摘要

本論文之重點在於整合SiNx capped Cu/Ta/SiO2 air-gap 銅導線damascene 結構，其中將利用電鍍銅、擴散阻障層Ta、犧牲層HSQ以及佈護層SiNx…等技術來完成銅導線結構。並討論air-gap damascene平行導線的電性特徵(漏電流、崩潰電場)。
在犧牲層HSQ方面，利用旋轉塗佈(spin on)方法將HSQ(hydrogen silsesquioxane，precursor : Fox15)和MIBK以比例2:1塗佈在樣品上，發現在預烤3500C 3分鐘的條件下，將cage-network-like HSQ浸泡在BOE溶液內，HSQ可由SiO2與其界面間快速掀去，故為一個良好之犧牲層。
在化學機械研磨(CMP)方面，定義銅平行導線width/space分別為0.5/0.5μm, 銅研磨漿料以Al2O3顆粒(0.05μm)、HNO3與citric Acid 調製而成，之後嚐試搭配不同正/背壓(D.P/B.P)= 5.0/4.0、4.0/3.0、3.0/2.0 psi來移除銅，最後以Levasil Silica 50CK 、H2O2 及H2O調製而成的Ta研磨漿料，配合D.P/B.P =5.0/2.0 psi來移除Ta膜，並以SEM觀察研磨後的銅導線，找出其最佳研磨條件。
將所有製程技術，包括犧牲層HSQ、擴散阻障層Ta和有電極電鍍銅方法配合化學機械研磨製作出SiNx capped air-gap Cu damascene平行導線結構，在漏電流量測方面，量測不同溫度(室溫、50℃、100℃、150℃、180℃)條件之下平行導線的漏電流，並討論 SiNx capped air-gap Cu damascene平行導線結構的漏電機制，在不同溫度下(室溫、100℃、195℃)量測SiNx capped air-gap Cu damascene平行導線結構的崩潰電場，並由量測到電場強度與SEM照片討論平行導線結構發生崩潰的原因。

Abstract

The purpose of this study is to fabricate the SiNx capped Cu/Ta/SiO2 air-gap damascene structure. It included the integration of the sacrificial layer HSQ, diffusion barrier layer Ta, copper electroplating, and the passivation layer SiNx. The electric characteristic of the air-gap damascene structure was investigated, and discussed the leakage current and breakdown field.
For the sacrificial layer, we spun HSQ with MIBK at ratio=2:1 on SiO2 substrate. It was found that with pre-bake temperature 350℃3min, HSQ was a good sacrificial layer. The cage-network-like HSQ can be removed by BOE solution easily from the interface with SiO2.
For CMP, the Cu lines were defined with width/space = 0.5/0.5μm. The slurry mixed with Al2O3 particle (0.05μm)、 HNO3 and citric acid. The polishing down pressure /back pressure varied 5.0/4.0、4.0/3.0、3.0/2.0 psi to remove Cu film. The slurry for Ta is mixture of Levasil Silica 50CK、H2O2, and H2O. From the SEM pictures, the best CMP condition for the structure can be determined. The optimum D.P/B.P=5/2 psi is applied to remove Ta film.
The SiNx capped Cu/Ta/SiO2 air-gap damascene structure with diffusion barrier layer Ta (150□), the sacrificial layer HSQ and capped layer SiNx (200□) was fabricated. The SiNx capped samples were studied by the I-V measurement. The leakage current measurement was done at different temperature(RT、50℃、100℃、150℃、180℃), and leakage current mechanism can be analyzed. The breakdown electric field was also measured at different temperature (RT、100℃、195℃) and analyzed. The SEM images were taken in order to correlate to the electrical breakdown measurements.

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