Patent ID: 6827833
Filing Date: 2004-12-07
Classification: C25D,H05K

Abstract:
A method for depositing a uniform layer of a metal on the interior surface of a cavity having an aspect ratio greater than about 8:1 comprisingproviding an electrically conductive substrate having a cavity therein, said cavity having a ratio of depth to at least one transverse dimension greater than 8:1; immersing said substrate as an electrode in an electroplating bath containing ions of a metal to be deposited onto said surface, wherein said electroplating bath is devoid of levelers and brighteners; immersing a counter electrode in said electroplating bath; passing an electric current between said electrodes; wherein, said electric current is a modulated reversing electric current comprising train of pulses that are cathodic with respect to said substrate and pulses that are anodic with respect to said substrate, said cathodic pulses have a charge transfer ratio with respect to said anodic pulses greater than one, said cathodic pulses have a duration in the range from about 100 &mgr;s to about 19.8 milliseconds, and said anodic pulses are shorter than said cathodic pulses and have a pulse duration in the range from about 2 &mgr;s to about 10 milliseconds.