- 學位論文
二維聲子晶體與表面聲波元件之整合製程
Integration and fabrication of 2-d phononic crystals and surface acoustic wave devices
摘要
本文旨在使用新穎方法，設計並將微米級的週期性介電質結構(聲子晶體)與一組叉指狀電極表面聲波元件整合製程，電磁波通過聲子晶體時由於反射波對入射波造成干涉，發生所謂的頻溝現象，阻擋在某些頻率振盪之電磁波通過。將聲子晶體與光子晶體所產生頻溝現象予以類比，聲子晶體的頻溝現象可應用於表面聲波濾波器，阻止特定角度與頻率入射的聲子傳遞，藉以達成濾波之效果。本研究所使用微機電製程包含面型微加工與體型微加工方式，整合於聲子晶體和表面聲波元件發射端與接收端之製程。製程流程為：先將矽基板上濺鍍厚度1.5微米的氧化鋅壓電薄膜，其次以蒸鍍方式叉並使用掀舉技巧製作叉指狀換能器電極。隨後將黃光製程定義聲子晶體後的矽基版以深蝕刻技術加以蝕刻產生二維聲子晶體之週期性柱狀結構。微米級高深寬比的聲子晶體柱狀結構以改良式的電鍍方式加以填充進入電鍍銅金屬，以求達成所設計的表面聲波頻寬，與實驗相符合。
並列摘要
This work presents an innovative design and fabrication of phononic crystals integrated with two sets of interdigital (IDT) electrodes for frequency band selection of surface acoustic waves (SAW). Analogous to the band-gap generated by photonic crystals, the phononic crystals can prohibit the propagation of elastic waves with either specific incident angles or certain bandwidth. Both IDT electrodes are deposited and patterned on a thin piezoelectric layer. Both surface and bulk micromachining are employed and integrated to fabricate the crystals as well as SAW resonator and receiver altogether. Firstly, a 1.5-micron zinc oxide, which provides well-defined central frequency, is sputtered and patterned onto silicon substrate. Second, the IDT electrodes are evaporated and patterned by lift-off technique. Then the exposed silicon substrate is etched using DRIE to generate two dimensional phononic crystals. To tune the prohibited SAW bandwidth, the crystal pores are filled with copper by electro plating.