Preliminary work on what the inventors, Isoflux and the Kurt J. Lesker Company, have named ‘SPION’ (sputter ion) technology will be presented by Dr. David Glocker, of Isoflux, Inc., in a talk titled “Operation of a Combined Sputter Deposition and Ion Source”, Session Number: E-8, on Tuesday - April 28, 2015 - 10:40AM - 11:00AM, Room: Grand Ballroom F, SVC TechCon 2015 in San Jose, CA.
From the presentation abstract:
A multipurpose source has been constructed that can operate either as a magnetron sputtering cathode, an end-Hall ion source, or both simultaneously depending on the applied voltage. A conical electrode with a major diameter of 6.5 cm and included angle of 90 degrees is combined with a magnetic field that forms a plasma trap above the electrode and also extends beyond the electrode opening. A hot filament generates electrons when operating as an ion source. Using an Al electrode, all three modes of operation have been demonstrated. Sputtering with an applied voltage of -390 V produced an Al film at a specific deposition rate of 4.0 (nm/min)/(W/cm2). By applying +340 V to the electrode at an Ar pressure of 1 mT and filament current of 25 A, a thermally grown SiO2 layer was etched at a rate of 5.2 nm/min. Finally, using a 40 kHz bipolar power supply to apply an alternating positive and negative voltage to the electrode at a total power of 200 W, a reactively sputtered Al2O3 film was deposited arc-free at a specific rate of 1.1 (nm/min)/(W/cm2). The values for n and k (632 nm) for the Al2O3 were 1.67 and 0.001 respectively.
Background and significance of the innovation:
Ion sources and sputtering sources are two of the most commonly used components in thin film coating applications. They both offer advantages for their respective applications and in some cases even work together to enhance the properties of thin film coatings.
Many sputtering systems are configured with both sputtering magnetrons and ion deposition sources. In addition to the space requirements of two components, each source requires its own power supply for operation. The SPION (sputter ion) Source was developed to provide a flexible solution for sputtering applications. It can be used as a magnetron sputtering cathode, or ion source, or combined, working simultaneously, as a sputtering/ion source in an ion assist mode.
SPION – represents a new tool for sputtering optimization and flexibility: a multipurpose single source with three modes of operation, which can be used as a magnetron sputtering cathode, an ion source, or working simultaneously as a sputtering/ion source in ion-assisted applications.
This not only allows for more capability in a compact system design, but also yields a more user-friendly tool and adds overall efficiency to the process.
Ion Source Summary:
Gridless ion sources use a source of electrons, a positively charged anode and a magnetic field to create atomic and molecular ions. The anode accelerates the electrons and the magnetic field causes them to travel in complex orbits and increases the probability that they will ionize the gas atoms or molecules. They are capable of generating significant ion currents and are used to bombard growing films and produce high quality evaporated or sputtered coatings.
Magnetron Sputtering Source Summary:
Magnetron sputtering sources utilize a magnetic field to create a plasma discharge. The plasma is sustained by energetic electrons that are trapped by the magnetic field and collide with a working gas in a vacuum atmosphere to produce ions. The ions strike the atoms on the surface of a target, propelling them via momentum transfer from the target and depositing them onto the substrate.
Key Features of the SPION:
Through careful design of the magnetic field, the SPION deposition source can operate either as an ion source, a sputter source, or as an ion and sputtering source simultaneously. The 6 cm diameter conical electrode functions as either an anode, a sputter target, or both depending on the operating conditions. The SPION can be used with either a filament or hollow cathode source of electrons in both modes, which gives it unique capabilities as an ion source and a low pressure sputtering cathode.
Ion Source Operation:
Using a filament to generate electrons, at a pressure of 1 mTorr the SPION etched a thermally grown silicon dioxide layer at a rate of 5.5 nm/min. The operating voltage was +340 V, the discharge current was 150 mA, and the source to substrate distance was 10 cm. This compares favorably with the performance of other gridless ion sources.
Magnetron Sputtering Source Operation:
In the sputtering mode, the SPION can be operated either with or without a hollow cathode electron source. With hollow cathode enhancement, it can sputter at pressures down to 0.5 mTorr. At a power of 200 W, pressure of 3 mT and substrate distance of 13 cm the aluminum deposition rate in the magnetron mode is 16 nm/min. At that distance the film thickness uniformity is ±6.5% over an 8 cm diameter.
Sputtering / Ion Assist Operation:
When using the SPION to sputter with ion assist it operates with an electron source and the electrode is powered by a mid-frequency AC power supply. Under these conditions the electrode both sputters material and bombards the growing coating with ions, alternating at the frequency of the power supply. In this configuration the SPION can deposit high quality ion enhanced metal and dielectric coatings. For example, aluminum oxide with excellent properties has been deposited arc-free at a rate of 7 nm/min at a power of 200 W.
The SPION provides a unique combined capability in a single compact package ideal for research or even small production environments. It provides three different modes of operation from a single source powered with a single power supply to squeeze the most flexibility out of your system.