Abstract
Two objectives are involved in the thesis. First, the fabrication of air-gap Cu damascene structure integrated with sacrificial layer HSQ, diffusion barrier TaN, adhesion layer Ta, electrochemical plating (ECP) of copper, and chemical mechanical polish (CMP) is demonstrated. Second, the air-gap formation by HSQ removal through a dielectric cap using MEMS technique is investigated, and the resistivity of copper lines is also studied. HSQ with MIBK at ratio 2:1 was spun on etch stop layer SiNx. The HSQ film pre-baked at 350℃ for 3 minutes was a good sacrificial layer which could easily and quickly be removed from the interface with other dielectric materials by BOE solution treatment. 100□ Ta and 100□ TaN served as the adhesion and diffusion barrier layer, respectively. After trench filling by copper ECP, several CMP parameters were applied to remove unnecessary Cu/Ta/TaN without damaging the samples, and Cu damascene structure was done. Then 4000□ SiNx deposited by PECVD was used as the dielectric cap. Etching windows with 1.5x line width / 2.5μm (window width / window length) on SiNx were formed by RIE with CF4 etchant and separated with 10μm along Cu damascene lines. The air-gap Cu damascene structure will be fabricated by BOE etching process. High resolution OM and SEM revealed the structure. The resistivity of Cu lines was measured by HP 4156A with a probe station and Conductive AFM. The measurement results of the two approaches were discussed in the thesis.