Carbon Nanotubes Directly Integrated in CMOS by Local Synthesis - Towards a Wafer-Level Process
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Original versionAasmundtveit, K. E., Roy, A., & Ta, B. Q. (2018). Carbon Nanotubes Directly Integrated in CMOS by Local Synthesis-Towards a Wafer-Level Process. I 2018 IEEE 13th Nanotechnology Materials and Devices Conference (NMDC) (s. 1-5). IEEE. https://doi.org/10.1109/NMDC.2018.8605926
Integrating nanomaterials in electronic circuitry and in microsystems is highly desired for fully exploiting the functionality of nanomaterials such as Carbon Nanotubes (CNTs), utilizing the signal processing of micro/nano-electronics such as CMOS. An example device is a CNT-based gas sensor, where the extreme surface-to-volume ratio of CNTs provides ultra-high sensitivity, and direct integration with CMOS enables a device rendering processed, amplified and calibrated signals in a single, low-cost device. The CNTs should be synthesized on-chip directly into electric circuits. One challenge to overcome is the contradiction between temperature requirements for CNT growth (800-1000 °C) and CMOS compatibility (<; 300°C). We can achieve local CNT growth temperatures while keeping the main part of the chip at CMOS compatible temperatures by designing resistive micro-heaters. Synthesized CNTs are directed towards an electrode for desired contact by applying a voltage that gives a guiding electric field. All process parameters are controlled electrically, enabling a wafer-level process compatible with high-volume, low-cost manufacturing. This paper shows results from CNT integration in test vehicles manufactured in MEMS processes (using silicon microheaters), as well as our status towards realizing CNT integration in a purpose-designed CMOS chip (optionally using the chip's metal or polysilicon layers for microheaters).