This dissertation constitutes two major sections. In the first major section, a
kinetic analysis was established to investigate the electromigration (EM), enhanced
intermetallic compound (IMC) growth and void formation for Sn-based Pb-free solder
joints to Cu under bump metallization (UBM). The model takes into account the
interfacial intermetallic reaction, Cu-Sn interdiffusion, and current stressing. A new
approach was developed to derive atomic diffusivities and effective charge numbers
based on Simulated Annealing (SA) in conjunction with the kinetic model. The finite
difference (FD) kinetic model based on this approach accurately predicted the
intermetallic compound growth when compared to empirical observation. The ultimate
electromigration failure of the solder joints was caused by extensive void formation at the
intermetallic interface. The void formation mechanism was analyzed by modeling the vacancy transport under electromigration. The effects of current density and Cu
diffusivity in Sn solder were also investigated with the kinetic model.
The second major section describes the integration of Step and Flash Imprint
Lithography (S-FIL®) into an industry standard Cu/low-k dual damascene process. The
yield on a Back End Of the Line (BEOL) test vehicle that contains standard test
structures such as via chains with 120 nm vias was established by electrical tests. S-FIL
shows promise as a cost effective solution to patterning sub 45 nm features and is capable
of simultaneously patterning two levels of interconnect structures, which provides a low
cost BEOL process. The critical processing step in the integration is the reactive ion
etching (RIE) process that transfers the multilevel patterns to the inter-level dielectrics
(ILD). An in-situ, multistep etch process was developed that gives excellent pattern
structures in two industry standard Chemical Vapor Deposited (CVD) low-k dielectrics.
The etch process showed excellent pattern fidelity and a wide process window.
Electrical testing was conducted on the test vehicle to show that this process renders high
yield and consistent via resistance. Discussions of the failure behaviors that are
characteristic to the use of S-FIL are provided. / text
| Identifer | oai:union.ndltd.org:UTEXAS/oai:repositories.lib.utexas.edu:2152/7607 |
| Date | 02 June 2010 |
| Creators | Chao, Huang-Lin |
| Source Sets | University of Texas |
| Language | English |
| Detected Language | English |
| Format | electronic |
| Rights | Copyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works. |
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