International Business Machines Corporation

Maris A Sturans

Hans C Pfeiffer

Michael S Gordon

John George Hartley

Timothy R Groves

George J Giuffre

James F White

Rodney A Kendall

Werner Stickel

Joseph J Senesi

Robert R Wilbarg

James D Rockrohr

David J Pinckney

Wayne A Barringer

William A Enichen

Donald E Davis

Guenther O Langner

Cecil T Ho

Scott A Messick

Lonn E Moore

Ken Tze-Kin Chan

Jon Erik Lieberman

Rajinder S Dhaliwal

Gunther O Langner

Douglas G Cullum

Joseph E Santilli

Embodiments of the present invention provide an apparatus employing an electron beam to expose the structure of a micro device and produce an image of the structure. The apparatus includes an electron gun producing the electron beam; an electron beam column having one or more segments that shape, focus and/or deflect the electron beams; and one or more center tubes along the electron beam column that provides a high vacuum environment for and guiding the electron beam to a target object coated with an electron sensitive resist. At least one of the center tubes is a carbon tube made of solid carbon material.

Carbon tube for electron beam application

A method and apparatus for clamping a semiconductor mask to a carrier device is taught. The apparatus is comprised of a base member to which is attached an elongated spring. Both the base and the spring have affixed to them a means for compressively contacting the mask surface when the mask is put in place. In the preferred embodiment, that contact means is made of sapphire shaped in the form of a dome. The clamp further includes an adjustment screw that can be used to adjust the height of the contact means affixed to the base member. In this manner, the surface of the mask can be adjusted so that it is planarized to the right orientation relative to an e-Beam or laser source that will be used to scribe a pattern on the mask. Finally, the clamp includes electrical contacts, and the materials out of which the clamp is made are deliberately selected, so that no electrical or magnetic forces can build up on the clamp or the wafer that might adversely affect the scribing process.

Mask clamping device

A multi-beam e-beam system employs a set of independently controllable (for blanking and deflection) subsystems placed in a solenoid field, each system having a demagnifying lens comprising at least one passive pole piece, so that the final image demagnifies imperfections in the upstream electron beam. Upper and lower sections of the system employ the focusing effect of the solenoid field to form an image at a shaping aperture and a demagnified image of the beam at the shaping aperture on the workpiece. Small focus corrections due to magnetic lens field non-uniformity and/or target height variations, are accomplished with an electrostatic unipotental lens built into the pole pieces and target voltage variations.

Multi-beam hybrid solenoid lens electron beam system

A magnetic lens employs a solenoid field containing a passive pole piece that shapes the solenoid field to create a demagnifying lens that has very low geometrical aberrations by adjusting the field upstream and downstream of the gap between the pole pieces to create a negative term in the formula for spherical aberrations, subtracting a significant amount from the contribution to the aberrations that comes from the field in the gap.

Solenoid electron beam lenses with high demagnification and low aberrations

Forming poles from sectors of a tube of carbon or a material with similar conductive properties and supporting the poles by bonding an insulating support ring thereto before removing end rings formed at the ends of the tube which temporarily support the poles provides a multipole deflector element of robust structure of high dimensional accuracy and stability in which eddy current and charging effects are avoided. The manufacturing method is much simplified, reduced in cost and increased in reliability, repeatability and yield over manufacturing techniques for known multipole deflectors.

Multipole electrostatic e-beam deflector

Motion of a block carrying a grid for backscattering portions of a pattern of charged particles incident on the grid is moved generally axially of a charged particle beam tool while the position of the block is measured, preferably to optically, with a grazing incidence laser beam or interferometer, in the axial direction for any or all of the degrees of freedom of the block. Backscatter is correlated with known grid position to correct the backscatter measurement to compensate for lateral components of motion parallel to the target plane in measurement of actual beam position at different axial locations. Telecentricity and landing angle can thus be observed to an accuracy of 0.003 milliradians in substantially real time; permitting substantially real time adjustment thereof. The basic principles of this process and apparatus can be extended to measurement of numerical aperture and are equally applicable to probe-forming and beam projection lithography tools.

Accurate real-time landing angle and telecentricity measurement in lithographic systems

A dynamic focus coil produces different selected ampere-turns while consuming constant power and therefore maintaining constant temperature. The focus coil comprises a set of coils that all consume the same power. A selected subset of coils (e.g. two or three) are energized at any given time, the subset being selected to produce the desired focus adjustment. Illustratively, the coils all have the same resistance and are driven by current having the same magnitude and selectable polarity. An alternative embodiment contains a &ldquo;coarse&rdquo; set of coils having selected values of ampere turns and a &ldquo;fine&rdquo; set of coils having values of ampere turns that fill in between the values of the coarse set.

