Ionization fraction of the sputtered metal flux in a hollow cathode magnetron

Plasma parameters of the hollow cathode magnetron inside and downstream

“…This results in a decrease in the rate of deposition, since the bulk density of the sputtered metal atoms is located inside this trap. In our case the deposition rate is large enough (100 nm min −1 ) at Z =19 cm for 2.2 kW power and 10 mTorr pressure [12]. This also speaks in favor of our assumption that the main ionization of copper atoms takes place outside of the cathode, where the potential barrier is small.…”

“…As mentioned above, electron temperature rises in this area. Without magnets around the anode rings, the plasma density is reduced by one half at this location [12]. Figure 5 shows that plasma density increases greatly at large radii.…”

“…These measurements raise the question: where is there a large ionization of sputtered metal atoms? Recall that for the same parameters of discharge, the ionization fraction of the Cu flux cm reaches 25% at Z = 19 cm [12]. Inside the cathode the layer of dense plasma is thin and probability of ionization of the metal atoms is small.…”

“…The experimental setup of the magnetron discharge with a hollow cathode is shown in figure 1 [12]. The cathode consists of a cup-shaped Cu target (diameter 0.14 m, length 0.11 m) made of copper and cooled with water.…”

“…An HCM uses a single dc power supply to both sputter and ionize the target material, unlike other IPVD tools that use secondary inductively coupled or ECR plasma sources for ionization of sputtered atoms. HCMs have been investigated both experimentally and via computer modeling [1,2,[10][11][12] but many phenomena remain unclear. In particular, to our knowledge, measurements of plasma parameters inside the HCM have not been performed.…”