CD-SEM Beam Landing Angle Calibration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The variation in electron beam landing angle during image shift in CD-SEM measurements leads to reduced measurement reproducibility and instrumental errors across different apparatuses, as the beam tilt angle fluctuates with the stage stop position, affecting the accuracy of semiconductor pattern dimension measurements.
Innovation Solution
A calibration method using polyhedral structural objects with known angles, produced by crystal anisotropic etching technology, is employed to calculate and equalize the electron beam landing angle within the viewing field, registering beam control parameters to maintain consistent landing angles during measurements, thereby reducing variations and instrumental errors across apparatuses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If image shift is performed to capture high-power images, then the scanning position of the primary electron beam is changed to center on the pattern to be measured, but the electron beam landing angle varies depending on the stage stop position, reducing measurement reproducibility
Solution Approach 1:
The patent performs preliminary calibration by capturing images of polyhedral structures at multiple stage positions before actual measurements. This preliminary action establishes the relationship between stage position and beam landing angle, allowing the system to compensate for angle variations during subsequent high-power imaging and measurements, thereby maintaining measurement reproducibility despite image shift operations
Solution Approach 2:
The patent implements feedback by using the captured images of polyhedral structures to calculate and determine the actual beam landing angle at each stage position. This feedback information is then used to adjust and equalize the landing angle across different positions, ensuring consistent measurement conditions and improving reliability
2Productivity
If multiple apparatuses are used to increase throughput, then semiconductor production volume is maintained, but instrumental errors increase due to differences in beam landing angles across apparatuses
Solution Approach 1:
The patent creates a universal calibration approach that can be applied across multiple different CD-SEM apparatuses. By using the same polyhedral structure calibration method and data processing algorithm on all apparatuses, the system achieves consistent beam landing angle equalization across different devices, enabling multi-apparatus operation with maintained measurement precision and reduced instrumental errors
3Adaptability or versatility
If the stage stop position varies, then different positions within the viewing field are measured, but the beam tilt angle fluctuates, affecting CD value accuracy
Solution Approach 1:
The patent changes the parameter of beam landing angle based on the measured position. By capturing polyhedral structure images at various stage positions and calculating the corresponding beam landing angles, the system creates a position-dependent angle correction map. This allows the measurement system to adapt to different positions while maintaining accurate CD measurements through appropriate angle compensation
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 stabilizes the electron beam landing angle, eliminating variations in CD values and instrumental errors, enhancing measurement reproducibility and accuracy by ensuring consistent beam alignment across multiple apparatuses.
Implementation Method 1
An electron beam image can be obtained by capturing secondary electrons generated from the sample by electron beam irradiation
Implementation Method 2
polyhedral structural objects with known angles, produced by crystal anisotropic etching technology
Data Source
AI summary
The present invention provides a charged particle beam apparatus used to measure micro-dimensions (CD value) of a semiconductor apparatus or the like which captures images for measurement. For the present invention, a sample for calibration, on which a plurality of polyhedral structural objects with known angles on surfaces produced by the crystal anisotropic etching technology are arranged in a viewing field, is used. A beam landing angle at each position within a viewing field is calculated based on geometric deformation on an image of each polyhedral structural object. Beam control parameters for equalizing the beam landing angle at each position within the viewing field are pre-registered. The registered beam control parameters are applied according to the position of the pattern to be measured within the viewing field when performing dimensional measurement. Accordingly, the present invention provides methods for reducing the variation in the CD value caused by the variation in the electron beam landing angle with respect to the sample with an equal beam landing angle and methods for reducing the instrumental error caused by the difference in the electron beam landing angle between apparatuses.