The present disclosure relates generally to sputtering for producing vapor deposition of films, and, more specifically, to High Power Impulse Magnetron Sputtering (HIPIMS) where sputtered material is drawn and directed from a magnetron target by applied fields to substrates.
Use of a magnetron with a magnetron target to produce a vapor that can be deposited on a substrate is known and widely used. To use this technique it has been known to position substrates in the vicinity of magnetron targets and to allow sputter produced vapors to expand and hereby contact and be deposited on substrate surfaces. Additionally, bias voltages have been applied to substrates to draw ionized sputtered materials to substrates and thereby control ion energy and resulting surface and film properties.
Use of magnetic fields to control deposition processes also has been utilized. Magnetic fields created adjacent and between magnetron targets and substrates have been used to guide and focus magnetron produced ionized sputter vapors. To be effective in this guiding and focusing, therefore, it is necessary to produce magnetron generated sputter vapors having high ionized fractions. This requirement has necessitated use of pulsed magnetrons such as High Power Impulse Magnetron Sputtering (HIPIMS) systems as opposed to direct current (DC) or radio-frequency (RF) magnetron sputtering which, depending on power level, discharge geometry, magnetron target material and magnetic field geometry typically produce much less than 10% ionization of sputtered material.
A further benefit of HIPIMS systems is the realization of highly ionized vapors without production of target material droplets—such as may be produced by cathodic arc evaporation. As typically operated, HIPIMS systems produce sputter discharge vapors having pulse widths on the order of 100 microseconds (μs) or less. Accordingly, magnetic fields applied by electric current passing through field coils between magnetron targets and substrates are driven with Direct Current (DC) electric power. A reason why DC electric power is used as opposed to pulsed electric currents that could be increased over DC electric power to produce increased magnetic fields is because of self-inductance effects that decrease the produced magnetic field in time regimes on the order of 100 μs magnetron pulses. This consequence of self-inductance has resulted in use of guiding and focusing magnetic field strengths that are produced by applied DC electric power.
A primary object of the present disclosure is to provide increased guiding and focusing magnetic field strengths to bring ionized magnetron produced target vapors to substrates where they are deposited.
An object of the present disclosure is to provide increased electric field strengths used to direct and focus ionized magnetron produced target vapors.
A further object of the present disclosure is to drive a magnetic field coil with a pulsed power supply having output current pulse widths that are greater than 100 μs in duration.
Another object of the present disclosure is to use the same power supply to drive both the magnetron and the magnetic field coil.
Yet another object of the present disclosure is to apply an electric voltage bias between the magnetron anode and the pulse power driven magnetic field coil.
The invention includes an apparatus and method for facilitating the directing and focusing of magnetron produced ionized sputter material onto a substrate. As one aspect of the invention, a magnetic field coil (hereinafter also referred to as a field coil) is provided between a magnetron target where ionized sputter material is produced and a substrate where the ionized sputter material is to be deposited. The magnetron is powered by a pulsed high voltage power supply to produce pulsed sputter outputs having pulse widths of greater than 100 μs. The field coil can be powered by a separate power supply. Alternatively, the magnetic field coil can be powered together with the magnetron by the magnetron pulsed high voltage power supply.
As a further aspect of the disclosure, a coil bias voltage of about 5 Volts (V) or greater can be supplied between the magnetron anode and the magnetic field coil.
Yet another object of the present disclosure is to apply an electric voltage bias between the magnetron anode and the pulse power driven field coil.
A first HIPIMS system for practicing the present disclosure is shown in
Included in the vacuum chamber 18 is a substrate 20. Sputtered material from the magnetron target 14 is supposed to be deposited on the substrate 20. A substrate bias voltage power supply 22 is connected to the substrate 20 to generate an electric field that is intended to direct and focus ionized sputter material onto substrate 20. The applied substrate bias voltage accordingly is adjusted to attract ionized sputter material to the substrate 20 in order to control the energy of the arriving ions, thereby affecting the surface and film properties in a desired way.
Positioned between the magnetron target 14 and the substrate 20 is a field coil 24. This field coil 24 is energized by a DC power supply 26. When energized by the DC power supply 26, the field coil 24 produces a static magnetic field to guide and focus ionized sputter vapor produced at the magnetron target 14 toward the substrate 20. The ionized sputter vapor is thus directed and focused onto the substrate 20.
