Reliability in a maskless lithography system

A maskless lithography system for transferring a pattern onto the surface of a target, comprising:

• at least one first beamlet generator for generating a plurality of beamlets;
• at least one second beamlet generator for generating a plurality of beamlets;
• at least one modulator unit comprising a plurality of modulators, said modulator unit aligned with said first beamlet generator, for modulating each of the beamlets of said first beamlet generator;
• at least one beamlet controller for controlling the scanning of each beamlet of said first beamlet generator;
• at least one control unit for generating and delivering pattern data to said modulator unit and for controlling said beamlet controller;
• wherein said first and second beamlet generator are positioned with respect to one another to allow projection of said beamlets of said second beamlet generator on the same position as said beamlets of said first beamlet generator.

A maskless lithography system for transferring a pattern onto the surface of a target, comprising:

• at least one first beamlet generator for generating a plurality of beamlets;
• at least one second beamlet generator for generating a plurality of beamlets;
• at least one modulator unit comprising a plurality of modulators, said modulator unit aligned with said first beamlet generator, for modulating each of the beamlets of said first beamlet generator;
• at least one beamlet controller for controlling the scanning of each beamlet of said first beamlet generator;
• at least one control unit for generating and delivering pattern data to said modulator unit and for controlling said beamlet controller;
• wherein said lithography system further comprises at least one actuator for displacing said first beamlet generator and said second beamlet generator with respect to one another to allow projection of said beamlets of said second beamlet generator on the same position on said surface as said beamlets of said first beamlet generator.

A method for transferring a pattern onto a surface of a target using a maskless multi-beamlet lithography system, comprising the steps of

• generating a plurality of beamlets;
• measuring properties of each beamlet;
• transferring said pattern onto said surface by scanning valid beamlets which have measured beamlet properties which are within a predefined range of properties over said surface and preventing invalid beamlets which have measured beamlet properties which are outside a predefined range of properties from reaching said surface, thus leaving unwritten pattern elements;
• shifting said surface and at least part of said lithography system with respect to one another, to replace each invalid beamlet with a valid replacement beamlet, and
• transferring said unwritten pattern onto said surface by scanning the valid replacement beamlets over said surface.

The method of the previous claim, further comprising the step of

• providing a controller with pattern data;
• storing information for identifying said invalid beamlets;
• separately modulating each beamlet in dependence of said pattern data by means of a modulator which is controlled by said controller;
• scanning said plurality of beamlets over said surface by means of a scanner in a scanning direction while advancing said target in another direction than said scanning direction;
• performing an additional scan over said surface after having performed said shift.

A maskless lithography system for transferring a pattern onto a surface of a target, comprising:

• at least one beamlet optical unit for generating a plurality of beamlets;
• at least one measuring unit for measuring properties of each beamlet;
• at least one control unit for generating and delivering pattern data to said beamlet optical unit, said control unit being operationally coupled to said measuring unit,
• the system thereby being set up for determining a validity and an invalidity of generated individual beamlets;
• at least one control unit for switching off a selection of beamlets, including said invalid determined beamlets, during an exposure scan;
• at least one actuator for inducing a shift of said beamlet optical unit and said target with respect to one another, wherein said actuator is operationally coupled with said control unit and is adapted for inducing a shift, thereby positioning valid beamlets over the position of determined beamlets that were switched off during the preceding scan.