High Power Impulse Magnetron Sputtering

High Power Impulse Magnetron Sputtering (HIPIMS, also known as High Impact Power Magnetron Sputtering and High Power Pulsed Magnetron Sputtering, HPPMS) is a method for physical vapor deposition of thin films which is based on magnetron sputter deposition. HIPIMS utilises extremely high power densities of the order of kWcm^-2 in short pulses (impulses) of tens of microseconds at low duty cycle (on/off time ratio) of < 10%.

HIPIMS is used for:
*adhesion enhancing pretreatment of the substrate prior to coating deposition (substrate etching)
*thin film deposition

The first patent on HIPIMS was filed by Vladimir Kouznetsov (priority date 9 Dec 1997), Kouznetsov US 6296742 B1.

HIPIMS Plasma Discharge

HIPIMS plasma is generated by a glow discharge where the discharge current density can reach up to 6 Acm^-2, whilst the discharge voltage is maintained at several hundred volts.Citation
last=Ehiasarian
first=Arutiun P.
last2=New
first2=R.
last3=Munz
first3=W.-D.
last4=Hultman
first4=L.
last5=Helmersson
first5=U.
last6=Kouznetsov
first6=V.
year=2002
editor-last=
editor-first=
title=Influence of High Power Densities on the Composition of Pulsed Magnetron Plasmas
journal=Vacuum
volume=65
issue=
publication-date=
pages=147-154
doi=10.1016/S0042-207X(01)00475-4 .] The discharge is homogeneously distributed across the surface of the cathode of the chamber.HIPIMS generates a high density plasma of the order of 10¹³ ions cm^-3 containing high fractions of target metal ions.The ionisation degree of the metal varpour is a strong function of the peak current density of the discharge. At high current densities, sputtered ions with charge 2+ and higher - up to 4+ for Ti - can be generated. The appearance of target ions with charge states higher than 1+ is responsible for a potential secondary electron emission process that has a higher emission coefficient than the kinetic secondary emission found in conventional glow discharges. The establishment of a potential secondary electron emission may enhance the current of the discharge.
HIPIMS is typically operated in short pulse (impulse) mode with a low duty cycle in order to avoid overheating of the target and other system components. In every pulse the discharge goes through several stages:
*electrical breakdown
*gas plasma
*metal plasma
*steady state, which may be reached if the metal plasma is dense enough to effectively dominate over the gas plasma

ubstrate pretreatement by HIPIMS

Substrate pretreatment in a plasma environment is required prior to deposition of thin films on mechanical components such as automotive parts, metal cutting tools and decorative fittings. The substrates are immersed in a plasma and biased to a high voltage of a few hundred volts. This causes high energy ion bombardment that sputters away any contamination. In cases when the plasma contains metal ions, they can be implanted into the substrate to a depth of a few nm. HIPIMS is used to generate a plasma with a high density and high proportion of metal ions. When looking at the film-substrate interface in cross-section, one can see a clean interface. Epitaxy or atomic registry is typical between the crystal of a nitride film and the crystal of a metal substrate when HIPIMS is used for pretreatment. [Citation
last=Ehiasarian
first=Arutiun P.
last2=Wen
first2=J.G.
last3=Petrov
first3=I.
year=2007
editor-last=
editor-first=
title=Interface microstructure engineering by high power impulse magnetron sputtering for the enhancement of adhesion
journal=Journal of Applied Physics
volume=101
issue= 5
publication-date=
pages= item 054301, 10 pp.
doi=10.1063/1.2697052 .] HIPIMS has been used for the pretreatment of steel substrates for the first time in February 2001 by A.P. Ehiasarian.Citation
last=Ehiasarian
first=Arutiun P.
last2=Munz
first2=W.-D.
last3=Hultman
first3=L.
last4=Helmersson
first4=U.
last5=Petrov
first5=I.
year=2003
editor-last=
editor-first=
title=High Power Pulsed Magnetron Sputtered CrNx Films
journal=Surface and Coatings Technology
volume=163-164
issue=
publication-date=
pages=267-272
doi=10.1016/S0257-8972(02)00479-6 .]

Thin Film Deposition by HIPIMS

Thin films deposited by HIPIMS at discharge current density > 0.5 Acm^-2 have a dense columnar structure with no voids. Copper films deposited by HIPIMS are able to fill high aspect ratio trenches [ Citation
last=Kouznetsov
first=V.
last2=Macak
first2=K.
last3=Schneider
first3=J.
last4=Helmersson
first4=U.
last5=Petrov
first5=I.
year=1999
editor-last=
editor-first=
title=A novel pulsed magnetron sputter technique utilizing very high target power densities
journal=Surface and Coatings Technology
volume=163-164
issue=2-3
publication-date=
pages=290-293
doi=10.1016/S0257-8972(99)00292-3 ]

HIPIMS has been used for the deposition of transition metal nitride (CrN) thin films for the first time in February 2001 by A.P. Ehiasarian. The films had a dense microstructure, were free of large scale defects and had low sliding wear coefficient.

Industrial application

HIPIMS has been successfully applied for the deposition of thin films in industry. SVS Vacuum Coating Technologies GmbH is the first company which integrated HIPIMS into its R&D, pilot and industrial production coating machines routinely.

References

Further reading

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External links

*http://svs-vct.com/
*http://materials.shu.ac.uk/ncpvd
*http://www.ifm.liu.se/plasma/reshppms.html
*http://www.ionsputtering.com