Doping of Cu Surface by Self-Aligned Metal DiffusionRreaction
Publication Date: 2010-Oct-26
The IP.com Prior Art Database
Disclosed is a process to dope the surface of the Cu with alloying elements to improve adhesion of the SiN cap layer and to improve the reliability of the Cu interconnects.
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Aligned Metal DiffusionRreaction
The adhesion at the SiN-Cu interface is important for ensuring the reliability of on-chip Cu interconnects. Adhesion (and hence reliability) can be improved by doping Cu (alloy seed layer) or by adding a refractory metal cap. Doping Cu with Al or Mn (alloy seed layer) is effective for improving reliability of thin Cu wires, but is more difficult to implement with thick Cu wires, due to the long diffusion distance from the seed layer to the top surface of the Cu. Refactory metal capping layers (CoWP, CoWB) are very effective for improving electromigration reliability, but the electroless deposition process is difficult to control and requires expensive equipment.
A simple process is required to dope the surface of the Cu with alloying elements to improve adhesion of the SiN cap layer and to improve the reliability of the Cu interconnects.
In the disclosed solution, a thin layer of Ti or Sn is deposited on the surface of wafer after Cu CMP. Wafer is annealed, driving the metal into Cu. Metal is stripped selective to Cu (HF etch for Ti), then SiN cap is deposited.
Doping of Cu Surface by Self
Doping of Cu Surface by SelfDoping of Cu Surface by Self -
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Aligned Metal DiffusionRreactionAligned Metal DiffusionRreaction
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