Statistical Study of Electromigration Line-width Dependence in Cu/Low-k Interconnects

Journal Article · Wed Dec 08 00:00:00 EST 2004 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.1845849· OSTI ID:20630474

Xia, Lu; Ho, Paul S ^[1]; Lee, Ki-Don ^[2]; Lu, Michael ^[3]

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1. Microelectronics Research Center, University of Texas at Austin, TX 78712 (United States)
2. Texas Instruments Inc., Dallas, TX 75243 (United States)
3. LSI Logic Corp., Gresham, OR 97030 (United States)

Electromigration (EM) remains a major reliability concern due to the aggressive scaling of interconnect dimensions and increasing current density. In addition, the migration towards low k dielectrics poses significant process and reliability challenges. In this work, a statistical approach combined with physical failure analysis using focused ion beam imaging was used to investigate the process-induced effects and EM line-width dependence in a Cu/CVD MSQ low k interconnect. Experiments were performed on structures of 0.175{mu}m, 0.25{mu}m and 0.50{mu}m line widths with two current flow directions. In up-current EM, statistical evidence of bimodal failure obtained with Monte-Carlo simulation was consistent with the presence of both strong and weak modes and verified by failure analysis. The strong mode failure due to trench voiding scaled linearly with line width (via size). No line width dependence was found for the weak mode via failure, which seemed to be controlled by process-related issues. In down-current EM, failure analysis revealed that EM failures were caused by voiding either in M1 under the via or away from the via in M1 trench. The EM lifetime depended on the location of initial void formation and subsequent void growth. However, the two failure modes were not clearly resolved by the statistical approach within the testing temperature range (300 deg. C{approx}350 deg. C). The activation energy was found to be {approx}1.0eV, suggesting that failures were caused primarily by mass transport along the Cu/cap layer interface.

• OSTI ID: 20630474
• Journal Information: AIP Conference Proceedings, Vol. 741, Issue 1; Conference: 7. international workshop on stress-induced phenomena in metallization, Austin, TX (United States), 14-16 Jun 2004; Other Information: DOI: 10.1063/1.1845849; (c) 2004 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ACTIVATION ENERGY
CHEMICAL VAPOR DEPOSITION
COMPUTERIZED SIMULATION
COPPER
CURRENT DENSITY
DIELECTRIC MATERIALS
ELECTRIC CURRENTS
ELECTROPHORESIS
FAILURES
INTEGRATED CIRCUITS
INTERFACES
ION BEAMS
LAYERS
LIFETIME
LINE WIDTHS
MONTE CARLO METHOD
PERMITTIVITY
RELIABILITY
SOLIDS
TESTING
VOIDS