Charged Particle Beam Drift Correction Using Multi-Height Marks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In charged particle beam drawing apparatuses, beam drift caused by electric fields generated due to reflected electrons leads to inaccurate drift correction, resulting in shifts in the electron beam irradiation position and reduced pattern drawing accuracy, especially when workpiece surfaces and mark surfaces are not flush, causing errors in drift amount measurement.
Innovation Solution
A charged particle beam drawing apparatus and method that utilize multiple marks with different heights on the stage, where the irradiation position detector measures the electron beam position on each mark, and the drift-amount calculation unit calculates the real drift amount on the workpiece surface by using the drift amounts from at least two marks, allowing for accurate correction of the electron beam position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If drift correction is performed using a single mark on the stage, then the drift correction process is simple, but the drift amount measurement contains errors when the workpiece surface and mark surface are not flush
Solution Approach 1:
The invention divides the drift measurement function into multiple segments by providing multiple marks at different heights on the stage. Each mark serves as an independent measurement point, allowing the system to segment the measurement task across different height levels. This segmentation enables accurate drift measurement for workpieces at various heights without requiring a complex single-mark system that must accommodate all height variations.
Solution Approach 2:
The invention adds the height dimension to the drift measurement system by positioning marks at different heights on the stage. This dimensional expansion allows the system to measure drift amounts accurately regardless of the workpiece height, transforming a two-dimensional measurement problem into a three-dimensional solution that accounts for vertical variations in workpiece positioning.
2Measurement precision
If multiple marks with different heights are used to measure drift accurately, then drift correction precision is improved, but the device complexity increases
Solution Approach 1:
The drift correction function is segmented across multiple marks positioned at different heights on the stage. Each mark handles a specific height range, allowing the system to manage complexity by dividing the correction task into discrete, height-specific segments rather than requiring a single complex adaptive system.
Solution Approach 2:
The invention changes the parameter of mark height to optimize drift measurement accuracy. By varying the height parameter of marks across different positions on the stage, the system adapts to workpieces of different heights without requiring complex mechanical adjustments or reconfiguration, thereby improving precision while maintaining manageable device complexity.
3Speed
If the electron beam angle of incidence is abruptly changed due to electric field disappearance, then the beam responds quickly to field changes, but the error between drift amount on mark surface and real drift amount on workpiece surface increases
Solution Approach 1:
The invention performs preliminary drift measurement actions by scanning multiple marks at different heights before the actual drawing process. This preliminary measurement establishes baseline drift data across various height levels, allowing the system to pre-correct for angle of incidence errors that would otherwise occur when electric fields change abruptly during beam irradiation.
Solution Approach 2:
The system implements feedback by continuously measuring drift amounts using multiple marks and using this information to adjust beam positioning in real-time. When electric fields change and cause angle of incidence variations, the feedback mechanism detects drift changes across multiple height levels and compensates for the resulting measurement errors, maintaining accuracy despite rapid beam response to field changes.
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 eliminates errors in drift correction by accurately determining the real drift amount on the workpiece surface, enhancing pattern drawing accuracy even when the electric field changes, and reduces processing time by using only two marks for precise drift amount calculation.
Implementation Method 1
reflected electrons are generated due to irradiation of the workpiece with the electron beam
Implementation Method 2
charge-up occurs due to collision of the generated reflected electrons with an optical system, a detector or the like in the apparatus
Implementation Method 3
a new electric field is generated
Implementation Method 4
The electric field changes an orbit of the electron beam, and thus the beam drift occurs
Implementation Method 5
an irradiation position detector configured to, when any of the marks is irradiated with the charged particle beam, detect an irradiation position of the charged particle beam on a mark surface of the mark
Data Source
AI summary
A charged particle beam drawing apparatus of an embodiment includes: a drawing unit to perform drawing on a workpiece on a stage by using a charged particle beam; multiple marks located on the stage and having different heights; an irradiation position detector to, when any of the marks is irradiated with the charged particle beam, detect an irradiation position of the charged particle beam on a mark surface of the mark; a drift-amount calculation unit to calculate a drift amount of the charged particle beam on the mark surface by using the irradiation position; a drift-amount processing unit to obtain a drift amount on a workpiece surface by using the drift amounts on at least two of the mark surfaces; and a drawing controller to correct an is irradiation position of the charged particle beam by using the drift amount on the workpiece surface.