Objective lens with deflector plates immersed in electrostatic lens field
AssigneeKLA-Tencor Corporation
InventorsAlexander J. Gubbens, Ye Yang
Life of this patent
Estimating the term…
Abstract
One embodiment relates to an objective lens utilizing magnetic and electrostatic fields which is configured to focus a primary electron beam onto a surface of a target substrate. The objective lens includes a magnetic pole piece and an electrostatic deflector configured within the pole piece. An electrostatic lens field is determined by the pole piece and the electrostatic deflector, and the electrostatic lens field is configured by adjusting offset voltages applied to plates of the electrostatic deflector. Other embodiments, aspects and features are also disclosed.
Claims18
An electron beam apparatus comprising:
- an electron source for generating a primary electron beam;
- a magnetic immersion objective lens configured to focus the primary electron beam onto a surface of a target substrate;
- a pole piece of the magnetic immersion objective lens;
- an electrostatic deflector including a plurality of plates configured within the pole piece;
- an electrostatic lens field determined by the pole piece and the electrostatic deflector, wherein the electrostatic lens field is configured to be controllably adjusted by applying DC offset voltages to all of the plates of the electrostatic deflector;
- a top shunt configured within the pole piece above the electrostatic deflector such that the primary electron beam passes through an opening in the top shunt before passing through the electrostatic deflector,
- wherein a high voltage is applied to the pole piece, and
- wherein the top shunt is conductively connected to an electrical ground.
An objective lens utilizing magnetic and electrostatic fields which is configured to focus a primary electron beam onto a surface of a target substrate, the objective lens comprising:
- a magnetic pole piece;
- an electrostatic deflector configured within the pole piece;
- an electrostatic lens field determined by the pole piece and the electrostatic deflector, wherein the electrostatic lens field is configured to be controllably adjusted by applying DC offset voltages to all plates of the electrostatic deflector;
- a top shunt configured within the pole piece above the electrostatic deflector such that the primary electron beam passes through an opening in the top shunt before passing through the electrostatic deflector,
- wherein a high voltage is applied to the pole piece, and
- wherein the top shunt is conductively connected to an electrical ground.
A method of focusing an electron beam onto a target specimen, the method comprising:
- applying a high voltage on a magnetic pole piece;
- applying electrical ground to a top shunt within the magnetic pole piece;
- adjusting DC offset voltages applied to a main deflector which is below the top shunt within the magnetic pole piece, the DC offset voltages being adjusted so as to fine tune an electrostatic lens field determined by the DC offset voltages on the deflector and the high voltage on the magnetic pole piece surrounding the deflector;
- and
- passing the electron beam through an opening in the top shunt and through the main deflector.
Dependencies are inferred from the claim text.