金屬微米及奈米狹縫之近場光學顯微研究

Near-field optical microscopy study of metal micro- and nano-slits

曾名輝(Ming-Hui Tseng)

指導教授 ： 林鶴南

國立清華大學/工學院/材料科學工程學系/碩士(2006年)

https://doi.org/10.6843/NTHU.2006.00315

摘要

我們成功製備出針尖孔隙大小約為60 nm - 150 nm的鍍金光纖探針，量測其相對光通量對應掃描式電子顯微鏡所呈現的孔隙寬度約為10-9 - 10-3，而我們發現光通量與由掃描式電子顯微鏡影像量得的孔隙大小，有相當好的對應關係。因此，光纖探針的相對光通量可方便地用作判定針尖端孔隙大小的依據。
利用本實驗室已成熟之原子力顯微術的奈米加工技術製備出具有數十至數百奈米之金屬狹縫的試片，也運用光學微影技術製備出具有2 μm以及10 μm寬之多道金屬狹縫的試片，最後以掃描式近場光學鏡偵測試片經由綠光雷射(532 nm)照射過後之近場光學顯微影像。對這些金屬狹縫一系列的分析，將對其在近場光學生醫掃描器以及使用於微影技術中光罩的應用，提供相當大的貢獻。
研究結果顯示，當奈米狹縫尺寸略大於或近似於照射光波波長時，可看到類似單狹縫繞射之光學干涉現象，且亮紋間的間距約為1.8 μm；而當奈米狹縫尺寸小於二分之一照射光波長時，則無此現象。而且實驗可觀察到入射光通過2 μm的多道狹縫結構後，在金屬膜上形成週期性的光學干涉條紋，且亮紋間的間距約為1.74 μm。

關鍵字

金屬狹縫 ； 近場光學

並列摘要

We successfully fabricate gold-coated optical fiber probes with apertures of around 60 ~ 150 nm and corresponding relative optical throughputs of 10-9 ~ 10-3. The correspondence between the relative optical throughputs and the aperture diameters carefully determined by scanning electron microscopy has been found quite consistent. As a result, the relative optical throughput of a fiber probe can be used conveniently for the determination of the aperture size.
The atomic force microscopy nanomachining technique developed in our lab is used to fabricate samples with metal slits of tens to hundreds of nanometers. Optical lithography is also used to fabricate samples with multiple metal slits of 2 μm and 10 μm. Finally, the near-field optical images of the prepared samples illuminated by a 532 nm green laser are obtained by using a near-field scanning optical microscope. The serial analysis of the metal slits contributes a lot to the applications for the near- field optical bio-scanner and the metal mask in the lithography technique.
The results show that the optical interference phenomenon analogous to the single-slit diffraction can be observed when the size of the nano-slit is approximately or a little wider than the wavelength of the incident optical wave. And the distance between the bright lines is about 1.8 μm. Whereas the phenomenon can’t be observed when the size of the nano-slit is narrower than half of the wavelength of the incident optical wave. And the periodic optical interference fringe can be observed after the incident optical wave passed through the structure of 2 μm wide multiple slits. And the distance between the bright lines is about 1.74 μm.

並列關鍵字

metal slit ； near-field optical microscopy

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