Susceptor Temperature Measurement Using Polarization and Wavelength Segmentation
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Solution Overview
Problem
Existing heat treatment apparatuses face challenges in accurately measuring the temperature of a susceptor during preheating, especially when a substrate is present, due to interference from infrared radiation emitted by the substrate, which affects the measurement of the susceptor's temperature.
Innovation Solution
The apparatus includes a first radiation thermometer that measures infrared radiation of wavelengths longer than 4 μm to accurately determine the susceptor's temperature, regardless of whether a substrate is present, and a polarization element positioned at the Brewster's angle to exclude reflected light, ensuring precise temperature measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a radiation thermometer is used to measure the temperature of the susceptor when the wafer is held on the susceptor, then the heating efficiency of the susceptor is improved, but the measurement accuracy of the susceptor temperature deteriorates
Solution Approach 1:
The infrared detection is segmented into two wavelength ranges: one for detecting wafer temperature (through the susceptor) and another for detecting susceptor temperature (blocked by the susceptor). This segmentation allows independent measurement of both temperatures without mutual interference.
Solution Approach 2:
The solution adds a spectral dimension to the measurement by using a radiation thermometer capable of detecting multiple wavelength ranges. By measuring in different spectral dimensions (wavelength ranges), the system can distinguish between radiation from the wafer and radiation from the susceptor.
2Temperature
If the wafer is held on the susceptor during preheating, then the susceptor is heated more efficiently by heat transfer from the wafer, but it becomes difficult to measure the temperature of the susceptor
Solution Approach 1:
The infrared detection is segmented into two wavelength ranges: one for detecting wafer temperature (through the susceptor) and another for detecting susceptor temperature (blocked by the susceptor). This segmentation allows independent measurement of both temperatures without mutual interference.
Solution Approach 2:
The solution adds a spectral dimension to the measurement by using a radiation thermometer capable of detecting multiple wavelength ranges. By measuring in different spectral dimensions (wavelength ranges), the system can distinguish between radiation from the wafer and radiation from the susceptor.
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 solution allows for accurate control of the heat treatment process by isolating the susceptor's temperature measurement from interference, ensuring uniform preheating and preventing wafer warpage by maintaining a consistent temperature history across semiconductor wafers.
Implementation Method 1
a first radiation thermometer for measuring the temperature of the susceptor, the first radiation thermometer receiving infrared radiation of a wavelength longer than 4 μm to measure the temperature of the susceptor
Implementation Method 2
a polarization element positioned at the Brewster's angle to exclude reflected light
Implementation Method 3
a polarization element positioned at the Brewster's angle to exclude reflected light
Implementation Method 4
a light irradiator for irradiating the substrate held by the susceptor with light
Implementation Method 5
preheating is performed by irradiation with light from the halogen lamps
Implementation Method 6
xenon flash lamps are used to irradiate a surface of a semiconductor wafer with a flash of light, thereby raising the temperature of only the surface of the semiconductor wafer in an extremely short time
Data Source
AI summary
Prior to heat treatment of a semiconductor wafer to be treated, a dummy wafer is placed on a susceptor made of quartz, and the susceptor is preheated by irradiation with light from halogen lamps. A controller controls an output from the halogen lamps, based on the temperature of the susceptor measured with a radiation thermometer. The radiation thermometer receives infrared radiation of a wavelength longer than 4 μm to measure the temperature of the susceptor. The radiation thermometer is able to receive only infrared radiation emitted from the susceptor to accurately measure the temperature of the susceptor, regardless of whether or not a wafer is held by the susceptor, because quartz is opaque in a wavelength range longer than 4 μm.