| 摘要: | 太陽光經大氣吸收後，能量主要集中於紫外、可見與紅外波段，其中紅外光因瑞利散射弱與背景雜訊低，具備高SNR與遠距傳輸能力。紅外光依波長可分為NIR、SWIR、中紅外與遠紅外等，其中SWIR的1350 nm與1550 nm具備良好穿透性，低散射與低吸收特性，廣泛應用於感測與通訊領域，且波段位於人眼安全範圍，適合長距離與高雜訊環境下使用。
本實驗延續對純鍺與鍺化合物的前期研究，前期研究中已經完成在製程溫度500°C以及200°C的參數優化，並且均成功鍍製出高穿透率的短波紅外窄帶濾光膜。為了實際應用在晶圓級光學薄膜的製程中，後續微影製程中光阻材料的熱穩定性的問題需將製程溫度降低，且透過摻雜錫能夠使折射率差擴大，使後續在鍍製濾光膜整體厚度降低、降低成本、薄膜應力等優點。在本研究中會針對濺鍍功率、反應氣體流量等製程參數進行優化，並以光譜儀及軟體Essential Macleod分析薄膜光學性質；EDX、XPS分析薄膜化學成分的組成；SEM、XRD、AFM、FTIR分析薄膜的材料、鍵結與表面性質，得到最佳化參數鍍製出高穿透的短波紅外窄帶濾光膜。
本實驗切分為四個部分，第一部份針對製程溫度與錫含量去做優化。第二部份針對高折射率材料鍺錫進行製程優化，依序以製程功率、氫氣通量作為製程調控，在氫氣通量低時，無法和所有懸鍵有效鍵結；在氫氣通量高時，薄膜空缺增加、緻密性下降，因此氫氣需在一定的通量。優化後薄膜呈非晶態且表面平坦。第三部分為低折射率材料氧化鍺錫，在通過量氧氣時造成靶材毒化，因此對氧氣通量的調控進行優化，同時探討不同通量下鍺錫氧比，優化後薄膜亦呈非晶態表面平坦。第四部分利用上述兩最佳化參數設計後鍍製在1550 nm的窄帶濾光片，成功升高折射率差異、降低製程溫度、降低膜厚、穿透率超過80%。
;After passing through the Earth’s atmosphere, the energy of sunlight is primarily concentrated in the ultraviolet, visible, and infrared regions. Infrared light, due to its low Rayleigh scattering and background noise, offers high signal-to-noise ratio (SNR) and excellent long-distance transmission capability. Based on wavelength classification, infrared light can be divided into near-infrared (NIR), short-wavelength infrared (SWIR), mid-infrared, and far-infrared bands. Among them, the SWIR wavelengths at 1350 nm and 1550 nm exhibit high transmittance, low scattering and low absorption. These properties make them highly suitable for sensing and communication applications, particularly in long-distance and high-noise environments. Moreover, their wavelengths lie outside the retina-sensitive range of the human eye, ensuring biological safety.
This study extends previous research on pure germanium and its oxides, where optimized deposition temperatures at both 500°C and 200°C were established, successfully achieving high-transmittance SWIR narrowband filters. To meet the practical demands of semiconductor-compatible optical thin film processes, the deposition temperature must be further reduced to accommodate the thermal stability of photoresist materials in subsequent lithography steps. Additionally, tin doping is introduced to increase the refractive index, thereby reducing total film thickness, cost, and internal stress of the multilayer filters.
In this work, single-layer films were optimized through variations in sputtering power and reactive gas flow rates. The optical properties of the films were analyzed using spectrophotometry and Essential Macleod software, while their composition and material properties were characterized through EDX, XPS, SEM, XRD, AFM, and FTIR measurements.
This experiments are divided into four main parts. The first focuses on optimizing the process temperature and tin content. The second involves optimizing the high refractive index layer, Germanium-tin by tuning power and hydrogen flow. At low hydrogen flow, hydrogen cannot effectively passivate all dangling bonds; at excessively high flow, film porosity increases and density decreases, indicating an optimal range is required. The resulting films are amorphous with smooth surfaces. The third part optimizes the low refractive index layer, Germanium-tin oxide by adjusting oxygen flow to avoid target poisoning, while examining the Ge/Sn/O ratio under different flow conditions. These films also exhibit amorphous structure and smooth morphology. Finally, the optimized high- and low-index layers were stacked into a seven-layer narrowband filter centered at 1550 nm. The final structure achieves increased refractive index contrast, reduced processing temperature, lower film thickness, and transmittance exceeding 80%. |
