高κ栅介质肖特基源、漏极Ge-pMOSFET的电学特性

Electrical characteristics of Ge-pMOSFET devices with high κ gate dielectrics and Schottky sources and drains

利用紫外曝光光刻技术和精简的半导体加工工艺,用一步光刻制备了以HfO_2为高κ栅介质,NiGe为肖特基源、漏极的Ge-pMOSFET器件,并在栅极中引入厚度1 nm的Si层对HfO_2和Ge接触界面进行了钝化处理.器件的电学特性测试结果表明,Si钝化效果显著,不仅可确保HfO_2有较高的κ值(22),约为钝化前(κ=10)的两倍,还提高了器件的开启速度和开关比;器件亚阈值摆幅降低为钝化前的50%,开关比从钝化前的105提高至770,提高了约7倍,表明Si钝化是提高器件性能的关键.探讨了Ge-pMOSFET器件呈现双极性的原因,认为肖特基源、漏极在正向栅压下易击穿是导致该现象的主要因素.

With HfO2 as high κ gate dielectrics and NiGe as Schottky sources and drains, Ge-pMOSFET devices were developed under concise semiconductor processing technologies with only one step of ultra- violet lithography exposures. A thin layer of Si was introduced as a passivation layer between HfO2 and Ge in partial samples, and all of the devices＇ were tested on the electrical characteristics. The results showed that the Si passivation layer introduced in the samples not only protected the HfO2 for its high κ values to 22, but also made the devices open faster and switch ratio higher than those without Si passiv- ation. The subthreshold swing was reduced to half and the switch ratios increased from 105 to 770; having been raised more than seven times; which indicated that the Si passivation was the key to improv- ing the device performance. The main causes for the presented bipolar form in the transfer characteristic curves of Ge-pMOSFET devices were also discussed, which could be mainly attributed to the Schottky sources and drains breaking down easily under the positive voltages.