Paper EM-TuA1
Interface Engineering of Porous and Non-Porous ILD Layers Using Molecular Layer Deposition for Interconnect Applications

Tuesday, October 30, 2012, 2:00 pm, Room 009

As the dimensions continue to scale in interconnect processing, having a stable and controlled interface between the metal line and the dielectric material becomes more and more important. Molecular Layer Deposition (MLD) has been investigated as a method of growing thin films on dielectric surfaces which act as metal barriers, as blocking layers and as adhesion promoters. The advantage of MLD growth over conventional self-assembled monolayer (SAM) processing is the ability of MLD to easily grow films of varying thickness with tunable chemical functionality.

In this paper, we will discuss the growth and thermal stability of poly-urea-based MLD thin films on both porous and non-porous Carbon Doped Oxide (CDO) dielectric surfaces and compare this work to similar MLD films grown on conventional SiO₂. A variety of characterization techniques, including thermal stress test, secondary ion mass spectrometry, x-ray photoelectron spectroscopy, and electron microscopy, were used to determine film composition, film stability, film adhesion, and degree of penetration into porous substrates. We investigate the importance of surface preparation on the anchoring of MLD films to CDO surfaces. Surface preparation is especially important when growing controlled layers on the surface of a porous dielectric, and we show that surface treatments influence the depth of penetration of the MLD film within porous CDO. Finally, we examine the deposition of thin metal films on top of MLD coated CDO layers (both blanket and patterned) and we show that the metal deposition process impacts both the MLD stability and the metal penetration into the ILD.