixed data collection cycles.
Innovation Solution
A heat treatment method and apparatus that adjusts the data collection cycle based on the waveform of the flash light, using a variable cycle to capture temperature data before and after flash light irradiation, and employing a warning signal to set starting point temperature data, ensuring accurate temperature profiling regardless of temperature rise times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed data collection cycle is used for temperature measurement, then the measurement system is simple, but the temperature profile becomes incomplete or inaccurate when temperature rise time varies
Solution Approach 1:
The data collection cycle is changed from fixed to variable, dynamically adjusted according to the flash lamp waveform characteristics. The control unit determines the data collection cycle based on the waveform duration, ensuring the measurement system adapts to different heating conditions and captures complete temperature profiles accurately.
Solution Approach 2:
The measurement parameter (data collection cycle) is changed from a constant value to a variable value that depends on the flash lamp waveform. By linking the data collection cycle to the waveform characteristics, the system achieves accurate temperature profiling without requiring overly complex measurement infrastructure.
2Loss of information
If temperature data is collected at fixed intervals, then the data collection process is simple, but maximum temperature and heat input cannot be accurately obtained
Solution Approach 1:
The control unit uses feedback from the flash lamp waveform characteristics to dynamically adjust the data collection cycle. By monitoring the waveform duration and adjusting the sampling interval accordingly, the system ensures complete capture of temperature data including maximum temperature and heat input information, while maintaining automated operation.
Solution Approach 2:
The system performs preliminary determination of the data collection cycle based on the flash lamp waveform before actual temperature measurement begins. This pre-adjustment ensures that the measurement parameters are optimized for the specific heating condition, preventing data loss and ensuring accurate capture of temperature profile characteristics.
3Measurement precision
If a short data collection cycle is used, then rapid temperature changes are captured accurately, but the measurement time increases and productivity decreases
Solution Approach 1:
The data collection cycle dynamically adapts to the specific flash lamp waveform being used. For shorter waveforms, a correspondingly shorter data collection cycle is selected, capturing temperature changes efficiently without unnecessary extended measurement time. This dynamic matching maintains measurement precision while optimizing productivity for different processing conditions.
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 allows for reliable creation of temperature profiles that include the entire temperature rise and maximum reaching temperature, preventing erroneous data collection and ensuring accurate heat treatment processes.
Implementation Method 1
measuring a surface temperature of the substrate with a radiation thermometer
Implementation Method 2
irradiating a surface of a substrate with a flash of light from a flash lamp to heat the substrate
Implementation Method 3
The wavelength of light emitted from the xenon flash lamp is shorter than that of light emitted from a conventional halogen lamp, and approximately coincides with a fundamental absorption band of a silicon semiconductor wafer. Thus, when a semiconductor wafer is irradiated with a flash of light from the xenon flash lamp, the temperature of the semiconductor wafer can be rapidly raised with a small amount of transmitted light.
Data Source
AI summary
The semiconductor wafer is preheated by halogen lamps and then heated by a flash of light irradiation from flash lamps. A length of a light emission waveform of a flash of light applied from the flash lamps can be adjusted as appropriate. A data collection cycle (sampling interval) of a radiation thermometer that measures a surface temperature of the semiconductor wafer is made variable, and the longer the light emission waveform of the flash of light, the longer the data collection cycle. Even when a rising and falling time of the surface temperature of the semiconductor wafer changes due to the length of the light emission waveform of a flash of light, a temperature change can be included in a temperature profile with a constant number of data points until the surface temperature rises, goes through a maximum reaching temperature, and falls.