In a semiconductor manufacturing process, it is important to discover a defect occurring in the manufacturing process early and take measures, to secure a high yield.
A scanning electron microscope (SEM)-type defect observation device (also called a defect review device) is a device to observe a defect occurred in the semiconductor manufacturing process, particularly. The SEM-type defect observation device is generally a device to observe an image of the defect coordinates detected by an upper defect inspection device with definition higher than definition in the upper defect inspection device. Specifically, the SEM-type defect observation device moves a sample stage to the defect coordinates output by the upper defect inspection device, executes imaging with a low magnification where a defect to be observed enters a view, detects the defect coordinates from an imaged low-magnification image, moves the sample stage such that the defect is positioned at the center of the view or moves the center of the imaging, and acquires a high-magnification image for observation with the high magnification suitable for the defect observation.
As such, the defect coordinates are detected from the low-magnification image, because error is included in the defect coordinates output by the upper defect inspection device, in a range of a device specification, and processing for correcting the error is necessary when the high-definition defect image is acquired by the SEM-type defect observation device.
Automatic defect review or automatic defect redetection (ADR) automates a process for acquiring the high-definition defect image. In the ADR, an acquisition condition of the low-magnification image to detect the defect or an acquisition condition of the high-magnification image to observe the defect should be optimized while a balance of the defect detection rate and the throughput of the ADR is considered, according to coordinate precision of defect detection in the upper defect inspection device, a characteristic of a sample, or a kind of the defect to be observed.
Patent Literature 1 describes “acquiring an image including a defect with a first magnification using a scanning electron microscope, generating a reference image from the acquired image including the defect with the first magnification, comparing the acquired image including the defect with the first magnification and the reference image generated from the image including the defect with the first magnification to detect the defect, and imaging the detected defect with a second magnification larger than the first magnification. According to this, “because a process for imaging the reference image with the low magnification can be omitted, the defect can be reviewed more efficiently” is described.