According to the present disclosure, a coil bias power supply 28 also is provided. This coil bias power supply 28 energizes a bias potential between the magnetron anode 16 and the field coil 24. This applied electric field can be generated by applied voltages of 5 Volts or more. The electric field generated using the coil bias power supply 28 further assists the generated magnetic field to direct and focus ionized sputter vapors onto the substrate 20.
A second HIPIMS system for practicing another aspect of the present disclosure, shown in
According to the present disclosure, both the coil bias power supply 28 and a pulsed coil power supply 32 for the HIPIMS system 30 are provided. The coil bias power supply 28 energizes a bias potential between the magnetron anode 16 and the field coil 24. The applied electric field can be generated by applied voltages of 5 V or more. This electric field assists the generated magnetic field to direct and focus ionized sputter vapors onto the substrate 20.
The field coil 24 is further energized by the pulsed coil power supply 32 to generate pulsed magnetic fields. The purpose of the pulsed magnetic fields is to direct and focus ionized sputter vapor produced at the magnetron target 14 toward the substrate 20. To accomplish this directing and focusing it is necessary to synchronize the pulsing of the magnetron high voltage power supply 12 that produces ionized sputter vapor with the pulsing of the pulsed coil power supply 32. This synchronization is accomplished using a synchronization line 34. To avoid and overcome self-induction effects in the field coil 24 that would retard generation of magnetic fields, the pulsing of the magnetron high voltage power supply 12 and the pulsed coil power supply 32 are adjusted to pulse widths that are greater than 100 μs. With these synchronizations and pulse width adjustments, the magnetudes of pulse produced magnetic fields are significantly increased over those produced by DC systems. Therefore, ionized sputter vapor is much more effectively directed and focused onto the substrate 20.
Shown in
As a further aspect of the invention, the substrate 20 can be physically moved perpendicular to magnetic field lines to enlarge the coating areas across the front surface of the substrate 20.
A third HIPIMS system for practicing yet another aspect of the present disclosure is shown in
According to the present disclosure, the magnetron high voltage power supply 12 for HIPIMS system 36 energizes both the magnetron and field coil 24. Again to avoid and overcome self-induction effects in the field coil 24 the pulsing of the magnetron high voltage power supply 12 is adjusted to produce power pulse widths that are greater than 100 μs.
The field coil 24 in HIPIMS system 36 has one end connected to ground. This end connection can be made at the magnetron anode 16, as shown in
According to another aspect of the disclosure, a pair of sweeping or deflection coils may be used to direct ionized sputter vapor produced at the magnetron target 14 exiting the field coil 24. Referring to
The embodiment depicted in
Although not shown, the sweeping coils 38 are connected to receive a controllable current so as to generate an appropriate magnetic field intensity and direction in the area between field coil 24 and substrate 20 so as provide a desired amount and direction of off-axis beam deflection. Note that this capability of using deflection or sweeping coils 38 to direct a plasma beam is based on the charged ion flow produced by a HIPIMS system that would not otherwise be possible in a conventional (i.e., non-HIPIMS) sputtering system.
While embodiments and application of this disclosure have been shown and described, it would be apparent to those skilled in the art having the benefit of this disclosure that many more modifications than mentioned above are possible without departing from the concepts disclosed herein. The disclosure, therefore, is not to be restricted except in the spirit of the appended claims.
This application claims priority of U.S. Provisional Application No. 61/046,921, entitled “METHOD AND APPARATUS FOR IMPROVED HIGH POWER IMPULSE MAGNETRON SPUTTERING,” filed Apr. 22, 2008, the disclosure of which is expressly incorporated herein by reference in its entirety.
This invention was made with government support under contract No. De-AC02-05CH11231 awarded by the United States Department of Energy to the Regents of the University of California for management and operation of the Lawrence Berkeley National Laboratory. The government has certain rights in this invention.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US2009/034272 | 2/17/2009 | WO | 00 | 12/15/2010 |
Publishing Document | Publishing Date | Country | Kind |
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WO2009/131737 | 10/29/2009 | WO | A |
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20110089024 A1 | Apr 2011 | US |
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61046921 | Apr 2008 | US |