ELECTRO-DEPOSITION OF NANO TWINNED COPPER STRUCTURES

A copper structure having a high density of nano twins is deposited on a substrate. Electroplating conditions for depositing a nano twinned copper structure may include applying a pulsed current waveform that alternates between a constant current and no current, where a duration of no current being applied is substantially greater than a duration of a constant current being applied. In some implementations, the nano twinned copper structure is deposited by applying a pulsed current waveform followed by a constant current waveform. In some implementations, the nano twinned copper structure is deposited on a highly-oriented base layer, where an electroplating solution contains an accelerator additive. In some implementations, the nano twinned copper structure is deposited on a non-copper seed layer. In some implementations, the nano twinned copper structure is deposited at a relatively low flow rate.