懸浮式奈米線通道電晶體於氣體感測器之應用與具懸浮式閘極之垂直電晶體特性研究

Abstract

在本篇論文中，我們成功地製作出兩種新穎的元件結構，分別為懸浮式奈米線通道電晶體及具懸浮式閘極之垂直電晶體。其中，前者的懸浮式奈米線通道、與後者的懸浮式閘極電極及垂直通道皆利用一簡單且低成本的非等向性電漿蝕刻技術來完成。 首先，我們成功地將懸浮式奈米線通道電晶體用應用於氣體感測器。在含氨氣的環境中，懸浮式奈米線通道電晶體的基本電性會隨著氨氣的濃度而有所反應。我們可以藉由觀測汲極電流(ID)和啟動電壓(Vth)隨著氨氣濃度的變化，來偵測氨氣的濃度，並且分析氨氣在奈米線表面的反應機制。另外，我們藉由改變懸浮式閘極電晶體元件光罩的設計，成功地改善了兩段式啟動現象，並且探討該元件改善後的基本電性。最後我們移除犧牲氧化層，且成功地使閘極電極懸浮於空氣中。

In this thesis, we have successfully fabricated two kinds of devices including the suspended-NW-channel TFTs and the SG vertical-MOSFETs. The sidewall spacer NW in suspended-NW-channel TFTs and the sidewall spacer gate electrode in the vertical channel of SG vertical-MOSFETs are both formed by a simple anisotropic plasma etching technique. We have successfully applied the suspended-NW-channel TFT to gas sensor application. In the environments containing ammonia (NH3), the basic electrical characteristics of the suspended-NW-channel TFT are changed with the variation in the concentration of NH3. The shift in threshold voltage (Vth) or the change of drain current (ID) with varying NH3 concentration can be used as an indicator to sense the NH3. The possible reaction mechanisms between NH3 molecules and nanowire surface are discussed and analyzed. Besides, we have also successfully improved the undesirable two-step turn-on phenomenon encountered in the characterization of SG vertical-MOSFETs conducted in a previous work by changing the mask layout, and studied the basic electrical characteristics of the newly designed and fabricated SG vertical-MOSFETs. Finally, we have successfully removed the sacrificial oxide layer to suspend the side gate and studied the characteristics of the devices.