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The kSA BandiT is a non-contact, non-invasive, real-time, absolute wafer temperature sensor. Using the temperature-dependent optical absorption edge of semiconductor materials, the kSA BandiT provides a viable solution for wafer temperature monitoring that pyrometers cannot measure: IR transparent films (including GaN and SiC) and in temperatures down to room temperature. Combining that capability with an integrated pyrometer gives BandiT the ability to monitor the full range of temperatures for most semiconductor substrate materials in the most demanding process environments.
Because BandiT also is insensitive to changing view port transmission, stray light sources, and signal contribution from substrate heaters, BandiT is the most accurate and repeatable optical method for measuring true wafer surface temperature.
Features of the kSA BandiT
Features of using the kSA BandiT include:
• Optical temperature measurement of IR transparent films now possible!
• Low temperature measurement of GaAs, InP, and Silicon substrates
• Virtually immune to stray light from filaments and heaters
• Integral pyrometer with user selectable wavelength
• Multi-wavelength pyrometric oscillations can be used for growth rate analysis
• Tailored hardware for commercial R&D and multi-wafer MOCVD and MBE systems
Benefits of the kSA BandiT
Benefits of using the kSA BandiT include:
• Proven for GaN, GaAs, Si, SiC, ZnO, and InP
• Accurate wafer temperature measurement
• Reproducible measurements along the full range of substrate temperatures
Pyrometer reads high at low temperatures. kSA BandiT matches RHEED at GaAs oxide desorb.
Spatially resolved GaN on sapphire temperature during rotation. Only kSA BandiT can directly measure GaN film temperature.
kSA BandiT Specifications
kSA BandiT specifications are outlined in the following table:
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Temperature Range
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GaN
SiC
GaAs
InP
Si
ZnO
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400-1300°C
400-1300°C
RT-690°C
RT-650°C
RT-600°C
400-1300°C
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Accuracy
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GaN, SiC, ZnO, GaAs, InP, Si
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±2°C
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Resolution
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GaN, SiC, ZnO
GaAs, InP, Si
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1.0°C
0.1°C
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Stability
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GaN, SiC, ZnO
GaAs, InP, Si
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±1.0°C (4 hours)
±0.2°C (4 hours)
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Flexible Chamber Mounting Options and Full Software Control
The kSA BandiT runs in either transmission mode or reflection mode. In transmission mode, the substrate heater is used as the light source. In reflection mode, a BandiT light source is mounted on one port and the BandiT detector is mounted on a second, nonspecular port. A third option allows reflection-mode operation using a single 1.33” CF view mount.
To ensure empirically-derived temperature measurement, a full library of calibration tables (wafer absorption edge versus temperature) is integrated into the software. I/O includes real-time temperature display as well as process output and control through real-time spectra and curve fitting to a wide variety of data streams. The efficient software that controls and monitors the light source, spectrometer, and all I/O easily runs on a laptop with just a single USB-port connection!
How The kSA BandiT Works
Step 1. BandiT is installed onto available view port(s) to measure diffusely reflected light from the wafer sample.
Step 2. Band-edge absorption signal is detected and fit in real time.
Step 3. The absorption edge is referenced to empirically generated kSA calibration files and output as temperature.
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