基于原子层沉积IGZO场效应晶体管的接触电阻优化

Optimization of Contact Resistance in IGZO Field-effect Transistors Fabricated Using Atomic Layer Deposition

氧化铟镓锌(IGZO)具有宽带隙、高迁移率、和CMOS后道工艺兼容等优势,可用于下一代高密度三维堆叠存储器。随着IGZO场效应晶体管的尺寸不断微缩,源漏接触电阻在开态时会主导器件总电阻。因此,IGZO场效应晶体管的接触电阻优化成为需要研究的一个关键问题。本文采用原子层沉积的IGZO作为沟道并制备出场效应晶体管,探究了接触金属种类及后退火工艺对IGZO场效应晶体管接触电阻的影响。结果表明,退火前镍和钛的接触电阻相当。但在Ar/O2氛围、250℃条件下退火2小时后,采用钛接触的IGZO场效应晶体管的接触电阻降低到镍接触的8.3%,实现接触电阻低至0.86 kΩ·μm,同时阈值电压正移实现了增强型器件。与此同时,制备出超短沟长(Lch=80 nm)的IGZO场效应晶体管,开态电流高达412.2μA/μm、亚阈值摆幅为88.6 mV/dec,漏致势垒降低系数低至0.02 V/V。这些结果表明,通过优化接触金属种类及后退火条件,可实现高性能IGZO场效应晶体管,并为IGZO大规模实际应用提供新思路。

Indium gallium zinc oxide(IGZO)possesses advantages such as a wide bandgap,high mobility,and compatibility with CMOS back-end-of-line processes,making it suitable for next-generation high-density threedimensional stacked memories.As the dimensions of IGZO field-effect transistors(FETs)continue to shrink,the source-drain contact resistance becomes a dominant factor in the device's total resistance in the on-state.Therefore,optimizing the contact resistance of IGZO FETs has become a critical research issue.In this study,IGZO deposited by atomic layer deposition was used as the channel to fabricate FETs,investigating the influence of contact metal types and annealing processes on the contact resistance of IGZO FETs.The results indicate that the contact resistances of nickel and titanium were comparable before annealing.However,after annealing at 250℃for 2 hours in an Ar/O2 atmosphere,the contact resistance of IGZO FETs with titanium contacts decreased to 8.3%of that with nickel con-tacts,achieving a contact resistance as low as 0.86 kΩ·μm,with a simultaneous enhancement in threshold voltage shift for enhancement-mode devices.Meanwhile,IGZO FETs with an ultra-short channel length(Lch=80 nm)were fabricated,exhibiting a high on-state current of 412.2μA/μm,a subthreshold swing of 88.6 mV/dec,and a low drain-induced barrier lowering coefficient of 0.02 V/V.These results demonstrate that high-performance IGZO FETs can be achieved by optimizing the contact metal type and annealing conditions,providing new insights for large-scale practical applications of IGZO technology.