Wafer-scale integration of carbon nanotube transistors as process monitors for sensing applications

We report on the fabrication of carbon nanotube transistors designed as process control monitors for applications such as gas and pressure sensing. We demonstrate the concept for an integration process used for gas sensor fabrication on a 100 mm wafer. From a maximum possible of 9348 devices, 4463 working devices were fabricated, of which 2702 semiconducting were identified, allowing the extraction of distributions of threshold voltage, minimum device resistance, process yield and wafer uniformity data. We show a fabrication yield of 29% for transistors (for semiconducting tubes only), a median minimum-resistance of 122 kΩ (interquartile dispersion: 179 kΩ), and a threshold voltage of -0.75 V (interquartile dispersion: 1.46 V). Distribution profiles of transistor parameters over the wafer are also quantified.