Method of compensating for an effect of electrode distortion, assessment system
AssigneeASML Netherlands B.V.
InventorMarco Jan-Jaco Wieland
Life of this patent
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Abstract
Assessment systems and methods are disclosed. In one arrangement, an effect of electrode distortion in an objective lens array is compensated. An electrode distortion is adjusted by varying an electrostatic field in the objective lens array. The adjustment is such as to compensate for an effect of electrode distortion on sub-beams of a multi-beam impinging on a sample. A sub-beam is refocused in response to the variation in electrostatic field in the objective lens array. The adjusting and the refocusing comprises changing potentials applied to at least two electrodes of the objective lens array.
Claims20
A method of compensating for an effect of electrode distortion in an objective lens array of a multi-beam charged particle assessment system, the method comprising:
- adjusting an electrode distortion by varying an electrostatic field in the objective lens array, the objective lens array comprising a hardware correction for compensating a predicted effect on sub-beams from a predicted electrode distortion in the objective lens array, the adjustment being such as to compensate for an effect of electrode distortion on sub-beams of the multi-beam impinging on a sample;
- and
- refocusing a sub-beam of the multi-beam in response to the variation in electrostatic field in the objective lens array, wherein:
- the adjusting and the refocusing comprises changing potentials applied to two electrodes of the objective lens array and the adjustment of the electrode distortion comprising adjusting the electrode distortion to substantially match the predicted electrode distortion.
An assessment system configured to direct charged particles in sub-beams arranged in a multi-beam towards a sample, the system comprising:
- a plurality of electrodes defining an objective lens array configured to direct the sub-beams onto a sample, the electrodes being arranged in series along at least one sub-beam path of the sub-beams;
- a stage for supporting a sample;
- and
- an intermediate element positioned between the objective lens array and the stage, the intermediate element being electrically isolated from both the objective lens array and the stage.
Dependencies are inferred from the claim text.