Charged Particle Beam Pre-dosing for Uniform Electrification
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Solution Overview
Problem
The challenge in observing high aspect ratio contact holes in semiconductor devices is the non-uniform electrification during preliminary electron beam irradiation, which leads to deflection of electron trajectories and image blurring due to varying material properties and pattern densities within the irradiation area.
Innovation Solution
A charged particle beam irradiation method and apparatus that divides the preliminary irradiation area into multiple sub-areas, applying different beam conditions to each area to achieve uniform electrification, thereby suppressing electrification non-uniformity and maintaining electron beam trajectory accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform beam irradiation is applied over the whole preliminary electrification area, then the electrification deposition process is simple, but electrification becomes non-uniform within the irradiation area due to varying material properties and pattern densities
Solution Approach 1:
The preliminary irradiation area is divided into multiple divisional areas based on pattern density variations. Each divisional area is irradiated with optimized beam conditions independently, allowing uniform electrification deposition across the entire area despite varying material properties and pattern densities.
Solution Approach 2:
Different beam irradiation conditions are applied to different divisional areas according to their local characteristics (pattern density, material composition). This local optimization ensures that each area receives appropriate electrification without affecting the uniformity of other areas.
2Measurement precision
If preliminary electrification is performed to pull up secondary electrons from hole bottom, then electron detection from hole bottom improves, but electron beam and emitted electrons are deflected by uneven electrification causing image blurring
Solution Approach 1:
By dividing the irradiation area into divisional areas and optimizing beam conditions for each, the patent achieves uniform electrification distribution. This uniformity provides consistent pull-up electric field strength across the observation area, preventing electron beam deflection and maintaining image sharpness while still enabling secondary electron detection from hole bottoms.
Solution Approach 2:
Beam irradiation parameters (such as beam current, scanning speed, or number of passes) are adjusted for different divisional areas to achieve uniform electrification. This parameter optimization ensures that the pull-up electric field is uniformly distributed, allowing secondary electron detection without causing image blurring from excessive or non-uniform electrification.
3Adaptability or versatility
If multiple materials with different properties are present in the preliminary irradiation area, then device complexity and functionality increase, but electrification bias occurs that cannot be eliminated sufficiently even with magnification changes
Solution Approach 1:
The irradiation area containing multiple materials is divided into divisional areas based on material type and pattern density. Each divisional area is irradiated with beam conditions optimized for its specific material composition, eliminating electrification bias that would occur with uniform irradiation across heterogeneous materials.
Solution Approach 2:
Beam irradiation conditions are locally optimized for each divisional area containing specific materials. This local adaptation allows the system to handle complex multi-material semiconductor structures effectively while maintaining uniform electrification distribution across the entire area.
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 uniform electrification distribution, reducing electron beam deflection and image blurring, improving observation accuracy and throughput by tailoring pre-dosing conditions to specific areas within the irradiation zone.
Implementation Method 1
an observation method has been known which makes use of electrification generated by irradiation of an electron beam
Implementation Method 2
an electron beam irradiation is carried out through pre-dosing (preliminary irradiation)
Implementation Method 3
a pull-up electric field needs to be formed by applying a positive electrification to the outer surface (entrance) of the hole
Implementation Method 4
secondary electrons generated at the hole bottom are pulled up to the outside of the hole with the help of the pull-up electric field
Data Source
AI summary
The present invention has for its object to provide a charged particle beam irradiation method and a charged particle beam apparatus which can suppress unevenness of electrification even when a plurality of different kinds of materials are contained in a pre-dosing area or degrees of density of patterns inside the pre-dosing area differs with positions.To accomplish the above object, a charged particle beam irradiation method and a charged particle beam apparatus are provided according to which the pre-dosing area is divided into a plurality of divisional areas and electrifications are deposited to the plural divisional areas by using a beam under different beam irradiation conditions. With the above construction, the electrifications can be deposited to the pre-dosing area on the basis of such an irradiation condition that the differences in electrification at individual positions inside the pre-dosing area can be suppressed and consequently, an influence an electric field has upon the charged particle beam and electrons given off from the sample can be suppressed.