Pattern defect inspection method and apparatus using image correction technique

An image correction method adapted to be used in a pattern inspection method for emitting light falling onto a workpiece with a pattern formed thereon and for performing inspection by comparing test pattern images resulted from pickup of respective optical images of transmission light and reflection light of the workpiece to an inspection fiducial pattern image corresponding thereto, said image correction method comprising:

• generating a system of equations describing therein an input/output relation using a 2D linear prediction model with respect to any one of the test pattern images based on the transmission light and the reflection light and its corresponding inspection fiducial pattern image;
• estimating by a least-squares technique the equation system describing the input/output relation to thereby obtain more than one parameter of said equation system;
• using the parameter to combine together an estimation model image and said any one of the test pattern images;
• obtaining a centroid of said parameter;
• adding to said centroid a predefined offset value to thereby provide an added centroid position value;
• and
• using said added centroid position value to apply interpolation to a remaining one of said test pattern images which is out of the 2D linear prediction, thereby generating a corrected image.

A pattern inspection method for emitting light falling onto a workpiece with a pattern formed thereon and for inspecting a pattern image resulting from pickup of an optical image of the workpiece by comparing the pattern image to a corresponding inspection fiducial pattern image, said method comprising:

• generating a collection of equations describing therein an input/output relation using a 2D linear prediction model with respect to the pattern image being tested and the fiducial pattern image;
• estimating the equations describing the input/output relation by a least-squares technique to thereby obtain more than one parameter of said equations;
• obtaining a centroid position of the parameter;
• performing interpolation using a value of the centroid position to thereby generate a corrected image;
• and
• comparing the corrected image to said fiducial pattern image.

A pattern inspection method for emitting light falling onto a workpiece with a pattern formed thereon and for performing inspection by comparing test pattern images resulted from pickup of respective optical images of transmission light and reflection light of the workpiece to a corresponding inspection fiducial pattern image, said method comprising:

• generating simultaneous equations describing therein an input/output relation using a 2D linear prediction model with respect to any one of the test pattern images due to the transmission light and the reflection light and its corresponding inspection fiducial pattern image;
• estimating by a least-squares method the simultaneous equations describing the input/output relation to thereby obtain more than one parameter of the equations;
• using the parameter to combine together an estimation model image and said any one of the test pattern images;
• obtaining a centroid of said parameter;
• adding to said centroid a prespecified offset value to thereby provide an added centroid position value;
• using the added centroid position value to apply interpolation to a remaining one of said test pattern images which is free from the 2D linear prediction;
• and
• comparing said corrected image to said fiducial pattern image.

A pattern inspection apparatus for emitting light falling onto a workpiece with a pattern formed thereon and for performing pattern comparison inspection by use of a pattern image to be tested resulting from pickup of an optical image of the workpiece and an inspection fiducial pattern image corresponding thereto, said apparatus comprising:

• first means for generating a set of simultaneous equations describing therein an input/output relation using a 2D linear prediction model with respect to the pattern image being tested and the fiducial pattern image;
• second means for estimating the equations describing the input/output relation by a least-squares technique to thereby obtain a parameter of said equations;
• third means for obtaining a centroid position of the parameter;
• fourth means for performing interpolation using a value of the centroid position to thereby generate a corrected image;
• and
• fifth means for comparing the corrected image to said fiducial pattern image.