[[alternative]]Research on Nano CMOS MEMS Gas Sensor

碩士機電工程學系[[abstract]]摘要 本研究提出兩種不同型式的CO氣體感測器，其中一種利用離子感測場效電晶體(Ion Selective Field Effect Transistor, ISFET)來進行一氧化碳氣體感測之方式，以及其介面電路技術與設計，並結合感測元件結構，整合而成氣體感測晶片。一氧化碳感測器是以矽(Silicon)當作基材，P型多晶矽( P-poly Silicon )當微型加熱器電阻，N型多晶矽( N-poly Silicon )當蝕刻停止層，在N型多晶矽上，再加熱成長一層薄氧化層，最後使用溶膠-凝膠法( sol-gel method )製作二氧化錫滴附在感測結構上偵測CO氣體。當微加熱器電阻提供工作溫度時，所偵測到的ISFET電訊號(Vs)在不同的CO濃度中有不同變化。我們使用TSMC 0.35μm之CMOS 2P4M 標準製程以及後製程製作設計一氧化碳感測器，藉由ISFET放大器電路微小量的信號輸入而得到不同的電壓輸出，但實際量測的結果並沒有如預期有明顯的感測訊號，對於感應起電式的氣體感測晶片，感測出的電訊號雖然不靈敏且跳動量很大，我們可以嘗試設計電荷清除機制，將反應後的電荷量在量測後，重置歸零 ，藉以提高它感測的電訊號以避免訊號飽和現象。 I 另一種為電阻型的一氧化碳氣體感測器，其中感測電極設計為蜂窩狀指叉式型式，利用TSMC 2P4M 0.35um標準製程之金屬層Metal1做為Metal Mask，並以Metal4/Via34/Metal3/Via23/Metal2層次串聯金屬做為感測電極，並藉由P型多晶矽( P-poly Silicon )當微型加熱器電阻4.2kΩ，提供加熱功率120 υW，使用溶膠-凝膠法( sol-gel method )製作二氧化錫滴附在感測電極上偵測CO氣體，當CO氣體分子落在感測區域內時，吸附於感測電極上，使得電極板與電極板間的電阻值產生變化，量測結果對應到最小電阻的靈敏度為0.08%，而所對應到的CO濃度最小限制為4ppm以下。 關鍵字：一氧化碳、微型加熱器、溶膠-凝膠法、二氧化錫、離子感測。 II[[abstract]]Abstract This study proposes two different types of CO gas sensors, one of the ion sensor using field effect transistors (Ion Selective Field Effect Transistor, ISFET) to carry out carbon monoxide gas sensor manner, and its interface circuit technology and design combined with the sensing element structure, integrated gas sensor chip is made. Carbon monoxide sensors based on Si (Silicon) as substrate, P-type polysilicon (P-poly Silicon) when the micro-heater resistance, N-type poly (N-poly Silicon) When the etch stop layer, the N-type polysilicon, the re-heating a thin layer of oxide growth, the sensing material SnO2 was deposited onto the electrodes after sol-gel formation to detect the structure of CO gas. When the micro-heater temperature resistance to provide work, the number detected in the ISFET Telecommunications (Vs) at different CO concentrations in different variations. We use the TSMC 0.35μm CMOS 2P4M standard process and the production design process, after carbon monoxide sensors, ISFET amplifier circuit through the small amount of input and output voltages are different, but the actual measured results, as expected, did not significantly sensor signal, for sensing the gas from the electric sensor chip, the sensor out of the telecommunications insensitive and beating No. Although a large volume of design that we can try to clear the mechanism of the charge, the charge will reflect the volume after the measurement, the re- set to zero, in order to improve its telecommunications number of sensor in order to avoid signal saturation. III Another model for the resistance of carbon monoxide gas sensor, which is designed to honeycomb sensing electrode Finger type, using standard TSMC 2P4M 0.35um process of the metal layer Metal1 as Metal Mask, and to Metal4/Via34/Metal3/Via23/Metal2 level as a series of metal sensing electrode, and by P-type polysilicon (P-poly Silicon) when the micro-heater resistance 4.2kΩ, to provide heating power 120uW, the sensing material SnO2 was deposited onto the electrodes after sol-gel formation to detect CO gas, CO gas molecules when the sensor falls within the region, the adsorption on the sensor electrode, making electrode plate and the resistance value between electrodes changed, the corresponding measurements The sensitivity to the smallest resistor is 0.08%, while the CO concentration corresponding to the minimum limit of 4ppm the following. Keyword : Carbon monoxide、micro-heater、sol-gel、SnO2、ISFET