AVS 50th International Symposium
    Thin Films Monday Sessions
       Session TF-MoA

Invited Paper TF-MoA6
Processes and Properties of Porous CVD Low-k Materials

Monday, November 3, 2003, 3:40 pm, Room 329

Session: Atomic Layer Deposition and Low-k
Presenter: Y. Travaly, IMEC / SPDT / ITSMI, Belgium
Authors: Y. Travaly, IMEC / SPDT / ITSMI, Belgium
M. Van Hove, IMEC / SPDT / ITSMI, Belgium
G. Beyer, IMEC / SPDT / ITSMI, Belgium
K. Maex, IMEC / SPDT, Belgium
Correspondent: Click to Email
The aggressive down scaling of device dimensions in integrated circuits requires the introduction of non-traditional materials such as porous CVD low-k dielectrics together with thinner copper diffusion barrier with improved step coverage and conformality along via and trench side walls. This results in a number of concerns with respect to both the low-k film and Cu diffusion barrier to be implemented. Regarding the low-k dielectric, it appeared over the last few years, that not only its electrical properties are of importance but also its compatibility with the process steps encountered in the course of its integration. We therefore identified a number of key properties such as porosity, bulk diffusion of wet chemicals, slurries and barrier precursors, etc. and studied them in relation with surface sealing by plasma treatments, liner deposition or metallic barrier. For the Cu barrier, a number of factors come into play and influence dramatically the interconnect delay (RC delay) especially for the most aggressive pitches. Among these factors, one can easily control the quality of the barrier interface with the low-k or the Cu as well as the minimum barrier thickness. The cross-sectional barrier profile in interconnect appears also to be of prime importance for both RC delay and barrier reliability. To improve the step coverage and minimize the barrier area, we have considered various approaches including a highly conformal atomic layer deposition (ALD) process. However, when used in combination with porous low-k dielectrics, an ALD process gives rise to other issues such as the diffusion and interaction of ALD precursors with the various layers (low-k, hard masks) present in the dielectric stack. We studied these interactions and identified suitable methods to prevent detrimental effects. Ultimately, we studied the reliability of the Cu/low-k system in relation to barrier integrity.