International audienceThe authors conducted a physico-chemical analysis of tensile sequential-nitrogen-plasma-treated silicon nitride films, which function as stressor liners in complementary metal oxide semiconductor (CMOS) technologies. These films are made of stacked nanometer-thick, plasma-enhanced, chemical vapor-deposited layers which were individually treated with N(2)-plasma, to increase stress. This study allowed us to monitor the evolution of the films' chemical composition and stress as a function of process parameters such as deposition and post-N(2)-plasma duration. Consistent with secondary ion mass spectroscopy (SIMS), transmission electron microscopy (TEM) and other physico-chemical analysis results, it was shown that the elementary component of the films can be modeled with a bi-layer consisting of an untreated slice at the bottom that is covered by a more tensile post-treated film. In addition, we observed that longer plasma treatments increase residual stress, SiN bond concentration and layer density, while reducing hydrogen content. The stress increase induced by the plasma treatment was shown to correlate with the increase in SiN bonds following a percolation mechanism that is linked to hydrogen dissociation. Kinetics laws describing both SiN bond generation and stress increase are proposed and it is demonstrated that stress increase follows first-order kinetics. (C) 2011 American Vacuum Society
Alternative approaches are now required to fulfill the strict requirements of photoresist (PR) dry strip process after high-dose implantation. A better understanding of the PR degradations induced by the ion bombardment during the implantation is thus required. In this study, in-depth characterizations of PR films after arsenic and phosphorus-high-dose implantation have been made. The influence of the dopant species (As or P) as well as the implantation energy has been investigated. The experimental results have then been confronted to simulations performed with stopping and range of ions in matter (SRIM). The experimental results show the formation of a “crust layer” enriched in carbon and depleted in oxygen and hydrogen whose density, hardness, and elastic modulus are higher than the nonimplanted PR (pristine). SRIM simulations confirm that the PR degradation is mainly due to crosslinking phenomenon. Chemical analyses have revealed that the dopants are present in their elemental and oxidized forms in the PR and that they are also linked to the PR carbon atoms. The knowledge of the dopants' chemical environment is key information to understand the presence of residues after dry strip processes and develop alternative processes to avoid their formation.
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