Multibeam Inspection Sensitivity Adjustment for Beam Intensity Variations
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Solution Overview
Problem
Current pattern inspection apparatuses face challenges in accurately detecting defects in ultrafine patterns on semiconductor wafers and masks due to the miniaturization of LSI patterns, requiring enhanced accuracy and throughput, especially with the use of multibeam technology which struggles with beam intensity variations.
Innovation Solution
A multibeam inspection apparatus featuring a stage, a multibeam column, and a multi-detector system with first and second detection pixels that compare beam intensity differences between overlapping frame images, and a sensitivity adjustor to correct for beam intensity variations, allowing for real-time calibration and improved defect detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multibeam technology is used to improve throughput, then inspection speed increases, but beam intensity variations cause detection accuracy to deteriorate
Solution Approach 1:
The patent implements a feedback mechanism where the intensity of each primary electron beam is monitored by detecting secondary electrons, and this intensity information is fed back to adjust the detection sensitivity of corresponding detection pixels. This closed-loop feedback system compensates for beam intensity variations in real-time, maintaining detection accuracy while using multibeam technology for high-throughput inspection.
Solution Approach 2:
The patent dynamically changes the detection sensitivity parameter for each detection pixel based on the actual intensity of the corresponding primary electron beam. By adjusting the detection sensitivity in proportion to the beam intensity, the system compensates for intensity variations across multiple beams, enabling accurate defect detection throughout the entire inspection area while maintaining high throughput.
2Measurement precision
If detection sensitivity is increased to improve defect detection accuracy, then measurement precision improves, but false detections increase due to beam intensity variations
Solution Approach 1:
The patent dynamically adjusts the detection sensitivity parameter for each detection pixel based on the actual intensity of the corresponding primary electron beam. This parameter change compensates for beam intensity variations, allowing the system to maintain high detection sensitivity without increasing false detection rates, as each pixel's sensitivity is tailored to its specific beam's intensity characteristics.
Solution Approach 2:
The patent applies different detection sensitivity settings to different detection pixels based on their local beam intensity conditions. Each detection pixel has its sensitivity independently adjusted according to the intensity of its corresponding primary electron beam, creating a locally optimized detection system that maintains high accuracy and reliability across the entire inspection field.
3Use of energy by moving object
If beam intensity is increased to improve signal strength, then detection capability improves, but beam damage to the sample increases
Solution Approach 1:
The patent dynamically adjusts the detection sensitivity parameter based on the actual beam intensity used for inspection. This allows the system to operate with optimized beam intensities that provide sufficient signal strength for defect detection while minimizing sample damage, as the detection system adapts to the actual energy conditions rather than requiring uniformly high beam intensity across all areas.
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
The apparatus achieves enhanced accuracy and throughput in detecting defects by real-time adjustment of detection sensitivity, effectively addressing beam intensity variations and improving defect detection sensitivity, thereby improving yield in semiconductor manufacturing.
Implementation Method 1
a multibeam column that irradiates the object to be inspected with multi-primary electron beams
Implementation Method 2
a first secondary electron beam emitted after a first beam scanning region of the object to be inspected is irradiated with a first primary electron beam
Data Source
AI summary
A pattern inspection apparatus according to an aspect described herein includes: a stage on which an object to be inspected is capable to be mounted, a multibeam column that irradiates the object to be inspected with multi-primary electron beams, and a multi-detector including a first detection pixel that receives irradiation of a first secondary electron beam emitted after a first beam scanning region of the object to be inspected is irradiated with a first primary electron beam of the multi-primary electron beams and a second detection pixel that receives irradiation of a second secondary electron beam emitted after a second beam scanning region adjacent to the first beam scanning region of the object to be inspected and overlapping with the first beam scanning region is irradiated with a second primary electron beam adjacent to the first primary electron beam of the multi-primary electron beams; a comparison unit that obtains a difference in beam intensity between the first primary electron beam and the second primary electron beam by comparing overlapping portions of a first frame image acquired through entering of the first secondary electron beam into the first detection pixel and a second frame image acquired through entering of the second secondary electron beam into the second detection pixel; and a sensitivity adjustor that adjusts detection sensitivity of the first detection pixel and/or the second detection pixel so as to correct the difference in beam intensity.