- kSA 400
- kSA BandiT
- kSA BandiT PV
- kSA MOS
- kSA MOS Ultra/Thermal Scan
- kSA RateRat Pro
- kSA ICE
Reduction of Process Variation Through Automated Substrate Temperature Uniformity Mapping in Multi-Wafer MBE Systems
Thomas J. Rogers, Likang Li, Robert Yanka, Chris Santana, Jason R. Williams, Charles A. Taylor II, Darryl Barlett
Adsorption-controlled molecular-beam epitaxial growth of BiFeO3
J.F. Ihlefeld, A. Kumar, V. Gopalan, D.G. Schlom, Y.B. Chen, X.Q. Pan, T. Heeg, J. Schubert, X. Ke, P. Schiffer, J. Orenstein, L.W. Martin, Y.H. Chu, and R. Ramesh
Applied Physics Letters 91, 2007, pp. 071922 » View All References
Substrate temperature measurement using a commercial band-edge detection system
I. Farrer, J.J. Harris, R. Thomson, D. Barlett, C.A. Taylor II, and D.A. Ritchie
Growth related interference effects in band edge thermometry of semiconductors.
R. N. Sacks, D. Barlett, C. A. Taylor II, and J. Williams
In situ temperature control of MBE growth using band-edge thermometry.
Shane Johnson, Chau-Hong Kuo, Martin Boonzaayer, Wolfgang Braun, Ulrich Koelle, Yong-Hang Zhang, and John Roth
Precision of noninvasive temperature measurement by diffuse reflectance spectroscopy.
T.P. Pearsall, Stevan R. Saban, James Booth, Barrett T. Beard Jr., and S.R. Johnson
Diffuse optical reflectivity measurements on GaAs during MBE processing.
C. Lavoie, S.R. Johnson, J.A. Mackenzie, T. Tiedje, and T. van Buuren.J.V.S.T. A 10, 1992, pp. 930-933 » View All References
Wafer and Film Temperature Monitor – Go Where Pyrometers Can’t!
The kSA BandiT is a non-contact, non-invasive, real-time, absolute wafer and film temperature monitor used during thin-film deposition and thermal processing.
Using the temperature-dependent optical absorption edge inherent in semiconductor materials, kSA BandiT provides wafer temperature monitoring in ranges that pyrometers cannot measure: substrates transparent in the IR (including GaN, SiC, ZnO, and SrTiO3), as well as low temperature monitoring, e.g. LT GaAs, InP, and Si deposition. Furthermore, BandiT is immune to changing viewport transmission, stray light, and signal contribution from substrate or source heaters, all sources of measurement error for pyrometers.
Combined with its patented blackbody emission monitor, kSA BandiT has the ability to monitor the full range of temperatures for most substrate materials, including low band-gap substrates and metal films. Finally, because kSA BandiT uses a solid-state spectrometer, real-time film thickness and surface roughness can also be measured – read further for more details! See the kSA BandiT in action.
Band Edge Temperature/Thermometry (BET)
The most common application of the kSA BandiT tool is for direct substrate temperature measurement. By measuring the position of the substrate absorption edge, the absolute temperature of the wafer can be determined. This absorption edge, which is directly proportional to the band gap of the material, is temperature dependent. It is this temperature dependence that we rely on to determine the wafer temperature. A solid-state spectrometer is used to acquire either diffusely reflected, or transmitted light from the wafer. This spectra is then analyzed in real-time by the BandiT software, fitting to the absorption edge, and determining the absolute wafer temperature from the position of the absorption edge.
GaAs temperature ramp monitored with BandiT
Multiwafer and Full Platen Scan Capability
kSA BandiT can be configured to synchronize to substrate rotation. For production applications, or where multiwafer platens are used, the kSA BandiT MW (MultiWafer) system allows you to monitor the temperature of all wafers on the platen. Markers can be placed where you are interested in temperature measurement, for example at wafer centers and edges.
If you desire full platen maps of temperature, the kSA BandiT Platen Scan option allows you to control the position of the BandiT detector head, yielding wafer temperature maps of the entire platen. A computer-controlled motor on the BandiT head steps to every desired radius position on the platen, and data is taken synchronously during rotation at every radial position. Detailed temperature maps then allow you to adjust heater zone tuning ratios, determine hot or cold spots in the platen pockets, etc.
Blackbody Temperature Measurement
In addition to kSA’s patented band edge temperature measurement, BandiT offers a complimentary measurement technique, blackbody temperature measurement. This approach, also patented by k-Space, fits the radiation emitted from the wafer to Planck’s equation. In this approach, the emissivity of the wafer can be changing, without effecting the temperature measurement. This is because it is the functional shape of the blackbody spectra, not its amplitude, that dictates the temperature of the emitting material. This is unlike pyrometry, which relies solely on the absolute signal level in a given (small) wavelength range.
The kSA BandiT blackbody temperature measurement is typically used when the band edge of the material cannot be measured. This occurs typically when looking at a non-semiconductor substrate, a heavily doped substrate, or a very narrow band gap substrate (e.g. Ge or InAs). The blackbody temperature measurement technique typically has a lower limit in temperature of ~ 250 °C, due to limited emitted radiation at low temperatures.
Film Thickness and Roughness Measurement
Because a solid-state spectrometer is used with the kSA BandiT system, the full diffuse spectra is obtained. This spectra contains a wealth of information in addition to the material absorption edge. By analyzing the below gap interference fringes, the total film thickness can be very accurately determined. By analyzing the above gap scatter signal, changes in roughness can be easily monitored. Combined with real-time temperature measurement, kSA BandiT offers a very powerful in-situ monitoring tool for your thin-film deposition and processing needs.
Real-time BandiT thickness measurement from below gap interference fringes
What You Get With a kSA BandiT System
The kSA BandiT system comes in several different flavors, depending on what type of growth or materials processing chamber you have. Our most common BandiT configuration includes a light source optics, a detector optics head, and a 19” rack mount electronics controller. In many cases, e.g. high temperature MBE growth, the substrate heater can be used as the light source, and a light source optics head is not needed. In most MOCVD applications, the viewport to sample distance is relatively short and the optical access is limited. As such our optics heads for most MOCVD reactors are small, and integrate a light source and detector into a single head.
Whatever your chamber configuration, we’re confident we can supply a BandiT system for your in-situ metrology needs. We look forward to hearing from you!
- Blackbody Temperature Measurement Growth Rate GaN BET vs. ECP SiC Substrate Temperature Hot MBE Sources BET vs. Pyrometry
kSA offers per-sample testing and analysis services using our most advanced optical metrology tools.
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