運用分子自我組裝在矽晶片上-微影圖形製作與化學感測器之應用研究

Abstract

在最近研究報告中，利用分子自我組裝的技術被寬廣的運用在許多的領域，尤其是在分子元件、奈米元件和生物科技上的運用，但是我們知道在許多的應用當中不管是被運用在電子、化學或生物感測器、顯示器、或著是生物晶片上，皆需要創造微影的圖案在不同的表面上。因此如何去對分子自我組裝的薄膜製作出圖案將會是未來重要的一個方向，特別是當尺寸縮小到次微米或奈米尺寸時。而在單分子層之領域中烷基矽化合物或芳香基矽化合物之單分子層是最常被拿來當作一種奈米光阻層之運用，如本論文所研究之十八個烷基三氯矽化合物(OTS)和八個烷基三乙氧基矽化合物(OTES)，由於單分子層光阻在厚度上遠低於傳統的高分子光阻層，故在曝光顯影後具有良好的圖形轉移的效果，也因此常被運用在奈米等級微影上。而另一方面為末端一胺基或醇基矽化合物之單分子層則常被拿來當作一連接者(或初始物)來連接生物分子、奈米粒子或奈米碳管等等，如本論文所研究之3-胺基-丙烷基-三乙烷氧基矽化合物(APTS) 。但由於分子自我排列所形成的單分子層，會因所製備的條件和環境不同所產生的結果也不同如鍵結在晶片上密度不同和結構上的不同（單分子層、次分子層），而單分子層鍵結在晶片上之密度，特別對被使用在光阻上之運用，將會有很大的影響。 因此在本篇論文研究中，我們的焦點首先放在運用不同製備分析方法，來製備十八個烷基三氯矽化合物(OTS)並與末端為乙氧基之八個烷基三乙氧基矽化合物(OTES)利用化學蝕刻的方式來測試在晶片上的鍵結密度相比較並探討其光阻之可用性，最後在討論製備分析3-胺基-丙烷基-三乙烷氧基矽化合物(APTS) 第二部分我們則放在上運用電子直寫和掃瞄式探針微影技術來對分子我組裝薄膜製作出二維圖案，並將3-胺基-丙烷基-三乙烷氧基矽化合物(APTS)和奈米金球選擇性的鍵結在其微影的地方，在這部分我們已成功的製作出次微米到奈米尺寸。第三部分將其上面的技術整合到我們所設計的薄膜電晶體感測元件表面上。作為其pH值的感應研究，3-胺基-丙烷基-三乙烷氧基矽化合物修飾在元件傳導層上，其末端為一胺基的有機團修飾在元件表面上時，因元件內的載子傳導率會隨著其元件上所修飾之分子末端在溶液會發生去質子化或質子化改變而與pH值有相當關係，作為感測之原理，另一方面選用了烷基矽化合物當作其光阻修飾在元件表面上（不包括元件上的傳導層）來作為隔絕溶液中的離子，另一方面用來製作一模板將3-胺基-丙烷基-三乙烷氧基矽化合物 和奈米金球選擇性的鍵結在元件的傳導層上。 最後我們完成製作薄膜電晶體pH值感測元件.雖然有些結果不是我們最後可預期的，像是運用探針陽極氧化方法在元件來製作圖案是不太可行，因為此方法底材必須為導體或半導體材料，而元件上多了一絕緣層的影響之下使其氧化的效果不大，只有一些機械刮除分子層的效應，結果造成3-胺基-丙烷基-三乙烷氧基矽化合物的鍵結在元件上的密度很低，進而影響金球少量的吸附在多晶矽傳導層上，最後pH元件的製作是直接整個表面接上APTS與金球來做量測，而在不同pH值下，其電性量測結果皆沒有一良好的規律性，當然造成原因有很多種，不過在我們的討論中，其元件尺吋與結構之設計 (敏感性)和量測的方法所影響之電性效應;遠大於元件表面單分子層的影響，但在這過程中;我們也學到了一些經驗，像是分子自我組裝技術製備與分析，運用電子直寫和掃瞄式探針微影技術來對分子自我組裝薄膜製作出一二維之奈米模板，和一些量測電性方法與元件的設計。

In recent research reports, self-assembled monolayer (SAM) has been studied in many filed , especially in molecular device、nanodevice and biotechnology. As we know many applications in electronic, chemical or biosensor, display, or biochip almost requires the two-dimensional pattern for different substrates. Therefore how to pattern the SAM, especially the feature size down to sub-micron or nano-scale, would become a more and more important direction for the future. The alkyl silane and aromatic silane are typical used as nanoresist for SAM application, such as Octadecyltrichlorosilane (OTS) and Octyltriethoxysilane(OTES) in this thesis studying. The SAM’s resist usually has a good pattern transfer property after developed. Because it is thinner than typical polymer resist and it’s also suitable used in nanolevel lithography. On the other hand, the terminal with amino or hydroxyl groups of SAM are often used as linker (or precursor)for bonding or absorbing the biomolecular 、nanoparticle、or carbon nanotube….etc, such as 3- Amino-propyl triethoxy silane(APTS) in this thesis studying. But the packing density and structure (monolayer or sub-monolayer) of SAM on silicon may have variety changes by different conditions of prepared mode and surroundings, especially it may stronger effecting used as resist for application. Due to that, in this thesis, we firstly focus on choosing the different prepared mode by self-assembly OTS on silicon and compare the OTES using the chemical etch to test their packing density and also study the reliability for the resist application. And finally we will also discuss the prepared mode and analysis of APTS. The second part we will focus on using the E-beam writer and Scanning Probe Microscopy (SPM) lithography to pattern the SAM. After the pattern transfer, it will further selectively immobilize APTS and gold nanoparticle on the pattern region. In this part, the sub-micron to nanoscale pattern of gold nanopareicle has been developing. Integrated the above techniques on our design thin film transistor (TFT) for pH sensor was in the third part. The tail of amino group of APTS, it’s behavior exhibit like pH-dependent conductance that change when surface charge during protonation and deprotonation in solution. In the other hand, the Alkyl silane is used as the resist and modifies on sensor surface (except channel) for isolating the charge affecting and further pattern the APTS and gold nanoparticle. Using the SPM lithography create 2-D patterns on TFT device, the result is not well. Because the substrate must be conductor or semiconductor by this way, but there is a insulator to effect oxidation on device, so it only see some mechanical scrape the monolayer, resulting the APTS packing density on poly-Si channel is very weaker and further effecting the gold nanoparticle absorb on poly-Si surface. Therefore the pH –sensor fabricate, in here, it is direct modify of APTS and gold nanoparticle on overall device. But there are very random results of electricity measurement by different pH detection. There are many factors may possibility effecting of the detection. But the dimension and structure of device and measurement may stronger effect the pH detection and it’s also more than surfaces modify the SAM effecting of our discussion. But we also learn something in this study, like prepare and analyze the SAM, and using the SPM or E-beam techniques pattern the monolayer, electronic device measurement, and design of electronic device.