Abstract: An electron beam or similar charged particles may be deflected by passing through an electrostatic field produced in a deflecting structure. The degree of deflection is controlled by rotating the deflecting structure and path relative to one another. The beam may be rotated relative to the structure by a magnetic beam deflector which compensates for a range of electron energies within the beam so that all electrons are deflected in the electrostatic field by an equal amount.

Abstract: A scanning electron microscope arrangement has an integral image store connected to receive signals from an electron collector which collects the secondary electrons emitted from the specimen surface in response to impingement by the electron beam. The latter is scanned over the specimen by scanning coils driven by a scan generator. A cathode ray tube is provided which has its separate scan generator and responds to the previously stored signals as they are read out from the store under control of a control unit. Because the arrangement has an integral store, the beam scanning rates of the electron beam and the CRT beam can be entirely independent. The scan generator for the electron beam may therefore have a relatively low rate and therefore a low power rating. The CRT can be a standard type and does not need to be high persistance. The signal to noise ratio of the signals in the store can be increased by repeating the scan of the specimen before reading out the signals.

Abstract: A defect detection system for classifying defects in reticles (such as used in the manufacture of integrated circuit wafers) is described. An inspection unit, scanning the reticle in real time, compares it with the correct form and inputs signals representing each defect and its position in a store. The stored defects are then used to direct the inspection unit to inspect each defect more slowly. The inspection unit classifies each defect as either being an "excess metal" or a "missing metal" defect, and corresponding signals are stored in respective additional stores. The signals stored in these stores are then further processed and compared with the desired form of the reticle so as to classify the "excess metal" defects as either being a "pin spot" defect, an "extension" defect or a "bridge-type" defect. Similarly, the "missing metal" defects are classified as either being a "pinhole" defect an "intrusion" defect or a "break-type" defect. A size measuring unit measures the size of each defect.

Abstract: The invention is for comparing a master image, stored by means of binary signals, with an image under test, which is stored by means of corresponding binary signals. Both sets of binary signals are fed out into an EXCLUSIVE OR gate. This will therefore produce output signals defining any differences between the image under test and the master image. In addition, however, the gate output binary signals due to any misalignment or digitization errors between the images stored in the two stores. To reduce or eliminate the latter, the master image is fed into an edge detector which produces binary signals representing a peripheral edge region or "frame" around the master image. This peripheral edge region is "dilated" (that is, the peripheral edge region is thickened to a predetermined extent). The signals representing the stored and dilated edge region are inverted and ANDed with the output of the EXCLUSIVE OR gate.

Abstract: An automatic focussing arrangement for use with scanning electron beam apparatus such as a scanning electron microscope or electron beam microfabrication apparatus sets the focus coil (18) current at each one of a plurality of predetermined values in turn. At each setting, the scanning system (10, 12, 14) is activated to frame-scan the electron beam across a predetermined sharp-edged target. The resultant video signal (22) is monitored for each line of the frame scan to derive the mean value, then the mean value is subtracted from the instantaneous value of the video signal for that line (this may be carried out during a second scan of the same line), and the difference is then squared and integrated. The integrated outputs corresponding to each line scan are monitored to determine the greatest one. This is then stored (32) in association with the corresponding level of the focus drive current, and the process is then repeated.

Abstract: Substrates on which vapor deposition is to take place are mounted on the outside of a generally bell-shaped susceptor which is itself mounted immediately outside a similarly shaped shield which is transparent to infra-red radiation. Infra-red lamps are mounted within the shield and the radiant heat from them passes through the shield and heats the substrates through the susceptor. An outer, opaque, shield defines an annular gas passage through which reactant gases pass over the heated substrate to cause vapor deposition thereon. Purging gas may be passed between the transparent shield and the susceptor. The lamps and the susceptor may be relatively rotated. The arrangement substantially eliminates the possibility of the reactant gas causing deposition on the transparent shield which would interfere with the passage of radiant heat to the susceptor and the substrate.