International Business Machines Corporation

Nikon Corporation

William A Enichen

Christopher Frederick Robinson

John George Hartley

Samuel Kay Doran

Ken Tze-Kin Chan

Rodney A Kendall

Steven D Golladay

Paul F Petric

James D Rockrohr

Maris A Sturans

Guenther O Langner

Donald E Davis

Timothy R Groves

Edward V Weber

Henri A Khoury

Cecil T Ho

Michael Stuart Gordon

Rainer Butsch

Richard D Moore

Eileen V Clarke

Christophe F Robinson

Electron beam lithography tool image quality evaluating and correcting including a test pattern with a repeated test pattern cell, an evaluation method and correction program product are disclosed. The test pattern cell includes a set of at least three elongated spaces with each elongated space having a different width than other elongated spaces in the set such that evaluation of a number of space widths in terms of tool image quality and calibration can be completed. The evaluation method implements the test pattern cell in a test pattern in at least thirteen sub-field test positions across an exposure field, which provides improved focus and astigmatism corrections for the lithography tool. The program product implements the use of corrections from the at least thirteen sub-field test positions to provide improved corrections for any selected sub-field position.

Lithography tool image quality evaluating and correcting

Accuracy of correction of offset drift with temperature and noise are corrected in a high voltage, high current amplifier is improved by thermal isolation and/or temperature regulation of another amplifier having greater gain and connected to a different power supply in a closed loop feedback servo system. A clamping network connected to the higher gain amplifier to avoid hard saturation due to transient feedback signals from a reactive load, especially an inductive load, also prevents hard saturation of the high voltage, high current amplifier. An adjustable feedback circuit connected to the higher gain amplifier allows adjustment to obtain critical damping of a second order system and faster response to achieve proportionality of output current to input voltage with an accuracy of very few parts per million error and with minimum settling time.

Precision high speed magnetic coil driver circuit

A method of calibrating a projection particle beam lithography system, comprises the following steps which is embodied in a system provides a magnification reticle pattern of features and a magnification target pattern. Provide a rotation reticle pattern of features and a rotation target pattern, and a particle beam. Direct the particle beam through the magnification reticle pattern and scan its image over the magnification target pattern. Determine the distance between peaks of target patterns as indicated by particles backscattered from the magnification target pattern. Calculate the deviation from a standard for the distance between peaks of target patterns from the magnification target pattern and calculate the magnification deviation and use the magnification deviation to adjust the particle beam. Direct the particle beam through the rotation reticle pattern and scan its image over the rotation target pattern. Determine the distance between peaks of target patterns as indicated by particles from the rotation target pattern. Calculate the deviation for the distance between peaks of the rotation target pattern and calculate the rotation deviation. Then use the rotation deviation to adjust the rotational orientation of the particle beam.

Magnification and rotation calibration patterns for particle beam projection system

Variable space charge effects in the imaging portion of a particle beam projection system due to variations in transmitted beam current are compensated with an additional lens appropriately positioned within the imaging system and having a focal length which varies in response to the transmitted beam current.

Compensation of space charge in a particle beam system

Measurement marks are applied throughout the area of an e-beam projection mask on a grillage of struts extending between sub-field membrane mask areas concurrently with patterning the sub-field membrane mask areas. The thickness of the struts prevents printing of the measurement marks on the resist at the target plane even if inadvertently illuminated by the e-beam system. Measurement of the relative locations of the measurement marks after fabrication and incremental periods of use supports the development of compensation or correction in the electron-optical system for distortions of the mask which may be detected from the measurement marks by adjustment of operating parameters thereof.

