利用SOI製作之吸收式微型光點形狀量測系統

Abstract

隨著光儲存等應用系統的迅速發展，微光點的量測變得越來越迫切和重要，利用傳統的遠場光學方法並不能直接量測聚焦光點，且解析度受限於光感測器的像素大小(約5 μm)。然而，使用近場光學量測卻因為要將物體擺設在待測光場的近場範圍內，系統架設複雜、高成本又不易實現即時量測，而且其解析度也受限於探針的孔徑。因此，為了提供高解析度、降低成本又方便使用的微光點量測方法，我們提出了一種利用掃瞄刀緣法(scanning knife-edge method)的微光點大小及形狀量測系統，整合了梳狀致動器、光感測器和平整的刀緣掃瞄板以直接對微光點作量測。 為了實現此一系統，我們選擇了透過SOI和可以整合電路的CMOS後製程兩方面作為目標前進，在本文中，成功的利用SOI整合了上述元件並提出了一個新的背向乾蝕刻方式去改善良率，我們也對完成的元件作測試和討論，包括致動器動態響應和光感測器的響應度。另外，透過CIC的製程服務，設計並佈局的CMOS製程中整合了上述元件和電路，經過了測試實驗，也驗證了所提出CMOS後製程的可行性。 最後，我們將完成的反射式和吸收式SOI元件對雷射聚焦光點大小作量測，利用反射式元件量測的光點大小和形狀成功的驗證此一系統。在吸收式系統的量測方面，將討論面臨到的問題和改善的方向以奠定日後對微光機電整合晶片研發的基礎。

As the optical spot size in applications such as optical data storage gets smaller, the measurements of focused laser spot become more necessary and important. In conventional far-field optical distribution, the micro spot size can not be acquired directly. The measurements performed by near-field scanning optical microscopes (NSOM) are more complex and costly because the detector must be placed in the near-field proximity. Therefore, a microelectromachanical system (MEMS) optical spot profile measurement system based on the scanning knife-edge technique is proposed. In the fabricated device, a knife-edge plate and a photo detector are integrated on the micro actuator to scan across the optical distribution. The fabrications are performed by using SOI (silicon-on-insulator) MEMS and CMOS (complementary-metal-oxide-semiconductor) MEMS. In the thesis, a new approach is proposed for SOI process to dry etching the backside silicon. The fabricated components, including comb actuator and photo detector, are measured and discussed. The CMOS device is also designed to attempt a fully integration with circuits. By the test experiments, the feasibility of the proposed CMOS post processes is verified. At last, the focused laser spot measurements are performed by the SOI device. The obtained spot size and profile shows a good agreement to the theoretical value and demonstrate the system. In the absorption type, the encountered problems are discussed to provide fundamentals for further researches.