|
|
 |
 |
Electroplating involves transferring copper contained in a chemical fluid (the electrolyte) to the surface of the wafer (the cathode). By completing an electric circuit from the wafer to the copper anode in the fluid, copper ions are removed from the electrolyte and deposited on the wafer. At the same time, copper from the anode replaces the metal ions removed from the electrolyte, making the electrolyte electrically neutral.
The tiny, sub-micron-sized interconnect structures that make up the chip's circuitry involve new challenges for electroplating. These spaces must be filled with copper from the bottom up, to avoid creating voids in the lines and vias. The deposited film's thickness uniformity across the wafer surface also must be controlled within one percent (one sigma) or less. Furthermore, the entire process must be performed at deposition rates that are economical to chipmakers in production lines. |
|
|
|
|
