Dependence of Optical Emission Spectra on Argon Gas Pressure during Modulated Pulsed Power Magnetron Sputtering (MPPMS)

Masaomi Sanekata,Keizo Tsukamoto,Masahide Tona,Kiyokazu Fuke,Nobuo Nishimiya,Yuki Nakagomi,Fuminori Misaizu,Yoshihiro Hirai,Naoyuki Hirata,Keijiro Ohshimo,Hiroaki Yamamoto,Hiroshi Nishida

doi:10.3390/plasma4020018

Abstract

Modulated pulsed power magnetron sputtering (MPPMS) of titanium was investigated as a function of argon gas pressure using optical emission spectroscopy (OES). Delays in discharge and the formation of comb-like discharge current waveforms due to splitting and pulsing were observed with a decrease in pressure. This observation corresponds to the evolution from MPPMS condition to deep-oscillation-magnetron-sputtering (DOMS)-like condition by changing discharge gas pressure. The optical emission intensities of the ionic species (Ar+ and Ti+) increased as the comb-like current waveforms were formed with decreasing Ar pressure. This behavior showed a marked contrast to that of the neutral species (Ar and Ti). The Ar pressure dependence of OES was revealed to be due to the plasma build-up stage, which is the initial generation process of plasma discharge in pulsed dc magnetron sputtering, from the temporal profile for the atomic-line intensities of the optically emitting species in MPPMS and DOMS-like plasmas.

Highlights

High power pulsed magnetron sputtering (HPPMS), including high power impulse magnetron sputtering (HiPIMS), is attracting attention as an ionized physical vapor deposition (I-PVD) technique [1,2,3,4,5] that enables the formation of high-performance films with high hardness, smoothness and adhesiveness [6,7,8]
Comb-like discharge current waveforms [28] as used in deep oscillation magnetron sputtering (DOMS), and strong optical emission of Ar+ atomic lines which has not been reported in a pure metallic sputtering mode (, not in metal-oxide sputtering mode [29,30]) by modulated pulsed power magnetron sputtering (MPPMS) of a Ti target were observed as the gas pressure decreased
The influence of the working Ar pressure on optical emission spectroscopy (OES) was investigated in MPPMS

Summary

Introduction

High power pulsed magnetron sputtering (HPPMS), including high power impulse magnetron sputtering (HiPIMS), is attracting attention as an ionized physical vapor deposition (I-PVD) technique [1,2,3,4,5] that enables the formation of high-performance films with high hardness, smoothness and adhesiveness [6,7,8]. HiPIMS (m-HiPIMS), in which HiPIMS is performed with a few serial short bipolar pulses, has been developed [19,20,21] Both of these techniques have been proposed as new methods to increase the deposition rate by avoiding arcs in DOMS and reducing metal. The effect of the working gas pressure on the correlation between the discharge current/voltage and OES in MPPMS plasma was investigated to obtain further information on the optimal conditions for the formation of a deposited film using. Comb-like discharge current waveforms [28] as used in DOMS, and strong optical emission of Ar+ atomic lines which has not been reported in a pure metallic sputtering mode (, not in metal-oxide sputtering mode [29,30]) by MPPMS of a Ti target were observed as the gas pressure decreased. We will discuss the relationship between the evolution of OES and the MPPMS current waveforms based on the pulse discharge stage

Materials and Methods

Discharge Pulse Waveforms

Conclusions