Lens for a charged particle beam apparatus, charged particle beam apparatus, and method of focusing a charged particle beam

A method of focusing a charged particle beam with a lens having lens components on a sample, comprising:

• providing a first current to a first magnetic lens;
• providing a second current to a second magnetic lens, wherein the first magnetic lens and the second magnet lens have one common pole piece;
• and
• providing a voltage to a lower electrode of an electrostatic lens to decelerate the charged particle beam, wherein the lower electrode is a portion of a lower pole piece of the lens.

A method of focusing a charged particle beam on a sample, the charged particle beam focused with a lens having lens components comprising:

• a first magnetic lens having an upper pole piece and a middle pole piece;
• a second magnetic lens having the middle pole piece and a lower pole piece;
• a first coil arranged in the first magnetic lens and to provide a first magnetic field between the upper pole piece and the middle pole piece;
• a second coil arranged in the second magnetic lens and to provide a second magnetic field between the middle pole piece and the lower pole piece;
• and
• an electrostatic lens having an upper electrode and a lower electrode, wherein at least one of a first inner diameter defined by the upper pole piece and a second inner diameter defined by the middle pole piece is larger than a third inner diameter of the lower pole piece;
• wherein the method comprising:
• providing a first current to the first magnetic lens;
• providing a second current to the second magnetic lens;
• and
• providing a voltage to the lower electrode of the electrostatic lens to decelerate the charged particle beam, wherein the lower electrode is a portion of the lower pole piece of the lens.