整合延伸閘極與無接面環繞式閘極奈米線場效電晶體之生醫感測研究

Abstract

本論文的研究目標為整合環繞式閘極奈米線場效電晶體與延伸式閘極感測晶片於微流道系統中進行即時偵測生物分子。首先利用電子束微影，製作出通道厚度7奈米、寬度約80奈米的無接面(Junctionless)及反轉式(Inversion Mode)兩種環繞式閘極矽奈米線電晶體。電性量測顯示無接面及反轉式電晶體皆擁有良好的電性：陡峭的次臨界擺幅 (SS; 63~71 mV/decade)、極低的汲極引發位能障降低(DIBL; 0 mV/V) 和高開關電流比 (~5×106 , VD= 0.1 V)。且延伸式電晶體閘極應用於微流道系統中進行酸鹼值離子感測，同時運用多種條件改變下的偵測條件，例如：改變延伸式閘極的表面材料、電晶體操作在不同工作區域的閘極電壓下、降低汲極端供給的電壓、改變感測區的電極面積、以及是否帶有-NH2鍵的修飾表面來測試元件之感測靈敏度。另外，利用在晶片表面修飾APTES與NHS-biotin，來測試不同濃度Streptavidin蛋白與NHS-biotin進行專一性結合後，造成延伸式閘極的表面電位變化。再以相同修飾模式透過螢光和電容阻抗分析修飾步驟的穩定性與可靠度。由實驗結果看出無接面及反轉式環繞式閘極電晶體均適合做為生物分子感測元件，並作為即時偵測的生醫檢驗平台的傳感器。不過無接面環繞式閘極矽奈米線電晶體具有較簡單的元件製程，在元件持續微小化的過程將具有較高的良率。

Integration of gate-all-around (GAA) silicon nanowire (NW) field-effect-transistor (FET) and extended gate as sensor for real-time detection of biomolecules in microfluidic system is the focus of this thesis. Both junctionless (JL) and inversion mode (IM) GAA nanowire FETs with 7-nm thick and 80-nm wide channel were prepared on the same chip for comparison. Both GAA NW devices exhibit outstanding electric properties such as a very steep subthreshold slope (SS; 63~71 mV/decade), a virtual absence of drain-induced barrier lowering (DIBL; 0 mV/V) and a high ON/OFF current ratio (~5×106, VD= 0.1 V). Then, capacitive extended gates were connected to JL and IM GAA nanowire FETs for both pH and biosensing in microfluidic system. For sensitivity of pH sensing, both the surface dielectric materials of extended gate and working regions of SiNW FETs under different gate voltages were investigated. By modification of APTES and NHS-biotin on the surface of extended gate, real-time streptavidin detections were evaluated. The reliability of modifications was justified by using the fluorescence technique and electrochemical impedance spectroscopy. Based on the experimental results, JL and IM GAA nanowire FETs are both applicable as biomolecule sensing transducers. However, JL GAA NW FETs need simpler fabrication process and thus provides high yield when preparing the devices.