Abstract:
An inspection system comprises a beam generator module for deflecting spots across scan portions of a specimen. The system also includes detection channels for sensing light emanating from a specimen in response to an incident beam directed towards such specimen and generating a detected image for each scan portion. The system comprises a synchronization system comprising clock generator modules for generating timing signals for deflectors of the beam generator module to scan the spots across the scan portions at a specified frequency and each of the detection channels to generate the corresponding detected image at a specified sampling rate. The timing signals are generated based on a common system clock and cause the deflectors to scan the spots and the detection channels to generate a detected image at a synchronized timing so as to minimize jitter between the scan portions in the response image.
Abstract:
An inspection system comprises a beam generator module for deflecting spots across scan portions of a specimen. The system also includes detection channels for sensing light emanating from a specimen in response to an incident beam directed towards such specimen and generating a detected image for each scan portion. The system comprises a synchronization system comprising clock generator modules for generating timing signals for deflectors of the beam generator module to scan the spots across the scan portions at a specified frequency and each of the detection channels to generate the corresponding detected image at a specified sampling rate. The timing signals are generated based on a common system clock and cause the deflectors to scan the spots and the detection channels to generate a detected image at a synchronized timing so as to minimize jitter between the scan portions in the response image.
Abstract:
A method of scanning a sample includes simultaneously forming a plurality of co-linear scans. Each scan is formed by a sweep of a spot by an acousto-optical device (AOD). The co-linear scans are separated by a predetermined spacing. A first plurality of swaths are formed by repeating the simultaneous forming of the plurality of co-linear scans in a direction perpendicular to the co-linear scans. The first plurality of swaths have an inter-swath spacing that is the same as the predetermined spacing. A second plurality of swaths can be formed adjacent to the first plurality of swaths. Forming the second plurality of swaths can be performed in an opposite direction to that of the first plurality of swaths or in a same direction. An inspection system can implement this method by including a diffractive optical element (DOE) path after a magnification changer.
Abstract:
Disclosed are apparatus and methods for inspecting or measuring a specimen. An incident beam is directed across a plurality of consecutive scan portions of a specimen so that an output beam profile from each scan portion is consecutively collected by a photomultiplier tube (PMT), and the scan portions include at least one or more first scan portions and a next scan portion that is scanned after the one or more first scan portions. After or while the incident beam is directed to the one or more first scan portions of the specimen, an output signal for each first scan portion is obtained based on the output beam profile that is collected by the PMT for each first scan portion. An expected output beam profile for the next scan portion is determined based on the output signal that is obtained for each one or more first scan portions. As the incident beam is directed towards the next scan portion, a gain input to the PMT for the next scan portion is set based on the expected output beam profile so that the gain for such next scan portion results in a measured signal at the PMT that is within a predefined specification of the PMT or other hardware components that receive a measured signal from the PMT.