Beam Profile Monitoring Using Multi-Exposure Image Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In charged particle beam systems, particularly in semiconductor manufacturing, the limited space within vacuum chambers prevents the use of conventional power meters and beam profilers to monitor the power and quality of light beams, such as laser beams, which are essential for controlling accumulated charges on semiconductor wafers during inspection processes.
Innovation Solution
An image sensor integrated within the charged particle beam microscope captures a sequence of images of the beam spot at different exposure times, and a controller processes these images to obtain the beam profile and power, adjusting for dynamic range limitations and coordinate transformations to accurately assess the beam's interaction with the wafer surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional power meters and beam profilers are used to monitor light beam, then measurement accuracy is improved, but device complexity and space requirements increase
Solution Approach 1:
The image sensor performs multiple functions: it captures beam profile images, measures beam power through grey level analysis, and monitors beam position. By making the image sensor multi-functional, the system eliminates the need for separate power meters and beam profilers, resolving the contradiction between measurement accuracy and device complexity
Solution Approach 2:
The patent combines the functions of power measurement and profile monitoring into a single integrated system using the image sensor. The controller processes images to extract both power information (through total grey level summation) and profile characteristics, merging multiple measurement functions into one device
2Measurement precision
If conventional power meters and beam profilers are used to monitor light beam, then measurement accuracy is improved, but the available space in vacuum chamber is insufficient
Solution Approach 1:
The image sensor serves multiple measurement purposes within the limited vacuum chamber space, eliminating the need for additional external equipment. By capturing images that contain both power and profile information, the system achieves accurate measurements without requiring extra physical space
Solution Approach 2:
The system uses optical imaging to create a visual copy of the beam spot on the wafer surface. This optical copy contains all necessary information about beam power and profile, allowing measurements to be made without physical contact or additional space-consuming devices in the vacuum chamber
3Device complexity
If image sensor is used to monitor beam, then device complexity is reduced, but measurement precision deteriorates due to dynamic range limitations
Solution Approach 1:
The beam profile measurement is segmented into multiple exposure time intervals. The controller captures images at different exposure times to accurately represent both bright and dark regions of the beam profile, overcoming the dynamic range limitation of the image sensor while maintaining measurement precision
Solution Approach 2:
The system changes the exposure time parameter to adapt to different beam intensity regions. By adjusting exposure time based on the specific measurement needs and beam characteristics, the image sensor can accurately capture both high and low intensity areas of the beam profile without losing precision
4Measurement precision
If multiple images at different exposure times are combined, then beam profile accuracy is improved, but measurement time increases
Solution Approach 1:
The measurement process is segmented into multiple rapid exposure time intervals that are quickly captured and then processed. This allows the system to collect necessary data for accurate beam profile representation without requiring prolonged measurement time, as the multiple exposures are taken in quick succession
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables in-situ monitoring of the light beam's power and profile within the vacuum chamber, ensuring effective charge regulation and improving the accuracy of semiconductor inspections without the need for additional equipment.
Implementation Method 1
an image sensor configured to collect a sequence of images of a beam spot of a beam formed on a surface
Data Source
AI summary
A system and a method for monitoring a beam in an inspection system are provided. The system includes an image sensor configured to collect a sequence of images of a beam spot of a beam formed on a surface, each image of the sequence of images having been collected at a different exposure time of the image sensor, and a controller configured to combine the sequence of images to obtain a beam profile of the beam.