AVS 53rd International Symposium
    Plasma Science and Technology Wednesday Sessions
       Session PS2+TF-WeM

Paper PS2+TF-WeM11
Methods of Producing Plasma Enhanced CVD Silicon Nitride Thin Films with High Compressive and Tensile Stress

Wednesday, November 15, 2006, 11:20 am, Room 2011

Session: Plasma Deposition
Presenter: M.P. Belyansky, IBM Microelectronics
Authors: M.P. Belyansky, IBM Microelectronics
N. Klymko, IBM Microelectronics
A. Madan, IBM Microelectronics
M. Chace, IBM Microelectronics
S. Molis, IBM Microelectronics
P.A. Ronsheim, IBM Microelectronics
J. Kempisty, IBM Microelectronics
A. Mallikarjunan, IBM Microelectronics
Y. Li, IBM Microelectronics
Correspondent: Click to Email
High stress plasma enhanced chemical vapor deposition (PECVD) films are becoming an integral part of the state-of the-art metal oxide semiconductor field effect transistor (MOSFET) technology. Generation of a uniaxial strain in a silicon channel is shown to substantially increase device speed, which is achieved by an application of high stress tensile or compressive silicon nitride (SiN) films leading to either electron or hole mobility enhancement respectively. Various methods of generating high stress in thin PECVD SiN films are discussed. Besides the mainstream variation of plasma power and other process parameters, novel techniques of stress build-up in thin films like creation of specific types of interfaces and multilayer structures by PECVD or exposure of SiN films to ultraviolet (UV) radiation are reported. Thin PECVD SiN films (about 50nm) have been analyzed by a variety of analytical techniques including Fourier Transform Infrared Spectroscopy (FTIR), X-ray reflectivity (XRR), Secondary Ion Mass Spectrometry (SIMS) and Rutherford backscattering (RBS) to collect data on bonding, density and chemical composition. Mechanisms of stress formation in both compressive and tensile SiN thin films are discussed. Level of bonded hydrogen as well as film density has been found to correlate with film stress. Interface formation and creation of a multilayer structure helps to build up more stress compared to a standard single layer film deposition. Both the density and number of interfaces in a film, characterized by XRR, affect the stress. Exposure of multilayer SiN films to elevated temperature results in a loss of a well-defined interface structure and leads to the predictable increase in tension and degradation in compressive stress. Interface composition and barrier properties of multilayer films are discussed. Effect of UV radiation exposure on PECVD SiN and the resulting increase in film tensile stress is also delineated.