AVS 52nd International Symposium
    Electronic Materials and Processing Tuesday Sessions
       Session EM-TuP

Paper EM-TuP27
Remote Plasma-Enhanced Chemical Vapor Deposition of Tantalum Diffusion Barrier

Tuesday, November 1, 2005, 4:00 pm, Room Exhibit Hall C&D

Session: Electronic Materials and Processing Poster Session
Presenter: P.R. McCurdy, Colorado State University
Authors: E.R. Fisher, Colorado State University
P.R. McCurdy, Colorado State University
Correspondent: Click to Email
In recent years, copper (Cu) has become the interconnection material of choice, replacing aluminum (Al) and Al alloys in integrated circuits (ICâ?Ts). Cu is preferred over Al because of its lower resistivity and higher melting point. The lower resitivity is especially important in reducing the resistance-capacitance delay, which becomes dominant as the gate size continues to decrease. Unfortunately, Cu is susceptible to diffusion into SiO2, and suffers from poor adhesion to low dielectric constant materials. Therefore, it is imperative to have a diffusion barrier that can also act as an adhesion layer to integrate Cu into ICâ?Ts. Currently, tantalum (Ta) and Ta nitrides are widely used for this purpose. Ta metal is especially attractive because of its low resistivity; however, because of the ever increasing aspect ratio of metal lines, tradition methods for depositing Ta metal are deficient. Physical vapor deposition is a line-of-sight method that does not work well on high aspect ratio trenches; alternative deposition methods must, therefore, be developed. One potential technique is plasma-enhanced-chemical-vapor-deposition (PECVD). This technique is especially promising for the deposition of Ta in high aspect ratio trenches because it gives extremely good step coverage and can be done at much lower temperatures than traditional CVD processes. We have successfully deposited high quality Ta films using H2 and TaCl5 in a remote PECVD system. Our Ta films show low levels of impurities and excellent step coverage on patterned Si substrates. Data on deposition rate, conformality, film composition, and electrical properties will be presented.