Research On Novel Copper Contact And The Impacts Of Slurry On Low-k Dielectric

As the technology node reduces to32nm and beyond, the RC delay has become the bottleneck for better performance of ULSI. To reduce the RC delay, the advanced Cu contact technology to suppress the influence of R to the RC delay and the impact of CMP slurries on the low dielectric constant material (low-k) to affect capacitance, have been studied.This dissertation first presents results from studies of the thermal stability of Cu contact on the NiSi substrate with Co/TaSiN and Ru/TaSiN barrier stack. The barrier system has good thermal stability. The electrical properties of the Cu/Ru/TaSiN/NiSi/Si system shows that, by introduction of Si thin film between barrier layer and NiSi substrate, the contact has lower leakage current. The better property is credited to the better adhesion between barrier and NiSi due to adding of Si either into the TaSiN or as a single layer. We have made preliminary attempts to measure the adhesion energy of TaSiN/NiSi interface, using4Pt bending test platform.Concerning the reliability of the usage of the low-k material to BEOL process, the effects of acidic and alkaline slurries on the properties of the SiOCH low-k films are studied. After either acidic or alkaline treatment, though the sample surface becomes less hydrophobic, comparable chemical, mechanical and electrical performances were obtained. The reason for the comparable property is that the alkaline treatment was conducted under weak alkaline environment.The impact of pH of a commercial slurry on the low-k samples with different K value (K=2.25, K=2.35) is studied. The sample becomes more hydrophilic after dipping into the slurry. It is due to the loss of the hydrophobic Si-C groups after slurry treatment. Finally, we used the4Pt Bending testing tool mentioned above to examine different adhesion abilities between barrier materials and low-k substrate.