Airflow controlling apparatus
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The apparatus controls airflow in semiconductor cleanrooms. It is made up of a plastic or ceramic grille that has numerous air vents and a shutter assembly with a fixed plate that also has several openings. The shutter assembly has two plates, a fixed plate and a moving plate. The moving plate is situated between the grille and fixed plate and an open-ratio controlling screw at the center of the grille moves along a rack on the moving plate to allow adjustment of airflow.
Patent number: 5,984,775
Date granted: November 16, 1999
Inventors: Kun-hyung Lee and Tae-jin Hwang,
Samsung Electronics Co. Ltd. (Suwon, Korea)
Welding process for sterile filling
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A mechanical seal to a vial can later make opening difficult and even cause fractures to what should be a leak-proof assembly. This method, used in the pharmaceutical industry, adheres seals to plastic vials or containers. A seal is mechanically fastened to the container opening. A heated die with a concave contact surface fuses the seal to the vial or container. This method can also be used on liquid food, solvent and lubricant containers.
Patent number: 6,009,691
Date granted: January 4, 2000
Inventor: Arthur F. Lifshey,
Merck & Co. Inc. (Rahway, NJ)
Airflow rate regulator
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Air filtration systems rely on electric actuators to alter airflow. They are usually slow to react to fluctuations. This invention is an airflow rate regulator, installed in a vacuum unit that collects contaminants from a processing station in a controlled space. It enables a vacuum unit to maintain a continuous suction of particles from a processing station when there are pressure variations in the controlled space. The regulator is mounted in a cabinet and connected to a vacuum source. It has a casing divided into two chambers separated by a wall having a passageway through which air flows from one chamber to the next. When a pressure disturbance occurs in the controlled room from a door opening, or when a hose leading to the contaminant source is disconnected, the valves react to maintain sufficient vacuum pressure at the contaminants' source. Because the airflow rate regulator is mechanical, its response time to pressure is nearly instantaneous.
Patent number: 6,009,894
Date granted: January 4, 2000
Inventor: Michel Trussart,
Les Systems Et Procedes, Dynapharm Inc. (Canada)
Etch chamber cleaning method
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The increasing trend of miniaturizing semiconductor integrated circuits requires a more stringent control of cleanliness in the processing chamber. When the dimension of a miniaturized device approaches the sub-half-micron level, even the slightest amounts of contaminants can reduce the yield of the manufacturing process. The method, for etching polysilicon or metal, uses chlorine gas fed from a supply tank through an inlet into the chamber. Electrode power remains on after etching is completed. The valve to let chlorine gas into the chamber is then closed, while another valve is opened to allow the contaminated cleaning gas to drain from the chamber. Suitable cleaning gases contain at least one inert gas of argon, helium or a mixture containing oxygen. Cleaning process is 5 to 10 seconds.
Patent number: 6,003,526
Date granted: December 21, 1999
Inventors: Chi-Hsin Lo, Hsing-Yuan Cheu,
Tawain Manufacturing Co. Ltd. (Hsin-Chu, Taiwan)
Wet process contamination reduction
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The method reduces contamination in wet processing of semiconductor substrates by removing sources of gas contamination. A process liquid is pumped through a degasifier. A vacuum pump can also be used, depending on the degasifier type, to improve performance. Semiconductor wafers are placed in a tank filled with degasified processing liquid, removing any sources of gas contamination. The liquid is then recirculated through the system and returned to the tank.
Patent number: 6,001,189
Date granted: December 14, 1999
Inventors: J.Brett Rolfson,
Micron Technology Inc. (Boise, ID)
Low concentration particle measurement
Using photon correlation spectroscopy was thought to be useful only for measuring high particle concentrations suspended in liquid. Concentrations of less than 200 particles are difficult to measure because the particles are more susceptible to inherent kinetic energy, which alters the measuring signal. This system uses a laser, whose emitted light is scattered by particles. A light detector, providing a measurement of light intensity, receives light deflected from particles. That measurement is converted to an electrical signal, which is received by the correcting device that is outfitted with a low-pass or high-pass filter. Measurements taken with the high-pass filter indicate particle movement fluctuations, and particles of low frequency are eliminated from the measuring signal calculations. A low-pass filter hones in on actual particle size and concentration.
