適用於ISFET之介面電路設計

A design of ion-sensitive field-effect transistor interface

王昀偲(YUN-SZU WANG)

指導教授 ： 林致廷

國立臺灣大學/電機資訊學院/生醫電子與資訊學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202102292

摘要

離子感測場效電晶體(ISFET)在化學與生醫感測領域扮演至關重要的角色。目前ISFET的主流架構為延伸式閘極ISFET (EGISFET)，主因為其相容於CMOS製程，並且藉由轉阻放大器-電流電壓轉換器電路(TIA)，量取ISFET元件的汲極(drain)與源極(source)間的電流變化。將輸入電流轉換為成比例的輸出電壓。
本論文利用TSMC 0.35 um Mixed-Signal 2P4M Polycide 3.3/5V製程製作平面及立體感測結構的ISFET及其介面讀取電路。經過後程處裡，形成所有的平面及立體感測結構的ISFET。藉由分析各元件於不同pH值溶液中的IdVg曲線，可以獲取該ISFET元件的感測特性。並且將ISFET所產生的電流，做為TIA的輸入訊號。
結果顯示，ISFET，佔地面積相同時，立體感測結構的ISFET比傳統平面結構的ISFET，立體結構的感測靈敏度可至多提升到1.7倍。在D35-109A製作的晶片，當TIA輸入電流範圍為80-120uA時，TIA電路的電壓輸出為0.68~1V，且具線性度。修改D35-109A的TIA電路後，再次於D35-109C製作晶片，其輸入電流範圍為60-140uA時，TIA電路的電壓輸出為0.62~1.49V，亦具線性度。

關鍵字

離子感測場效電晶體 ； 延伸式閘極 ； 介面電路 ； 電流電壓轉換器

並列摘要

The ion-sensitive field-effect transistor (ISFET) is crucial to the field of chemical and biological sensing. ISFET with extended gate configuration is the trend for application due to compatibility with standard CMOS process. In addition, a transimpedance amplifier current-to-voltage converter circuit (TIA) is used to measure the current change between the drain and source of the ISFET. Convert the input current to a proportional output voltage.
This paper uses TSMC 0.35 um Mixed-Signal 2P4M Polycide 3.3/5V process to make ISFETs with planar and three-dimensional sensing structures and their interface reading circuits. After the post process, all ISFETs with planar and three-dimensional sensing structures are formed. By analyzing the IdVg curve of each element in a solution with different pH values, the sensing characteristics of the ISFET element can be obtained. And the current generated by ISFET is used as the input signal of TIA.
The results show that when the ISFET has the same floor area, the ISFET of the three-dimensional sensing structure can increase the sensing sensitivity of the three-dimensional structure by up to 1.7 times compared with the ISFET of the traditional planar structure. The chip was produced in D35-109A, when the TIA input current range is 80-120uA, the voltage output of the TIA circuit is 0.68~1V, and it has linearity. After modifying the TIA circuit of D35-109A, the chip was produced in D35-109C again. When the input current range is 60-140uA, the voltage output of the TIA circuit is 0.62~1.49V, which is also linear.

並列關鍵字

ISFET ； extended gate ； interface circuit ； transimpedance amplifier

參考文獻

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