Flash Lamp Annealing Temperature Measurement
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Solution Overview
Problem
Accurate measurement of front surface temperature during flash lamp annealing of semiconductor wafers is challenging due to rapid temperature changes and the complexity of temperature measurement with radiation thermometers, especially when the wafer has a film on its back surface altering emissivity.
Innovation Solution
A heat treatment method involving preheating with continuous lamps, followed by flash heating with xenon flash lamps, where the back surface temperature is measured continuously using a first radiation thermometer and the front surface temperature increase is measured with a second radiation thermometer, allowing for accurate calculation of the front surface temperature by adding the temperature increase to the preheated back surface temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If radiation thermometers are used to measure front surface temperature during flash lamp annealing, then temperature measurement is attempted, but the rapid temperature change in sub-millisecond units makes accurate measurement difficult
Solution Approach 1:
The patent applies preliminary action by preheating the substrate with continuous lighting lamps before flash lamp annealing. This creates a baseline temperature state that can be measured by radiation thermometers, allowing the subsequent rapid temperature increase during flash annealing to be accurately detected as a change from a known initial state
Solution Approach 2:
The patent uses the substrate's back surface temperature as an intermediary measurement. Since the back surface temperature changes more slowly and can be measured accurately by radiation thermometers, this measurement serves as a reference to calculate the front surface temperature, indirectly solving the direct measurement problem
2Measurement precision
If radiation thermometers measure temperature of a semiconductor wafer with films, then temperature measurement is performed, but the changed emissivity makes measurement more difficult
Solution Approach 1:
The patent measures the back surface temperature as an intermediary, which has more stable and predictable emissivity characteristics compared to the front surface with its complex film structure. This intermediary measurement bypasses the emissivity variation problem caused by films on the front surface
Solution Approach 2:
The patent assumes temperature homogeneity across the substrate thickness during preheating, allowing the back surface temperature measurement to represent the overall substrate temperature state, simplifying the measurement problem despite film presence
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 precise measurement of front surface temperature during flash lamp annealing, regardless of the film type on the back surface, improving temperature control and measurement accuracy.
Implementation Method 1
preheating the substrate by irradiating the substrate with light from a continuous lighting lamp
Implementation Method 2
irradiating a front surface of the preheated substrate with a flash of light from a flash lamp to heat the substrate by flash heating
Implementation Method 3
measuring continuously temperature of the back surface of the substrate with a first radiation thermometer provided obliquely below the substrate
Data Source
AI summary
A semiconductor wafer is heated by a flash of light emitted from a flash lamp after being preheated by a halogen lamp. Temperature of the semiconductor wafer immediately before the flash of light is emitted is measured by a lower radiation thermometer. At the time of irradiation with a flash of light, an upper radiation thermometer measures temperature increase of a front surface of the semiconductor wafer. Front surface temperature of the semiconductor wafer is calculated by adding the temperature increase of the front surface of the semiconductor wafer at the time of irradiation with a flash of light measured by the upper radiation thermometer to the back surface temperature of the semiconductor wafer measured by the lower radiation thermometer.