Apparatus and method for tilted particle-beam illumination

A method of inspecting a substrate using charged particles, the method comprising:

• generating an incident charged-particle beam;
• controllably tilting the incident beam by a first tilt angle;
• bending the incident beam through a prism array;
• focusing and decelerating the incident beam such that the incident beam impinges on a substrate at a second tilt angle;
• retrieving an emitted charged-particle beam;
• bending the emitted beam through the prism array;
• and
• projecting the emitted beam to a detection system.

A low-energy electron beam inspection apparatus, the apparatus comprising:

• an illumination system for generating an incident electron beam;
• an objective lens system for decelerating and focusing the incident beam to a substrate and for accelerating and refocusing an emitted electron beam;
• a projection system for projecting the emitted beam to a detection system to generate two-dimensional image data;
• a beam separator configured to bend the incident beam towards the substrate and further configured to bend the emitted beam towards the projection system;
• and
• a controllable tilting mechanism in the illumination system for controllably tilting the incident beam by a first tilt angle such that the incident beam impinges upon the substrate at a second tilt angle,
• wherein the second tilt angle is magnified substantially from the first tilt angle.