Interferometric Modalities

Spectral Interferometry (SI)

Spectral Interferometry analyzes interference as a function of wavelength to extract detailed information from thin films and multilayer structures. As broadband light interacts with layered materials, partial reflections from each interface interfere across the spectrum, generating a characteristic spectral signature. For example, when light reflects from both the top and bottom interfaces of a thin film, the resulting constructive and destructive interference produces oscillations in the measured spectrum. The frequency and shape of these spectral fringes are directly related to the film’s thickness and optical properties, enabling highly sensitive and repeatable measurements.

Within Nova Prism, Spectral Interferometry is combined with Spectral Reflectometry (SR) and Spectroscopic Ellipsometry (SE) to provide a comprehensive optical metrology solution. This multi-technique approach enables robust modeling and extraction of key parameters such as film thickness and optical constants (n, k) across complex material stacks. By leveraging the complementary strengths of SI, SR, and SE, Nova Prism delivers high-accuracy, high-throughput measurements for inline process control of deposition and etch, supporting advanced semiconductor manufacturing requirements.

Spectral Coherence Interferometry (SCI)

Spectral Coherence Interferometry combines broadband interferometry with Fourier-domain analysis to deliver depth-resolved measurements of complex structures. It enables accurate extraction of single- and multi-layer thickness as well as wafer shape parameters such as bow and warpage, within a unified optical measurement.

This makes SCI highly effective for advanced semiconductor applications where both stack complexity and wafer geometry must be tightly controlled. SCI is implemented in Nova WMC and Nova SemDex, providing high-resolution insight into multilayer structures and wafer-level characteristics in Advanced Packaging applications. WMC specifically supports simultaneous three-layer measurement using SCI technology in a dual-sensor configuration (top and bottom of wafer).

White Light Interferometry (WLI / Coherence Scanning Interferometry)

White Light Interferometry leverages low-coherence illumination to localize interference in space, enabling direct and absolute measurement of surface topography. By scanning along the vertical axis and identifying the position of maximum interference contrast, WLI provides robust, high-accuracy height measurements across a wide dynamic range.

This approach is highly effective for applications such as step height, surface roughness, and CMP profiling, where direct spatial measurement is critical. Within Nova’s portfolio, WLI is integrated into platforms such as Nova WMC and Nova SemDex, supporting high-precision surface characterization in Advanced Packaging applications.