The k-Space Integrated Control for Epitaxy system (ICE) is a modular in situ metrology tool designed for today’s MOCVD reactors. It combines kSA MOS, kSA BandiT and kSA RateRat Pro patented technologies along with an Emissivity Corrected Pyrometry (ECPR) module. The kSA ICE modular design allows the user to specify which modules will be used in their kSA ICE configuration.
The k-Space Integrated Control for Epitaxy system (ICE) is a modular in situ metrology tool designed for today’s MOCVD reactors. It combines kSA MOS, and kSA RateRat Pro patented technologies along with an Emissivity Corrected Pyrometry (ECPR) module. The kSA ICE modular design allows the user to specify which modules will be used in their kSA ICE configuration.
By integrating these various measurement modules into a single optics head, the kSA ICE metrology system is capable of measuring real-time temperature, reflectivity, growth rate, film thickness, substrate curvature and film stress during MOCVD deposition, at rotation speeds up to 1,500 RPM. Keep cool while gaining insight into your MOCVD process, maximizing device performance, and limiting process variation to increase yields with kSA ICE!
The kSA ICE can incorporate three temperature measurement modules.
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Emissivity Correcting Pyrometry Module (-ECPR):
The kSA ICE ECPR module measures the collected blackbody radiation intensity of a sample at a specified wavelength with a photodiode and integrates the measured signal into the standard pyrometry equations to determine temperature. Surface reflectance is determined in real-time via an LED at the same measurement wavelength and is used to correct the surface emissivity for accurate temperature measurement for temperatures > 450 ºC.
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SpectraTemp Calibrator Module (-SPECT):
The kSA ICE SpectraTemp Calibrator Module (-SPECT) measures the spectral radiation signature of a sample over a wide wavelength range, and curve fits the response in real time to Planck’s equation to determine absolute temperature. This is a self-calibrating technique: no temperature reference is required; It is used in situ to calibrate the ECPR module at any time. This system measures temperatures typically greater than 600 ºC on bare wafers or platen.
k-Space’s patented kSA BandiT has been adapted to the kSA ICE system for band edge (-BE) temperature monitoring. kSA BandiT measures the temperature-dependent semiconductor optical absorption edge (band gap dependence on temperature) and uses kSA-generated calibration files to determine absolute film/substrate temperature (not pocket temperature). For example, using a spectrometer over the range of 350- 600 nm and a Xenon light source –BE option measures absolute GaN film or GaN/SiC substrate temperature via band-edge thermometry for direct InGaN MQW temperature and LED emission wavelength control.
The ICE Reflectivity Module (-R) is based on the kSA RateRat Pro technology. It uses a laser in combination with a high speed photo detector to monitor and fit the surface reflectivity, yielding real-time film thickness, growth rate, and optical constants (n, k). Real-time capability is achieved by means of a proprietary algorithm which continuously updates the optical constants of the film, derived from a least-squares fit to the optical reflectivity curve. In this way the film-grower can have a continuous record of the progress of the film growth during its deposition, including all the critical parameters that are needed to characterize film quality and uniformity. The user is able to generate a thin-film deposition recipe, so multiple layers can be properly fit in real-time. Each layer can be triggered via an external trigger signal, or can be time-based. Using a 660 nm laser a GaN film thickness is measured with the accuracy of ±1% after 215 nm of growth.
For more information on reflectivity based film thickness, growth rate and optical constant measurement technologies, please visit our kSA RateRat Pro page.
Emissivity Corrected Pyrometry and Reflectivity Module (-ECPR)
The emissivity corrected pyrometry and reflectivity module (-ECPR) also offers 960 nm LED reflectivity measurement and subsequent growth rate and film thickness determination at this wavelength. (Optional) LED based reflectivity modules at additional wavelengths can also be added to the ICE tool.
Band Edge Module (-BE)
The kSA ICE band edge module (-BE) collects diffusely scattered light with a spectrometer and analyzes the below-gap spectral interference fringes to determine film thickness and growth rate in real-time during film deposition.
For more information on spectral interference film thickness and growth rate measurement technology, please visit the kSA BandiT page.
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Multi-Beam Optical Sensor (-MOS)
The kSA ICE system uses the kSA patented Multi-beam Optical Sensor (MOS) curvature/bow measurement technology to measure the substrate curvature with a 1D array of parallel laser beams, detecting changes in laser spot spacing due to film or thermal stress via a CCD detector. The -MOS module is capable of measuring curvature from 820/km (concave) to -1640/km (convex). Complete insight into the GaN and SiC growth process for HBLED and RF power devices is now possible by optical monitoring film stress during growth.
For more information on film stress, wafer curvature, and wafer bow measurement technology please visit our kSA MOS page.
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The system is ideally suited for real-time feedback to process control systems via a TCP/IP interface or analog channel I/O. Proven hardware designs are already in use on today’s commercial R&D and Production MOCVD systems available from Veeco, Aixtron, Taiyo Nippon Sanso, Structured Materials, and many others. Gain insight into your MOCVD process, maximize device performance, and limit process variation to increase yields with kSA ICE!