Wisconsin Alumni Research Foundation

Noah H Hershkowitz

Ferencz S Denes

Sorin Odisei Manolache

Scott Baalrud

Moshe Sarfaty

Benjamin Longmier

Perry W Sandstrom

Moo-Hyun Cho

Anthony K Quick

An electron generating device extracts electrons, through an electron sheath, from plasma produced using RF fields. The electron sheath is located near a grounded ring at one end of a negatively biased conducting surface, which is normally a cylinder. Extracted electrons pass through the grounded ring in the presence of a steady state axial magnetic field. Sufficiently large magnetic fields and/or RF power into the plasma allow for helicon plasma generation. The ion loss area is sufficiently large compared to the electron loss area to allow for total non-ambipolar extraction of all electrons leaving the plasma. Voids in the negatively-biased conducting surface allow the time-varying magnetic fields provided by the antenna to inductively couple to the plasma within the conducting surface. The conducting surface acts as a Faraday shield, which reduces any time-varying electric fields from entering the conductive surface, i.e. blocks capacitive coupling between the antenna and the plasma.

Non-ambipolar radio-frequency plasma electron source and systems and methods for generating electron beams

An apparatus is utilized for producing colloidal dispersions of nanoparticles of electrically conducting materials. The colloidal dispersions are produced in a dense media plasma reactor comprising at least one static electrode and at least one rotating electrode. The plasma reaction sputters off minute particles of the electrically conducting material from which the electrodes are made. Methods of using the colloidal dispersions thus made are also described. Colloidal dispersions of silver produced in this manner are highly effective for bactericidal purposes.

Colloidal nanoparticles and apparatus for producing colloidal nanoparticles in a dense medium plasma

A method and apparatus is utilized for producing colloidal dispersions of nanoparticles of electrically conducting materials. The colloidal dispersions are produced in a dense media plasma reactor comprising at least one static electrode and at least one rotating electrode. The plasma reaction sputters off minute particles of the electrically conducting material from which the electrodes are made. Methods of using the colloidal dispersions thus made are also described. Colloidal dispersions of silver produced in this manner are highly effective for bactericidal purposes.

Method and apparatus for producing colloidal nanoparticles in a dense medium plasma

A plasma generator includes several plasma sources distributed in an array for plasma treatment of surfaces. Each plasma source includes first and second conductive electrodes. Each second electrode has a gas passage defined therein, and one of the first electrodes is situated within the gas passage in spaced relation from the second electrode, with each gas passage thereby constituting the free space for plasma generation between each pair of first and second electrodes. An insulating layer is interposed between the first and second electrodes to facilitate plasma formation via dielectric barrier discharge (DBD) in the gas passages between the first and second electrodes. The first electrodes may be provided in a monolithic structure wherein they all protrude from a common bed, and similarly the second electrodes may be monolithically formed by defining the gas passages within a common second electrode member. The first electrode bed may then be situated adjacent the second electrode member with its first electrodes extending into the gas passages. The space between the first electrode bed and the second electrode member defines a plenum space onto which the gas passages open. The plenum space, and thus the gas passages, may then be provided with process gas to generate plasma within the gas passages between the first and second electrodes. Plasma ejected from the gas passages will impinge upon and treat an adjacently-situated workpiece without the need to pass the workpiece through the gas passages, and thus the size of the workpiece to be treated is not limited by the size of the gas passages (i.e., the free space wherein plasma is generated). The ability to utilize monolithically-formed first electrodes and/or second electrodes allows for significantly denser placement of plasma sources in arrays, thereby leading to more complete plasma treatment of surfaces.

Plasma generator

A plasma probe enables simultaneous localized electrostatic measurements and optical emission spectroscopy. The probe has a support arm with an elongated longitudinally extending section and a bend section at the end of which is supported an electrical probe element composed of back-to-back charge collection plates separated by an insulating spacer. The inner plate faces an opening in the end of the elongated support arm section which defines a collimating channel. An optical fiber extends through the support arm and has an aperture in the collimating channel to receive light emitted from the plasma between the end of the elongated section of the support arm and the inner charge collection plate. The electrical probe element acts as a blocking element to block light emitted from the plasma outside of the region between the electrical probe element and the end of the support arm section. Electrical wires extend through the probe from the charge collection plates to charge detectors, allowing measurements of electron density, Electron Energy Distribution Function and ion flow. The light received by the optical fiber is detected by a spectrometer to carry out Optical Emission Spectroscopy, which can be correlated with the information obtained from the charge collection plates. The probe can be moved around a plasma confinement chamber to provide spatially localized measurements of plasma characteristics at various positions within the chamber.

Electro-optical plasma probe

A device for measuring polymer build-up on plasma chamber walls provides a cooled window on which a film may form. Light passing through the window outside the chamber may be measured by interferometric techniques to determine change in film thickness and thus indicate when cleaning is required and the success of cleaning operations. A sapphire window may be used to allow for air cooling and to reduce etching by the plasma. A fiber optic cable may communicate the light between the window and measurement electronics.

Wall deposition thickness sensor for plasma processing chamber

A glow discharge etching apparatus includes a magnetic assembly for creating a surface magnetic field in close proximity to the walls of an etching chamber. An electrode is located within the chamber for supporting the object to the etched. A radio frequency signal is applied to the electrode so that it will emit secondary electrons upon bombardment by ions from an etching plasma created within the apparatus. A control plate may be positioned at various locations within the apparatus to regulate the amount of electron leakage to the control plate and thereby regulate the etching process. This apparatus provides improved uniformity and directionality of etching due to a low gas pressure and the surface magnetic field.

Growing community of inventors

Madison, WI, United States of America

Noah H Hershkowitz