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Electroplating (a.k.a. Electrochemical Deposition (ECD), Plating) is a process in which a thin conductive metallic film is deposited by the reduction of a metal ion from solution onto a conductive surface in an electrochemical cell. Electroplating, when possible, is a good choice to obtain conformal, thicker metallic deposit without the need of vacuum based techniques. In the semiconductor industry electroplating became widely used as a more economical alternative to CVD for filling trenches and vias.
|Other Names||Electrodeposition, Electrochemical deposition|
|Equipment||Gold Plating, Acid Bench 92|
|Materials||Au, Cu, Ni, In|
The following Wet Benches are used for plating films
Method of operation
Electroplating (also referred to as electrodeposition or electrochemical deposition) uses an electrical current to reduce a metal, M, in solution (called electrolyte) at the anode (negative electrode in a cell) turning the metal ions into solid metal. If the surface has a seed layer and it is patterned, the metal will only deposit into the patterned region, where the conductive seed layer is exposed. In the electro-deposition of metals, generally a metal ion Mz+ is transferred from the solution into the metal lattice of the electrode. This is accompanied by the transfer of z electrons from an outside source (power supply) to the metal to render Mo on the electrode. The addition of the metal onto the electrode follows several ion-transfer mechanism, which might produce different types of growth, depending on activation and final energies. Electroplating does not always produces uniform smooth surfaces. The use of chemicals, known as additives, that inhibit the columnar or dendritic growth, brighteners or leveling compounds are common in commercially available plating solutions. Other technique to improve or control the uniformity of the deposit are the use of pulse plating the optimization of the cell design.
Electroplating is generally used in the semiconductor industry to deposit films thicker than one micron. Evaporating or sputtering thicker than a micron thin films is wasteful and requires repeated equipment maintenance. Electroplating can also be used to deposit metallic compounds, like the NiFe alloy. Electroplating is recommended when depositing conductive compounds on hard to reach conductive surfaces as the case of filling wafer-through via or filling pores in an aluminum oxide film (AAO).
Electroplating is commonly used to deposit metals and conductive polymers whose electrochemical potential is less cathodic than that of water. Though some metal electroplating, i.e. Pt, does use organic electrolyte, they are not as common and easy to use as those that use aqueous electrolyte.
Figures of Merit
The quality of a deposited film can be measured in is roughness, stress, uniformity, grain size, composition and its deposition rate.
-  Wikipedia