鋯鈦酸鉛薄膜之微波水熱式退火並應用於感測器

Abstract

石英晶體微天秤(Quartz Crystal Microbalance)技術已經發展成熟，並廣泛應用在微小質量的偵測上，根據Sauerbrey方程式，若將QCM感測面積變小或提高感測器的振盪頻率，則可以提高其靈敏度，但是石英不易加工，在製程處理上受限制。本研究則是利用同樣具有壓電性質的材料鋯鈦酸鉛(PbZrxTi1-xO3)，以溶膠－凝膠法(Sol-gel)製成壓電薄膜，來取代傳統的石英晶體；再以微波反應系統進行水熱式退火，來取代傳統高溫製程上的熱處理方式，同時根據實驗結果，進一步推論水熱式退火的反應機制。再利用掃描式電子顯微鏡(SEM)、原子力顯微鏡(AFM)、X光繞射儀(XRD)…等，去討論在不同參數下PZT薄膜的性質，並以實驗所得之最佳參數，以半導體微影技術製成PZT薄膜感測器。另者，利用發展出的感測器對揮發性的有機物之蒸氣進行偵測，其振盪頻率約為30MHz，偵測極限約為1ppm。

QCM (Quartz Crystal Microbalance) has been received widely attraction for the application in the measurement of minute masses. According to the prediction of Sauerbrey equation, the sensitivity will be improved when the surface area is decreased or the resonance frequency of the unloaded resonator is increased. However, it is difficult for the quartz substrate to scale-down by photolithography. In this article, we develop another type of piezoelectric material, PbZrxTi(1-x)O3 (PZT), as a thin film by sol-gel route to replace the quartz crystal as a resonator. The novel hydrothermal annealing with microwave system is proposed to substitute the conventional furnace annealing. We also propose a reasonable mechanism for the hydrothermal annealing base on the experimental results. The films with different recipe of the treatments are analyzed by SEM, AFM, XRD and EDS. In addition, the films with good quality are applied to sense the vapor of volatile chemicals. The resonant frequency of the developed PZT sensor is about 30MHz and the sensing limit is estimated to about 1ppm.