AVS 57th International Symposium & Exhibition
    Plasma Science and Technology Thursday Sessions
       Session PS+TF-ThM

Paper PS+TF-ThM4
Role of PEALD System Plasma Source Operation on Substrate Ion Bombardment and the Impact on HfO2 and TiN Film Properties

Thursday, October 21, 2010, 9:00 am, Room Galisteo

Session: Plasma Deposition and Plasma Enhanced ALD
Presenter: M.J. Sowa, Cambridge NanoTech, Inc.
Authors: M.J. Sowa, Cambridge NanoTech, Inc.
G.M. Sundaram, Cambridge NanoTech, Inc.
E.W. Deguns, Cambridge NanoTech, Inc.
R. Bhatia, Cambridge NanoTech, Inc.
M.J. Dalberth, Cambridge NanoTech, Inc.
A. Bertuch, Cambridge NanoTech, Inc.
G. Liu, Cambridge NanoTech, Inc.
J.S. Becker, Cambridge NanoTech, Inc.
Correspondent: Click to Email
Plasma enhanced atomic layer deposition (PEALD) has seen increased interest in recent years. Replacing one of the half cycles of the ALD process with a plasma generated radical dose has been successfully demonstrated to improve film electrical properties, improve deposition rates, enable lower temperature processing, and enable the use of precursors unsuitable for thermal processes. It is typically advantageous to operate the plasma source of PEALD systems in a “remote” mode, such that the substrate being processed does not have any exposure to energetic charged species. Rather, the longer-lived radicals generated in the remote plasma source react with the chemisorbed precursor from the previous half-cycle to form the desired film. Exposure of the substrate to energetic ion bombardment during the plasma half cycle has been demonstrated to lead to decomposition of the chemisorbed precursor which gives thick, non-uniform films with poor electrical properties. We have observed that, depending on the processing conditions utilized for generating the plasma, the plasma may be confined to the remote plasma source or may extend into the ALD processing reactor to varying degrees. The remote plasma source on our system is an inductively coupled plasma design consisting of a cylindrical quartz tube surrounded by a water-cooled copper inductor. We have investigated the quality of HfO2 and TiN films grown in our PEALD system with various, controlled levels of substrate ion bombardment. Up to 300W of 13.56MHz rf is coupled to the copper inductor through an L-type matching network. Plasma gas mixtures of Ar with commonly used PEALD gases, O2 or N2, over a wide range of flow rates and pressures were investigated. We have quantified the encroachment of the plasma into the ALD reactor through the placement of Langmuir probes on the surface of a 200mm substrate which is placed onto the heated substrate holder of our PEALD system. We then deposited films of HfO2 with tetrakis(dimethylamino)hafnium and Ar/O2 plasmas and TiN with tetrakis(dimethylamino)titanium and Ar/N2 plasmas at various levels of substrate surface bombardment. Resulting films were evaluated for stoichiometry, impurities, crystallinity, and relevant electrical properties including dielectric constant and leakage current for the HfO2 and resistivity for the TiN.