Wide bandgap (WBG) semiconductor materials, like gallium nitride (GaN) and silicon carbide (SiC) continue to transform power electronics with greater efficiency, smaller footprints, and higher performance. Now, materials such as silicon germanium (SiGe) are joining the WBG portfolio, further optimizing the manufacturing of semiconductor devices, LEDs & Optoelectronics and high-power &high-frequency electronics. As devices grow more complex, precise metrology is critical. Among the most powerful techniques, Spectroscopic Ellipsometry enables high-resolution, non-destructive characterization of thin films, layer thicknesses, and optical constants across materials like GaN, SiC, and SiGe.

• As GaN-based High-Electron-Mobility Transistors (HEMTs) are widely used in high-frequency, high-power, and high-temperature applications, accurate measurement of layer thicknesses, refractive indices, and doping profiles is essential to ensure device performance and reliability. Spectroscopic Ellipsometry (SE) is a powerful, non-destructive optical technique ideal for the precise characterization of GaN-based high electron mobility transistor (HEMT) structures. It provides high sensitivity, even for the precise measurement of Al concentration, despite the presence of the thick p-GaN layer. SE enables rapid analysis of key layer properties, including thickness, refractive index, and composition, ensuring efficient optimization of device performance without the need for sample preparation.
• SiC Metal-Oxide Semiconductor Field-Effect Transistors (MOSFETs) are increasingly widespread and researched in power device applications due to their many advantages, and trench structures can further enhance their properties. The vertical channel in trench MOSFETs increases integration density, heat dissipation and channel mobility, simultaneously reducing on-resistance, enabling the production of more efficient devices with lower power consumption. Optical critical dimension metrology (OCD) offers a fast, non-destructive, non-contact method to investigate the geometrical parameters of the structure (sidewall angle (SWA), depth, critical dimension (CD) parameters, etc.). To characterize the trenches, Spectroscopic Polarized Reflectometry (SR) measurements are performed on the wafers. The measured spectra are also simulated by a fast and accurate model. Then the critical dimensions are extracted through nonlinear regression, by fitting the model parameters to match modelled and measured spectra. With an optimized evaluation algorithm, this allows fast full-wafer mapping and tight process control in many steps of the process.
• Silicon germanium (SiGe) is rapidly gaining momentum lately, as it is commonly used in integrated circuits for high-speed, high-frequency applications. The concentration of germanium has a strong impact on the optical properties of SiGe alloy, leading to noticeable differences in the Ψ and Δ spectra across different concentrations. By studying samples of varying thicknesses, in case of a sufficiently high germanium concentration, the thickness-related oscillations shift to the IR spectrum. Therefore, samples within the micron thickness range were examined using Spectroscopic Ellipsometry (SE) operating in the NIR range, where the oscillations related to larger thicknesses appear.

As a leading innovator in precision measurement solutions, Semilab is proud to introduce its new Compact Platform Microspot Spectroscopic Ellipsometer, the uSE-2300. This new extension to the highly acclaimed Semilab SE series is ready to address the needs of 4-8” wafer manufacturers and device makers, as it takes over from its predecessors with a completely new platform arrangement. With its improved platform stability and new generation metrology head, the uSE brings high throughput, precision & accuracy with various metrology options that can be combined within the same system. Thanks to its small footprint and back-to-back or to-the-wall placement, combined with the ideal automation support, the uSE-2300 is easy to include into the manufacturing process while saving precious cleanroom space as well.

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