Charged Particle Beam Resolution Measurement via Scattered Electron Fitting
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Solution Overview
Problem
Current electron-beam lithography systems face challenges in accurately calculating the resolution and aperture angle of charged particle beams, which are crucial for improving drawing accuracy in semiconductor device manufacturing.
Innovation Solution
A method involving changing the focus position of the charged particle beam, scanning a dot mark on a substrate, detecting reflected particles, and performing a convolution operation to calculate the aperture angle and resolution by fitting the scattered electron distribution with a convolution result, using a control computer to adjust the electron optical system and minimize errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional beam resolution calculation methods are used based on predetermined expressions from beam intensity distribution, then the measurement process is simple, but the measurement precision of aperture angle and resolution is insufficient
Solution Approach 1:
The invention changes the measurement approach from direct beam intensity distribution measurement to scattered electron distribution measurement. By detecting scattered electrons at multiple positions around the dot mark and performing convolution operations with mark shape data, the system achieves higher precision in determining beam resolution and aperture angle parameters without requiring complex additional hardware
Solution Approach 2:
The invention replaces the conventional mechanical/scanning-based beam intensity measurement system with an electron detection system that measures scattered electrons. This substitution uses electrical detection methods instead of physical scanning and measurement, enabling more precise and efficient beam parameter measurement through electronic signal processing and convolution operations
2Measurement precision
If the focus position is changed and scattered electron distribution is measured at multiple positions, then the measurement precision of beam parameters is improved, but the measurement time increases
Solution Approach 1:
The invention performs preliminary actions by first obtaining mark shape data through scanning the dot mark before measuring scattered electron distributions at multiple focus positions. This preliminary preparation allows the subsequent multi-position measurements to be processed more efficiently using pre-computed convolution operations, reducing the overall measurement time while maintaining high precision
Solution Approach 2:
The invention uses periodic action by measuring scattered electron distributions at multiple discrete focus positions in a systematic sequence. Each measurement at a different focus position provides complementary information that, when combined through convolution operations, yields highly precise beam parameters. This periodic sampling approach optimizes the balance between measurement time and precision
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 allows for high-accuracy measurement of the aperture angle and resolution of the electron beam, enhancing the precision of electron-beam lithography systems and improving drawing accuracy in semiconductor manufacturing.
Implementation Method 1
detecting a reflected charged particle reflected from the dot mark
Data Source
AI summary
In one embodiment, a method for measuring a resolution of a charged particle beam includes changing a focus position of the charged particle beam in a height direction, and scanning a dot mark formed on a substrate with the charged particle beam for each focus position, detecting a reflected charged particle reflected from the dot mark for each focus position, calculating a scattered charged particle distribution from a detection result of the reflected charged particle for each height corresponding to the focus position, performing a convolution operation on an approximate expression of a beam waveform of the charged particle beam and a mark shape of the dot mark, the approximate expression including an aperture angle and a resolution of the charged particle beam as parameters, and calculating the aperture angle and the resolution by fitting the scattered charged particle distribution by height and a calculation result of the convolution operation.