利用 CMOS-MEMS 技術與乾蝕刻 製作之微光點量測系統

Abstract

隨光儲系統發展過程中，微光點量測越來越重要。利用傳統的遠場光學方法較不容易直接量測聚焦光點，其解析度受限於像素的大小。光點的近場分佈可以利用近場光學顯微鏡進行，但探針易於量測中損壞、架設困難及高成本為其缺點。 為改善以上的缺點，我們以刀緣與針孔掃描法來量測。量測系統晶片整合平整的刀緣掃瞄板、梳狀致動器、光感測器及電路於同一晶片上以直接對微光點作量測。利用標準CMOS製程，可以將上述元件整合於同一晶片，再以後製程將結構懸浮。 於此論文中已成功將光學、機械及電路元件整合於同一晶片內。目前的研究結果有：一、刀緣與針孔掃描法的設計與模擬，包含轉阻放大器與梳狀致動器的效能與機械特性；二、利用台積電的0.35微米製程的D35-99B梯次製作之吸收式微結構結合on-chip轉阻放大器，量測結果包含刀緣光感測器的光響應、轉阻放大器的效能及梳狀致動器的機械特性，在RIE過程中減少了彈簧的尺寸，因此共振頻率的量測結果低於設計值。此外，在D35-100A梯次也製做的針孔掃描量測系統結合針孔式光感測器與on-chip轉阻放大器，量測結果包含針孔式光感測的光響應與二維的光點量測。CCD和D35- 100A之間的光點尺寸測量差別低於 5％。

As the development of data storage systems, micro optical filed measurement becomes more important. In conventional far-field optics, the micro spot size cannot be acquired easily. The resolution is limited by the pixel size. For near-field measurement, near-field scanning optical microscopes (NSOM) can be used to measure micro spot size with high resolution. However, the NSOM tip easily wears out in measurement. The setup of this system is complex and cost is high. To improve these disadvantages, a microelectromachanical system (MEMS) optical field measurement system based on the scanning knife-edge and pinhole technique are proposed. In the D35-99B device, a knife-edge plate, a micro actuator, a photo detector and transimpedance circuit were integrated on a standard CMOS chip to scan across the optical distribution. Post process is used to suspend the microstructure in this chip. In D35-99B, the mechanical characteristics of the microstructures were simulated and measured. The measured frequency was lower than design value because the spring width was reduced during the RIE process. The transimpedance circuit and responsivity of knife edge photodiode were measured. In D35-100A, the I-V curve of sidewall PN was presented. The measurement results of voltage signal from sidewall PN junction photodetector using integrate TIA, and the responsivity to the modulated light source was obtained. The measurement of optical spot was measured by using the CCD and the D35-100A device, and the spot diameter was calculated. The difference of the measured spot sizes between the CCD and the D35-100A device is less than 5 %.