一種具有懸浮奈米線通道之新式元件的研製與分析

Abstract

在本篇論文中，我們成功的製作出具有側閘極以及懸浮奈米線通道結構之新穎元件。利用邊襯蝕刻技術(sidewall spacer etching technique)以形成奈米線，同時，以去除犧牲氧化層之方式形成空氣介電層並使奈米線通道懸浮。因空氣介電層的存在，我們可利用調變閘極電壓使奈米線通道受靜電力吸引而擺動。同時，懸浮奈米線通道元件展現了較小的次臨界擺幅(相較於未去除犧牲氧化層之元件)，以及有趣的振盪現象。在本篇論文中，首次發表藉由奈米線通道擺動所引發之遲滯(hysteresis)現象。儘管大部份的元件未展現出非常陡峭的轉換特性(次臨界擺幅低於60mV/dec)，我們提出一漸進式吸引模型以解釋此一現象。

In this thesis, a novel device featuring a side-gate and suspended nanowire (NW) channels is proposed and demonstrated. The nanwire channels are formed with sidewall spacer etching technique, and become suspended by stripping the sacrificial oxide layer between the gate nitride and nanowire channels. The presence of air gap leads to a movable channel controlled by the gate bias. Despite a much larger equivalent oxide thickness due to the air gap, the suspended nanowire channel devices depict a better subthreshold swing over the devices without stripping the sacrificial oxide (i.e., no air gap). Moreover, an interesting oscillation phenomenon of suspended nanowire during the device operation is observed. The hysteresis phenomenon in the subthreshold characteristics due to the motion of the suspended nanowire is reported, for the first time, in this thesis. Nevertheless, most of the suspended nanowire devices do not show an abrupt turn-on behavior (i.e., with S.S. < 60mV/dec). A model considering the gradual contact of NW channel with the gate nitride is proposed to explain the operation principles of the fabricated devices.