摘要:
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.
摘要:
The magnetic axis of a stigmation yoke is varied from the mechanical axis of the stigmation yoke by differentially driving pairs of coils in a quadrupole configuration with currents which differ from a nominal stigmation current by approximately equal amounts, applied in opposite senses. Set-up procedures for electron beam deflection systems, such as in e-beam tools, are automated by emulating manual procedures in combination with electric alteration of the magnetic axis of the stigmator yoke. Stigmation errors can also be collected under automated set-up procedure control to allow dynamic correction of astigmatism in electron beam deflection system. Electrically variability of the magnetic axis of the stigmator yoke also allows the placement of the stigmator yoke at a position in the electron optical column other than prior to deflection stages as well as improved freedom from positional and aberrational errors.
摘要:
A charged particle beam deflection system provides a three or more level charged particle beam deflection arrangement and is therefore capable of extremely high speed and positional accuracy. The system preferably employs a major/minor magnetic deflection arrangement as well as orthogonal electrostatic deflectors at a level of speed and positional accuracy and which minimizes the need for dynamic correction to achieve high linearity and positioning accuracy at extremely low aberration levels. The system can also be made relatively noise insensitive by providing one or more split deflectors which are also useful in providing increased speed and adjustment of radial and azimuthal telecentricity. The use of a transfer lens allows the cluster and subfield deflectors to be optimally placed to exploit different forms of LAD to obtain telecentricity at all levels of the deflection hierarchy. The use of such lens assisted deflection allows the electron optical system and drivers therefor to be minimized in number or enabled noise to be reduced and adjustments of telecentricity to be made without increase of complexity over the prior art. By employing the deflection arrangement of the present invention in electron beam lithography apparatus, the throughput of such apparatus can be greatly improved.
摘要:
A system of testing the continuity of electrical conductors extending through an insulating layer without contact. A flood gun irradiates one side of the body to charge the exposed conductors to a given potential. A steerable electron beam scans the front side to generate secondary electron emission from those conductors. The secondary emission is enhanced from conductors with conductivity between front side and back side as a result of the surface potential established by the rear flood beam. The secondary emission varies depending on the state of continuity in the three dimensional network of conductors and produces signals at the detector which allow clear discrimination between uninterrupted and interrupted conductors. The system is applicable for unfired ceramics where contact destroys the specimen.
摘要:
The magnetic axis of a stigmation yoke is varied from the mechanical axis of the stigmation yoke by differentially driving pairs of coils in a quadrupole configuration with currents which differ from a nominal stigmation current by approximately equal amounts, applied in opposite senses. Set-up procedures for electron beam deflection systems, such as in e-beam tools, are automated by emulating manual procedures in combination with electrical alteration of the magnetic axis of the stigmator yoke. Stigmation errors can also be corrected under automated set-up procedure control to allow dynamic correction of astigmatism in electron beam deflection system. Electrically variability of the magnetic axis of the stigmator yoke also allows the placement of the stigmator yoke at a position in the electron optical column other than prior to deflection stages as well as improved freedom from positional and aberrational errors.
摘要:
The technique of measuring the spotsize and edgewidth of an electron beam by incrementally scanning the beam through discrete scan locations across a sharp edge is improved by processing the resulting beam current signals directly rather than the differentiated beam current signal. A linear regression is performed on beam current data points expected to fall in the linear portion of the beam current versus beam position characteristic in order to provide a linear approximation of the overall characteristic. Extrapolation of the linear function to its intersections with the maximum (I.sub.1) and minimum (I.sub.0) beam current levels yields corresponding beam positions Z.sub.B and Z.sub.A, such that (Z.sub.B -Z.sub.A) is a measure of spotsize in the scan direction. Edgewidth between the twelve and eighty-eight percent amplitude levels is obtained by locating measured beam currents at incremental scan locations on both sides of beam positions Z.sub.A and Z.sub.B, and interpolating to find the actual beam currents I.sub.A and I.sub.B at these positions. Edgewidths D.sub.A and D.sub.B are computed as D.sub.A =4.sqroot..pi.(Z.sub.B -Z.sub.A)(I.sub.A -I.sub.0)(I.sub.1 -I.sub.0) and D.sub.B =4.sqroot..pi.(Z.sub.B -Z.sub.A)(I.sub.1 -I.sub.B)(I.sub.1 -I.sub.0). In the case of a square beam with rounded corners, spotsize (i.e., side of square) is measured by a diagonal incremental scan and determination, by interpolation, of the beam positions Z.sub.C and Z.sub.D at which the beam current is I.sub.C =I.sub.0 +19(I.sub.1 -I.sub.0)/64 and I.sub.D =I.sub.0 +45(I.sub.1 -I.sub.0)/64. The spotsize is then computed from the formula 3.01816 (Z.sub.C -Z.sub.D).
摘要:
An improved 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 correction elements generating compensating aberrations of the same type, comprising at least one wire pair perpendicular to the system axis and carrying fixed currents to introduce a gradient in the field, together with three coils centered on the system axis to cancel a bias field introduced by the wire pair.
摘要:
A scanned electron beam system employs an electron beam source using an NEA activated photo-emitter as the cathode. The activated photo-emitter cathode produces a pre-shaped electron beam having a relatively small spot focussed on a target plane. The beam is selectively deflected to scan the beam spot along the target plane to expose desired patterns on that plane. The distance between the cathode and anode can be made large enough to accommodate in situ replenishment of cathode material, such as Cesium, without obstructing the electron optical path. The system includes two vacuum chambers which are differentially pumped through respective ports. The first chamber, in which the anode and cathode are located, is utilized for establishing the required electrostatic field. The second chamber is employed to produce the necessary focussing and selective beam deflection.
摘要:
An all-electrostatic variable spot charged particle (electron) beam shaping sub-system which is compact and of much smaller size than known similar systems designed for the same purpose and operating with magnetic lenses. The improved electrostatic variable spot-shaping sub-system does not require mechanical rotation of the spot-shaping apertures for maintaining alignment or orientation. The improved sub-system includes both beam steering and beam blanking requiring less than 3 volts for operation of the blanking controls to turn the beam on and off. The novel system easily accomodates a variety of different beam-shaping apertures for use as the second beam shaping aperture in the sub-system including rectilinear triangles of different orientation to provide smooth 45 degree pattern delineation, rectangles, squares, and even different diameter circles where such configurations are required by a particular pattern to be written in the target plane.
摘要:
An automatic focus correction system for E-beam lithography uses optical light from a narrow angle light source to illuminate a horizontal slit, the image of which is projected onto a target surface. Prior to and after reflection of the slit image from the target surface the light beam is projected parallel to the target surface to minimize vertical space requirements in the E-beam column. Variations in height, z-position, cause the slit image to move vertically and the focus of reflection to shift laterally and this image is redeflected in the horizontal plane by a prism to a linear diode array used to produce a video-type output signal. Autofocus electronics are used to convert the video output signal into an analog correction signal to the E-beam fine focus coil. The video-type signal is also converted to a digital height value to be used for corrections in beam magnification and rotation.