Wafer-Scale Integration of Metal Oxide Nanocrystals on Gas Sensor Chips via Direct Lithographic Patterning

Nanomaterial-based gas sensors are essential due to their high sensitivity and scalability, enabling efficient gas detection across diverse applications. However, a key challenge hindering their practical applications is the variation in sensing performance between devices. Addressing this requires careful consideration of the relationship between on-chip sensing materials and miniaturized devices. As feature sizes reduce to the microscale, accurately and uniformly positioning sensing nanomaterials onto specific regions of the device electrodes becomes increasingly difficult. This challenge arises from the incompatibility between the bottom-up nanomaterial synthesis methods and the top-down lithography-based fabrication processes. Herein, we introduce a cleanroom-compatible fabrication workflow for chemiresistive gas sensors employing direct lithographic patterning of metal oxide nanocrystals. Gas sensors located across different regions of a 4 in. wafer exhibit highly consistent gas-sensing performances, highlighting the potential of this approach, which integrates the strengths of both top-down and bottom-up approaches. This approach opens new opportunities for integrating a wide range of bottom-up synthesized functional nanomaterials into diverse types of chemical sensors.