Publication: Micromachined Faraday cup array using deep reactive ion etching
Date
01-01-2002
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Abstract
A micromachined Faraday cup array (MFCA) has been developed using a deep reactive ion etching (DRIE) process for applications in position sensitive charged particle detection. Deeply etched trenches with vertical sidewalls create an effective ion collection structure, and the formation of MOS capacitors on the interior surfaces produces an array of low-leakage, high stability Faraday cups that can be independently addressed. Closely spaced, linear arrays of 64, 128 and 256 cups with pitches of 150 and 250 uμm have been fabricated and characterized. The narrow 50 uμm silicon web between each pair of Faraday cups provides electrostatic isolation with linear fill factors of 67 and 80%, respectively. These Faraday cup arrays enable a new generation of compact mass spectrometers which feature true multi-channel ion detection capability over a wide mass range. Since the entire array is always open to the incident ion flux, no ions are lost as in scanning mass spectrometer systems, and the overall sensitivity is drastically improved by a factor that is approximately equal to the number of cups in the array. The MFCA is thus an ideal component for miniaturized mass spectrometers, ion beam profiling, and chemical analyzers which must handle very small samples.
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Keywords
Electronic multiplexing, Faraday cups, Ion sensors, Mass spectrometers