Method for forming circular patterns on a surface

A method for fracturing or mask data preparation for charged particle beam lithography, the method comprising:

• determining a set of shots that forms a set of circular or nearly circular patterns on a surface, wherein the set of circular or nearly circular patterns comprises patterns in a plurality of sizes, and wherein the set of shots comprises:
• a first shot using a first circular or nearly-circular character projection (CP) character;
• and
• a second shot using a second circular or nearly-circular CP character,
• wherein the first CP character is smaller than the second CP character, and wherein the determining is performed using one or more computing hardware processors.

A stencil for charged particle beam lithography comprising:

• a first aperture comprising a first diameter, wherein the first aperture is capable of forming, in one shot, circular or nearly-circular patterns in a first range of sizes on a surface by varying shot dosage;
• and
• a second aperture comprising a second diameter larger than the first diameter, wherein the second aperture is capable of forming, in one shot, circular or nearly-circular patterns in a second range of sizes on the surface by varying shot dosage, and
• wherein the first range of sizes is discontinuous with the second range of sizes.

A system for forming patterns on a surface using charged particle beam lithography comprising:

• a stencil comprising a first aperture and a second aperture, wherein a first size of the first aperture is different than a second size of the second aperture;
• a device configured to input a set of charged particle beam shots;
• and
• a device configured to form circular or nearly circular patterns in a first plurality of sizes using the first aperture and in a second plurality of sizes using the second aperture.