臺灣博碩士論文加值系統

由於黃金不論在物理性質(如:電性)或機械性質上都具有良好特性，所以GaAs元件上的電鍍大多以黃金為主。好的電鍍金品質，將可使黃金的高導電性，抗氧化性及延性等優點發揮極致。
在假晶性高電子遷移率電晶體 (Pseudomorphic High Electric Mobility Transistor， PHEMT)製程中，我們便利用電鍍金作為M1及M2金屬層。在整個電鍍過程中，我們發現影響粗糙度與均勻度最甚的參數為電流密度，並且利用修正電流量及正確的電鍍面積，即可達到所需電鍍厚度。除此之外，隨著電流密度的增加，將導致較差的粗糙度與均勻度，較大的電鍍液通量可得到較佳的均勻度,但其對粗糙度無顯著的影響,而在電鍍前加上Descum (一種電漿清潔的過程)的步驟，即可消除金薄膜上水紋，氣泡的現象。
利用化學分析電子術 ( Electron Spectroscopy for Chemical Analysis， ESCA)，我們發現在Descum後，會使金表面產生金的氧化物，因而使金表面的片電阻值明顯提昇。然而，昇高的片電阻值又會隨時間的增加回復到原來未Descum前的值，並且靜置溫度越高，則回復成原片電阻值所需的時間越短。除此之外產生的金氧化物亦會隨時間增加而消失 (在室溫下共耗時四天)。

Plating on GaAs devices is almost always gold. Gold has many advantageous properties for electronic components. Gold plates well, have high electrical conductivity, are resistant to oxidation, and are ductile.
In the first stage of our project, we used plating gold to be Metal 1 and Metal 2 in PHEMT process. In order to get good roughness, uniformity and desired target, the aim of this study is to find the important parameters of plating operation. It is well known that plating flow rate and current density are the essential parameters of plating process. However, from this study, we found that the most important parameter affect roughness and uniformity is current density. In addition, we have achieved target by making sure real plating area and correcting plating current. Subsequently, the uniformity and roughness became worth with increased current density while the plating flow rate affected only the uniformity. When the plating flow rate increased, the uniformity was improved. In addition, we have taken step against watermark by using Descum treatment (the kind of plasma cleaning) before plating.
In the second stage of our project, the gold surface was investigated by ESCA after the process of Descum. We found the Au-O compound was produced in the surface of Au and this compound was reduced with the time increased at room temperature. It is interested that the sheet resistance of Au-surface was increased significantly initially and decreased to the original value (before the process of Descum) with the time increased. In addition, the time required for the restoration of the sheet resistance was reduced with the temperature increased.

摘要…………………………………………………………Ⅰ
Abstract ……………………………………………………Ⅱ
致謝……………………………………………………………Ⅲ
Contents ……………………………………………………Ⅳ
List of Tables ………………………………………………Ⅴ
List of Figures ………………………………………………Ⅵ
Chapter 1 Introduction …………………………………………………1
1-1 Background …………………………………………………………1
1-2 Outline ………………………………………………………………5
Chapter 2 Experimental ………………………………………………8
2-1 Wafer preparing and Plating Condition …………………………8
2-2 Watermark Elimination ……………………………………………8
2-3 Desirable Thickness ………………………………………………10
2-4 Improving Roughness (Ra) and Uniformity (%) …………………12
2-5 The relationship between temperature and the time required for the restoration of resistance ……………………………………13
Chapter 3 Conclusion …………………………………………………15
3-1 Experience Conclusion ……………………………………………15
3-2 Bath maintenance …………………………………………………16
3-3 Problem and solution ………………………………………………18
Chapter 4 Future Work ………………………………………………20
References ……………………………………………………59

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