雙閘極多晶矽牛角型奈米線感測器之製程與應用

Abstract

隨著科技的日益發展，我們始終希望能將科技回饋於人類，因此，近幾年來，生物感測器的重要性與日俱增且著重於能夠創造更便利的生醫感測環境。而為了達到更好的訊號響應，奈米線場效電晶體成為強而有力的新興感測器，用於檢測化學/生物種類。我們提出了一種與互補金屬氧化半導體兼容，且利用側壁技術以形成新穎的牛角型多晶矽奈米線生物感測器，並提供一個低成本且高感測度的元件來檢測酸鹼值和生物分子。 多晶矽奈米線的製程是利用梯型形狀的假閘極結構來完成這個特殊的側壁牛角型多晶矽奈米線。而這個牛角的尖端會造成一個很強的電場使得以雙閘極模式下的不同液體電極的汲極電流，會展現一個被限制的情況。而我們利用這樣的現象，找出在液體電極2V以及下閘極電極3V的情況下是能夠偵測出最大的即時汲極電流變化量區域。 牛角型多晶矽奈米線生物感測器透過下閘極模式感測其每度酸鹼值可高達132.9 mV，透過電容耦合超越了能斯特限制，但這個方法在互補場效電晶體的實際訊號下卻沒有發現能因此獲得有效的改善，所以我們提出一個新的方法，利用感測電流的方式以牛角型奈米線結構去感測酸鹼值和生物分子。在鐵蛋白研究上面，我們發現抗體及抗原的結合，能夠使的汲極電流有一個立即且顯著的變化。因此，牛角型多晶矽奈米線生物感測器在生物感測方面是一個非常具有潛力的元件。

Biosensors have gathered great importance in recent years with the rapid development of technology, thus we hope to bring more benefit for people to achieve an easily biomedical sensing environment. In order to obtain a better signal response, nanowire field effect transistors are emerging as powerful sensors for detecting chemical/biological species. We proposed the novel horn-like poly-Si nanowire biosensors by using spacer technology which is complementary metal-oxide- semiconductor (CMOS) compatible for pH and biomolecule detection with low cost and high sensitivity. The poly-Si nanowire is fabricated by using the trapezoidal-shape dummy gate structure with the spacer wire process to form the special shape of horn-like nanowire. The horn-like sharp inducing a strong electrical field which operates in the bottom-gate mode will limit the drain current with different liquid gate voltage. We use this phenomenon to find a largest difference of the drain current between liquid gate voltage at 2V and 3V as a best real time sensing condition. The horn-like nanowire sensors exhibited a higher sensitivity to 132.9mV/pH exceeding Nernst limit at bottom-gate mode operation amplified by capacitive coupling. However, the actual CMOS readout signal has not been effectively improved by this way. Moreover, a new method for detection of pH and biomolecule from current of horn-like nanowires structure is suggested. The significant change in the drain current with real-time measurement was shown when the specific binding occurred between antibody and antigen of ferritin. Hence, the horn-like nanowires show a promising potential for the development of biosensors.