Leveling sensor in multiple charged-particle beam inspection
AssigneeASML Netherlands B.V.
InventorsJian Zhang, Yan Wang, Liang Tang, Yixiang Wang
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Abstract
An improved leveling sensor and method for adjusting a sample height in a charged-particle beam inspection system are disclosed. An improved leveling sensor comprises a light source configured to project a first pattern onto a sample and a detector configured to capture an image of a projected pattern after the first pattern is projected on the sample. The first pattern can comprise an irregularity to enable a determination of a vertical displacement of the sample.
Claims19
A charged-particle beam inspection system comprising:
- a stage configured to hold a sample;
- and
- a leveling sensor configured to determine a vertical displacement of the sample and comprising:
- a light source configured to project a first pattern onto the sample;
- and
- a detector configured to capture an image of a projected pattern after the first pattern is projected on the sample,
- wherein the first pattern comprises an irregularity to enable a determination of the vertical displacement of the sample.
A non-transitory computer readable medium that stores a set of instructions that is executable by at least one processor of a computing device to cause the computing device to perform a method for adjusting a sample height in a charged-particle beam inspection system comprising a leveling sensor, the method comprising:
- generating a light intensity image of a projected pattern on a sample, wherein the projected pattern is formed by projecting a first pattern on the sample by a light source of the leveling sensor;
- conducting a cross-correlation between the light intensity image and a reference image;
- and
- determining a vertical displacement of the sample based on the cross-correlation,
- wherein the first pattern comprises an irregularity to enable a determination of the vertical displacement of the sample.
Dependencies are inferred from the claim text.