Specific Process Knowledge/Thin film deposition/Deposition of Copper/Deposition of Copper

Roughness of Cu layers

The roughness of Cu layers deposited in the Alcatel was examined by AFM measurements.

Experimental

Cr was deposaited in Alcatel onto Si wafers. (Part of the surface was covered with resist, and a lift-off process followed). The deposition rate was 10 Å/s (the thickness of the layers were between 70 nm and 200 nm). AFM measurements shows the surface structure.

Results

The Cu surface is rather un-uniform and rough. Large grains, randomly distributed, can be seen on the film surface. The largest part of the surface consists of smaller, circular grains, with a diameter of about 25-40 nm. These are seen in the AFM picture with a height of a few nm, as can be observed below. The largest grains are upp to 70 nm in diameter, and have a height of up to 20 nm.

E-beam deposited Cr layer; deposited in the Wordentec, rate 10 Å/s.

AFM picture of a Cu surface deposited in Alcatel. A profile of the surface is shown to the right, where the height of some structures can be seen.