Key takeaways:
NXT offers optical metrology tools for inline and batch process monitoring across photovoltaic manufacturing
The company’s Helios family addresses texturing, coating and TOPCon poly-Si characterization
The product portfolio also includes photoluminescence and coherence tomography systems for advanced process inspection
Germany-based NXT GmbH develops optical spectroscopic measurement systems for industrial production process control and laboratory characterization. These systems perform non-destructive characterization of thin-film properties such as layer thickness, refractive index, reflectance, and transmittance. This supports process quality control across different stages of PV cell manufacturing.
NXT’s tools are available in both inline and batch application scenarios, with batch versions offered as manually operated laboratory tools or motorized x-y mapping systems. They are compatible with dielectric, semiconductor, and oxide layers deposited on silicon, glass, and thin-film substrates.
For silicon cell production, NXT offers Helios-rc, Helios-tn, and Helios-r8, each addressing different process steps in the production line.
The Helios-rc is intended for monitoring the texturing and etching process. It measures the total reflectance of the textured front and spatial angle reflectance of the rear. Additionally, it can determine the color and thickness of thin-film coatings deposited on either surface. It also supports a spectral acquisition speed of less than 100 ms for high-speed inline process monitoring.
The Helios-tn tool is designed for characterization of deposited layers, including SiNx, AlOx, SiOx, SiOxNy, TCO, ITO, and AZO. It measures layer thickness, optical constants (n&k), and ellipsometric parameter Psi for both single and multi-layer stacks, with simultaneous measurement capability of two or three parameters.
For TOPCon lines, NXT offers Helios-r8 to measure the thickness and optical constants of poly-Si layers deposited on top of tunneling oxide. The tool includes an eight-channel multi-optics configuration to maintain measurement accuracy despite the wafer rotation, distance, and tilt, which adds to the advantage over conventional ellipsometers. The company says that there are over 700 Helios-r8 systems installed globally.
Additionally, for perovskite PV characterization, the company offers a photoluminescence (PL) tool, which monitors the layer quality by evaluating active-layer bandgap from PL spectra. It also uses up to eight different illumination channels and optical filters for wavelength flexibility. The company also offers its Octis 850 that is based on coherence tomography that inspects height profiles in silver and other metallization prints. The company’s Octis 1550 tool helps measure the thickness of silicon wafers. Both Octis tools are available in inline and batch variants.
