Process control in the semiconductor manufacturing environment using a high pressure quadrupole mass spectrometer

Abstract

The presence of quadrupole mass analysers in the semiconductor processing environment is as common today as that of the mass flow controller or total pressure ion gauge. However, the need for manufacturers to monitor process ‘purity’ and yields to improved levels of accuracy requires the application of an instrument suitable for reliable determination of contaminant down to the ppm or sub-ppm level. An analyser is described that allows both leak checking and residual gas analysis at chamber base pressure along with true reagent gas and contamination monitoring during the process itself. It will be shown that an ion source operating at (or close to) the process pressure gives significant advantages with respect to signal over background ‘noise’ levels, whilst electron emitting filaments sited outside the ion source ensure minimal filament/gas interaction. Combination of such an ion source with high performance triple filter quadrupole design ensures that important process parameters such as target purity, gas line integrity and pump down characteristics can be faithfully and routinely monitored.