單晶矽場發射結構之研製和特性分析

Abstract

近年來，結合了真空管與半導體元件的優點，真空微電子已經引起莫 大的注意。在這新領域中，最重要的關鍵就是高效率冷陰極之製造。 為了實行低場電子發射的場發射陣列，除了降低場發射元件的微小尖端半 徑外，我們更研究了降低表面功函數的材料。 在此篇論文中，為了增 加低電壓操作和發射之穩定度，我們利用微波電漿化學氣相沉積法 (MPCVD)，在矽尖錐基板上均勻的沉積多種不同的碳膜，其中包括多晶鑽 石膜、類鑽石膜、類石墨碳膜。經由電流電壓和材料的特性和分析，可證 實了碳膜沉積表面的效果。在更進一步分析中，我們亦製造了加磷和硼的 鑽石塗佈矽尖端，以便增強電子發射。再者，在低壓下（小於15 Torr ） ，我們也利用了偏壓輔助孕核（ＢＥＮ）方法成功的得到一極尖的碳化矽 尖端。不同的沉積壓力和不同的CH4/H2之反應氣體流量比在場發射特性中 也已經研究。此技術將可滿足平面顯示器所需之低溫，大面積和妥適性的 沉積。 在考慮發射的穩定度上，藉由選擇性的沉積在方的和楔形的洞 中，我們發展出一種新穎的方法，在不同形狀下製造出環狀的鑽石發射器 ，藉由此新技術，我們發現這些新穎的結構在穩定度和可靠度上要比其它 鑽石塗佈的矽尖端來得優越。除了微小尖端的製造外，用一種新的自我對 準技術，我們已經成功的製造出具有深次微米之閘極開口之場發射三極體 。更進一步，我們開發了另一種利用反蝕刻的技術以降低閘極化元件的閘 極到陰極基板間之電容的新製程。 Vacuum microelectronics has recently attracted much attention because of combining the advantages of both vacuum tubes and solid-state semiconductordevices. The key issue of this new field is the fabrication of high efficientcold cathode. Exception for tip radius reduction, another approach to impleme- nt the field emitter arrays (FEAs) capable of low-field electron emission isthe application of low work function material. In order to enhance both the low-voltage operation and emission reliabil-ity, in this thesis, various carbon films includingve been uniformly depos-ited on the sharp Si tips using microwave plasma chemical vapor deposition(MPCVD). Both electrical and material properties were characterized and anal-yzed in details to survey the effects of carbon-based surface coatings. More- over, the P-doped and B-doped diamond-clad silicon microtips were also fabri-cated to further enhance electron emission from diamond coating. Furthermore, ultra-sharp carburized Si microtips were successfully formedbased on bias-enhanced nucleation (BEN) under low pressure (< 15 Torr). Effectsof deposition pressure and reactive gas flow ratio of CH4/H2 on the emissioncharacteristics were also investigated. Advantages of low temperature, largearea and conformal deposition, make them desirable for the application onflat-panel display. Considering the reliability issue, a novel fabrication method of ring-shapeddiamond emitters with different geometries were developed by selectively depo-siting diamond films on the square holes and trenches. It is found that theemission stability and reliability of these novel structures were superior toother diamond-clad Si tips. In addition to fabricate the pure field emitters, the gated field emitterarrays (GFEA) with deep- submicron gate aperture have also been successfullyfabricated using a new self-aligned process. Furthermore, a new self- aligned fabrication method based on etching-back techniques has been developed to forma GFEA with a larger gate-emitter distance.