Patent number: 6,011,621
Date granted: January 4, 2000
Inventors: Johannes Cornelis Maria Marijnissen;
Alexander Willem Willemse; and Andre Roos,
Technische Universiteit Delft (Netherlands)
High-efficiency metal membrane filter
The invention is referred to as a point-of-use filter for semiconductor process gases. It absorbs such substrate-harming gases as silane, arsine, hydrochloric acid and phosphine. A porous membrane filter has a sintered element and a matrix of interconnected pores. The filter is made from pure filamentous nickel powder and has a porosity of at least 55%. The filter can be sealed within a housing to form a porous device with a filtered-fluid flow path. Nickel powders are compacted into a mold to make a “green form.” The form is then sintered to join the metal particles to provide strength. The final filter elements or membrane may be cut from a flat sintered sheet of metallic powder, or molded into the final shape of the molding step.
Patent number: RE36249
Date granted: July 13, 1999
Inventors: Robert S. Zeller,
Millipore Investment Holdings, Inc. (Wilmington, DE)
Hydrophilic foam cleaning
This method is suited for cleaning metal, glass or plastic without scratching or scoring the surface. Surfaces are wiped with an article made from an open cell, hydrophilic, static-dissipative, polyurethane foam. The cleaning article may be a wiper, a sponge, a roller, a swab mounted on a handle, or a cylindrical-shaped plug. Cleaning articles are also laundered so that in deionized water fewer than 36×106 particles of size greater than 0.5 micron per square meter of surface area fewer than 2.5 parts per million of chloride, fluoride, sodium, sulfate, sulfite or silicon ions are released. The method may also comprise washing the surface with deionized water.
Patent number: 6,004,640
Date granted: December 21, 1999
Inventors: Ferdinand Frederick Pisacane and
Alan R. Seacord, Wilshire Technologies (Carlsbad, CA)
Particle trap
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Plasma ignition is thought to be a major generator of particles in a magnetron sputtering chamber. Some particles are drawn to the plasma, while others strike and stick to the wafer. The invention is an altered plasma sputtering reactor in which a magnet is linearly scanned over the back of the sputtering target to enhance the sputtering. The magnet's linear scan is extended to beyond the wafer processing area. When the magnet reaches that point, conditions are changed within the reactor to cause particles otherwise trapped by the magnet to fall into an area of the reactor where they do not fall on the substrate being processed. The changed conditions may include extinguishing the plasma, reducing or reversing the target voltage, positively charging walls of the trap area, or pulsing gas through the plasma. Also, the plasma is ignited with the magnet positioned over the trap area so that particles generated in the ignition process are not immediately deposited on the wafer or the walls of the processing area, and they tend to stay in the trap area.
Patent number: 6,013,159
Date granted: January 11, 2000
Inventors: Bret W. Adams and Ivo Raaijmakers,
Applied Materials Inc. (Santa Clara, CA)
Contamination control device for electrostatographic development station
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The magnetic brushes used in electrostatographic reproduction equipment tend to generate particles, which, if not controlled, may escape and contaminate the interior. The invention is a device that uses a mixture of pigmented- and magnetic carrier particles to develop latent image charge patterns on a dielectric member. The development station has a housing adjacent to a dielectric member. The housing has a reservoir for a particle material mixture, and an opening facing the dielectric member. Within the housing is a mixer for combining material, a magnetic brush for applying pigmented particles from the material mixture to a latent image charge pattern, and a device for transporting the material from the mixer to the magnetic brush. A contamination control device is provided for collecting airborne particles. The contamination-collecting device includes an elongated tube located outside of the housing. Passages by the housing between the magnetic brush and the mixer work in conjunction with the tube opening, and a vacuum is supplied to the interior of the tube to prevent contamination of the reproduction apparatus and its environment.
Patent number: 5,881,338
Date granted: March 9,1999
Inventors: Timothy Gilbert Armstrong;
James C. Maher; Susan Pike Farnand,
Eastman Kodak Co. (Rochester, NY)
Send your inventions
Information on the patents highlighted above was obtained through the U.S. Patent and Trademark Office. Inventors who have been granted patents within the last six months for new cleanroom and contamination technology are encouraged to submit them to CleanRooms magazine for publication. Send a brief description of the invention along with a detailed drawing to Mark A. DeSorbo, associate editor, CleanRooms, 98 Spit Brook Road, Nashua, NH 03062, or e-mail at [email protected].