LayTec - Model EpiTT -Combines Measurements Instruments
EpiTT combines measurements of temperature and reflectance at three wavelengths in one tool. For True Temperature (TT), we apply the method of Emissivity Corrected Pyrometry, which delivers the precise surface temperatures of opaque materials at 950 nm (Si, GaAs, InP). For materials that are transparent at 950 nm (GaN, Sapphire, SiC), EpiTT measures the temperature on the top side of the carrier. Measuring reflectance at three wavelengths monitors all essential properties of the growing layers, such as growth rate, film thickness, stoichiometry changes and morphology.
Temperature measurements
- wafer selective true temperature measurements, pyrometer calibrated against a black body radiation source
Reflectance measurements
- wafer selective reflectance measurements at two wavelengths: 950 nm and a customized sec-ond wavelength (405 nm or 488 nm or 633 nm or 950 nm)
- multiple position reflectance and temperature measurements in multi-wafer configurations (e.g. for comparison center to edge on the wafer)
- line scan measurements across the wafers for uniformity evaluation
- on-line wafer selective growth rate fits using virtual layer approach or alternatively oscillator fits
- recipe controlled automated growth rate fit for multi-layer structures
- measurements on single and multiple wafers, supporting planetary susceptor even with multiple wafers per satellite (such as 24x2" and 42x2")
- optical wobble compensation included
- optimized for 24 h/7day operation in production environment
Communication / integration
- direct communication with AIXTRON CACE and Aixact software
- data exchange with growth system control computer via hardware interfaceand/orTCP/iP protocol based software interface
- remote controllable from growth recipe
- heartbeat/watchdog signals for sps integration
Measurable growth parameters
- reflectance: typical noise better than+0.5%
- growth rate: typical accuracy better than t \% (down to 0.001 nm/s)
- wafer temperature: typical accuracy better than+IK: tern peratu re range: 450-l3008cforAlx Planetary* and single-wafer systems; 1400 ac for Aix ccs* (others on request)
EpiTT offers industry-standard metrology for all kinds of epitaxial growth systems and is compatible with different main rotation frequencies in the range from 0-1500 rpm.
LayTec offers multi-head configurations of tools in the EpiTT family, which are specifically designed for multiple wafer ring reactors. These models have two (EpiTwin TT) or three (EpiTriple TT) optical heads for taking temperature and reflectance measurements at independent positions. Nearly all the LayTec EpiTTs can be upgraded to multi-head systems.
Both emissivity-corrected temperature monitoring and reflectance measurement at three wavelengths are included in all products in ourEpiCurve® TT family of products. For reactors with multiple wafer ring configurations, the models with two or three EpiTT heads (EpiCurve®Twin TT and EpiCurve®Triple TT) allow for temperature and reflectance measurements at two or three independent positions respectively.
For our systems that contain an EpiTT optical head, we offer a unique temperature calibration tool AbsoluT. This small, handheld device sets up exactly the same absolute temperature reference point for pyrometry measurements on each EpiTT head, on different rings and in different reactors and runs, enabling perfect ring-to ring, reactor-to-reactor and run-to-run temperature calibration. ... more
All LayTec in-situ systems are equipped with LayTec software specially developed for process optimization, analysis and control. Our software solutions can control several systems in an MOCVD fab, monitoring all runs simultaneously and supporting operators when making “stop or go” decisions based on Advanced Process Control (APC). ... more
All products in the EpiTT family (EpiTT, EpiTwin TT, EpiTriple TT) are available for various MOCVD growth systems such as:
- systems with satellite rotation
- showerhead-like systems
- systems with main susceptor rotation speed up to 1500 rpm
- R&D type and customized MOCVD growth systems
LayTec’s sensors are adaptable to many MBE systems by Riber, Veeco, DCA and VG. Adaptation to other manufacturers’ products and custom-built systems is available on request. Find more in our Application Notes:
In HVPE applications, EpiTT controls:
- Surface roughness
- Growth rate determination of the first 10 µm
- Reflectance and pyrometry at 950 nm
- GaN LED and laser diode production
- GaAs/AlGaInP/InP laser diode production
- Triple-junction solar cell production on GaAs, Ge, Si
- SiC for power electronics
- R&D for new materials and devices