Measurement marks for e-beam projection mask and method of using

A method for monitoring resist charging in an electron beam lithography system is disclosed. The method involves the use of a reference plate (REFP) registration scheme in which a resist-coated REFP having registration marks on a substrate is prepared and scanned. The scanning process includes the deposition of an amount of charge on the surface. Then the REFP is coated with a resist to be tested and scanned again. The difference between the two scans is calculated. Preferably, each scan is performed first with the stage moving in a forward-ordered serpentine path in the tool to determine the perceived positions of the registration marks and then in a backward-ordered serpentine path. As the tool's stage moves from field to field, a small charge is deposited on the REFP to simulate the effect of a writing process. The difference between the forward and reverse scan position measurements is then determined. As any intrinsic positional errors in measurement will cancel out, the forward/backward error provides a monitor of the magnitude of resist charging.

Method for monitoring resist charging in a charged particle system

A method and system for calibrating a projection electron beam. The electron beam is directed through a first mask pattern and onto a first calibration plate. The electron beam is directed through a second mask pattern and onto a second calibration plate. The first mask pattern and the first calibration plate are used to adjust the orientation of the electron beam, and the second mask pattern and the second calibration plate are used to adjust the magnification of the electron beam.

Calibration patterns and techniques for charged particle projection

A process smooths the edges of rectangles written by an E-beam lithography system to improve critical dimension (CD) control in these shapes in the preparation of X-ray masks. The CD tolerances of X-ray masks are improved without the usual postprocessing costs normally associated with multipass solutions, thereby saving time and money when multipass writing is used in X-ray lithography. Two enhancements are provided to an X-ray mask maker that allow use of the same E-beam drive code for each exposure of a multipass write operation.

Hardware/software implementation for multipass E-beam mask writing

An electron beam nanometer-level metrology tool includes an ambient temperature electron source and a movable stage for mounting a workpiece. The stage is adapted to position the workpiece's surface in a beam interrogation region. Electrostatic focus lenses convert electrons emitted by the electron source into a beam with a focal point that is positioned in the beam interrogation region. The lenses cause the electron beam to traverse a path that is generally orthogonal to the workpiece surface. Along the beam path are positioned upper and lower electrostatic deflection plates which are connected to an adjustable voltage source that applies ganged, opposite-sense d/c potentials thereto. Those potentials enable a scanning of the beam across the beam interrogation region while the beam remains substantially orthogonal to the workpiece surface, thereby enabling more accurate measurements of surface features. Within the metrology tool, all beam control surfaces are electrostatic so as to minimize power dissipation and temperature differentials.

Electron beam nano-metrology system

An X-ray mask includes one or more X-ray transparent mask windows and at least one pattern-to-mask alignment mark etched into the mask substrate from the same side as the mask windows. The pattern-to-mask alignment marks can be etched at the same time as the mask windows and are detectable from the front surface of the mask substrate by an electron beam lithography system prior to creating the circuit pattern. The alignment marks are detected by the absence of backscattered electrons at the pattern-to-mask alignment marks.

Registration and alignment technique for X-ray mask fabrication

An exposure mask for a particle beam projection system used in the manufacture of semiconductors includes pseudo-random mask alignment marks positioned on the exposure mask that match up with corresponding pseudo-random substrate alignment marks. The substrate alignment marks are made up of three repetitions of the pseudo-random code in the mask alignment marks formed as features on the substrate. The alignment marks act together to produce a backscattered alignment signal with an arbitrarily large capture distance, a single peak on a uniform background that makes it easy to detect the aligned position, a high signal to noise ratio and no false peaks that might lead to misalignment.

Pseudo-random registration masks for projection lithography tool

A pattern is aligned and exposed with a lithography system so that chips larger than the deflection field can be formed by exposing M.times.N fields in a mosaic pattern. The method corrects the deflection field to compensate for the orientation of a previous pattern on a substrate and compensates for errors due to height caused by the beam landing non perpendicular to the target. Two basic procedures disclosed are called '3-mark' which are only applicable to 2.times.2 arrays of fields, and 'M.times.N' which covers the general situation, but with slightly less accuracy.

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Poughkeepsie, NY, United States of America

William A Enichen