AVS 46th International Symposium
    Plasma Science and Technology Division Wednesday Sessions
       Session PS-WeA

Paper PS-WeA8
High Density Plasmas Etching of Low Dielectric Constant Materials

Wednesday, October 27, 1999, 4:20 pm, Room 609

Session: Dielectric Etching
Presenter: D. Fuard, CNRS, France
Authors: D. Fuard, CNRS, France
O. Joubert, France Telecom-CNET and CNRS
L. Vallier, France Telecom-CNET and CNRS
Correspondent: Click to Email
The etching step remains one of the key technological issue for low K integration in advanced CMOS technologies. We have studied the etching mechanisms of SiO@sub2@ masked fluorine free aromatic hydrocarbon polymer. Experiments are performed in a high density plasma helicon source operated at low pressure. Previous work has shown that the SO@sub2@/O@sub2@ chemistry, even if suitable for a good profile control, induces the formation of sulphur-based acids which may generate corrosion latter in the process. In this paper, we present results using sulphur free chemistries based on N@sub2@, H@sub2@ and O@sub2@. First, we have used X-Ray Photoelectron Spectroscopy (XPS) analyses to understand the etch mechanisms of the polymer. XPS analyses reveal that under high energy ion bombardment conditions, the polymer structure is strongly graphitized : C1s binding energy originating from the polymer shifts from 285 to 283.5 eV. The graphitization phenomenon is also dependent on the chemistry used. Without changing the plasma operating conditions, very reactive chemistries, such as pure O@sub2@, prevent the polymer graphitization whereas adding N@sub2@ to O@sub2@ may lead to a severe graphitization by decreasing the chemical component and favoring the physical component of the etch. Using appropriate gas mixture and plasma operating conditions, high aspect ratio contact holes are etched with a good profile control. XPS analyses of the etched structures reveal that the passivation layer formed on the polymer sidewalls is also strongly graphitized, suggesting that the passivation layer originates from the etch products. Some results obtained in other high density plasma tools using identical chemistries will be presented and general conclusion on polymer etching in high density plasmas will be drawn. @FootnoteText@ @footnote 1@ This work has been carried out within the GRESSI Consortium between CEA-LETI and France Telecom-CNET