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- J.G. Lopes
ISEL, Lisboa, Portugal
- F.A. Corrêa Alegria
IT, Lisboa, Portugal
- J.G. Lopes, L.M. Redondo
CFNUL, Lisboa, Portugal
- J. Rocha
ITN, Sacavém, Portugal
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A high resolution system designed for measuring the ion beam profile in the ion implanter installed at the Ion Beam Laboratory of the Technological Nuclear Institute (ITN) is described. Low energy, high current ion implantation is becoming increasingly important in todays technology. In order to achieve this, the use of electrostatic lens to decelerate a focused ion beam is essential, but one needs to measure, with high resolution, the 2D beam profile. Traditional beam profile monitors using a matrix of detectors, like Faraday Cups, were used. They are, in essence, discrete systems since they only measure the beam intensity in fixed positions. In order to increase the resolution further, a new system was developed that does a continuous measurement of the profile, made of a circular aluminum disc with a curved slit which extends approximately from the center of the disc to its periphery. The disc is attached to the ion implanter target, which is capable of rotating on its axis. A cooper wire, positioned behind the slit, works like a Faraday Cup and the current generated, proportional to the beam intensity, is measured. As the ion implanter is capable of scanning the beam over the target, the combination of vertical beam scanning with aluminum disc rotation allows the beam profile to be measured continuously in two dimensions. Hence, the developed system including the computer controlled positioning of the beam over the moving curved slit, the data acquisition and the beam profile representation, is described.
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