Charged Particle Beam Device Image Shift Compensation
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Solution Overview
Problem
The increase in image shift during high magnification measurements in charged particle beam devices leads to aberration, resulting in a larger beam diameter and reduced measurement resolution, which affects reproducibility and tool-to-tool matching in semiconductor dimension measurements.
Innovation Solution
A charged particle beam device that creates and utilizes a lookup table to associate image shift positions with varying beam diameters, allowing for the calculation and compensation of beam diameter variations during dimension measurement processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If image shift is performed to capture high magnification images after low magnification imaging, then measurement location precision is improved, but beam diameter increases due to aberration
Solution Approach 1:
The patent performs low magnification imaging before high magnification imaging to preliminarily locate the measurement position. This preliminary action enables precise positioning without requiring large image shift amounts during high magnification mode, thereby avoiding excessive beam diameter increase while still achieving accurate measurement location precision.
Solution Approach 2:
The patent dynamically adjusts the imaging magnification and image shift amount based on the measured position. By making the image shift amount variable rather than fixed, the system optimizes the balance between positioning precision and beam diameter control, reducing aberration effects while maintaining measurement accuracy.
2Adaptability or versatility
If image shift amount increases during measurement, then positioning flexibility is improved, but measurement resolution deteriorates
Solution Approach 1:
The patent makes the image shift amount dynamic and adaptive based on the actual measurement needs and position. Rather than using a fixed large image shift, the system adjusts the shift amount to be just sufficient for positioning, thereby maintaining positioning flexibility while preventing resolution deterioration from excessive beam diameter increase.
Solution Approach 2:
The patent changes the imaging parameters (magnification, image shift amount) according to the measurement position and requirements. By optimizing these parameters dynamically, the system achieves both positioning flexibility and maintained measurement resolution, avoiding the trade-off between the two.
3Productivity
If multiple CD SEM devices are used for production, then productivity is improved, but tool-to-tool matching becomes difficult
Solution Approach 1:
The patent performs preliminary low magnification imaging to accurately locate measurement positions before high magnification measurement. This preliminary positioning action reduces the required image shift amount during high magnification mode, minimizing beam diameter variations across different devices and improving tool-to-tool matching while maintaining high productivity through parallel device operation.
Solution Approach 2:
The patent uses feedback from the low magnification imaging to adjust and optimize the high magnification measurement parameters. This feedback mechanism ensures consistent measurement conditions across multiple devices, improving tool-to-tool matching while allowing each device to operate at full capacity for high productivity.
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 approach improves measurement reproducibility and reduces tool-to-tool matching by equalizing dimension values across different devices, enhancing the precision of semiconductor pattern dimension measurements.
Implementation Method 1
a primary electron beam emitted from an electron gun 010 is narrowed and converged by convergence lenses 011 and a specimen is two-dimensionally scanned with the electron beam through a deflector 012
Implementation Method 2
an objective lens 013, with the result that an electron beam image is obtained
Data Source
AI summary
A charged particle beam device enabling prevention of degradation of reproducibility of measurement caused by an increase of the beam diameter attributed to an image shift and having a function of dealing with device-to-device variation. The charged particle beam device is used for measuring the dimensions of a pattern on a specimen using a line profile obtained by detecting secondary charged particles emitted from the specimen when the specimen is scanned with a primary charged particle beam converged on the specimen. A lookup table in which the position of image shift and the variation of the beam diameter are associated is prepared in advance by actual measurement or calculation and registered. When the dimensions are measured, image processing is carried out so as to correct the line profile for the variation of the beam diameter while the lookup table is referenced, and thereby the situation where the beam diameter is effectively equal is produced irrespective of the position of the image shift. Whit this, measurement by the charged particle beam excellent reproducibility can be carried out.