EP1654394A2 - Alimentation pulsee pour plasma a puissance de crete elevee avec gestion d'arc - Google Patents

Alimentation pulsee pour plasma a puissance de crete elevee avec gestion d'arc

Info

Publication number
EP1654394A2
EP1654394A2 EP04778755A EP04778755A EP1654394A2 EP 1654394 A2 EP1654394 A2 EP 1654394A2 EP 04778755 A EP04778755 A EP 04778755A EP 04778755 A EP04778755 A EP 04778755A EP 1654394 A2 EP1654394 A2 EP 1654394A2
Authority
EP
European Patent Office
Prior art keywords
plasma
voltage
pulse
arc
voltage pulse
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP04778755A
Other languages
German (de)
English (en)
Inventor
David J. Christie
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Advanced Energy Industries Inc
Original Assignee
Advanced Energy Industries Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US10/626,330 external-priority patent/US20040124077A1/en
Application filed by Advanced Energy Industries Inc filed Critical Advanced Energy Industries Inc
Publication of EP1654394A2 publication Critical patent/EP1654394A2/fr
Withdrawn legal-status Critical Current

Links

Definitions

  • This invention relates generally to apparatus and methods for magnetron sputtering, and more particularly to magnetron sputtering apparatus that delivers high peak powers to a sputtering magnetron plasma load with arc handling capability.
  • 6,296,742 Bl describes a method of producing a fully ionized plasma for use in magnetron sputtering applications.
  • a pulse generator delivers pulses of up to 10 MW to a sputtering target, thereby completely ionizing a sputtering gas.
  • the sputtering gas is described as first adopting a glow discharge state, then continuing to an arc discharge state, and finally adopting a fully ionized state.
  • the arc discharge state is described as a break-down condition occurring at current densities beyond those of the abnormal glow discharge region, and is characterized by a sudden drop in plasma impedance, as shown by an abrupt drop in plasma voltage as the current density further increases.
  • this is usually represented by a drop in the voltage across the plasma to at most a few tens of volts and may be accompanied by a discharge between some part of the sputtering target and the chamber.
  • the '742 patent indicates that, under that patent's teachings, the plasma, after passing through this arc region, develops into a fully ionized state.
  • Part of the appeal of these techniques is the ability to generate a large population of ionized species that can in turn be attracted to the work piece by the application of a bias voltage.
  • the above references on the high peak power techniques appear to use a simple capacitor discharge through an inductor.
  • arc control and arc diverting apparatus have been comprised of circuits that either detect the arc and disconnect the power supply from the load or are comprised of a switching circuit that effectively short circuits the power supply to extinguish the arc.
  • a pulsing circuit comprised of an energy storage capacitor is repetitively charged and then discharged through an inductor in series with the plasma.
  • the combination of the inductor and capacitor serve to shape the pulse, which accomplishes three functions.
  • a network is added for the purpose of controlling the voltage rate of rise, the undamped peak amplitude of the voltage pulse in the event that the plasma does not ignite, and the frequency at which the voltage waveform rings, particularly in the case that the plasma does not ignite.
  • This circuit in this embodiment amounts to a resistor in series with a capacitor shunt connected at the output of the pulser, or its equivalent implemented as a distributed circuit with a number of discrete capacitors and resistors, possibly also utilizing parasitic capacitors and resistors in devices and circuit conductors.
  • a circuit is provided to clamp or limit the voltage pulse to a maximum level, implemented with a diode, normally reverse biased in series with a capacitor held at the clamp voltage, connected to the output of the pulser.
  • This circuit is activated when the amplitude of the voltage pulse exceeds a preset adjustable value and acts to prevent the voltage from exceeding a preset level. This has the benefit of preventing undesirable arcs both inside and outside the vacuum chamber. All of this makes it possible to reach a highly ionized plasma state without first passing through the arc state.
  • the pulsing network, or mesh serves to provide an impedance match to the plasma.
  • the network serves to limit the current rate of rise and peak magnitude in the event of a later occurrence of an arc. -An arc may be detected by either the fall of the discharge voltage below a preset voltage threshold during a pulse, or an increase in discharge current above a preset current threshold.
  • the arc condition represents a lowering of the impedance of the plasma, which is represented by the ratio of the voltage to the current, so either or both detection methods will serve.
  • the energy storage capacitor is disconnected from the series inductor to stop the current rise.
  • the pulsing circuit is then disconnected from the plasma load and the inductor energy is recycled to the energy storage capacitor.
  • the proportion of ionized species is relatively low, on the order of a few percent at most.
  • sputtering plasmas in a highly ionized state may be achieved, having ionization fractions often percent or more.
  • a highly ionized plasma may be achieved using the present invention by raising the proportion of ionized species in the plasma by a factor of five or more.
  • a sputtering plasma in a highly ionized state may be created without first adopting an arc discharge state.
  • the arc handling features of the invention serve to mitigate and extinguish any arcs that develop while the sputtering plasma is present.
  • Figure 1 is a schematic representation of a magnetron plasma processing system incorporating the principles of this invention.
  • Figure 2 illustrates the waveforms for normal operation of the magnetron plasma processing system shown in Figure 1.
  • Figure 3 illustrates the waveforms for arc handling operation.
  • Figure 4 illustrates the current, voltage, and impedance characteristics of the sputtering plasma during operation of the magnetron plasma processing system.
  • FIG. 1 there is shown one embodiment of a magnetron plasma processing system 10.
  • a DC power supply 12 is connected to a magnetron plasma- processing chamber 14 via a pulsing circuit 16.
