中文摘要

本論文之目的在於製作Sn cap及SiNx cap/Cu/Ta/SiO2 air-gap damascene structure及討探電遷移機制，其中包括電鍍銅、擴散阻障層Ta、犧牲層HSQ以及Sn鍍製的製程整合。
在Sn cap方面，以Immersion plating技術能夠選擇性的沈積錫於銅膜上，進一步以Auger、GIAXRD了解 Sn薄膜成份，以AFM量測Sn薄膜表面平整度。
在犧牲層(sacrificial layer)方面，以旋轉塗佈的方式將HSQ(hydrogen silsesquioxane，precursor : Fox15)和MIBK比例為2:1塗佈在晶圓上，來得到所需的膜厚，在預烤3500C 3分鐘後將cage-network-like HSQ浸泡在BOE溶液內可由SiO2與其界面間快速被去除，為一個良好的犧牲層。
在化學機械研磨(CMP)方面，銅平行導線其width/space為0.6/0.6μm以Al2O3顆粒0.05μm、HNO3、Citric Acid的銅研磨液分別以不同正/背壓(D.F/B.P)= 5.0/4.0、4.0/3.0、3.0/2.0 psi來移除銅，之後以Silica Levasil 50CK 、H2O2 及 H2O配合D.F/B.P =3.0/2.0來移除Ta，並以SEM觀察研磨結果，找出其最佳研磨條件。
將犧牲層HSQ、擴散阻障層Ta和有電極電鍍銅配合化學機械研磨及immersion plating的技術完成SiNx cap及Sn cap air-gap Cu damascene平行導線結構，在電遷移量測方面，將SiNx cap及Sn cap air-gap 銅導線樣品置於溫度為1750C、定電流密度為4*106 A/cm2、壓力為2mtorr下進行電遷移量測，發現Sn cap air-gap銅導線的lifetime比SiNx cap air-gap銅導線的lifetime長了約4.5倍左右。為了了解Sn cap air-gap 銅導線電遷移發生時之活化能，因此將其置入不同的溫度分別為1500C、1750C、2000C量測電遷移，找出Sn cap air-gap銅導線電遷移發生之活化能為(activation energy Ea) 1.07 ev。

Abstract

The fabrication of Sn cap and SiNx cap Cu/Ta/SiO2 air-gap damascenes structures which includes the integration of electroplating copper, diffusion barrier Ta, sacrificial layer HSQ and capping layer Sn is the main goal in this thesis. The electromigration on this single damascene structure is also investigated.
We developed the selective immersion plating Sn on copper, use Auger、GIAXRD to examine the composition of Sn thin film, and use AFM to measure the surface Morphology of Sn film. We mixed HSQ with MIBK at ratio=2:1 and spun it on SiO2 substrate. The HSQ film with pre-bake temperature 350℃ 3min is a good sacrificial layer. The cage-network-like HSQ can be removed by BOE solution easily from the interface with SiO2.
Cu interconnect lines with width/space = 0.6/0.6μm deposited on Ta barrier layer are under chemical-mechical polished by using Al2O3 0.05μm particle with mixture HNO3 and Citric Acid , down force/back pressure varying 5.0/4.0、4.0/3.0、3.0/2.0 psi to remove Cu and by using Silica Levasil 50CK with H2O2 and H2O, D.F/B.P =3.0/2.0 to remove Ta. From the SEM pictures, We determine the best CMP conditions.
Final, the Sn cap and SiNx cap Cu air-gap damascene structures with diffusion barrier Ta , sacrificial layer HSQ and capping layer Sn were fabricated. Sn cap and SiNx cap samples were studied by electromigration tests at 1750C with a current density of 4*106A/cm2, at pressure of 2 mtorr. The electromigration lifetimes for Sn cap air gap Cu interconnect lines were found to be longer than that of SiNx cap air gap Cu interconnect lines about 4.5 X. In order to determine the activation energy of electromigration, we measured the I-V under current stress at varying temperature with 1500C、1750C、2000C. The activation energy for Sn cap air-gap Cu interconnect lines is found to be 1.07eV.

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