The emergence of sensors, MEMS, and other IoT devices is driving the revival of legacy equipment using new processes and different chemistries relative to conventional CMOS devices. But without accurate monitoring, fabs cannot know the composition of a given chemical stream. Errors may not be detected until the etch rate drops below specification, the particle counter spikes, or a lithography or CMP step fails to deliver the desired results.
In situ refractive index measurements are a cost-effective tool for fast and accurate measurement of chemical composition. Light from a calibrated LED source reflects off the interface between the liquid being measured and an optical window. A CCD camera detects the position of the reflected light in order to determine the so-called “critical angle” at which the light demonstrates total reflection. This critical angle in turn yields the index of refraction of the fluid. This method can be used with opaque fluids and is not affected by bubbles and other flow irregularities. Overlapping refractive index values are rare; even very similar mixtures generally have unique index values.
About K-Patents Process Instruments
Headquartered in Finland, with subsidiaries in the US and China, K-Patents designs and supplies specialized in-line liquid analysers and process refractometers for industrial process instrumentation and control. The company combines innovations in several technical fields to offer superior design and process-specific expertise across a wide range of industries, from semiconductor manufacturing to pharmaceuticals and biorefining. For more information, please visit www.kpatents.com.
Mona Kokkonen, Communications Manager. Email: mona.kokkonen[at]kpatents.com
Marcus Kavaljer, Area Manager. Email: marcus.kavaljer[at]kpatents.com