Browsing by Author "Chen, Kuan-Chia"

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In-situ Transmission Electron Microscopy Study of Nanotwinned Copper under Electromigration
(2010)
Liao, Chien-Neng
;
Chen, Kuan-Chia
;
Wu, Wen-Wei
;
Chen, Lih-Juann
;
Tu, K. N.
Nanotwinned copper has drawn growing attention recently due to its substantially enhanced mechanical strength and negligible increase in electrical resistivity. The stability of nanotwins under mechanical and electrical stressing becomes a critical consideration. Using a high resolution transmission electron microscopy, we observed that the {112} incoherent twin boundary (TB) and {111} coherent TB migrate at a rate of 0.06 similar to 0.09 nm/s in copper under an electric current density of 2x10(6) A/cm(2). The TB migration is possibly associated with an atomic step moving along either (111) or {112} plane and the TB migration rate is mainly controlled by the incubation time of forming new atomic steps. To form such atomic steps, EM-induced diffusion at junctions where TBs meet a grain boundary or free surface may play an important role.
Observation of atomic diffusion at twin-modified grain boundaries in copper
(2008-08-22)
Chen, Kuan-Chia
;
Wu, Wen-Wei
;
Liao, Chien-Neng
;
Chen, Lih-Juann
;
Tu, K. N.
Grain boundaries affect the migration of atoms and electrons in polycrystalline solids, thus influencing many of the mechanical and electrical properties. By introducing nanometer- scale twin defects into copper grains, we show that we can change the grain- boundary structure and atomic- diffusion behavior along the boundary. Using in situ ultrahigh- vacuum and high- resolution transmission electron microscopy, we observed electromigration- induced atomic diffusion in the twin- modified grain boundaries. The triple point where a twin boundary meets a grain boundary was found to slow down grain- boundary and surface electromigration by one order of magnitude. We propose that this occurs because of the incubation time of nucleation of a new step at the triple points. The long incubation time slows down the overall rate of atomic transport.
Stability of nanoscale twins in copper under electric current stressing
(2010-09-15)
Chen, Kuan-Chia
;
Wu, Wen-Wei
;
Liao, Chien-Neng
;
Chen, Lih-Juann
;
Tu, K. N.
Migration of {112} incoherent twin boundary (ITB) in nanotwinned Cu under electric current stressing has been observed using in situ high-resolution transmission electron microscopy. The current-driven ITB migration is found to be four orders of magnitude faster than that driven thermally. We propose that electric current plays a role of shuffling Cu atoms at ITB/coherent twin boundary junctions, which enhances nucleation of {112} steps and facilitates twin boundary migration in Cu. By understanding how twin boundaries respond to electric current force we shall be able to trace the property change in nanotwinned Cu under electric current stressing, which would be an essential assessment of interconnect reliability. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3483949]
Stability of nanoscale twins in copper under electric current stressing
(2010-09-15)
Chen, Kuan-Chia
;
Wu, Wen-Wei
;
Liao, Chien-Neng
;
Chen, Lih-Juann
;
Tu, K. N.
Migration of {112} incoherent twin boundary (ITB) in nanotwinned Cu under electric current stressing has been observed using in situ high-resolution transmission electron microscopy. The current-driven ITB migration is found to be four orders of magnitude faster than that driven thermally. We propose that electric current plays a role of shuffling Cu atoms at ITB/coherent twin boundary junctions, which enhances nucleation of {112} steps and facilitates twin boundary migration in Cu. By understanding how twin boundaries respond to electric current force we shall be able to trace the property change in nanotwinned Cu under electric current stressing, which would be an essential assessment of interconnect reliability. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3483949]