Design And Research Of New Type Non-inverted Majority Carrier Channel TFET

With the rapid development of integrated circuit technology,the feature size of MOSFETs has been reduced to nanometers,and device power consumption has gradually become one of the main factors restricting the development of integrated circuits.The tunneling field effect transistor(TFET)is based on the working principle of band-band tunneling,and its sub-threshold swing can reach below 60mV/dec.The advantages of low power consumption in integrated circuits are gradually emerging.However,the current traditional silicon-based TFET adopts a minority carrier inversion working mechanism,and the probability of carrier tunneling is low and the tunneling area is insufficient,resulting in small on-current and low switching current ratio,which is difficult to meet practical applications.Therefore,the exploration of new TFET device structure has become a research hotspot at home and abroad.In this paper,aiming at the problem of small conduction current of P-I-N type TFETs,a new type of non-inverted multi-subchannel TFET structure(P-N-N type TFET)is proposed.Compared with the conventional TFETs,this PNN-type TFET works in flat band mode or accumulation mode,which greatly increases the tunneling area and improves the on-state current of the device.However,in order to ensure that the channel is fully depleted in the off state,the gate metal work function of the PNN-TFET must be greater than 5.1 e V,which introduces a peak electric field at the edge of the gate,resulting in a significant GIDL effect and worsening the off-state current and switch current ratio of the device.So,this article based on the PNN-TFET and focuses on optimizing the gate structure,and proposes a heterogeneous gate(DMG)structure,a heterogeneous gate dielectric(HGD)structure and a stepped gate oxide(SGO)structure of PNN-TFET,which can weaken the surface peak electric field and realizes the suppression of the off-state current.The simulation results show that:compared with the P-I-N type TFET,the new P-N-N structure increases the on-current of the TFET by nearly 4 orders of magnitude.Respectively,only using a heterogeneous gate structure,a heterogeneous gate dielectric structure or a stepped gate oxide structure can reduce the turn-off current of the PNN-type TFET without sacrificing its turn-on current,and effectively suppress the GIDL effect which is resulted from the too large function of the gold gate has an impact on the turn-off characteristics of the PNN-TFET,which increases the switching current ratio of the PNN-TFET by 2 to 3orders of magnitude.In addition,by increasing the width of the aluminum gate,the width of Si O₂,or the length and thickness of the stepped gate oxide layer,the off-state current of the PNN-TFET can be further reduced.The on-current,off-current and switching current ratio of SGO PNN-TFET have obtained good simulation results,and without bring in other gate metal or gate dielectric is introduced in SGO PNN-TFET,the process difficulty is low,and it can be used as the focus of follow-up research.The results of this paper can lay a theoretical and technical foundation for the application of TFET in low-power chips.