Charged Particle Beam Incident Angle Control
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Solution Overview
Problem
Existing charged particle beam apparatuses face challenges in accurately measuring the dimensions of deep grooves and holes with high aspect ratios due to varying incident angles of primary electrons, requiring complex control methods and tables to adjust for different optical conditions, which are time-consuming and cumbersome.
Innovation Solution
A charged particle beam apparatus equipped with a control unit and storage unit that uses first and second control parameters to adjust the deflection of the primary electrons, allowing for easy adjustment of incident angles by transforming the optical axis from the object lens center axis to a perpendicular incident axis using image shift deflectors, simplifying the control method and reducing the need for extensive correction tables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If primary electrons are deflected to measure three-dimensional structures, then measurement capability is improved, but incident angles vary causing measurement precision to deteriorate
Solution Approach 1:
The patent applies preliminary anti-action by pre-calculating and storing correction values in a correction table that compensate for incident angle variations. Before actual measurement, the system determines the appropriate correction value based on deflection amounts and applies it to cancel out the expected incident angle variations, thereby maintaining measurement precision while enabling three-dimensional structure measurement.
Solution Approach 2:
The patent changes the parameter of incident angle by using a correction table that provides different correction values based on deflection amounts. The correction value is determined by calculating the incident angle variation caused by deflection and selecting the appropriate correction from the table, thereby transforming the variable incident angle into a controlled parameter that maintains measurement accuracy.
2Measurement precision
If correction tables for each optical condition are created to control incident angles, then measurement precision is improved, but device complexity and operation time increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating correction values for various deflection amounts and storing them in a correction table before actual measurement. The correction table is created in advance with correction values corresponding to different deflection amounts, so that during measurement, the system only needs to look up and apply the appropriate correction value without performing complex real-time calculations, thereby reducing operational complexity.
Solution Approach 2:
The patent uses copying by creating a correction table that stores pre-calculated correction values for different optical conditions and deflection amounts. Instead of performing complex incident angle calculations for each measurement, the system copies the appropriate correction value from the table based on the current deflection amount, simplifying the control process while maintaining precision.
3Measurement precision
If correction tables for each optical condition are created, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction values in a correction table before actual measurement operations. The correction table contains pre-computed values for various deflection amounts and optical conditions, eliminating the need for time-consuming real-time calculations during measurement, thereby reducing adjustment time while maintaining measurement precision.
Solution Approach 2:
The patent applies beforehand cushioning by preparing the correction table in advance with all necessary correction values for different measurement conditions. This pre-preparation cushions against time loss during actual measurement operations, as the system can quickly retrieve and apply correction values without performing complex calculations in real-time, thereby reducing overall measurement time.
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 efficient and accurate adjustment of primary electron incident angles, facilitating high-accuracy measurements of three-dimensional structures like deep grooves and holes with minimal impact from optical conditions, reducing measurement time and complexity.
Implementation Method 1
a charged particle source for generating a charged particle beam
Implementation Method 2
converges the primary electrons using an electrostatic lens or an electromagnetic lens
Implementation Method 3
plural image shift deflectors for deflecting the charged particle beam
Implementation Method 4
an object lens for converging the charged particle beam and irradiating the converged charged particle beam to the specimen
Data Source
AI summary
There is provided a charged particle beam apparatus including: a charged particle source; a condenser lens and an object lens for converging a charged particle beam from the charged particle source and irradiating the converged charged particle beam to a specimen; and plural image shift deflectors for deflecting the charged particle beam. In the charged particle beam apparatus, the deflection of the charged particle beam is controlled using first control parameters that set the optical axis of a charged particle beam to a first optical axis that passes through the center of the object lens and enters a predefined position of the specimen, and second control parameters that transform the first control parameters so that the first control parameters set the optical axis of the charged particle beam to a second optical axis having a predefined incident angle different from the incident angle of the first optical axis.