Pulse reverse electrodeposition for metallization and planarization of semiconductor substrates
First Claim
1. A method for depositing a smooth layer of a metal onto a microrough substrate comprisingimmersing an electrically conductive substrate having a microrough surface in an electroplating bath containing ions of a metal to be deposited onto said surface, said plating bath being substantially devoid of levelers, immersing a counter electrode in said plating bath passing an electric current between said substrate and said counterelectrode, wherein said electric current is a modulated reversing electric current comprising a 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 duty cycle less than about 50% and said anodic pulses have a duty cycle greater than about 50% the charge transfer ratio of said cathodic pulses to said anodic pulses is greater than one, and the frequency of said train of pulses ranges from about 10 Hertz to about 12000 Hertz.
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Abstract
A smooth layer of a metal is electroplated onto a microrough electrically conducting substrate by immersing the substrate and a counterelectrode in an electroplating bath of the metal to be electroplated and passing a modulated reversing electric current between the electrodes. The current contains pulses that are cathodic with respect to said substrate and pulses that are anodic with respect to said substrate. The cathodic pulses have a duty cycle less than about 50% and said anodic pulses have a duty cycle greater than about 50%, the charge transfer ratio of the cathodic pulses to the anodic pulses is greater than one, and the frequency of said pulses ranges from about 10 Hertz to about 12000 Hertz. The plating bath is substantially devoid of levelers and may be devoid of brighteners.
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Citations
24 Claims
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1. A method for depositing a smooth layer of a metal onto a microrough substrate comprising
immersing an electrically conductive substrate having a microrough surface in an electroplating bath containing ions of a metal to be deposited onto said surface, said plating bath being substantially devoid of levelers, immersing a counter electrode in said plating bath passing an electric current between said substrate and said counterelectrode, wherein said electric current is a modulated reversing electric current comprising a 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 duty cycle less than about 50% and said anodic pulses have a duty cycle greater than about 50% the charge transfer ratio of said cathodic pulses to said anodic pulses is greater than one, and the frequency of said train of pulses ranges from about 10 Hertz to about 12000 Hertz.
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