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High-Uniformity Wafer-Level Porous TiO<sub>2</sub>–WO<sub>3</sub> Heterojunction Sensor Chips for Highly-Sensitive Ethanol Detection
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李
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DOI：10.1109/led.2026.3705079.png)
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Abstract
En 中文
Chip-scale gas sensors based on metal oxide semiconductors (MOS) have attracted extensive research interests; however, the poor sensitivity and selectivity of single-type MOS materials have greatly limited their practical applications. Recently, MOS heterojunctions with porous structures have emerged as an effective strategy, attributed to their high specific surface area and tailored band structures. Nevertheless, the synthesis of such structures usually relies on chemical methods incompatible with semiconductor manufacturing processes and remains challenging to fabricate directly on wafers. Herein, we report a facile strategy for preparing porous TiO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>-WO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> heterojunction thin films at the wafer level, which is applicable to the batch fabrication of ultrasensitive ethanol gas sensor chips. Specifically, TiO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and WO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> are co-sputtered onto a wafer, followed by room-temperature HCl wet-etching to reconstruct the porous structure and subsequent annealing. The fabricated sensor chip exhibits an excellent response (5.83 @ 10 ppm) and high selectivity toward ethanol vapor under UV irradiation, accompanied by outstanding repeatability and response uniformity. Meanwhile, the proposed strategy demonstrates excellent inter-device consistency across the wafer: the relative standard deviation (RSD) of the sensing response is as low as 3.08%. Coupled with the low fabrication cost, this work provides a promising route for the large-scale production of high-performance miniaturized gas sensors.
Keywords:
MEMS gas sensors
porous TiO2–WO3 heterojunction
wafer-level fabrication
wet etching
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