Total ion flux density.
Answers
4.03.5 High Target Utilization
Due to the strong inhomogeneous ion current density, the target material utilization of a planar magnetron is limited to 25–30% (this holds for a standard magnet set with fixed magnets).
Around 1985, the development of circular magnetrons was driven by the need for fast and cost-effective metallization of a new entertainment medium, the compact disc (CD).
One of the first attempts to improve the target utilization was the so-called interpoles target-hollow magnetron (IPT-HM) (4) outlined in Figure 16. In such a configuration, a race track-shaped target is located between the poles of the magnet system (please note that for a standard system, the magnets are behind the target). A very flat magnetic field is realized by soft magnetic pole pieces positioned on top of permanent magnets. The erosion zone is broadened, and the material utilization increases up to 60%. Such cathodes were mainly used in the early single disc-coating machines for the metallization of CDs. They marked the beginning of an era of high-rate disc metallization processes with deposition rates around 50 nm s−1. Self-sputtering was observed for Cu at high power densities (5). Self-sputtering (sputtering without inert gas) occurs if the power density is high enough to ionize sufficient sputtered material so that the metal ions can sustain the sputter process themselves. This might be seen as an early approach to high power impulse magnetron sputtering (HIPIMS).
Sign in to download full-size image
Figure 16. The interpoles target-hollow magnetron.
Using the IPT-HM together with a superimposed variable magnetic field created by an electromagnetic coil allows more degrees of freedom: the area of maximum erosion can be shifted across the target surface.
Further approaches to improve the life of planar sputtering targets were oscillating permanent magnet arrays (6) or the use of ferromagnetic sheets (7), where the modified field lines create two race tracks. Such configurations resulted in a material utilization of 50–60%.
In the early 1980s, a tubular magnetron was developed (8,9) and was transferred to industrial coaters as ‘C-MAG’ (cylindrical magnetron) a few years later. According to Figure 17, cathode body and target are tubes rotating around a fixed magnet array with a frequency of about 1 Hz. New target material is continuously ‘turned’ into the plasma zone. With a material utilization up to 90% and other advantages, such rotatable magnetrons are today state of the art in many industrial coaters
Answer:
there is more than 166 ion flux density
Explanation:
yess