Lucent Technologies Inc.

At+t Corp.

William D Reents, Jr

James D Sinclair

Adrian B Emerson

Stephen W Downey

Alka Swanson

Amy J Muller

Anthony M Mujsce

The present invention provides methods and apparatus for analyzing the particulate contents of a sample such that a high proportion of the sample particles are analyzed without discrimination against high electronegativity and high ionization potential elements. In an exemplary embodiment, the invention comprises an apparatus for analyzing the particulate content of a sample having particulate diameters in range of 0.001-10 microns. The apparatus comprises an evacuable chamber equipped with a chamber entrance through which a particle-laden gas stream enters. An inlet device, such as a capillary, communicates with the chamber entrance for inputting the particle-laden gas stream to the evacuable chamber. A laser is positioned to produce a focused laser beam which intersects the particle-laden gas stream at a position approximately 0.1 mm from the chamber entrance. The laser beam has a power density sufficient to fragment and ionize particles entrained within the particle-laden gas stream. A detector is positioned to detect the ionized species produced by the laser.

Laser-assisted particle analysis

Disclosed is an apparatus which can serve to detect, count, size discriminate and analyze the chemical composition of particles in the air or process gases. In a preferred embodiment, the particles enter via a capillary into a differentially pumped chamber. A pulsed laser which is continuously fired is focused at an opening in the chamber. When the particles come into the path of the laser beam, the particles are fragmented and ionized. A dual time of flight mass spectrum is produced, recorded with an oscilloscope and analyzed with a computer. The mass spectrum information enables the determination of the chemical nature and concentration of the species of the particles, the particle size and the elemental composition of airborne particles in real time. Once these parameters are determined the source of the particles can be determined and eliminated from the environment and process. Thus, the inventive apparatus is advantageously used in conjunction with a facility, i.e., a semiconductor manufacturing facility, that requires ultra-clean conditions.

Laser induced mass spectrometry

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Middlesex, NJ, United States of America

William D Reents, Jr