Dupont Photomasks, Inc.

Adam Woolfe

Michael J Penberth

Graham S Plows

A method for calibrating the scan amplitude of an electron beam lithography instrument by determining the position of a feature within the scan. The method is effective at the operating frequency of the scan and using a limited bandwidth video signal including the steps of determining the reference feature to be an edge over which the video signal rises abruptly from a background level to a white level. The method turns the beam on only over a short region of the scan and represents the degree of overlap between the beam on portion of the scan and the white part of the feature as the total video signal accumulated in that scan.

Method and system for calibrating the scan amplitude of an electron beam lithography instrument

The approach taken to provide variable writing speeds consists of the following: (1) Software in the Job Control subsystem that Identifies the minimum and maximum valid writing speeds, given the resist sensitivity, maximum beam current density, and requested write address size. if the variable writing speed option is enabled, Job Control selects the maximum valid speed. (2) Software in the Pattern Data Conversion subsystem that determines the number of stripes of pattern figure data to combine into each output bitmap for the selected writing speed. (3) Hardware in the Timing Logic Board to clock bitmap data to the serializer at the desired frequency. (4) Logic in the Blanking device to synchronize its blanking frequency with the clock rate used by the Timing Logic

Electron beam lithography system having variable writing speed

An electron beam blanking method and system for selectively interrupting the flow of electrons during an electron beam lithographic process minimizes electron beam movement during blanking as the electron beam reaches a target lithographic mask. A first deflection plate pair deflects electrons flowing in the electron beam in the direction of the target lithographic mask. The first deflection plate pair includes a first tapered gap that is formed so that electrons which enter the first tapered gap before the initialization of a blanking voltage experience progressively greater electric field as they pass through the plates for controlling the cumulative deflection as the electrons travel through the first deflection plate pair. A second deflection plate pair further deflects electrons flowing in the electron beam in the direction of the target lithographic mask and includes a second tapered gap for further variably controlling the commutative deflection of the electron beam traveling through the second tapered gap. One or more hybrid integrated circuits provide deflection voltages to the first and second deflection plate pairs for varying the respective degree of electron beam deflection.

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Cambridgeshire, United Kingdom

Adam Woolfe