Laytec enhances EpiNet software
While AlGaN/GaN and InAlN/GaN device structures are excellent platforms for making next generation RF and power electronics such as HEMTs, MOCVD growth of such structures on large SiC-4H wafers needs complex recipes for strain management and tight statistical process control (SPC) to obtain high yields.
For this technology, LayTec has recently enhanced the capabilities of its EpiNet control and analysis software (for EpiTT, EpiCurve TT and Pyro 400 products) by expanding its high-temperature nk database and implementing additional real-time analysis routines to feed SPC systems with highly accurate in- situ data.
Figure 1 (above) gives an example. The initial AlN layer is grown on SiC-4H is performed at very high wafer temperature (measured by Pyro 400 with ±0.5 K accuracy) in a sophisticated three-temperature process. This ensures significant defect reduction for the subsequent HEMT growth, according to the company.
According to Laytec, despite the varying wafer temperature in this AlN buffer growth process, the latest real-time analysis function of EpiNet library allows its tools to reach ±0.5 nm accuracy in real-time AlN film thickness measurement.
This has been achieved by tightly correlating the absolute SiC-4H wafer temperature with high accuracy SiC-4H and AlN nk optical data and implementing new analysis algorithms that separate reflectance changes caused by temperature ramping from the AlN growth effects.
