LABORATORY ALLOY and NANOLAYER SPUTTERING

The 4W-LANS Laboratory Alloy and Nanolayer Sputtering system address the needs of researchers in demanding, cross-disciplinary areas of dielectric, metallic, magnetic, superconducting and semiconducting thin film development. The system provides previously unobtainable degrees of layer thickness control, interface control, alloy composition control and materials flexibility in a small, cost-effective package.

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A new sputtering technology called Biased Target Deposition (BTD) pioneered by 4Wave employees is at the heart of this revolutionary new product for thin film materials development. BTD is a hybrid between Ion Beam Deposition (IBD) and conventional sputter deposition which combines the best of each technique. BTD is uniquely suited to demanding applications requiring atomically engineered thin films and interfaces as it offers a large range of process pressures, control of adatom energies, and excellent uniformity and repeatability.

Features: High output, low-energy plasma source 6 x 4" biased target carousel independent target biasing for alloy composition control 100mm diameter process surface <3% non-uniformity over 75 mm substrate plasma cleaning, etching oxidation, nitridation Water cooled, rotating, magnetic, shuttered stage, heating up to  600 C Single wafer load lock stage

Applications: Spin Valves /AMR/ GMR Magnetic Tunnel Junctions Dielectric Interference Coatings Rugate Filters High-k Materials Shape Memory Alloys Optoelectronic Materials Superconducting Materials

What is a Biased Target Deposition (BTD)?
In BTD, a low energy plasma source is directed at a negatively biased sputtering target. The maximum energy (typically < 25 eV) of the ions is less than the sputter threshold of the vacuum system materials. No effort is made to capture all of the ions on the target because ions that miss the target do not generate unwanted sputtering. The ion beam is generally broader than the target to improve target illumination uniformity

A plasma sheath develops at the surface of the negatively biased target that accelerates positive ions entering the sheath toward the target to produce sputtering. Because the sheath is very small (~ 2 mm) compared to the spacing between the ion source and target, the target bias has no substantial effect on the ion trajectories from source to target. Hence, for constant source operation, the ion current amplitude and distribution reaching the target are nearly independent of the target voltage. A grounded shield surrounds the target to prevent undesired sputtering of the target mounting hardware that is also biased. DC or pulsed DC target bias is used depending on the target material and desired process. A large range of target voltages (~100 to 2000 V) can be used while maintaining reasonable deposition rates. The selection of the target voltage, by virtue of its impact on sputtered ejection energy, has a profound impact on the atomic scale mixing at thin film interfaces and the overall roughness of the growing film. In addition, the ion source is capable of operating over a broad range of process pressures (~10-4 to 5x10-3 Torr), allowing control of the sputtered atom scattering from the background gas.