Constant power dynamic focus coil

A scattering target for use in a particle beam system is formed from a grid of gold on a substrate of carbon, with an intermediate smoothing layer (e.g. copper) on the carbon to provide a surface sufficiently smooth to provide an adequate target. An optional bonding layer may be used to improve adhesion between the gold and the smoothing layer.

Calibration target for electron beams

A magnetic lens having a lens bore for the passage of a particle beam includes a dynamic focus coil that is positioned outside the lens bore and within the pole piece that shapes the lens field, so that the magnetic flux lines from the dynamic focus coil all end on the pole pieces of the lens and the shape of the lens field between the pole pieces has its magnitude changed by the current passing through the dynamic focus coil, but the field shape is not changed, thus changing the focal plane of the beam without moving the beam transversely with respect to the system axis.

Particle beam system with dynamic focusing

The invention relates to a method and apparatus for measuring The landing angle of a particle beam is adjusted by scanning the beam over two cylindrical beam target surfaces that are positioned close to the system axis. The output of a beam detector is differentiated and displayed on an oscilloscope. The relevant lens current is adjusted until one side of the scan indicates that the focal plane of the beam is at the center of the beam target. The angle of the beam is then adjusted with the relevant deflector until both sides of the scan are the same, indicating that the beam is accurately vertical.

Adjustment of particle beam landing angle

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 improved structure for electron beam lithography grids and a method of fabricating such grids yields calibration grids having grid lines coplanar with the surface of the grid body and laterally supported by grooves formed in the grid body and which can also be cleaned after contamination by outgassing resist during use by virtue of the provision of such lateral support for the grid lines. The grid exhibits improved accuracy due to the technique of fabrication of the grooves. The invention thus allows the electron beam lithography process to be conducted with less expense and at greater speed. The improved accuracy of the calibration grid also permits integrated circuits and masks used in the fabrication of such devices to be designed more flexibly and fabricated at reduced cost and improved integration densities and manufacturing yields.

Method of forming planarized, reusable calibration grids

An improved structure for electron beam lithography grids and a method of fabricating such grids yields calibration grids having grid lines coplanar with the surface of a the grid body and laterally supported by grooves formed in the grid body and which can also be cleaned after contamination by outgassing resist during use by virtue of the provision of such lateral support for the grid lines. The grid exhibits improved accuracy due to the technique of fabrication of the grooves. The invention thus allows the electron beam lithography process to be conducted with less expense and at a greater speed. The improved accuracy of the calibration grid also permits integrated circuits and masks used in the fabrication of such devices to be designed more flexibly and fabricated at reduced cost and improved integration densities and manufacturing yields.

Planarized, reusable calibration grids

A three-stage E-beam deflection system employs breaking the entire field to be scanned into clusters and sub-fields. The scanning provided by the first stage of deflection which scans within the entire field is rectilinear and discontinuous with the scan stopping in the center of each of the clusters where an exposure is to be made, and scanning is the same within each cluster from sub-field to sub-field. The scanning within a cluster by the second stage stops in the center of each sub-field where exposure is to be made. The third stage uses high speed electrostatic deflection to provide scanning with a vector scanning mode within the sub-field being scanned.

Tri-deflection electron beam system

A two staqge, electron beam projection system includes a target, a source of an electron beam and means for projecting an electron beam towards the target with its upper surface defining a target plane. A magnetic projection lens has a principal plane and a back focal plane located between said means for projecting and the target. The means for projecting provides an electron beam directed towards the target. First stage means provides deflection of the beam from area to area within a field. Second stage means provides for deflection of the beam for providing deflection of the beam within an area within a field. The beam crossing the back focal plane produces a telecentric condition of the beam in the image plane with the beam substantially normal to the target plane from the principal plane to the target plane. The magnetic projection lens includes a magnetic structure providing for magnetic compensation positioned within the bore of the projection lens, which produces a compensating magnetic field substantially proportional to the first derivative of the axial magnetic projection field. The axial magnetic projection field provides substantially a zero first derivative of the axial magnetic projection field in the vicinity of the target. The projection system projects on the target plane from the projection system as deflected by the upper and lower stages, at all times maintaining the telecentric condition of the electron beam at the target plane throughout the entire range of deflection of the beam, assuring minimum errors due to target height variations.

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Wappingers Falls, NY, United States of America

Maris A Sturans