EUV Camera Exposure Testing for Sensor Surface Degradation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Cameras, particularly EUV cameras used in photomask inspection systems, deteriorate over time due to exposure to EUV light and purging gases, leading to reduced image performance and eventual replacement.
Innovation Solution
A test system comprising a camera and a first capture plate with a corresponding surface layer, allowing for exposure to higher EUV intensities over a shorter period to simulate long-term exposure conditions, and subsequent surface analysis to evaluate the camera's longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the camera is exposed to EUV light and purging gas during inspection, then the inspection performance is maintained, but the image sensor deteriorates over time due to degradation and contamination
Solution Approach 1:
The patent applies preliminary action by exposing the image sensor to a controlled vacuum environment and EUV light before actual inspection operations. This pre-conditioning process prepares the sensor for subsequent inspections by establishing a stable vacuum state, thereby reducing degradation during normal operation and extending camera longevity while maintaining inspection performance
2Object-affected harmful factors
If purging gas is used to counteract EUV-induced contamination, then contamination is reduced, but the purging gas erodes the image sensor surface layer
Solution Approach 1:
The patent employs an inert vacuum environment as the purging medium instead of reactive gases. By maintaining a high vacuum state in the camera housing, the system prevents both EUV-induced contamination and gas-induced erosion of the surface layer, simultaneously addressing both harmful effects without compromising surface layer integrity
3Loss of time
If higher EUV intensities are used for shorter periods in testing, then long-term behavior can be predicted, but the test system requires accelerated degradation conditions
Solution Approach 1:
The patent applies parameter changes by systematically varying EUV light intensity and exposure duration in controlled test cycles. By establishing a relationship between accelerated test conditions (higher intensity, shorter time) and actual operational conditions (lower intensity, longer time), the system enables prediction of long-term camera behavior through shortened test procedures, effectively reducing testing time while maintaining predictive accuracy
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
Enables the prediction of long-term camera behavior by simulating EUV-induced degradation, allowing for independent evaluation of the image sensor surface layer and providing insights into the longevity of cameras in photomask inspection systems.
Implementation Method 1
During the inspection process, the EUV light degrades the surface of the camera, especially the image sensor surface layer. The degradation can release particles from the image sensor surface layer which can lead to contamination
Implementation Method 2
Although purging helps against EUV-induced contamination, the purging gas also erodes surface layers of components in the inspection system, e.g., the image sensor surface layer
Data Source
AI summary
A test system for a camera, comprising a camera and a first capture plate. The camera comprises a camera housing and a vacuum flange formed on the camera housing. The vacuum flange is adapted for attaching the camera to a vacuum chamber. The camera housing supports an image sensor. The image sensor comprises an image sensor surface layer. The first capture plate comprises a first capture plate surface layer. The first capture plate surface layer corresponds to the image sensor surface layer. The invention also relates to a mask inspection system and to a method for testing a camera, in particular, an EUV camera.