Charged Particle Beam Focusing on Non-Planar Surfaces
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In electron beam writing apparatuses, the miniaturization of semiconductor patterns poses challenges in accurately focusing and correcting astigmatism due to the target object plane's non-planar nature, which often results in parts falling out of the dynamic range of the electrostatic lens, making precise pattern writing difficult.
Innovation Solution
A method involving the measurement of conversion factors for both the lens coil and electrostatic lens to adjust focal points and astigmatism corrections, allowing for intermediate level positioning within the dynamic range of the electrostatic lens, enabling accurate focusing and astigmatism adjustment across non-planar target object surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the dynamic range of the electrostatic lens is narrowed to improve focusing precision, then the resolution of the electrostatic lens is improved, but parts of the non-planar target object plane fall out of the dynamic range, making accurate focusing impossible
Solution Approach 1:
The patent applies dynamics by making the reference plane position adjustable and variable. Instead of using a fixed reference plane, the system dynamically selects different reference plane positions based on the target object's surface characteristics, allowing the electrostatic lens to maintain optimal focusing precision across different regions of non-planar surfaces.
Solution Approach 2:
The patent changes the parameter of reference plane position to resolve the contradiction. By varying the reference plane position parameter, the system adapts to different target object plane configurations, ensuring that the entire target area remains within the electrostatic lens's dynamic range while maintaining high focusing precision.
2Measurement precision
If the dynamic range of the electrostatic lens is narrowed to correct astigmatism with high accuracy, then the astigmatism correction precision is improved, but the correction cannot be applied to the entire non-planar target object plane
Solution Approach 1:
The patent makes the reference plane position dynamic and adjustable for astigmatism correction. By adaptively selecting reference plane positions based on the target object's surface topology, the system ensures that high-precision astigmatism correction can be applied across the entire non-planar surface area.
Solution Approach 2:
The system varies the reference plane position parameter to match different regions of the target object plane. This parameter change enables the electrostatic lens to maintain high astigmatism correction precision while extending the correction coverage to the entire non-planar surface.
3Ease of operation
If a fixed reference plane is used for focusing and astigmatism correction, then the adjustment process is simplified, but the non-planar nature of the target object plane causes positioning errors
Solution Approach 1:
The patent transforms the static reference plane into a dynamic, adjustable reference plane that adapts to the target object's surface. This dynamic approach maintains operational simplicity while eliminating positioning errors caused by non-planar surfaces, as the reference plane automatically adjusts to match the target surface geometry.
Solution Approach 2:
The system introduces variability in the reference plane position parameter based on target object characteristics. This parameter adaptation preserves the simplicity of the adjustment process while significantly improving pattern writing accuracy on non-planar surfaces.
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 ensures that the target object plane remains within the dynamic range of the electrostatic lens, allowing for real-time correction of focal points and astigmatism, thereby enabling the writing of patterns with accurate dimensions.
Implementation Method 1
measuring a first set value to focus a charged particle beam on a position of a predetermined reference plane by using a lens coil
Implementation Method 2
correcting a second set value of the electrostatic lens depending on a level position of the target object plane to correct a focal point position of the charged particle beam
Implementation Method 3
measuring a first set value to correct an astigmatism of the charged particle beam at a predetermined mark position by using an astigmatism adjusting coil
Implementation Method 4
correcting a second set value of the electrostatic electrode depending on the level position of the target object plane to correct an astigmatism of the charged particle beam
Data Source
AI summary
A focusing method of a charged particle beam includes measuring a first set value to focus a beam on a position of a reference plane by using a lens coil, acquiring a first factor to change a set value of an electrostatic lens depending on a distance and a second factor to change a set value of the coil depending on a distance, measuring a level distribution of a target plane, correcting the first set value by using the second factor to correct a focal point position of the beam in the coil from the position of the reference plane to an intermediate level position of the level distribution of the target plane, and correcting a second set value of the lens depending on a level position of the target plane by using the first factor to correct a focal point position of the beam by the lens.