離子感測場效電晶體對於溫度及閘極電壓應力調變之可靠度研究

Abstract

離子感測場效電晶體最初是由P.Bergveld在1970年代所提出來的一種化學感測器，主要是利用金屬半導體場效電晶體(MOSFET)的原理,ISFET與MOSFET不同的是將離子感應層(Ion Sensitive Layer) 、酸鹼緩衝溶液(pH Buffer Solutions) 和一外加之參考電極取代MOSFET之金屬閘極，ISFET的電性特性將會隨著離子感應層與溶液的表面接觸性質而改變。 此研究是以四種與CMOS製程相容的材料作為閘極感應層對於標準溶液進行探討。元件的所有製程均在國家奈米實驗室與國立交通大學奈米中心的一萬級無塵室中進行與完成。所有量測過程是利用HP4156儀器並且在黑箱中進行。在不同的溫度條件下對於不同緩衝溶液的pH值測其汲極電流與閘極電壓的曲線，藉由不同的汲極電流與閘極電壓曲線來定義靈敏度。為了尋求最佳的穩定條件，使用閘極電壓調變量來找出可靠度與酸離子之間的關係。 此篇論文將詳述離子感測器的製作流程及量測條件。在本研究裡有四個研究項目，溫度變化下的靈敏度、閘極對電壓應力調變的影響、溫度的遲滯效應以量測再現性。

The ion-sensitive field effect transistor (ISFET) is a chemical sensor that was first presented by P. Bergveld in 1970. The main point is used Metal Oxide Silicon Field Effect Transistor (MOSFET) principium. The ISFET is different with MOSFET on the metal gate of MOSFET which was replaced by an ion-sensitive layer, buffer solutions, and an additional reference electrode. The electrical characteristics of ISFETs will vary with the interface reactions of sensing layer and electrolyte solution. In this study, four CMOS fabrication compatible membranes were used to be the sensing layers on ISFETs. All processes of the devices were completed in the clean room (class 10000) of NDL and NFC in NCTU. All measuring processes was in a dark box using HP4156A semiconductor parameter analyzer. The devices were soaked in buffer solutions to get the ID_VG curves with varied temperatures and pHs. The sensitivities were defined by the disparities of ID_VG curves. In order to seek the optimum stabilization conditions, a gate voltage stress modulation was used to find the relations of reliability and acid ion. In this thesis, we will describe details on fabrication process flow and measurement conditions. In this study, there are four researches in sensitivities of varies temperature, the effects of gate voltage stress modulation, hysteresis of temperature, and repeatable use.