Micromachined faraday cup array using deep reactive ion etching

A micromachined Faraday cup array (MFCA) for position sensitive ion detection has been developed using a deep reactive ion etching (DRIE) process. Linear, closely spaced arrays of 64, 128, and 256 cups have been produced with pitches of 250 mum and 150 mum. Low leakage MOS capacitors formed into DRIE trenches form effective ion collection traps with stable and electrostatically isolated capacitances. These closely spaced arrays of Faraday cups enable a new generation of compact mass spectrometers with true multi-channel detection capability. Since all of the incident ion flux is continuously intercepted by the array, no ion flux is lost as in scanning systems, and the overall sensitivity of the mass spectrometer is drastically improved by a factor 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 work with very small sample volumes or high throughputs.