International Business Machines Corporation

Nikon Corporation

Werner Stickel

Hans C Pfeiffer

Steven D Golladay

Christopher Frederick Robinson

Michael S Gordon

Rodney A Kendall

Maris A Sturans

Guenther O Langner

Timothy R Groves

Paul F Petric

John George Hartley

Shinichi Kojima

Edward V Weber

Cecil T Ho

Robert A Simpson

Rainer Butsch

George J Giuffre

Clay S Clement

Douglas G Cullum

Don F Haire

This is a method for designing an optimized charged particle beam projection system. Specify lens configuration and first order optics. Calculate lens excitations. Configure the lens system, providing lens field distributions, beam landing angle, and imaging ray/axis cross-over. Provide an input deflector configuration. Solve a linear equation set, and thereby provide a curvilinear axis and associated deflection field distributions. Calculate the third order aberration coefficients yielding a list of up to 54 aberration coefficients. Provide an input of dynamic correctors. Calculate excitations to eliminate quadratic aberrations in deflection. Calculate third and fifth order aberrations, providing image blur and distortion vs. deflection, best focal plane, and depth of focus. Determine whether the current result is better than the previous result. If YES then change the axial location input to the solve linear equation set. If NO, test whether the current result is acceptable. If NO, provide a deflector configuration. If YES, test whether the deflection current is larger. If YES, change the input for the axial location of the deflectors to solve the linear equation set again. If NO then END the process.

Optimized curvilinear variable axis lens doublet for charged particle beam projection system

The presence of magnetic fields from lenses and other (e.g. parasitic) sources at locations in a charged particle beam system such as the charged particle emitter, where the particles have little or no kinetic energy, creates disturbances of the charged particle trajectories, generating undesired angular momentum and resulting in excessive aberrations and associated adverse effects on system performance. Solutions are provided by suppression of these magnetic fields, by relocating the charged particle emitter away from the field source and/or counterbalancing the field with a bucking field. In addition, residual irrepressible field asymmetries are compensated by a suitable element such as a stigmator located at the correct location in the beam path, permitted by relocation of the charged particle emitter.

High performance source for electron beam projection lithography

Proximity (exposure dose) effects and/or local Coulomb (space charge defocussing) effects, both dependent on local pattern density of exposed areas, are simultaneously compensated in a charged particle beam projection device or tool by a projection reticle having an apertured weakly scattering membrane with selective strongly scattering regions between the apertures in the membrane. A reticle so constructed provides at least three independent exposure dosage levels that can be mixed to provide a wide range of exposure levels with high contrast. The more weakly the electrons are scattered (in the extreme, the electrons are not scattered at all through apertures), the greater the number that pass through a given beam contrast aperture, the higher the corresponding dose received at the target plane and the more space charge is contained in the beam bundle. Therefore, to compensate for the proximity effect (i.e. provide dose boost) and the local Coulomb effect (i.e. provide additional space charge) regions with reduced scattering characteristics are employed. Use of a hybrid doped resist allows exposure corresponding to an intermediate exposure dose in a preferred variant implementation exploiting the three dosage levels developed.

Stencil reticle incorporating scattering features for electron beam projection lithography

An electronic beam lithography tool providing dimensional stability. The tool includes three or more deflection plates above an aperture diaphragm which allows the beam to be deflected away from an aperture and along a two-dimensional locus on the aperture diaphragm which is approximately symmetrical around the aperture therein. By doing so, the aperture diaphragm is symmetrically heated by the power of the charged particle beam and the geometry of the charged particle beam device is stabilized against variance in geometry of the device to a very small tolerance.

Symmetric blanking for high stability in electron beam exposure systems

A charged particle beam system with a source of charged particles produces a beam directed along a path. A given electromagnetic lens is located along the path. The given electromagnetic lens is adapted to produce a first field directed with a first orientation adapted for affecting a beam of charged particles directed along the path through the lens. A bucking electromagnetic lens is juxtaposed with the given electromagnetic lens adapted to produce a bucking field directed with a bucking orientation adapted for affecting the beam of charged particles directed along the path. The bucking field has an orientation opposing the first field. A fringe field from the bucking electromagnetic lens produces a nulling field to compensate for aberrations and/or beam disturbances.

Image position and lens field control in electron beam systems

A method of optimizing locations of correction elements of a charged particle beam system determines respective corrector element currents to achieve optimum correction as a function of individual corrector location. Substantially complete dynamic correction of FSD and SFD can be obtained consistent with efficiency of operation and minimization of deflection distortion. In particular, FSD and SFD corrections can be sufficiently separated for substantially complete correction of SFD and FSD simultaneously with two stigmators. Both of these types of correction can be provided in complex charged particle beam systems employing curvilinear axis (CVA) particle trajectories and or large area reduction projection optics (LARPO) which cause complex hybrid aberrations in order to achieve high throughput consistent with extremely high resolution supporting one-tenth micron minimum feature size lithography regimes and smaller.

Multi-element deflection aberration correction for electron beam lithography

Numerous largely unpredictable criticalities of operating parameters arise in electron beam projection lithography systems to maintain throughput comparable to optical projection lithography systems as minimum feature size is reduced below one-half micron and resolution requirements are increased. Using an electron beam projection lithography system having a high emittance electron source, variable axis lenses, curvilinear beam trajectory and constant reticle and/or target motion in a dual scanning mode wherein the target and/or wafer is constantly moved orthogonally to the direction of beam scan, high throughput is obtained consistent with 0.1 .mu.m feature size ground rules utilizing a column length of greater than 400 mm, a beam current of between about 4 and 35 .mu.A, a beam energy of between about 75 and 175 kV, a sub-field size between about 0.1 and 0.5 mm at the target at an optical reduction factor between about 3:1 and 5:1, a numerical aperture greater than 2 mrad and preferably between about 3 and 8 mrad and a scan length between about 20 mm and 55 mm. Reticle and target speed preferably differ by about the optical reduction factor.

