Multi-Column Beam Alignment Using Interferometer Stage Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing multi-column charged-particle exposure apparatuses face challenges in achieving high-accuracy positioning of charged-particle beams relative to a moving target due to intrinsic mechanical limitations and deviations in beam column positions, which affect the precision of image placement on the substrate.
Innovation Solution
A method involving a distance measurement system, such as an interferometer, is used to measure the precise position of a target and particle-optical columns, allowing for real-time correction of target deviations and beam displacements to ensure accurate positioning by calculating and applying beam displacements using deflection systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the target stage moves the substrate through a sequence of positions, then the entire exposure area can be exposed, but the mechanical positioning accuracy of the target stage is much smaller than the desired accuracy of beam image positioning
Solution Approach 1:
The patent implements a feedback control system where the actual position of the target stage is continuously measured using a distance measurement system (interferometer), and the measured position is fed back to the control unit. The control unit then calculates the deviation from the intended position and generates correction signals to the beam deflection units, ensuring that the beam images are accurately positioned on the target despite mechanical inaccuracies of the target stage.
Solution Approach 2:
The patent replaces reliance on mechanical positioning accuracy with an optical measurement and control system. Instead of depending on the mechanical precision of the target stage, the system uses a distance measurement system (interferometer) to measure the actual position and employs beam deflection units (electrostatic/magnetic) to correct positioning errors, substituting mechanical precision requirements with optical measurement and electromagnetic control.
2Manufacturing precision
If beam position correction is performed using charged-particle projection optics, then beam positioning accuracy can be improved, but intrinsic position deviations of the beam columns themselves limit the achievable accuracy
Solution Approach 1:
The patent measures the actual positions of multiple beam columns using the distance measurement system and feeds this information back to the control unit. The control unit calculates the deviation of each beam column from its intended position and generates individualized correction signals to the beam deflection units, compensating for intrinsic position deviations of the beam columns and achieving high positioning accuracy.
Solution Approach 2:
The patent divides the beam correction into individual column corrections. Each beam column's position is measured independently, and individualized correction signals are applied to each column's beam deflection unit. This segmented approach allows for precise compensation of each column's specific deviations rather than applying a uniform correction to all columns.
3Measurement precision
If multiple distance measurement beams are used to track target position, then positioning accuracy can be improved, but the system complexity increases
Solution Approach 1:
The patent divides the measurement task into multiple independent distance measurement beams, each tracking the position of the target at different locations. By segmenting the measurement into multiple beams rather than using a single complex measurement system, the patent achieves higher positioning accuracy through redundant measurements while keeping each individual measurement beam relatively simple.
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 achieves high-precision positioning of charged-particle beams on a moving target, ensuring accurate image placement by compensating for mechanical inaccuracies and beam column deviations, thereby improving the overall accuracy of the exposure process.
Implementation Method 1
A method involving a distance measurement system, such as an interferometer, is used to measure the precise position of a target and particle-optical columns
Implementation Method 2
calculating and applying beam displacements using deflection systems
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
For controlling relative positioning of a moveable target and a charged-particle beam array, in a charged-particle multi-beam processing apparatus for exposure of a target (107), a distance measurement system is employed which preferably includes an interferometer system employing two sets of interferometer beams (X1, X2; Y1, Y2) for measurements along different directions in a measuring plane substantially parallel to the target plane. When the target is moved through a sequence of target movement positions, at each such position the distance measurement system measures the precise current position of the target with respect to reference measuring points (55, 56) in the measuring plane. A target deviance, which describes the deviation of the calculated position and orientation of the target from the nominal target movement position and orientation, is calculated, further determining deviation amounts for the particle-optical columns, describing the deviation of the location of the base point of the columns, and respective beam displacements for the beams of the particle-optical columns which compensates the respective deviation amount, applied via deflection system of the particle-optical columns.