以空氣作為介電質在超大型積體電路上的應用

Abstract

在本篇論文中，我們提出一種以空氣作為金屬線間介電質的製程方法。以空氣作為介電質可以得到較低的電容質，以得到較快的元件操作速度。在製程上，則有幾個重要的關鍵要注意；一個是HSQ會借由表面張力而填入金屬線間的空隙，另一個則是把金屬線跟polyimide分開會遇到HSQ被剝落的情形。除此之外，對於把空氣應用到積體電路製程上，仍然有幾個問題要注意，這包括結構的機械強度、絕緣性以及導熱方面的問題。我們將會逐一討論，並且提出改進的方法。

In this thesis, we develop a novel process to fill the interconnect space with air to lower the intralevel capacitance. We can prevent the space from filling with HSQ by increasing the fluid velocity of HSQ. Another key point to form the air gap is the separation of metal lines from polyimide. We could use the backside bake to increase the adhesion between HSQ and the metal lines. Mechanical stability, isolation and the poor thermal conductivity are the potential barrier for introducing air to the IC technology. We discuss these properties and use some method to improve the performance. English abstract II Acknowledgment III Contents IV Table caption V Chapter 1 introduction 1 Chapter 2 The The Formation of air gap 3 2-1 The NURA Process 2-2 Air Gap Formed during SiO2 Deposition Chapter 3 Device Fabrication and Process Flow 6 3-1 Metal Line Fabrication 3-2 Beetle Pad Fabrication 3-3 The Basic Material Characteristic of HSQ 3-4 The Process of Air Gap Formation 3-5 The Process of Via Formation Chapter 4 Results and Discussion 10 4-1 Process Issues 10 4-1-1 Fluid Mechanics 4-1-2 Uniformity Issues 4-1-3 The Separation of HSQ from Polyimide 4-2 Relibility Issues 14 4-2-1 The Mechanical Stability 4-2-2 The Isolation Property 4-2-2-1 Townsend’s Breakdown 4-2-2-2 The Dielectric Breakdown 4-2-3 The Conduction Capability of Air 4-3 The Advantages of Our Process 19 Chapter 5 Conclusion 22 Reference Tables Figures Resume