化學電鍍金屬顆粒到矽表面的AFM研究

Investigation of chemical deposition of metal cluster on silicon surfaces

王昶然(Chang-Ran Wang)

指導教授 ： 羅榮立

國立清華大學/理學院/物理學系/碩士(2006年)

https://doi.org/10.6843/NTHU.2006.00389

摘要

摘要
利用化學置換電鍍在Si表面上的還原沉積的金屬粒子團可達到奈米尺度大小，可是置換鍍的氧化還原機制的詳細過程仍不是十分清楚，這方面已有許多相關文獻的研究探討。
本實驗是用原子力顯微鏡AFM來研究還原沉積金屬在Si表面上的性質，如金屬粒子吸附力，不同鍍液對於還原金屬的影響，H-Si與OH-Si表面對於還原反應的影響，以及加熱對於已還原金屬的效應。
我們發現使用不含HF的鍍液所沉積的金粒子吸附力很弱，用去離子水沖洗就可把顆粒沖掉。若使用含有HF的鍍液，則金顆粒吸附力較強，而且比不含HF的鍍液更容易還原沉積在Si上。
我們也發現在親水性OH-Si和斥水性H-Si這兩種不同的表面，OH-Si比H-Si表面更容易還原溶液中金屬離子，這可能與OH-Si表面的親水性質及較高的活性有關，使金屬還原反應更快。還有用含有甲醇的金鍍液也容易使置換還原反應發生，其原因可歸因於甲醇改進H-Si表面的活性。
把用置換鍍法鍍上金屬的樣品，放到真空中加熱到高溫500~600度，發現並不會像物理蒸鍍法一樣發生金顆粒聚集現象。我們還利用Si3N4和SiO2來當作遮罩，使金屬在Si表面的作選擇性還原沉積。最後我們實驗測試是否能用置換鍍法把Ni還原沉積到Si上。

關鍵字

化學鍍 ； 置換鍍 ； 原子力顯微鏡 ； 氧化還原電位

並列摘要

Abstract
Using the plating of galvanic displacement, nanometer-sized noble metal clusters can be grown on silicon surface. Although intensive applications and researches were focused on the issue, the detailed mechanism of galvanic displacement is not completely understood.
We use atomic force microscopy to study the adhesion of reduced metal on silicon substrates, effects of plating solutions and hydrophilicity of silicon surface on plating, and vacuum annealing effect on aggregation of deposited metal clusters.
We found that the adhesion of gold particles reduced in solution without HF is very weak. Being rinsed by de-ionized water, such gold particles can be depleted on the silicon surface. In contrast, the deposited gold particles have stronger adhesion and the reduction reaction is easier to occur when a HF-contained solution is used.
Reduction of metal ions is easier to occur on a hydrophilic OH-Si surface than on a hydrophilic H-Si surface. This may be ascribed to the hydrophilicity of OH-Si surface and its higher reactivity of redox reaction on Si. The methanol-contained solution is also found to enhance the reduction of metal ion. Improvement the reactivity of H-Si by methanol is likely the cause.
Unlike PVD, when the reduced gold clusters is annealed to 500~600∘in vacuum, aggregation of clusters does not happen. We can achieve selective deposition of metal on Si surface by using Si3N4 and SiO2 as mask. Finally, we use galvanic displacement method to reduce Ni on Si surface.

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