Polarization imaging
AssigneeRudolph Technologies, Inc.
InventorsScott A. Balak, Gang Sun
Life of this patent
Estimating the term…
Abstract
Methods of monitoring critical dimensions in a semiconductor fabrication process include capturing at least one image of a first structure that has an effect on the polarization state of light reflected therefrom. For at least some of the first structure images, a value is calculated indicative of intensity of light reflected from the first structure. A critical dimension of the first structure is obtained and correlated with the calculated value. At least one image of a subsequent structure is captured. A determination is made, based at least in part on the calculated value, of a critical dimension of the subsequent structure.
Claims13
A method of monitoring critical dimensions in a semiconductor fabrication process comprising:
- a. capturing at least one image of a first structure having a geometry which has an effect on the polarization state of light reflected therefrom;
- b. generating a differential image for each captured image;
- c. averaging pixel intensity differences of the respective differential images over the entire differential image to obtain an average image intensity value for each differential image;
- d. obtaining a critical dimension of the first structure;
- e. correlating a critical dimension of the first structure with the average image intensity value;
- f. capturing at least one image of a subsequent structure;
- and,
- g. determining, based at least in part on the average image intensity value, a critical dimension of the subsequent structure.
A substrate inspection system comprising:
- an optical sensor positioned to capture an image of a first structure having a geometry which has an effect on the polarization state reflected therefrom and an image of a subsequent structure;
- a computer coupled with the optical sensor to receive the image of the first structure in the image of the subsequent structure, the computer having instructions that, when implemented, generate a differential image for the image of the first structure, average pixel intensity differences of the differential image over the entire differential image to obtain an average image intensity value, obtain a critical dimension of the first structure, correlate a critical dimension of the first structure with the average image intensity value and determine, based at least in part on the average image intensity value, a critical dimension of the subsequent structure.
Dependencies are inferred from the claim text.