INSTRUMENTATION & ELECTRONICS
The sensors undergo a rigorous testing process
UNDER PRESSURE S
How barometric pressure sensors are ensuring accurate and reliable measurement within industrial applications
imply put, barometric pressure is a measurement of the air pressure in Earth’s atmosphere. While scientists
and engineers have been using traditional mercury-based barometers to measure barometric pressure since the 1600s, today’s technology has since evolved. Capacitive pressure sensors are now widely used within industrial manufacturing applications to detect pressure changes by monitoring fluctuations in electrical capacitance. “In various manufacturing
processes, maintaining optimal pressure is essential for ensuring product quality and consistency,” says Jing Lin, product manager, sensors, at Vaisala. “One such example is the semiconductor industry. Our PTB210 and PTB330 barometers are widely used in semiconductor production equipment and are deployed by global leading coater suppliers.”
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www.engineerlive.com A coater is equipment used in the
photolithography process to apply a thin and uniform layer of photoresist onto semiconductor wafers. “The air pressure within these
systems directly influences film thickness, making precise pressure measurement crucial,” Lin continues. “Vaisala’s barometers have been integrated into coaters to provide accurate air pressure readings, thereby ensuring high product quality.”
MICROMECHANICAL SENSORS First introduced in 1985, Vaisala’s Barocap pressure sensors are developed and designed in-house for barometric pressure measurement applications. In the 40 years since, the sensors have been optimised for various applications in which accurate and stable measurement is required. “The structure of Barocap is
very simple,” says Lin. “It is a micromechanical sensor that uses dimensional changes in its silicon membrane to measure pressure. As the surrounding pressure increases or decreases, the membrane bends, thereby increasing or decreasing the height of the vacuum gap inside the sensor. The opposite sides of the vacuum gap act as electrodes, and as the distance between the two electrodes changes, the sensor capacitance changes. The capacitance is measured and converted into a pressure reading.” The sensor combines two powerful
techniques for barometric pressure measurement: the capacitive sensor principle, and the use of single crystal silicon as the sensor material. “The Barocap sensor’s properties – good elasticity, low hysteresis, excellent repeatability, low temperature dependence, and superior long-term
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