New GSD Source from Plansee: All-Around Redesign with Benefits All-Around.

The GSD is a popular implanter system from Axcelis. Plansee stocks the appropriate implanter sources for all generations of GSD systems. Feedback from many users over the past years has shown that the standard source has plenty of room for improvement. Thus, Plansee has improved the source by increasing both its lifetime and efficiency. This redesign allows it to be used in any existing systems without any complications.

"Repetitive requests and feedback from system operators have revealed areas of individual components to improve the service life of the GSD implanter source," explains Kevin Chivatakarn from Plansee Electrograph in California. "Instead of improving individual components as the need arose, we overhauled the entire source. The result is a fully optimized GSD source in which all the measures taken work in perfect harmony," he continues. The engineers at Plansee implemented a large number of changes to improve the GSD implanter source. One focus of attention has been placed on the "halogen cycle."


Reduced impact of the halogen cycle


Fluorine is one of five reactive halogen elements. Source plasmas rich in fluorine accelerate the deterioration of ion source components and are routinely blamed for premature failures. The source of these failures, known as the tungsten-halogen cycle, is a regenerative process considered useful in lighting applications but is unbalanced in typical ion sources. In lighting applications, the halogen element reacts with evaporated tungsten forming a tungsten halide. The halide dissociates as it reaches higher temperatures within the chamber and thus releases tungsten back onto the filament.

In fluorine plasmas, the relatively high thermal stability of tungsten-fluoride ensures that the highest rate of tungsten re-deposition occurs on the hottest surfaces of the source (i.e. the cathode). Thus, tungsten sidewalls which are also etched by free fluorine gas contribute excess tungsten to the cycle resulting in a net migration of tungsten from chamber wall to cathode and frequently results in shorting and premature failure of components. An important objective of the GSD redesign was to reduce the effects of tungsten re-deposition caused by the formation of tungsten-fluorine halides. The new design employs specific mechanical and material changes to improve its thermal profile and to reduce etching. For example, lanthanated tungsten (WL) is used for its thermal and etch resistant properties.


Less material deposition and gas loss


In parallel to the halogen cycle, material deposition around the chamber represents a major challenge. This occurs when particles from components escape from the chamber and are deposited onto insulation components. Plansee changed the design of the cathode in order to reduce material deposition at critical locations in the ion source chamber. The design not only reduces material deposition, but also gas loss from the chamber, which results in cost reductions for system operators.



Simplified installation


Even the repeller was subjected to reworking. Plansee transformed the many components into a simple 4-part construction, which is easy to install and replace. Moreover, the new design is not only easier to handle, but it also makes the gas paths longer, an additional factor contributing to further gas loss reduction.

Furthermore, the self-adjusting system automatically establishes an optimum gap between the cathode and coil, which further exemplifies how much easier the system is to install.


The new GSD source from Plansee is extremely adaptable. Plansee offers different cathode and repeller thicknesses, and the source is available in vaporizer and non-vaporizer versions for high-current and low-current operation. It can be used in existing systems and fits the standard mounting in the GSD.

"The bottom line is that our design increases the service life of the source and extends the maintenance intervals," says Kevin Chivatakarn. "Our system improves temperature distribution in the chamber, is able to more accurately focus the plasma beam, uses less process gas and saves on energy as a result of higher plasma densities. The stability of the process is also enhanced, which makes it easier to tune the system. Although there are several additional advantageous details that I could mentionwe prefer to describe the many benefits of our system to our customers face to face." Chivatakarn and his colleagues are looking forward to handling all of your inquiries.


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