SEM Objective Lens and Triple Deflector Layout for Wider Field Imaging
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Solution Overview
Problem
Current electron beam inspection systems for semiconductors face challenges with narrow field of view and low throughput due to off-axis aberration, limiting their ability to detect small defects efficiently in semiconductor manufacturing processes.
Innovation Solution
A scanning electron microscope device with a deflection mechanism comprising three electrostatic deflectors and an objective lens assembly that includes a magnetic yoke and a shielding plate, which reduces off-axis aberration and expands the available field of view by adjusting the electron beam's direction and angle, enhancing detection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional electron beam inspection system is used, then the system can detect defects on semiconductor substrates, but the field of view is narrow and the throughput is low due to off-axis aberration
Solution Approach 1:
The deflection mechanism is divided into three separate electrostatic deflectors (first, second, and third deflectors) positioned at different locations in the electron beam path. Each deflector handles specific deflection tasks, with the third deflector specifically positioned between the second deflector and the objective lens assembly to correct off-axis aberration. This segmentation allows independent optimization of each deflector's function, reducing overall aberration and expanding the field of view while maintaining inspection precision.
2Productivity
If the field of view is expanded to improve detection efficiency, then more defects can be inspected, but off-axis aberration increases and reduces image quality
Solution Approach 1:
The third electrostatic deflector acts as an intermediary element between the second deflector and the objective lens assembly. It specifically addresses off-axis aberration by introducing a corrective deflection field that compensates for the aberration introduced by the first two deflectors. This intermediary deflector enables the system to maintain high image quality across a broader field of view, allowing expanded detection efficiency without sacrificing measurement 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
The solution significantly reduces off-axis aberration, increasing the field of view and detection efficiency, allowing for more effective inspection of semiconductor substrates and improving the operational efficiency of electron beam inspection apparatuses.
Implementation Method 1
each of the first deflector, the second deflector and the third deflector is an electrostatic deflector
Implementation Method 2
an electromagnetic lens is typically as an objective lens arranged behind or after an electron beam deflection mechanism
Implementation Method 3
bombard the surface of the sample which is being detected with high-energy electron beam
Implementation Method 4
detect both secondary electrons (SE) and backscattered electrons (BSE) generated in a bombarded area of the surface of the sample
Implementation Method 5
detect both secondary electrons (SE) and backscattered electrons (BSE) generated in a bombarded area of the surface of the sample
Data Source
AI summary
A scanning electron microscope device for a sample to be detected and an electron beam inspection apparatus are provided, the scanning electron microscope device being configured to project electron beam to a surface of the sample to generate backscattered electrons and secondary electrons, and comprising: an electron beam source, a deflection mechanism, and an objective lens assembly. The deflection mechanism comprises a first deflector located downstream the electron beam source and a second deflector located downstream the first deflector. The objective lens assembly comprises: an excitation coil; and a magnetic yoke, formed by a magnetizer material as a housing which opens towards the sample and comprising a hollow body defining an internal chamber where the excitation coil is accommodated, and at least one inclined portion extending inward from the hollow body at an angle with reference to the hollow body and directing towards the optical axis, with an end of the at least one inclined portion being formed into a pole piece. The deflection mechanism further comprises a third deflector located between the second deflector and the objective lens assembly and disposed in an opening delimited and circumscribed by the pole piece, and each of the first deflector, the second deflector and the third deflector is an electrostatic deflector.