Masanori Idesawa

Scanning moiré method and automatic measurement of 3-D shapes.

A new type of moiré and its application to topography are discussed. moiré fringes are generated by observing a grating projected on an object under test with a scanning imaging device. The general equations of the projection-type moiré topography are given. By controlling the phase, the pitch, or the direction of the virtual grating corresponding to the scanning lines of the imaging device, the automatic sign determination of the contour lines is accomplished. By the use of a high precision flying spot scanner with CRT(DD-tube) and a minicomputer system, an experimental measurement system is developed. Very significant is the fact that a contour line system and a sectional shape of the object are automatically reconstructed and displayed on a color TV monitor.

Design of a variable‐aperture projection and scanning system for electron beam

Results of design calculations of a variable‐aperture projection and scanning exposure system is presented. Use is made of newly developed aberration formulas for the focus deflection system, which can handle systems consisting of a set of focus and deflection coils with superimposed fields and of deflection coils arranged in rotated angular positions, taking into account the finiteness of the object. The aberration of less than 0.2 μm and the incident angle less than 1 mrad with the normal, at the corners of a 5×5 mm deflection field, is expected for the 25 μm (maximum) square and 3 mrad semi‐angle probe, in the linear MOL deflector, with object to image distange of 100 mm, consisting of only an axially symmetric lens and five linear deflectors without dynamic corrections.

Design of a Lisp machine - FLATS

Design of a 10 MIPS Lisp machine used for symbolic algebra is presented. Besides incorporating the hardware mechanisms which greatly speed up primitive Lisp operations, the machine is equipped with parallel hashing hardware for content addressed associative tabulation and a very fast multiplier for speeding up both arithmetic operations and fast hash address generation.

Considerations on space charge effect for high current variable shaped beam forming

Variable shaped beam schemes are very promising for advanced VLSI pattern generation. In such a device, beam blurring caused by the space charge effect becomes greater as the beam current increases and the focal length of the electron lens is varied as the beam current changes. In order to keep the beam blurring within a permissible amount, refocusings are required whenever beam sectional areas are changed dramatically. However, it is often difficult to complete refocusing in negligible short time in comparison with the shot time of an element pattern and total exposure time is influenced considerably. Investigating the results of computer simulations and fundamental experiments, it is found that beam blurring caused by defocusing is almost proportional to the deviation of the beam current from that at the optimum focusing point and is kept under the permissible value in certain intervals of beam current. Considering this characteristic, the defocusing problem can be improved significantly by rearranging ...

Discontinuity reduction method in pattern connection

A method of reducing the discontinuities which appear in the connecting boundaries of element patterns or in the stitching boundaries of sub‐scanning‐fields is proposed. Pattern elements are overlapped in the connecting region, and the beam dose in the overlapping area of each pattern element is controlled so that they are compensated by each other. Computer simulations and experiments were performed proving that the proposed method is very effective in reducing these discontinuities. For instance, by selecting an overlapping area which is several times wider than the expected positioning errors or edge definition of element pattern, discontinuities in pattern connection can be reduced remarkably without any special improvement of positioning accuracy.

Triple slit scheme for high current variable‐shaped beam forming

Variable‐shaped beam schemes are very promising for advanced VLSI pattern generation. Some of them are made up of two beam shaping apertures, beam shaping deflectors, and projection lenses. In such devices, exposure speed is proportional to the total beam current finally projected onto the target. When the beam current is increased in this scheme, beam blurring caused by space charge effect becomes greater as the beam current increases. The observed beam blurring becomes much greater on the edges corresponding to the sides of the first beam shaping aperture than on those of the second one. A new beam shaping scheme is proposed for reducing this blurring. In this scheme, auxiliary beam shaping means are provided in the upper stream of the previously developed beam shaping system. The beam is preshaped by the new scheme so as to reduce the beam current between the first and the second beam shaping apertures by an amount which is the sum of the finally required and marginal portions, and a clearer beam shape...