Combining a visible light spectral-domain optical coherence tomography (SD-OCT) sensor with a high-speed nanometer-encoded X/Y/Z motion-control stage, the QuickOCT-4D can capture the plane of each layer within transparent film samples in a single measurement, at up to 60 kHz. The QuickOCT-4D penetration depth and axial resolution is optimized for the measurement of multi-layer transparent films, flat substrates, and functional layers in the semi-conductor, life science and pharmaceutical industries. 

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An ideal application for the QuickOCT-4D is the measurement of patterned photoresist (or similar transparent coatings) on a silicon or GaAs wafer for backend semiconductor, advanced packaging, display, LED, VCSEL and MEMS as a quality control post-develop and pre-etch. 

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Below is sample data from patterned photoresist on a GaAs wafer. The photoresist has been exposed and developed to create ~ 1.2 µm steps as a first step in the laser (VCSEL) formation process. Step height uniformity is critical before going to etch, hence the value of this measurement and the QuickOCT-4D product.