  • the magnetron plasma-processing chamber may be a conventional magnetron chamber well known to those skilled in the art having a magnetron cathode 18 and an anode 20. In sputtering applications, a material target serves as the cathode 18.
  • the pulsed DC supply 16 may be of the type such as a MegaPulserTM model manufactured by Advanced Energy Industries, Inc. which supplies a high voltage pulse across the cathode 18 and anode 20 to ignite a plasma 22 between the electrodes.
  • the plasma acts upon the material of the cathode 18 so as to result in a coating on a substrate 26 located within the chamber. This is accomplished by bombarding the material target or cathode 18 with ions from the plasma 22, which results in the atoms sputtered from the target being then deposited on the surface of the substrate 26.
  • the embodiment of Figure 1 also comprises a smaller optional dc power supply 28 that maintains a minimum voltage to the magnetron to keep the plasma ignited between the high voltage pulses from the pulse circuit 16. This power supply may also be used to initially ignite the plasma before the high pulse operation begins.
  • the pulsing circuit 16 is comprised of energy storage capacitor Ci serially connected to an inductor Li via switch Si.
  • the inductor Li is connected to the cathode of the magnetron via switch S 2 .
  • Figure 2 illustrates the waveforms for normal operation of the circuit. S 2 is closed and S 3 are open for the whole sequence.
  • the capacitor is charged to its initial voltage by the dc power supply 12.
  • the discharge is initiated by Si, and capacitor Ci is discharged through inductor Li into the plasma load.
  • a control circuit initiates the timing of the switches to control the charge time of the capacitor Ci and its pulse discharge to the load.
  • the shapes of the V c , Iinductor, VLOAD, and I loa d waveforms are determined solely by the initial value of Vc, the values of and Li and the characteristics of the plasma load and the output cable.
  • Figure 3 shows waveforms representative of an arc occurring during a pulse from the pulsing circuit 16. The sequence begins as shown in Figure 2 and described above, but when an arc occurs the current rises and the voltage falls until the arc is detected.
  • Arcs are detected by one of two means. Specific circuit techniques required to implement the arc detection means are well known to those skilled in the art. First, an arc may be detected as the load current exceeding a preset threshold. This threshold can actually be updated on a pulse by pulse basis by predicting the output current, based on plasma load characteristics and the initial value of Vc and the values of Ci and Li and adding a margin to prevent false detections. Prediction of the output current based on these parameters is well known to those skilled in the art.
  • the current threshold may be based on the average peak current, with some margin added to prevent false arc detections. In this case, it may be desirable to leave pulses with high arc currents out of the average calculation.
  • an arc may be detected as the load voltage being below a preset threshold when the load current is above a second current threshold, used only for this second method.
  • Si is opened immediately and S 3 is closed after a short delay, and then S 2 is opened after another short delay. This disconnects the load from the pulse circuit 16 and initiates the resonant transfer of energy from inductor Li to capacitor . The result is that the energy present in inductor Li when the arc occurred is recycled to capacitor .
  • the embodiment depicted in Figure 1 also comprises circuitry for shaping the voltage pulse delivered to the magnetron plasma.
  • a ring-up circuit 30 is provided for the purpose of controlling the voltage rate of rise of the pulse, the magnitude of the voltage pulse, and the frequency at which the voltage waveform rings.
  • the ring-up circuit 30 comprises a resistor Rj in series with a capacitor C 2 shunt connected at the power supply output.
  • the ring-up circuit may also be implemented as distributed networks of discrete capacitors or resistors, and may make use of parasitic capacitance or resistance found in other circuit elements or components of the device.
  • the voltage pulse generated by the embodiment of Figure 1 is also shaped and controlled by a clamp circuit 32.
  • the clamp circuit comprises a diode D 3 , reverse biased in series with a combination of a capacitor C 3 in parallel with a clamp voltage supply 34.
  • the clamp circuit 32 acts to prevent the voltage level of a pulse from exceeding a predetermined maximum level.
  • the clamp circuit prevents arcing conditions from developing due to voltage excursions, as when for example the pulse voltage increases due to parasitic capacitance at the power supply output.
  • the clamp voltage may be set to a value that is high enough to allow the plasma to reach a highly ionized state, but not so high as to lead to arcing conditions due to overvoltage.
  • Figure 4 demonstrates operation of the magnetron plasma processing system to create a sputtering plasma in a highly ionized state without first adopting an arc discharge state. Illustrated in Figure 4 are the voltage, current, and impedance characteristics of the sputtering plasma as a function of time during one pulse in the operation of the device.
  • the pulsed DC power supply first applies a high negative voltage, exceeding minus 1800 volts, to the material target (cathode) of the sputtering system.
  • a high negative voltage exceeding minus 1800 volts
  • current develops through the plasma, rising to a level approaching minus 400 amps.
  • the plasma is in a highly ionized state.
  • the voltage suddenly drop to levels of a few tens of volts, which would be characteristic of an arc discharge state.
  • the plasma state can also be understood with reference to the plasma impedance.
  • the plasma impedance is high at first, and then settles to a nearly constant value of approximately 3.5 ohms.
  • the present invention therefore provides a novel high peak power plasma pulsed supply for magnetron sputtering with arc handling that minimizes damage due to arcs. It accomplishes this by tailoring the initiation of the pulse to prevent entering the arc state before entering the highly ionized state, and further by disconnecting the pulsing circuit from the plasma load and recycling the inductor energy stored for the high peak power pulse back to the energy storage capacitor at the detection of an arc condition, should such a condition occur once the highly ionized state is established.

