Charged Particle Beam Charge Control Without Acceleration Voltage Tuning
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Solution Overview
Problem
Charged particle beam devices struggle to specify irradiation conditions for primary electrons to achieve a desired charged state without adjusting acceleration voltage, limiting throughput when inspecting wafers with multiple patterns, and existing methods do not adequately address the need for controlling the charged state of samples during low magnification observations.
Innovation Solution
A charged particle beam device that adjusts irradiation conditions of primary charged particles by controlling the relationship between specified irradiation conditions and observation image acquisition, allowing for switching between positive and negative charges without altering acceleration voltage, using an arithmetic unit to determine optimal current density and voltage settings based on material properties and electric field conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If low magnification imaging with high current is used to increase inspection throughput, then inspection efficiency is improved, but image distortion and charging phenomena increase
Solution Approach 1:
The patent changes the energy parameter of primary electrons to control the secondary electron emission rate, thereby controlling the charged state of the sample. By adjusting electron energy rather than simply increasing current, the system achieves both high throughput and minimal charging effects
Solution Approach 2:
The patent introduces feedback control by detecting the charged state of the sample and adjusting the energy of primary electrons accordingly. The arithmetic unit calculates the charged state based on detection signals and modifies irradiation conditions to maintain optimal inspection conditions
2Manufacturing precision
If the energy of primary electrons is adjusted to control sample charge, then charging phenomenon is controlled, but setting and adjustment of optical conditions is required
Solution Approach 1:
The system performs self-adjustment by automatically changing the energy of primary electrons based on detected charged state. The arithmetic unit calculates required energy adjustments and the control unit implements them without manual intervention, making the system self-regulating
Solution Approach 2:
The patent creates a universal control mechanism that handles different patterns and materials through a single integrated system. The arithmetic unit stores relationship data for various materials and shapes, allowing the same control system to optimize conditions across diverse inspection scenarios
3Manufacturing precision
If acceleration voltage is adjusted to control charged state, then charge control is achieved, but throughput is limited when inspecting wafers with multiple patterns
Solution Approach 1:
The patent changes from adjusting acceleration voltage to adjusting electron energy through other means (current density, irradiation conditions). This allows charge control without the time-consuming voltage changes, maintaining high throughput while achieving precise charge state control for multiple patterns
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
Enables precise control of the charged state of samples, minimizing image distortion and improving inspection accuracy and throughput by determining optimal irradiation conditions for various patterns and materials, thereby enhancing the efficiency of semiconductor inspections.
Implementation Method 1
the emission rate (secondary electron yield) of the secondary electrons depends on the energy of the incident electrons
Implementation Method 2
The charge of the sample is determined by a balance between incident charged particles (for example, primary electrons) and charged particles emitted from the sample (for example, secondary electrons or backscattered electrons)
Data Source
AI summary
The purpose of the present invention is to provide a charged particle beam device that can specify irradiation conditions for primary charged particles that can obtain a desired charged state without adjusting the acceleration voltage. The charged particle beam device according to the present invention specifies the irradiation conditions for a charged particle beam in which the charged state of a sample is switched between a positive charge and a negative charge, and adjusts the irradiation conditions according to the relationship between the specified irradiation conditions and the irradiation conditions when an observation image of the sample has been acquired (see FIG. 8).