Proximity effect correction in electron beam lithography

A lithography system, comprising:

• a wafer stage;
• a charged particle source;
• a beam forming unit configured to generate a charged particle beam;
• a focusing lens;
• and
• a controller;
• wherein the controller is configured to:
• receive a layout pattern comprising one or more features and information of a photo resist coated on a substrate disposed on the wafer stage;
• determine a first energy density indirectly exposed to a first feature of the one or more features of the layout pattern in the photo resist when the one or more features of the layout pattern in the photo resist are directly exposed by the charged particle beam;
• adjust a second energy density of the first feature when the first feature is directly exposed by the charged particle beam, wherein a total energy density of the first feature that is a sum of the first energy density from the indirect exposure and the second energy density from the direct exposure, and the total energy density is maintained at a threshold energy level that is a lowest energy density that fully exposes the photo resist;
• and
• generate a set of commands that comprises one or more timings and one or more deflection angles for the controller to control the charged particle beam to directly expose the first feature of the layout pattern to the second energy density.

A method, comprising:

• disposing a photo resist coated substrate on a wafer stage of a lithography system;
• receiving a layout pattern comprising one or more features and information of the photo resist coated on the substrate disposed on the wafer stage;
• determining a first energy density indirectly exposed to a first feature of the one or more features of the layout pattern in the photo resist when the one or more features of the layout pattern in the photo resist are directly exposed by a charged particle beam;
• determining a second energy density of the first feature when the first feature is directly exposed by the charged particle beam,
• generating a charged particle beam having a total energy density that is a sum of the first energy density from the indirect exposure and the second energy density from the direct exposure, wherein the total energy density is a lowest energy density that fully exposes the photo resist;
• selectively exposing the photo resist to the charged particle beam having the total energy density;
• and
• developing the selectively exposed photo resist to form a pattern in the photo resist.