Influence of ultrasound and cathode rotation on the formation of intrinsic stress in Ni films during electrodeposition

• The influence of 25 kHz ultrasound and cathode rotation during electroplating of Ni films on Si wafers has been studied with respect to intrinsic stress formation. Current densities from 1.6 A dm-2 up to 28.3 A dm-2 were used in an additive-free Ni sulphamate electrolyte. In general more efficient agitation by either ultrasound or cathode rotation was found to reduce intrinsic stress towards compressive levels compared to conventional agitation with an electrolyte circulation pump. Further more, intrinsic stresses become less dependent on changes in current density. The latter effect is most pronounced for ultrasonic agitation. Structure analysis of samples deposited by ultrasonic agitation show dense deposits with initially smaller grains at high ultrasonic effect. Locally increased temperature at the substrates surface could be an important effect of ultrasound agitation.

Nyckelord

Intrinsic stress; Electrodeposition; Ultrasound; Nickel; Electroforming

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