Research On CNT-ZnO TFTs Hybrid CMOS Digital Logic Technology

CMOS,with its low power consumption and high efficiency,has already occupied the dominant position in the field of digital logic.Thin film transistor(TFT),as a product of the same period as metal oxide semiconductor field effect transistor(MOSFET),has gradually obtained extensive applications in panel display driving fields in recent years with the improvement of process technology.However,due to the characteristics of TFT channel materials,many TFTs cannot produce NMOS and PMOS at the same time.For example,the zinc oxide(ZnO)and carbon nanotube(CNT)that this paper focuses on are difficult to effectively realize PMOS and NMOS devices due to their own material defects and operating principle.The inability to realize single material CMOS structure greatly limits the further application of such devices in the field of digital logic.Aiming at the above problem,this paper designs a compatible process by using ZnO as NMOS and CNT as PMOS,and successfully realizes the large-scale fabrication of CMOS logic devices on 4 inch substrates.Compared with the load type,E-D NMOS type and pseudo CMOS logic structures selected by TFT in the past,our devices have shown an excellent performance,including low static power consumption and strong fan-out capability.This low-cost,large-area CMOS circuit will help the large-scale application of Io T integrated circuits.In this work,the top gate ZnO NMOS device is fabricated in a large area by atomic layer deposition,these devices have excellent electrical performance consistency and stability.Subsequently,the work developed a large-area of CNT PMOS devices with bottom gate structure fabricated by solution drop coating method.Through multiple process iterations,it has shown an excellent performance in the same type of devices,including on-off ratio of over 10~5,-1.2 V opening voltage and sub-threshold swing of600 m V/decade.These devices consistency has also been well controlled.After that,this work developed a compatible process that can realize CNT-ZnO hybrid CMOS devices,and uses this process to realize the basic CMOS logic units.The inverter shows a high gain up to 140V/V,and also shows the low static power consumption,high noise margin and strong driving ability characteristics of CMOS.Thanks to the excellent single device performance and process structure design,its performance exceeds most other TFT logic devices.Finally,based on the CMOS basic circuit units,this paper designs a small-scale digital logic integrated circuit:radio frequency identification tag chip.By establishing the SPICE model of the device,the chip functions are pre-simulated in Cadence,and then fabricated by CNT-ZnO CMOS compatible process.Finally,the chip is tested and analyzed.The results show that our CMOS compatible process has the potential to realize small scale integrated circuits.