Electron-Optical Particle Trap for Breakdown Prevention
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Solution Overview
Problem
Electron-optical columns in semiconductor manufacturing are prone to electrostatic breakdown due to contaminant particles entering high field regions, which can lead to errors and damage during the manufacturing process of semiconductor IC chips.
Innovation Solution
An electron-optical system with a particle trap comprising an electrode assembly radially positioned outside the objective lens arrangement, generating an electric field to draw particles away from the sample surface as it moves relative to the electron-beam path, thereby reducing the risk of electrostatic breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high electric fields are used in the electron-optical column to maintain beam focus and intensity, then the electron beam quality is improved, but the risk of electrostatic breakdown increases due to contaminant particles entering high field regions
Solution Approach 1:
The particle trap is activated before the contaminant particles can enter the high field region of the objective lens. By detecting particles early and applying electrostatic forces to remove them preemptively, the system maintains high electric fields for beam quality without allowing particles to cause breakdown
Solution Approach 2:
The particle trap acts as an intermediary component between the sample stage and the objective lens. It uses electrostatic fields to capture and remove contaminant particles before they can reach the critical high field region, thereby protecting the system while allowing the main electron-optical path to operate at optimal field strengths
2Measurement precision
If the electron beam is focused tightly on the sample to improve inspection resolution, then the measurement precision is improved, but the electric field concentration increases the susceptibility to electrostatic breakdown
Solution Approach 1:
The particle trap extracts contaminant particles from the vicinity of the objective lens before they can be affected by the concentrated electric fields. By removing the harmful particles separately, the system can maintain tight beam focusing for high resolution without the compounded risk of particle-induced breakdown in the concentrated field region
3Manufacturing precision
If the objective lens is positioned close to the sample to reduce aberrations and improve focus, then the manufacturing precision is improved, but the risk of particle contamination in the high field region increases
Solution Approach 1:
The particle trap extends the protection volume radially outward from the objective lens-sample interface. By creating an electrostatic influence zone that reaches toward the sample stage, the system maintains close focusing for precision while adding a protective dimension that intercepts particles before they can enter the critical region
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
The particle trap effectively prevents contaminant particles from entering the objective lens area, minimizing the risk of electrostatic breakdown and ensuring stable operation of the electron-optical system, thereby improving the yield and throughput of semiconductor manufacturing processes.
Implementation Method 1
the electrode assembly for drawing a particle away from a surface of the sample and/or stage as the sample is moved relative to the electron-beam path
Data Source
AI summary
Electron-optical systems comprising a particle trap and methods of operating electron-optical systems using a particle trap are disclosed. In one arrangement, a stage supports a sample. An objective lens arrangement projects electrons towards the sample along an electron-beam path. A particle trap comprises an electrode assembly radially outside of the objective lens arrangement and facing the sample. The electrode assembly draws a particle away from a surface of the sample and/or stage as the sample moves relative to the electron-beam path.