Electron beam projection lithography system (EBPS)

A charged particle beam projection system includes a source of charged particles and a first doublet of condenser lenses with a first symmetry plane through which the beam is directed, located lower on the column. A trim aperture element is located at the first symmetry plane of the first doublet wherein the trim aperture serves as a first blanking aperture. Below the trim aperture there is a shaping aperture. Next is a second doublet of condenser lenses with a second symmetry plane. A third aperture, which is located at the symmetry plane of the second doublet serves as another blanking aperture.

Blanking system for electron beam projection system

An electron beam projection system comprises a source of an electron beam, a first doublet of condenser lenses with a first symmetry plane, a first aperture comprising a trim aperture located at the first symmetry plane of the first doublet also serving as a first blanking aperture. A second aperture comprises a shaping aperture located below the trim aperture. A second doublet of condenser lenses with a second symmetry plane is located below the second aperture, the second doublet having a symmetry plane. A third aperture is located at the symmetry plane of the second doublet wherein the third aperture comprises another blanking aperture. There are first blanking plates between the first condenser lens and the trim aperture, and second electrostatic alignment plates between the trim aperture and the second aperture. The second doublet comprises a pair of illuminator lenses including deflectors coaxial therewith and located inside the radius of the lenses and shielding rings located along the inner surfaces of the lenses, and correctors located coaxial with the deflectors and inside or outside of the radii thereof including stigmators, focus coils and a hexapole.

Illumination deflection system for E-beam projection

A charged particle beam performance measurement system includes a charged particle beam generator device for producing a charged particle beam, a test reticle having at least two areas of higher transparency than its surroundings that form a pattern, a reduction projection imaging device, a reference target having an essentially identical pattern as the test reticle, and a beam current detector. A patterned beam is generated by passing the charged particle beam through the pattern areas of the test reticle. The patterned beam is reduced and projected by the reduction projection imaging device and the reduced patterned beam is imaged onto a reference target. The reduced patterned beam is then exposed to the reference target, wherein some of the beam may pass through reference target pattern areas. Beam current detector records and measures the amount of beam current that is absorbed on, back-scattered from, or transmitted by the target reference, and determines from the measured beam current the accuracy of the projection system.

Charged particle beam performance measurement system and method thereof

A method is disclosed for improving the electron beam apparatus lithography process wherein the calibration procedure for the apparatus is improved by using the product pattern and stepping sequence used to make the mask on a calibration plate and/or calibration grid and to determine improved apparatus correction errors which errors are used to control the apparatus for making an improved mask. The well-known EMULATION procedure is improved by calculating additional field correction errors based on a two step registration procedure to determine X/Y apparatus stepping errors. The LEARN procedure based on a static calibration grid procedure is improved by employing the duty cycle of the product pattern to calibrate the apparatus to determine deflection beam errors.

Correction of pattern dependent position errors in electron beam

A method and system for studying the effect of electron-electron interaction in an electron beam writing system. First and second test reticles are provided that have different open areas. An electron beam is directed through the first test reticle to form a first pattern on a test surface, and the electron beam is then directed through the second test reticle to form a second pattern on a test surface. Because the open areas of the test reticles differ, the current of the electron beam is different when that beam passes through the first test reticle than when that beam passes through the second test reticle. The resolution of the first formed pattern is compared with the resolution of the second formed pattern to assess the effect of the different currents of the electron beam on the resolutions of the formed patterns.

Projection reticle transmission control for coulomb interaction analysis

A electron beam performance measurement system includes an electron beam generator device for producing an electron beam, a test reticle having a series of openings forming a pattern, a reduction projection imaging device, a reference target having an essentially identical pattern as the test reticle, and a beam current detector. A patterned beam is generated by passing the electron beam through the pattern openings of the test reticle. The patterned beam is reduced and projected by the reduction projection imaging device and the reduced patterned beam is imaged onto a reference target. The reduced patterned beam is then exposed to the reference target, wherein some of the beam may pass through reference target pattern openings. Beam current detector records and measures the amount of beam current that is absorbed on, back-scattered from, or transmitted by the target reference, and determines from the measured beam current the accuracy of the projection system.

Electron beam performance measurement system and method thereof

A charged particle lens has an axis that is shifted to follow the central ray of the beam as it is deflected through the lens creating, in effect, a variable curvilinear optical axis for the lens and introducing aberrations having depending on the object size and the distance off the lens symmetry axis. These aberrations are corrected by a set of coil pairs tilted with respect to the system axis, which generate compensating aberrations of the same type.

Curvilinear variable axis lens correction with crossed coils

A reticle for an electron beam system for direct writing applications has a base layer that contains a reticle pattern; a set of reinforcing struts connected to the base layer separating the base layer into a set of non-contiguous subfields; in which the pattern is carried by a set of apertures in said base layer; and in which the base thickness is set such that the probability that an electron traversing said base thickness will suffer a collision that removes it from the beam is greater than 90% while the probability that the electron will be absorbed is low; and in which, optionally, selected subfields of the reticle are compensated for errors in the remainder of the system.

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Ridgefield, CT, United States of America

Werner Stickel