By definition, spectroscopic ellipsometry covers a broad spectral range. Our ellipsometer model RC2 covers the range from 190 nm to 1700 nm. An extension of the spectral range towards longer wavelengths has always been asked to accommodate specific applications.
Woollam now offer the RC2 with an extended NIR option to 2500 nm.
It is the same established RC2 ellipsometer with identical measurement speed and the same great CompleteEASE software but with additional wavelengths into the infrared. Furthermore, the entire spectral range is collected simultaneously with CCD technology.
Fig. 1 shows experimental data of a 1000 nm thick thermal SiO2 layer on silicon, measured from 210 nm to 2400 nm.
Fig. 2 shows the refractive index of an uncoated fused silica substrate. The change in the dispersion curve above 1700 nm requires a Sellmeier function and cannot be described with Cauchy. The dispersion curve change is caused by a strong IR photon absorption in silicon dioxide.
Production wafers are often structured, which requires measurements with high lateral resolution. In addition, there are other samples with small structures, large inhomogeneity, etc. where it would be beneficial to map the sample automatically using very small spot size.
The focused FC2-XF is the perfect combination of small spot size (beam diameter = 25 µm), fast data acquisition and very broad spectral range. The patented RC2 data acquisition tool allows the simultaneous measurement of the entire spectrum with more than 1000 wavelengths from UV to NIR in only 0.3 seconds.
Please contact us to find out if you could benefit from the new RC2-XF. We are happy to perform test measurements on your samples.