The slow etching rate of conventional micro-machining processes is hindering the use of bulk silicon carbide materials in pressure sensing. This paper presents a 4H-SiC piezoresistive pressure sensor utilising a laser scribing approach for fast prototyping a bulk SiC pressure sensor. The sensor is able to operate at a temperature range from cryogenic to elevated temperatures with an excellent linearity and repeatability with a pressure of up to 270 kPa. The good optical transparency of SiC material allows the direct alignment between the pre-fabricated piezoresistors and the scribing process to form a diaphragm from the back side. The sensitivities of the sensor were obtained as 10.83 mV/V/bar at 198 K and 6.72 mV/V/bar at 473 K, which are at least a two-fold increment in comparison with other SiC pressure sensors. The high sensitivity and good reliability at either cryogenic and elevated temperatures are attributed to the profound piezoresistive effect in p-type 4H-SiC and the robust p-n junction which prevents the current from leaking to the substrate. This indicates the potential of utilising the laser scribing approach to fabricate highly sensitive bulk SiC pressure sensors for harsh environment applications.

中文翻译：

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低温和高温下的高灵敏度 4H-SiC 压力传感器

传统微加工工艺的缓慢蚀刻速率阻碍了体碳化硅材料在压力传感中的使用。本文介绍了一种 4H-SiC 压阻式压力传感器，该传感器利用激光划线方法对体 SiC 压力传感器进行快速原型制作。该传感器能够在从低温到高温的温度范围内工作，在高达 270 kPa 的压力下具有出色的线性和可重复性。SiC 材料良好的光学透明度允许预制压敏电阻和划线工艺之间直接对准，从而从背面形成隔膜。传感器的灵敏度在 198 K 下为 10.83 mV/V/bar，在 473 K 下为 6.72 mV/V/bar，与其他 SiC 压力传感器相比，这至少增加了两倍。在低温和高温下的高灵敏度和良好可靠性归因于 p 型 4H-SiC 中深刻的压阻效应和防止电流泄漏到衬底的坚固 pn 结。这表明利用激光划线方法制造用于恶劣环境应用的高灵敏度体 SiC 压力传感器的潜力。