Effects of He Plasma Pretreatment on Low-k Damage during Cu Surface Cleaning with NH3 Plasma

In this study, the effect of the sequential He and NH3 plasma treatments on a chemical vapor deposition SiOC:H low-k dielectric is evaluated in the wide range of experimental conditions. Results show that the active NH3 plasma radicals penetrate the porous low-k bulk and remove the hydrophobic Si-CH3 groups, which leads to hydrophilization and results in the degradation of dielectric properties. The implementation of He plasma pretreatment reduces the damage imposed by the NH3 plasma by a stimulation of the surface recombination of active radicals from NH3 plasma. He plasma causes a surface modification of 10-20 nm presumably due to the energy transfer from the extreme UV photons and the 2(1)S He metastable atoms to the low-k structure. The plasma damage reduction is proportional to He plasma density and the treatment time. The mechanism of plasma damage reduction is explained on the basis of the Knudsen diffusion mechanism and random walk theory.status: publishe

Integrated diffusion-recombination model for describing the logarithmic time dependence of plasma damage in porous low-k materials

This work proposes an extended model that describes the propagation of damage in porous low-k material exposed to a plasma. Recent work has indicated that recombination and diffusion play a more dominant role than VUV light [1-5] in oxygen plasma induced damage. Especially at low depths, the radical concentration is determined by the number of radicals that disappear back into the plasma while the final depth of damage is defined by recombination of oxygen atoms. A logarithmic equation has been proposed to describe the behavior as a function of time. In this work this equation is extended to take diffusion into account, next to recombination. The results are in agreement with experimental data and one-dimensional random walk theory calculations. (C) 2010 Elsevier B.V. All rights reserved.status: publishe

Mechanism of k-value Reduction of PECVD Low-k Films Treated with He/H2 Ash Plasma

The over-ash effect of He/H2 downstream plasma on various low-k materials (k = 2.3 – 2.5) is studied. The results show reduced k-value for PECVD materials. The k-value reduction mechanism of PECVD low-k materials is found to be a result of two competing phenomena: porosity increase (due to porogen residue removal) results in k-value reduction while minor silanol group incorporation results in k-value increase. Furthermore, it is shown that the k-value of the PECVD films with a lower porogen loading (k~2.5) can be reduced by the He/H2-DSP over-ash without a degradation of their mechanical properties.Conference internet page: https://imec-events.be/show-homepage?collection=76&currentpage=page_4 Presentation published online: https://imec-status: publishe