International Business Machines Corporation

Other

Magicground Technology LLC

Charles A Gaston

Joseph P Kirk

Alfred Mack

Chester A Wasik

Alan D Wilson

Brian C O'Neill

Charles H Locke

Warren J Pinckney

Vaughn G Silar, Jr

Karl W Beumer

The present invention is directed to a ground-current isolating circuit for providing a low voltage barrier between a service neutral conductor and an associated grounding system. The voltage barrier circuit comprises a first current unidirectional element and a second current unidirectional element connected in antiparallel. The unidirectional elements are preferably diodes having a characteristic threshold voltage. The current in a forward biased direction is blocked by the circuit until an applied forward biased voltage exceeds the threshold voltage. The present invention also is directed to a method of isolating a neutral conductor temporarily from an associated grounding system during testing of a structure grounding system. The method includes connecting a voltage barrier circuit in parallel with a conductor bonding the neutral conductor to the associated grounding system, then disconnecting the bonding conductor; conducting a test of the structure grounding system associated with the structure, and reconnecting the bonding conductor between the neutral conductor and grounding system.

Ground testing method and apparatus

The disclosure is for an apparatus and method for voting that are based on personal computers. All data and software, including the operating system, voting software, and original ballot information are on a single portable data storage medium, such as a diskette. During use, voting results and security-check information are added to the same portable storage medium. The apparatus also includes a tamper detectable seal for a diskette in the computer and means for officials to authorize each voter to begin voting. In one sealing system diskette removal is prevented by a blocking plate that slides into the diskette slot above the diskette and an extension fastened to the diskette is also attached to the blocking plate assuring that the diskette cannot be removed until a visible seal is broken.

Voting apparatus and method using personal computers

In electron beam lithography, formation of micron and submicron size features is complicated by undesired nonuniform (pattern-density dependent) resist exposure from electrons backscattered from the underlying substrate. The disclosed technique uses a combination of a scattering mask and a scattering filter to add a leveling background exposure automatically and thus provide uniform contrast across the entire exposure pattern.

Proximity effect compensation in scattering-mask lithographic projection

A high precision, high throughput submicrometer workpiece positioning system, particularly useful as a workpiece positioning means in electron beam lithography tools. The positioning system increases mechanical stability by essentially eliminating mechanical hysteresis, which allows state of the art electron beam lithography systems to provide the repeatable, accurate and dense circuit patterns that modern semiconductor trends demand. The positioning system in preferred form comprises a movable positioning table, a workpiece supporting superstructure which is elastically joined to the movable positioning table by three geometrically distinct kinematic support means and a two-stage coupling means which mounts a workpiece (i.e., semiconductor mask or wafer) to the workpiece supporting superstructure. A laser interferometer locating-positioning system is utilized to position the workpiece. The interferometer mirrors are integral with the workpiece supporting superstructure. The coupling means mounts a workpiece to the workpiece supporting superstructure with a minimum of mechanical distortion. Three two-stage coupling means are utilized in preferred form. The first stage is removable from the positioning, and allows for workpiece loading and unloading outside of the positioning system. The removable stage comprises an integral unit which includes two opposing arms with large radii spherical ends and a tab member. The spherical end center lines are collinear, providing for vertical clamping of the workpiece. The second stage is stationary and integral with the workpiece supporting superstructure. The stationary stage comprises two opposing arms with large radii spherical ends and clamps the tab of the removable stage by vertical clamping.

Workpiece mounting and clamping system having submicron positioning

An optical system and technique for monitoring a monotonic change in the thickness of a transparent film by means of optical interference, and for eliminating ambiguity in the identification of absolute film thickness. The system is particularly adapted for monitoring the etching of a dielectric film of uncertain initial thickness in microelectronic fabrication. The technique utilizes a white light source directed upon the film. Reflected light, modified by optical interference in the dielectric film, is monitored by photodetectors at two distinct wavelengths. The cyclic patterns of intensity change at the two wavelengths are compared to identify unambiguously the absolute thickness of the film, although the initial uncertainty in film thickness may have corresponded to several cycles of either wavelength pattern alone. To simplify phase comparison of the two cyclic patterns, wavelengths can be selected so that some particular coincidence of extrema in the two signals occurs at a film thickness less than the expected minimum initial thickness, and does not occur at any greater thickness up to and including the expected maximum. Determination of the absolute film thickness in this way permits further tracking of the etching process to the desired end point without overshoot.

Growing community of inventors

Lancaster, PA, United States of America

Charles A Gaston