In situ plasma diagnostics study of a commercial high-power hollow cathode magnetron deposition tool

Abstract

Using a newly designed and built plasma diagnostic system, the plasma parameters were investigated on a commercial 200 mm high-power hollow cathode magnetron ͑HCM͒ physical vapor deposition tool using Ta target under argon plasma. A three dimensional ͑3D͒ scanning radio frequency ͑rf͒-compensated Langmuir probe was constructed to measure the spatial distribution of the electron temperature ͑T e ͒ and electron density ͑n e ͒ in the substrate region of the HCM tool at various input powers ͑2-15 kW͒ and pressures ͑10-70 mTorr͒. The T e was in the range of 1-3 eV, scaling with decreasing power and decreasing pressure. Meanwhile, n e was in the range of 4 ϫ 10 10-1ϫ 10 12 cm −3 scaling with increasing power and decreasing pressure. As metal deposits on the probe during the probe measurements, a self-cleaning plasma cup was designed and installed in the chamber to clean the tungsten probe tip. However, its effectiveness in recovering the measured plasma parameters was hindered by the metal layer deposited on the insulating probe tube which was accounted for the variation in the plasma measurements. Using a quartz crystal microbalance combined with electrostatic filters, the ionization fraction of the metal flux was measured at various input power of 2-16 kW and pressure of 5-40 mTorr. The metal ionization fraction reduced significantly with the increasing input power and decreasing gas pressure which were attributed to the corresponding variation in the ionization cross section and the residence time of the sputtered atoms in the plasma, respectively. Both the metal neutral and ion flux increased at higher power and lower pressure. The 3D measurements further showed that the ionization fraction decreased when moving up from the substrate to the cathode.

Probe and Emission Spectrometry Diagnostics in Hollow Cathode Magnetron

“…Different results can be explained as follow. In [9] discharge pressure was in the range of 30 -50 mTorr and mean electron temperature has a maximum of 1.5 eV. Consequently the number of electrons with energy greater than 8 eV was much less than at pressure 5 -10 mTorr with the electron temperature 3 -4 eV.…”

“…This fact is not evident for high power IPVD discharges. In [3][4][5]9,10] the electron temperature decreases for high magnetron current due to very large number of sputtered metal atoms. The energy thresholds for electron impact excitation and ionization of metal atoms (<8 eV) are much lower than those for argon.…”

“…Such ion assistance allows the deposition of high quality films on complex shaped substrates. Only a few papers have been published which deal with investigation HCM [1,2,9,10]. The purpose of this paper is to study a mechanism for the production of excited argon and copper atoms and ions.…”

“…Discharge power is kWatts and metal flux is large. In the article [9] his issue is considered in details.…”

Downstream plasma transport and metal ionization in a high-powered pulsed-plasma magnetron

“…2 and the details of the design are described in another paper. 38 The GEA was placed above the QCM and had a ceramic casing with an inner diameter of 30 mm. Three layers of mesh grids were evenly placed inside with a gap of 6.4 mm.…”