Dual-Mode Electron Optical Inspection Apparatus for Wafer Defect Analysis
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Solution Overview
Problem
Existing electron optical inspection tools face challenges in efficiently detecting defects on semiconductor wafers, particularly due to limitations in resolution and throughput between inspection and review modes, leading to functional compatibility issues and increased costs and time consumption.
Innovation Solution
An electron optical inspection apparatus with dual modes of operation, utilizing an immersion condenser lens for inspection and a non-immersion condenser lens for review, along with a compound objective lens and deflection systems to maintain high resolution and throughput, and Wien filters for aberration compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If e-beam inspection tool with large field and large beam is used for inspection, then throughput is improved, but resolution deteriorates
Solution Approach 1:
The patent divides the inspection system into two distinct operational modes: inspection mode with large field and large beam for high throughput, and review mode with small field and small beam for high resolution. This segmentation allows each mode to be optimized independently without compromising the other.
Solution Approach 2:
The system dynamically switches between inspection mode and review mode based on operational requirements. The electron beam parameters (field size, beam size) are dynamically adjusted between the two modes to achieve optimal performance for each specific task.
2Measurement precision
If separate EB inspection and EB review tools are employed, then both throughput and resolution requirements are met, but device complexity and cost increase
Solution Approach 1:
The patent creates a universal inspection tool that can perform both inspection and review functions by switching between two operational modes. The same hardware platform supports both high-throughput inspection and high-resolution review, eliminating the need for separate dedicated tools.
Solution Approach 2:
The patent merges the previously separate EB inspection tool and EB review tool into a single integrated system. By combining both functionalities in one tool with mode switching capability, it reduces device complexity and eliminates the need for multiple separate instruments.
3Productivity
If single deflector system for large scanning field is used in review mode, then throughput is maintained, but spot size increases and resolution deteriorates
Solution Approach 1:
The patent employs dynamic switching of deflector systems based on operational mode. In review mode, the system switches to a second deflector system optimized for small scanning fields, while in inspection mode, the first deflector system for large scanning fields is used. This dynamic adaptation resolves the contradiction between throughput and resolution.
Solution Approach 2:
The patent applies different deflector system configurations optimized for specific operational requirements. The first deflector system is optimized for large scanning fields in inspection mode, while the second deflector system is optimized for small scanning fields in review mode, ensuring local optimization for each function.
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 apparatus enables reliable and accurate detection of defects with improved resolution and throughput, reducing the need for separate tools and minimizing noise interference, thus enhancing the efficiency of defect analysis in semiconductor manufacturing.
Implementation Method 1
the e-beam inspection applies the beam current to probe the select part of wafer and detects signal electrons
Implementation Method 2
an immersion condenser lens for an inspection mode of operation, an objective lens for focusing the beam current onto a specimen
Implementation Method 3
a first electron optical element in the objective lens to deflect signal charged particles emanated from the specimen and a second electron optical element to compensate aberrations
Data Source
AI summary
The present invention provides an improved electron-optical apparatus for the inspection and review of the specimen, and for the defect inspection, an inspection mode of operation is performed to generate inspection data, wherein the large beam current is formed by a magnetic immersion lens to scan the specimen, and preferably the objective lens system, a swing objective retarding immersion lens, focuses the beam current and generates the large scanning field, and for the defect review, the review mode of operation is performed to analyze the defects, wherein the large beam current is abandoned and the small beam current is adopted to examine the specimen without a large scanning field, and in order to properly select and detect signal charged particles excited from the specimen, a first Wien filter is utilized to select the acquired signal particles and a second Wien filter is used to compensate the aberrations induced when the signal particles pass through the first Wien filter.