結合光纖插孔、固態浸沒式透鏡與精密電鍍微孔之光學頭研究

Abstract

本論文之研究目的在探討整合性近場光學讀取頭之製程，將光纖插孔、固態浸沒式透鏡與次微米級微孔整合，改善光學讀取頭各元件間的整合製程，利用微影技術將各元件依序疊合加工，毋須個別製作再進行複雜且困難的結合步驟，大大簡化製作流程。 在製造方面，微孔是採用一種改進式的精密電鍍加工，利用電鍍增生原理解決蝕刻加工法之不可回復性，藉由金屬材料的電鍍補償使孔徑進一步的縮小，免於受到光學曝光系統線寬與蝕刻技術的限制。此外，利用熱回火原理使原始定義區之陡峭直立圓孔變形成角錐狀圓孔，然後將底下犧牲層作輕微的側向過蝕，則開孔自然成形，省略蝕刻加工時對時間與蝕刻液嚴格的控管程序，再以上述電鍍加工即可製得次微米級孔徑；微透鏡部分也是利用熱回火原理，將AZP 4620正光阻置於熱板昇溫至略高於其玻璃轉換溫度，此時表面能會趨向最小能量，接觸角因而改變，外形自然形成圓滑曲面，此法比一般蝕刻加工容易製得光滑表面。本論文提出之透鏡直徑範圍在50至110 微米；因熱回火時間增加使材料組成更為緻密，透鏡折射率範圍介於1.63至1.82。光纖插孔則用厚膜光阻SU-8製成，並可增加元件之結構強度。

The research describes the fabrication processes of an integrated optical pick-up head for near field recording that combines a tiny aperture, a smooth microlens, and a insertion socket for optical fiber. Conventionally, micro apertures and microlenses in optical pick-up head are fabricated separately, and then are assembled together. Here a fabrication process without bonding to combine all the desired components on a single substrate is proposed. The cone-shape aperture is fabricated by reflow and an improved electroplating method. Then a thermal reflow process is used to form the smooth microlens made of AZP 4620 with the refractive index from 1.63 to 1.82. The diameter ranges from 50 μm to 110μm. After that, SU-8 support is fabricated to act as the insertion socket of the optical fiber and to enforce the device strength.