Abstract: 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.

Abstract: An automatic control servo system having a number of cascaded loops equal in number to the number of voltage sources applied to elements of a high-emittance electron source provides accurate and stable electron emission current control independently of beam energy and accommodates large differences in thermal mass between the elements of the electron source, as may be encountered in high-emittance, indirectly heated cathode electron sources. Individual loops of the system may be critically tuned independently of each other.

Abstract: 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.

Abstract: A method for improving image fidelity on a resist. The method adjusts the intensity distribution of the electron beam such that the feature size at the edges and the center of a subfield have a same width “w”. This is accomplished by intentionally increasing the incident intensity where the images are small (more pronounced blurring), and intentionally decreasing the incident intensity where the images are large (less pronounced blurring). This can be achieved, for example, by maintaining a cathode temperature profile which increases or decreases radially by an appropriate amount.

Abstract: 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.

Abstract: Direct and indirect electron bombardment provide a sufficiently high degree of temperature uniformity across the emitting surface of a large-area electron source for an electron beam projection system such that a broad beam having illumination uniformity within 1% can be achieved. A diode gun is used to obtain extraction field uniformity and maintain uniformity of illumination. Power requirements and power dissipation in beam periphery truncating apertures is reduced by roughening the surface of a monocrystalline cathode or depositing materials having a higher work function thereon.

Abstract: 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.

Abstract: Resolution of a symmetric magnetic doublet charged particle beam projection lens is improved by applying a non-uniform electrostatic field having the same symmetry conditions as the lens through the magnetic doublet which provides a maximum particle velocity at the plane of symmetry of the magnetic doublet. Since the same symmetry conditions are used for both the electrostatic and magnetic fields, the performance of the magnetic doublet is not compromised. Electrode configurations which provide more intense fields provide further reduction in aberrations for a given potential superimposed on the accelerating voltage.

Abstract: A method of noncontact testing and an electron optical system includes an electron source for producing a high energy electron beam, a retarding field objective lens system for receiving and focussing the high energy electron beam to produce a focussed low energy electron beam, and a magnetic deflector for deflecting the focussed low energy electron beam to the sample, thereby to expose the sample to the low energy electron beam, and simultaneously maintaining a predetermined spot size of the beam. The retarding field objective lens system includes a device for retarding electrons in the low energy electron beam directed to the sample and for accelerating electrons, emitted by the sample upon being irradiated by the low energy electron beam.

Abstract: A method for measuring electrical characteristics of an electrical device having a conductive structure associated therewith involves the sequence of steps as follows: First, employ a low energy electron beam to charge all conductors on the surface of the device. Expose individual conductors to a focussed low energy electron beam serially. Make measurements of an induced current signal when individual conductors are exposed to the focussed electron beam. Analyze induced current measurements derived from the individual conductors. Then determine electrical characteristics of the device based on the analysis. A charge storage method and three capacitive test methods for defect detection and methods for shorts delineation are described.

Abstract: A method of noncontact testing and an electron optical system includes an electron source for producing a high energy electron beam, a retarding field objective lens system for receiving and focussing the high energy electron beam to produce a focussed low energy electron beam, and a magnetic deflector for deflecting the focussed low energy electron beam to the sample, thereby to expose the sample to the low energy electron beam, and simultaneously maintaining a predetermined spot size of the beam. The retarding field objective lens system includes a device for retarding electrons in the low energy electron beam directed to the sample and for accelerating electrons, emitted by the sample upon being irradiated by the low energy electron beam.

Abstract: A method for measuring electrical characteristics of an electrical device having a conductive structure associated therewith involves the sequence of steps as follows: First, employ a low energy electron beam to charge all conductors on the surface of the device. Expose individual conductors to a focussed low energy electron beam serially. Make measurements of an induced current signal when individual conductors are exposed to the focussed electron beam. Analyze induced current measurements derived from the individual conductors. Then determine electrical characteristics of the device based on the analysis. A charge storage method and three capacitive test methods for defect detection and methods for shorts delineation are described.

Abstract: An E-beam testing system uses the E-beam to test a sample with conductive elements thereon. The system charges conductive elements on the sample. Above the sample and parallel to its upper surface is a stacked pair of parallel extraction grids. One grid is biased positively to accelerate secondary electrons emitted from the sample. The other grid is biased at a voltage to control the angular distribution of secondary electrons passing through the grid. Rectangular double grid sets, tilted with respect to the beam and the sample, are located above and laterally of the sample and the E-beam. Those grids are charged to attract secondary electrons from the sample. Triangular grids between the rectangular grids and a top grid above and parallel to the sample with an aperture therethrough for the E-beam are biased negatively to repel secondary electrons. Below the rectangular and triangular grids is located a cylindrical attraction grid biased positively, coaxial with the E-beam.

Abstract: An E-beam testing system uses the E-beam to test a sample with conductive elements thereon. The system charges conductive elements on the sample. Above the sample and parallel to its upper surface is a stacked pair of parallel extraction grids. One grid is biased positively to accelerate secondary electrons emitted from the sample. The other grid is biased at a voltage to control the angular distribution of secondary electrons passing through the grid. Rectangular double grid sets, tilted with respect to the beam and the sample, are located above and laterally of the sample and the E-beam. Those grids are charged to attract secondary electrons from the sample. Triangular grids between the rectangular grids and a top grid above and parallel to the sample with an aperture therethrough for the E-beam are biased negatively to repel secondary electrons. Below the rectangular and triangular grids is located a cylindrical attraction grid biased positively, coaxial with the E-beam.

Abstract: An electron beam system and method for testing three dimensional networks of conductors embedded in an insulating material specimen without physical contact to detect open and short circuit conditions. Top to top surface wiring is tested by irradiating the specimen with an electron beam at a first beam potential to charge the specimen while negatively biasing a grid placed above the specimen surface, and then irradiating selected portions of the specimen with an electron beam at a second beam potential to read the charge on selected conductors while applying a zero or a positive bias to the grid. In one embodiment the charge beam is a focused scanning beam and the first beam potential is preferably greater than the second beam potential.

Abstract: A double deflection scanning system for electron beam instruments is provided embodying a means of correcting isotropic coma, and anisotropic coma aberrations induced by the magnetic lens of such an instrument. The scanning system deflects the beam prior to entry into the magnetic lens from the normal on-axis intersection of the beam with the lens according to predetermined formulas and thereby reduces the aberrations.