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Abstract

L'invention concerne un système de pulvérisation magnétron qui comprend un dispositif d'alimentation en courant continu pulsé, pouvant délivrer des puissances de crête de 0,1 MW à plusieurs MW, avec une densité de puissance de crête supérieure à 1kW/cm2. Selon l'invention, un plasma de pulvérisation, dans un état fortement ionisé, est créé sans passer au préalable par un état de décharge en arc. Le dispositif d'alimentation électrique présente un circuit de génération d'impulsions comprenant un condensateur d'accumulation d'énergie et un inducteur monté en série, pourvu d'un moyen de commutation servant à déconnecter le circuit de génération d'impulsions du plasma et à recycler l'énergie de l'inducteur vers le condensateur d'accumulation d'énergie lors de la détection d'une condition d'apparition d'arc. Le condensateur d'accumulation d'énergie et l'inducteur monté en série assurent une concordance d'impédance avec le plasma, limitent la vitesse d'élévation du courant et l'amplitude des crêtes en cas d'apparition d'un arc, et conforment les impulsions de tension au plasma.
EP04778755A 2003-07-24 2004-07-20 Alimentation pulsee pour plasma a puissance de crete elevee avec gestion d'arc Withdrawn EP1654394A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US10/626,330 US20040124077A1 (en) 2002-09-25 2003-07-24 High peak power plasma pulsed supply with arc handling
PCT/US2004/023402 WO2005010228A2 (fr) 2002-09-25 2004-07-20 Alimentation pulsee pour plasma a puissance de crete elevee avec gestion d'arc

Publications (1)

Publication Number Publication Date
EP1654394A2 true EP1654394A2 (fr) 2006-05-10

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP04778755A Withdrawn EP1654394A2 (fr) 2003-07-24 2004-07-20 Alimentation pulsee pour plasma a puissance de crete elevee avec gestion d'arc

Country Status (2)

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EP (1) EP1654394A2 (fr)
JP (1) JP2006528731A (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4842752B2 (ja) 2006-09-28 2011-12-21 株式会社ダイヘン プラズマ処理システムのアーク検出装置、アーク検出装置を実現するためのプログラム及び記憶媒体
TWI476289B (zh) * 2006-12-12 2015-03-11 Oerlikon Advanced Technologies Ag 在高能脈衝磁管噴濺中之消弧及產生脈波
DE102011112434A1 (de) * 2011-01-05 2012-07-05 Oerlikon Trading Ag, Trübbach Blitzdetektion in Beschichtungsanlagen
JP6084860B2 (ja) * 2013-02-27 2017-02-22 東京エレクトロン株式会社 プラズマ処理装置

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2005010228A3 *

Also Published As

Publication number Publication date
JP2006528731A (ja) 2006-12-21

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