Low Damage Sputtering Techniques

The challenges presented by standard planar magnetron sputtering.

The highly energetic nature of magnetron sputtering deposition makes it an ideal technology for many applications; however, certain aspects of the sputtering process can lead to challenges when depositing onto soft materials and organics.
Pin Holes

In a confocal or face-on-face sputter geometry (sputter cathode pointing towards the substrate), high-energy gas particles can be reflected off the face of the target to make direct contact with the substrate.

As these high-energy particles impinge upon the substrate, they can cause physical damage, most often ‘pinholes’, to any soft organic layers at the surface.  These pinholes can have serious implications on film properties and overall device performance.

Heat Damage

Another challenge with traditional magnetron sputtering is that although much of the electron density is captured at the surface of the target, radiation will reach the substrate, increasing heat.

Performance will suffer if these interactions cause the substrate temperature to rise above what is safe for the layers that make up a device.

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    Pinholes and heat damage can compromise the functionality, durability, and in some cases, even the viability of the film, making it essential to develop methods that prevent such damage.
    Facing Target Sputtering (parallel plate target)

    A source configuration in which two magnetron sources are positioned opposite one another and at right angles to the substrate. This creates a geometry in which any high-energy reflected particles are directed to the opposing cathode and not the substrate.

    When paired with the appropriate source, magnetics confines the plasma between the two sources and reduces the electron density allowed to reach the substrate.

    The result is a sputtering technology which minimizes both the physical and thermal damage of soft or organic layers.

    alt = Inside view of a facing target sputter deposition system, showing plasma discharge and metal targets opposite each other. The system is lightened with a purple glow, showing the plasma production process used for thin film deposition.
    Hollow Cathode Sputter

    HCS employs a similar strategy to facing target sputtering, except instead of two cathodes, it allows for a single, cylindrical cathode that accomplishes the same thing. Instead of directing the target plasma directly towards the substrate like standard sputtering, the cylindrical target and plasma ejects particles inward, where they collide and are directed toward the substrate after losing energy.

    Gas Flow Sputtering

    Going a step beyond pointing the sputter cathodes in towards one another in order to keep the energetic particles from coming into contact with the substrate. We have seen success with gas flow sputtering, which employs a specialized cylindrical sputter cathode with its own precise geometry and gas flow capabilities that keep the kinetic energy of the sputtered particles low while simultaneously allowing for high rates. In some cases, the kinetic energy from Gas Flow Sputtering are even lower than evaporative deposition techniques. This is accomplished by:

     

    1. Sputtering from directly inside the cathode cylinder. With no direct line to the substrate, the sputtered particles cannot damage it.
    2. Increasing the chamber pressure thereby increasing the probability that these particles will lose energy before finding the substrate,
    3. Helping to increase deposition rate by ‘flowing’ the argon carrier gas (and the sputtered material) towards the substrate.

    Configurations & Fixturing Options

    This technology is available in various source configurations and is compatible with many Angstrom Engineering® process control capabilities and advanced fixturing options.

    Process Control Software

    Aeres® Angstrom Engineering's® advanced process control software has been specifically configured with features and capabilities unique to high-performance deposition.

    Configurations & Fixturing Options

    This technology is available in various source configurations and is compatible with many Angstrom Engineering® process control capabilities and advanced fixturing options.

    Process Control Software

    Aeres®, Angstrom Engineering's® advanced process control software, has been specifically configured with features and capabilities unique to high-performance deposition.

    Out of all the systems I have used, yours is by far the most reliable, consistent and easy to use.

    Dr. Marc Baldo
    Massachusetts Institute of Technology