Research Triangle Institute

Other

Robert P Donovan

David S Ensor

Ravindran Periasamy

James C Fletcher

Jimmie J Wortman

Anthony Clint Clayton

Larry K Monteith

William H Kinard

Robert L O'Neil

Arthur D Brooks

A device for controlling the motion of particles suspended in a gas stream is provided, including a pipe, through which at least a fraction of the gas stream flows, a source of AC voltage, a source of DC voltage, and a plurality of electrode sets positioned within the pipe in series, generating an inhomogeneous electric field to cause the particles suspended in the gas stream to concentrate into a narrow axial region in the center of the pipe. Each electrode set includes a first pair of opposed hyperboloidally shaped electrodes connected to the AC voltage source and a second pair of opposed hyperboloidally shaped electrodes connected to the DC voltage. The first and second pairs of opposed electrodes are positioned at spaced apart intervals around the circumference of the pipe to define an opening through which at least a fraction of the gas stream flows. The electrode sets are positioned within the pipe in series such that the gas stream flows through the openings defined by each successive electrode set. The spaced apart distance between the electrodes of each successive electrode set is decreased to reduce the size of the openings, causing the particles suspended in the gas stream to focus or concentrate along successively narrower axial regions in the center of the pipe.

Device for focussing particles suspended in a gas stream

An apparatus and method including a droplet coating generator for generating a stream of electrically charged coating droplets within an evacuable chamber towards a substrate positioned within the evacuable chamber. A piezoelectric vibrator and orifice plate coupled thereto generate the stream of coating droplets. The coating droplets are urged to move in a sweeping motion across the substrate by at least one pair of opposing spaced apart electrodes powered by an electrical power supply. A uniform coating is thus produced while the evacuable chamber is maintained at subatmospheric pressure as required during typical semiconductor processing. Multiple applications of a photoresist coating may be applied by the coating apparatus without requiring that the evacuable chamber be repeatedly vented and pumped down to subatmospheric pressure.

Apparatus and method for uniformly coating a substrate in an evacuable

The invention is a device for counting aerosols and sorting them according to either size, mass or energy. The component parts of the invention are an accelerator, a capacitor sensor and a readout. The accelerator is a means for accelerating the aerosols toward the face of the capacitor sensor with such force that they partially penetrate the capacitor sensor, momentarily discharging it. The readout device is a means for counting the number of discharges of the capacitor sensor and measuring the amplitudes of these different discharges. The capacitor employed is a metal-oxide-silicon capacitor in which the metal and oxide layers are very thin. The aerosols are accelerated by the accelerator in the direction of the metal layer with such force that they penetrate the metal and damage the oxide layers, thereby allowing the electrical charge on the capacitor to discharge through the damaged region. The impacting aerosols create a discharge path which is self-healing; that is, each incident aerosol initiates a discharge path through the capacitor in such a fashion as to vaporize or blow out the conducting path in the process. Once the discharge action is complete, the low resistance path no longer exists between the two capacitor plates and the capacitor is again able to accept a charge. The active area of the capacitor is reduced in size by the damaged area each time a discharge occurs.

Particulate and aerosol detector

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Durham, NC, United States of America

Robert P Donovan