以電漿表面處理之新穎ReFET製程

Abstract

Ion-sensitive field-effect-transistor（ISFET）最早是由P.Bergveld在1970年所提出的，其結構是將傳統的金氧半場效電晶體中的金屬閘極以待測溶液與參考電極所取代之。一旦待測溶液中的離子被感測層(sensing layer)表面的斷鍵所束縛住時，將會對下面的通道做出調變的效應，進而改變通道的電阻。如此一來，元件的電性將會隨著溶液的不同而產生變化，同時我們也可藉由電性的變化來判定溶液的性質。 而在應用上的問題則是來自於過多干擾，其中不乏光照射所產生的內部現象以及熱現象，於是相對應的元件則由此而生，而此元件設計的目的則在於抵銷光照效應以及熱效應，於是設計的原則則是與原ISFET具有一樣的光特性以及熱特性，但卻對pH的變化具有相對應低的感測能力，而此元件則稱之為Reference field-effect-transistor(ReFET)，而在傳統的REFET設計，則是使用高分子有機化合物作為降低電場對通道的影響，而此在製程上的困難則是在於無法在同時間製作ISFET/REFET，而必須有特殊製程針對REFET¬而設計，而在此研究中，我們則是以修補斷鍵作為製程設計的主要想法，進而採用電漿處理的方式進行斷鍵的修補，以使其具有低pH的感測能力並且可同時進行ISFET/REFET的製程。

The ion-sensitive field effect transistor (ISFET) was first introduced by P.Bergveld in 1970. The metal gate is replaced by a reference electrode and the electrolyte . Once the ions in electrolyte are trapped by the dangling bond at the surface of sensing layer , which will induce the modulation of channel resistance . Therefore, the electric characteristics are changed by different kinds of electrolyte , and we can distinguish the properties of electrolyte . There are lots of interferences in application with ISFET. Such as lightening effect and thermal effect, to eliminate these effects and lower sensitivity of pH the Reference field-effect-transistor (REFET) were produced. The traditional REFET manufacturing is to gel macromolecular compounds reducing the modulation of channel by electric field. Then we need a special manufacturing process of REFET, and can not comanufacture ISFET/REFET. In this study, we use plasma to recover the dangling bonds from sensing layer. Then the comanufacturing process of ISFET/REFET pair is realized.