矽奈米草陣列的表觀楊氏係數量測及量測誤差分析

Abstract

國立交通大學工學院精密與自動化工程學程 摘要 奈米草為長條形的奈米結構，材質由純矽構成，使用乾式蝕刻來製作純矽的奈米草陣列，利用高密度電漿化學沉積HDP VCD，不使用任何的硬質罩幕，單純用氫氣作蝕刻氣體，製作出高細長比的奈米草，再以奈米壓痕儀進行機械性質的分析，奈米草的硬度、楊氏係數、挫曲特性、負載－壓深曲線（Loading Displacement Curves）的量測並利用掃描式電子顯微鏡（SEM）及穿透式電子顯微鏡（TEM）及聚焦離子束顯微鏡（FIB）觀察其結構和分析誤差大小。 奈米草已有許多研究，如利用場發射技術，將奈米草當背光源、多層金屬連線結構、太陽能電池，但目前研究大多集中奈米材料性質電性、物理、化學性質探討，很少研究奈米草機械性質或是現有設備量測是否有誤差，奈米草的應力應變行為或是變形破壞時所需的能量。 本研究以奈米壓痕儀及光學顯微鏡分析並配合力學公式，分析壓印奈米草陣列時的行為反應，從中找尋錯誤並修正，結果顯示奈米壓痕儀或是原子力顯微鏡所測出的材料的楊氏模數有二倍的誤差，原因是壓印子的形狀、柱狀排列的材料、奈米草間隙、機械本身變數的所造成，因此未來如要量測一維材料的機械性質，必須建立一套新的量測標準，而非以現有的壓印設備技術量測。

Nanograss is a long strip-shaped nanostructure composed of pure silicon. It is created through the use of dry etching in manufacturing pure silicon nanograss arrays, with high density plasma chemically depositing HDP VCD, without the use of any hard masks. Hydrogen is used as the dry etching gas in order to manufacture long and thin nanograss. Then, nanoindenters are used to perform mechanical property analysis ,measuring the hardness, Young’s modulus, buckling characteristics, and loading displacement curves .And the error between the measurement and the structure observed through SEM, TEM, and FIB are compared. There have already been numerous studies on nanograss, such as the use of nanograss as background lighting, multi-layered metal connection structures, and solar-powered batteries in multi-field emission technology. However, the majority of studies have focused on the electric, physical, and chemical properties of nano-materials, and very few study the mechanical properties of nanograss, whether or not there are errors in equipment measuring, the stress and strain behavior of nanograss, or the energy necessary for deformation and destruction. This study uses nanoindenters and optical microscopes for analysis in conjunction with mechanical formulas to analyze the behavior of nanograss arrays when indented, and searches for errors and corrections. The results show that materials measured by nanoindenters or atomic force microscopes have a Young’s modulus of two times the value as calculated directly from nanoindenter due to the shape of imprints, cylindrically arrayed materials, nanograss gaps, and mechanical variables. Thus, a new measuring standard needs to be established in future measurements of mechanical properties of materials instead of current imprinting technology measuring.