Electromigration on semiconductor surfaces

Control of Chaotic Wandering of an Isolated Step by the Drift of Adatoms

“…(4) based on the expansion by a parameter qx s ø 1 is then rather difficult to justify, since the diffusion length x s on Si(111) is extremely large there. But there are many other materials and combinations of adsorbates and substrates which show surface electromigration [12], and once the wandering instability takes place, the Benney equation may be applicable since the basic structure of the equation is determined by the symmetry of the system. Tilting of the electric field can then control the regularity and the periodicity of patterns formed on the crystal surface.…”

“…The asymmetry in the diffusion field results either from the energy barrier suppressing the interlayer transport (the Ehrlich-Schwoebel effect [6][7][8][9][10]) or from the drift of adatoms due to the external field (for instance, the electromigration [11,12]). In Si(111), a direct electric current is shown to induce the bunching instability [13,14], and this is attributed to the drift of adatoms perpendicular to the steps [3,[15][16][17][18][19].…”

Singular response to a dopant of an evaporating crystal surface

“…Indeed, positively charged foreign adatoms under uphill current (δ > 0) will be driven to a ascending step and eventually form a profile (17), for which (13) will apply. Proceeding along the lines (18)(19), we conclude that (13) cannot be satisfied, since δ > 0 and c 1 < 0, so that an instability reversal will not happen. Indeed, for a Cudoped surface, the reversal of bunching stability was not observed 16 .…”

“…1(b), with a diverging drift. To do so, we note that Au adatoms have a much larger effective charge than Si adatoms 18,19 , so that their dynamics in the electric field is faster. As a consequence, Si adatoms move in an established environment of Au adatoms, whose steady profile may be strongly inhomogeneous near the border.…”

Novel Silver Solid-State Bonding Designs Between Two Copper Structures

“…On the other hand, if current flow through Ag joints, current density would be relatively small because of the large bonding area. For another form of migration, which is caused by bias, it will not occur in this bonding design due to the absence of dielectric layer [17].…”