US 5,659,172 A · Reliable defect detection using multiple perspective scanning electron microscope images

Abstract

A method for fast and reliable defect detection on semiconductor devices by comparing SEM images from a single perspective followed by a cross-check between at least two perspectives. An SEM equipped with at least two electron detectors each of which is capable of collecting electrons from different angular sectors. `Base` images of an area of the semiconductor wafer which is to be inspected are generated from both perspectives. For each perspective base image, a perspective `reference` image is generated, which is suitable for comparison with the base image. The reference image is registered with respect to the base image, for each perspective, the reference image is compared with the base image, and a comparison map of possible defect locations is produced, and, finally, a cross-check is carried out between the perspective comparison maps. The cross-check filters out events in the perspective comparison maps relating to variations other than defects such as pattern variations and noise.

Claims17

Dependent claims

A method of detecting defects in objects, such as semiconductor wafers, which include an array of ideally identical parts, the method comprising the steps of:

(i) inspecting a base area and at least one corresponding reference area of an object which includes an array of ideally identical parts, each of said areas being inspected from a plurality of angular sections thereby forming a base perspective image for each of said plurality of angular sections and a corresponding reference perspective image for each of said plurality of angular sections, respectively, wherein said inspection is performed by a scanning electron microscope apparatus including at least two detectors, thereby generating said base and said corresponding reference perspective images;
(ii) for each of said perspectives, comparing said base perspective image and said corresponding reference perspective image, and, for each of said perspectives, creating a perspective comparison map;
and
(iii) if a difference is indicated, cross checking said comparison maps created for each of said perspectives.

1 more element

A method of detecting defects in objects, such as semiconductor wafers, which include an array of ideally identical parts, the method comprising the steps of:

(i) inspecting a base area and at least one corresponding reference area of an object which includes an array of ideally identical parts, each of said areas being inspected from at least two angular sections thereby forming a base perspective image for each of said at least two angular sections and a corresponding reference perspective image for each of said at least two angular sections, respectively, wherein said inspection is performed by a scanning electron microscope apparatus including at least two detectors, each of said detectors detecting electrons from a predefined angular section which is smaller than 180.degree. and thereby generating said base and said corresponding reference perspective images;
(ii) for each of said perspectives, comparing said base perspective image and said corresponding reference perspective image, and, for each of said perspectives, creating a perspective comparison map, said perspective comparison map indicating differences between said base perspective image and said corresponding reference perspective image;
and
(iii) if a difference is indicated, cross checking said comparison maps created for each of said perspectives, thereby indicating substantially solely of presence of a defect and a location of said defect on said inspected object.

1 more element

Dependencies are inferred from the claim text.

Reliable defect detection using multiple perspective scanning electron microscope images

Life of this patent

Reliable defect detection using multiple perspective scanning electron microscope images

Life of this patent

Abstract

Claims17