This paper presents a tiny 0.4 mm × 0.4 mm piezoresistive absolute pressure sensor chip with a fabrication cost as low as 0.01 US$/die. With the thin-film under bulk-silicon technique, a very thin but uniform poly-silicon pressure-sensing diaphragm is formed beneath a bulk-silicon beam-island structure to accommodate piezoresistors. The thin diaphragm exhibits a high sensitivity, and the beam-island-reinforced structure helps reduce deflection and improve linearity. The sensor is fabricated using a novel scar-free micro-hole inter-etch and sealing (MIS) process. In this newly developed process, seals are removed from the diaphragm area and placed on both the single-crystalline silicon island and single-crystalline silicon frame surrounding the poly-silicon diaphragm. Thus, the thin diaphragm is kept flat and smooth, thereby enhancing the sensing performance and fabrication yield. More importantly, the diaphragm-beam-island structure is small enough to fabricate sensor chips as small as 0.4 mm × 0.4 mm. With the high-yield process, a very low fabrication cost of 0.01 US$/die is realised owing to a high throughput of 90 000 die per 6 inch wafer. The ultra-small and low-cost pressure sensor exhibits sensitivity of 0.88 mV kPa−1/3.3 V, hysteresis of 0.15% full scale (FS), repeatability error of 0.04% FS, and non-linearity of 0.10% FS. Without any additional thermal compensation method, the sensor exhibits a low temperature coefficient of zero-point offset of −0.064%/°C FS and a temperature coefficient of sensitivity (TCS) of −0.22%/°C within the temperature range from −25 °C to +85 °C, at a full measurement range (i.e. full scale) of 100 kPa. With the new scar-free MIS process, the presented pressure sensor looks promising for smartphones, drones, and other consumer-electronic applications.

中文翻译：

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使用无疤痕微孔蚀刻和密封 (MIS) 工艺制造的超小型压力传感器

本文介绍了一种微型 0.4 mm × 0.4 mm 压阻式绝对压力传感器芯片，其制造成本低至 0.01 美元/芯片。使用体硅下薄膜技术，在体硅梁岛结构下方形成非常薄但均匀的多晶硅压力传感隔膜，以容纳压敏电阻器。薄隔膜表现出高灵敏度，梁岛加强结构有助于减少偏转并提高线性度。该传感器采用新型无疤痕微孔蚀刻和密封 (MIS) 工艺制造。在这个新开发的工艺中，密封件从隔膜区域去除，并放置在单晶硅岛和多晶硅隔膜周围的单晶硅框架上。因此，薄隔膜保持平坦和光滑，从而提高传感性能和制造良率。更重要的是，隔膜-梁-岛结构足够小，可以制造小至 0.4 mm × 0.4 mm 的传感器芯片。采用高产量工艺，由于每 6 英寸晶圆 90 000 个裸片的高吞吐量，实现了 0.01 美元/裸片的极低制造成本。超小型低成本压力传感器具有 0.88 mV kPa-1/3.3 V 的灵敏度、0.15% 满量程 (FS) 的滞后、0.04% FS 的重复性误差和 0.10% FS 的非线性。在没有任何额外的热补偿方法的情况下，该传感器在从 -25 ℃的温度范围内表现出 -0.064%/°C FS 的低零点偏移温度系数和 -0.22%/°C 的温度系数 (TCS) °C 至 +85 °C，在 100 kPa 的完整测量范围（即满量程）下。