Method for optically detecting height of a specimen and charged particle beam apparatus using the same
First Claim
1. A method for optically detecting a height of a specimen surface, comprising steps of:
- projecting two-dimensional slit light to an object from a position diagonally above the object;
detecting light of the projected two-dimensional slit light reflected by said object;
converting a two-dimensional slit image of the detected two-dimensional slit light into an electrical signal by a two-dimensional area sensor; and
eliminating slit parts, in which a detection error is large, from the electrical signal of the converted two-dimensional slit image and detecting the height of said object.
2 Assignments
0 Petitions
Accused Products
Abstract
The present invention provides an optical height detection method and electron beam apparatus to which the method is applied, in which the focusing accuracy of the CD-SEM apparatus, a SEM inspection apparatus, and others is improved by reducing detection errors and improving detection accuracy so as to improve the accuracy of the optical height detection method, and throughput of a CD-SEM apparatus or others is improved by reducing the processing time of automatic focus control performed based on the detected height according to the optical height detection method. An optical detection optical system projects two-dimensional slit light to a measurement object from diagonally above it, detects the light reflected by the measurement object, converts a detected two-dimensional slit image into an electrical signal by a two-dimensional area sensor, eliminates slit parts having a large detection error from the electrical signal, and detects the height of the measurement object.
21 Citations
9 Claims
-
1. A method for optically detecting a height of a specimen surface, comprising steps of:
-
projecting two-dimensional slit light to an object from a position diagonally above the object;
detecting light of the projected two-dimensional slit light reflected by said object;
converting a two-dimensional slit image of the detected two-dimensional slit light into an electrical signal by a two-dimensional area sensor; and
eliminating slit parts, in which a detection error is large, from the electrical signal of the converted two-dimensional slit image and detecting the height of said object. - View Dependent Claims (2, 3, 4, 5)
-
-
6. An apparatus using a charged particle beam, comprising:
-
a scanning electron microscope system including an electron beam source, a condenser lens which converges an electron beam emitted from said electron beam source, a deflector which deflects the electron beam converged by said condenser lens, an objective lens which converges said electron beam deflected by said deflector onto a measurement object to irradiate the object with the beam, a secondary electron detector which detects secondary electrons generated from said measurement object irradiated with said electron beam, and an image processing unit which measures a pattern formed on said measurement object based on a secondary electron beam image detected by said secondary electron detector;
a focus control system including a focus control unit which performs focus control by controlling an excitation current of said objective lens, and an automatic focus control unit which performs automatic focus control of said objective lens according to said secondary electron beam image; and
a height detection optical system including a projection optical unit which projects two-dimensional slit light to said measurement object from a position diagonally above the object, a detection optical unit which detects light of the two-dimensional slit light reflected by said measurement object, a two-dimensional area sensor which converts a two-dimensional slit image of the two-dimensional slit light detected by said detection optical unit into an electrical signal, and a height detection unit which detects the height of said measurement object by performing a process of eliminating slit parts, in which a detection error is large, from the electrical signal of said converted two-dimensional slit image. - View Dependent Claims (7, 8, 9)
-
Specification