Flash Lamp Annealing Temperature Measurement
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Solution Overview
Problem
Current flash lamp annealing techniques face challenges in accurately measuring the surface temperature of semiconductor wafers due to the intense and short-duration light emission, which interferes with the measurement of radiated light from the wafer, making it difficult to calculate the surface temperature effectively.
Innovation Solution
A heat treatment apparatus and method that includes a photodetector element to measure the intensity of radiated light from the substrate after the irradiation has stopped, allowing for the calculation of the surface temperature without interference from the intense radiation, using a chamber with a holder, irradiation part, and temperature calculating part to determine the substrate's surface temperature based on the measured radiated light intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If flash lamp annealing is used to rapidly heat the semiconductor wafer surface, then impurity activation is achieved without deep diffusion, but accurate surface temperature measurement becomes difficult due to the intense background radiation
Solution Approach 1:
The patent applies preliminary action by measuring the radiated light intensity from the wafer surface after the flash lamp irradiation has stopped. The temperature calculation is performed based on this post-irradiation measurement, avoiding the interference of intense background radiation during the heating process. This timing strategy allows accurate temperature determination while maintaining the benefits of rapid flash heating.
2Measurement precision
If conventional continuous heating methods are used, then temperature measurement is easier, but impurity diffusion becomes too deep and activation is insufficient
Solution Approach 1:
The patent employs periodic action by using flash lamp annealing with extremely short irradiation durations (microseconds to milliseconds). This pulsed heating approach rapidly raises the wafer surface temperature for impurity activation, then quickly stops to prevent excessive diffusion. The measurement is performed in the interval between pulses, when background radiation has ceased but the wafer remains at the target temperature.
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 accurate determination of the surface temperature of the substrate even during intense and short-duration light irradiation, overcoming the limitations of previous methods by allowing for precise temperature measurement post-irradiation, thus ensuring effective activation of impurities without deep diffusion.
Implementation Method 1
a photodetector element provided on the surface side of the substrate held by the holder, for receiving radiated light from the surface
Implementation Method 2
The wavelength of light emitted from the xenon flash lamps is shorter than that of light emitted from conventional halogen lamps, 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 emitted from the xenon flash lamps, the temperature of the semiconductor wafer can be raised rapidly
Implementation Method 3
The xenon flash lamps have a spectral distribution of radiation ranging from ultraviolet to near-infrared regions
Data Source
AI summary
A photodetector element for receiving radiated light from a surface of a semiconductor wafer loses a detection function because the intensity of the received light exceeds a detection limit while a flash lamp emits light. Measurement is not performed during the above-mentioned period, and the intensity of the radiated light from the surface of the semiconductor wafer is measured after the flash lamp stops emitting light and the photodetector element restores the detection function. Then, the temperature of the surface of the semiconductor wafer heated by irradiation with a flash of light is calculated based on the measured intensity of the radiated light. Accordingly, even in a case where intense irradiation is performed in an extremely short period of time, such as flash irradiation, the flash of light does not act as ambient light, which enables to obtain the surface temperature of the semiconductor wafer.