GaAs based

Integrated process control for GaAs devices from Epi to Etch.

Applications Metrology solutions Related products

As for all III-V materials precise control of temperature, composition and wafer bow is crucial for obtaining optimum thin film properties in epitaxially grown layers. GaAs-based materials and the corresponding ternary and quaternary compounds offer a wide range of compositions in order to tune the final optical properties of the layer stacks. However, this multi-compositional growth regime makes it particularly difficult to control growth parameters precisely in order to obtain optimum device properties. Here, in-situ process control based on accurate high temperature quaternary nk data can be key.

  • Reflectance at 3 wavelengths for monitoring of growth rate and morphology (EpiTT and EpiCurve®TT product families)

  • Wafer surface temperature (EpiTT and EpiCurve®TT product families)

  • Wafer curvature for strain management of layer stacks (EpiCurve®TT)

  • Accurate wafer temperature on transparent substrates for power electronics with Pyro 400

  • Improved temperature accuracy even for GaN on silicon by employing Pyro 400

  • Expanded nk database and advanced analysis for GaN/SiC-4H HEMTs

  • EpiNet software allows our tools to determine the AlGaAs composition at an accuracy of 1% or better

Name Size
EpiX data sheet 3.32 MB
Talk - How to enhance epitaxy process performance by in-situ data 3.4 MB
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Metrology solutions

Table 1: In a multiple 450 nm AlGaAs layer stack (sandwiched between 750 nm GaAs layers) the in-situ measured AlGaAs composition x and growth rate r exactly matches the XRD reference measurement. A new, highly accurate AlGaAs refractive index database in the 600°C-710°C temperature range and precise wafer temperature measurement with AbsoluT calibration have been applied.

LayTec’s EpiCurve® TT metrology system allows to monitor all crucial parameters needed for controlling the epitaxial growth of GaAs-based thin film. With LayTec’s emissivity-corrected pyrometry the true wafer temperature can be controlled precisely, whilst the actual layer growth can be monitored by EpiTT’s three dedicated reflectance wavelengths. At the same time wafer bowing and strain management can be addressed by the deflectometry in LayTec’s EpiCurve® TT. Furthermore, this tool will also enable the precise in-situ determination of the ternary composition right form the in-situ data.

All these methods are complemented by the comprehensive EpiNet® software which allows for detailed and precise quantitative analysis of the measurement results by employing our extensive high-temperature nk database.

Fig. 1: Screenshot of the EpiNet®: data analysis of an InGaAsP/InP device structure on InP(001): the thickness of the three very thin InGaAsP layers in steps 2, 6, 10 is: 28.5 nm, 48.7 nm and 100.3 nm respectively. The table in the lower part of the figure gives the sequence of analysis functions for routine and automated SPC of this device growth process.

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