Detection of buried features by backscattered particles
AssigneeASML Netherlands B.V.
InventorsJoe Wang, Chia Wen Lin, Zhongwei Chen, Chang-Chun Yeh
Life of this patent
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Abstract
Disclosed herein an apparatus and a method for detecting buried features using backscattered particles. In an example, the apparatus comprises a source of charged particles; a stage; optics configured to direct a beam of the charged particles to a sample supported on the stage; a signal detector configured to detect backscattered particles of the charged particles in the beam from the sample; wherein the signal detector has angular resolution. In an example, the methods comprises obtaining an image of backscattered particles from a region of a sample; determining existence or location of a buried feature based on the image.
Claims17
An apparatus comprising:
- a source of charged particles;
- a stage;
- optics configured to direct a beam of the charged particles to a sample supported on the stage;
- a signal detector configured to detect backscattered particles of the charged particles in the beam from the sample, wherein the signal detector comprises a first detector component and a second detector component, wherein the first detector component and the second detector component are configured to detect backscattered particles with different angles relative to an axis of the beam;
- wherein the apparatus is configured to detect a feature under a surface of the sample based on a comparison of signals corresponding to backscattered particles detected by the first and second detector components.
A method comprising:
- obtaining a first image of backscattered particles from a beam of charged particles from a region of a sample, the first image being formed with backscattered particles having a first angle;
- obtaining a second image of backscattered particles from a beam of charged particles from the region of the sample, the second image being formed with backscattered particles having a second angle different from the first angle;
- and
- determining existence or location of a buried feature based on a comparison of the first and second images.
A non-transitory computer readable medium having instructions recorded thereon, the instructions being executable by at least one processor of a system to cause the system to perform a method comprising:
- obtaining a first image of backscattered particles from a beam of charged particles from a region of a sample, the first image being formed with backscattered particles having a first angle;
- obtaining a second image of backscattered particles from a beam of charged particles from the region of the sample, the second image being formed with backscattered particles having a second angle different from the first angle;
- and
- determining existence or location of a buried feature based on a comparison of the first and second images.
Dependencies are inferred from the claim text.