AVS 46th International Symposium
    Plasma Science and Technology Division Thursday Sessions
       Session PS1-ThA

Paper PS1-ThA6
Process Optimization of Plasma Polymerized Resists for Advanced Lithography Applications

Thursday, October 28, 1999, 3:40 pm, Room 612

Session: High Fidelity Pattern Transfer
Presenter: O. Joubert, CNET/CNRS, France
Authors: O. Joubert, CNET/CNRS, France
C. Monget, CNET France Telecom
L. Vallier, CNET France Telecom
T.W. Weidman, Applied Materials
Correspondent: Click to Email
CVD photoresist processes based on the plasma polymerisation of organosilane precursors such as methylsilane or dimethylsilane are currently investigated as a technique to extend 248 and 193 nm lithography. Upon exposure to UV light in air, these materials are oxidized generating areas which become more etch resistant to halogen based plasma than unexposed areas, providing a versatile approch to negative tone processes. Films have been deposited in a DXZ chamber from Applied Materials dedicated to dielectric deposition. Exposures have been performed using 248 nm (ASML /300) and 193 nm steppers (ASML /900 and Exitech microstepper). Film development was performed in high density plasma sources using mixtures of Cl@sub 2@, HBr and O@sub 2@. In all cases, developed CVD resist images are transferred through 500 nm of hard baked organic resist using SO@sub 2@/O@sub 2@ gas mixtures. This work reports the lithographic performance at 248 and 193 nm obtained with these dry resists (resolution down to 0.18 µm L/S at 248 nm and 0.13 µm L/S at 193 nm is achieved). Photosensitivity of the films, which can be tuned using the deposition parameters is strongly correlated to the film structure and density. In particular, FTIR analyses show that the photosensitivity increases with the methyl groups content, which favors an increase of the oxygen permeability in the film. The plasma development step is the most critical step of the process since the most serious issues in the dry lithographic process to achieve a good CD control across the wafer. Etch process parameters such as selectivity and uniformity are the more relevant parameters to control the final line width and profile before transfer into the underlaying organic layer. The performance and limitations of the all dry CVD process will be presented. @FootnoteText@ @footnote 1@ This work has been carried out within the GRESSI Consortium between CEA-LETI and France Telecom-CNET