Multi-Electron Beam Wafer Inspection Without Scan Deflectors
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Solution Overview
Problem
Existing charged particle beam inspection systems, such as scanning electron microscopes, are complex, expensive, and limited in throughput due to the use of scan deflectors, which hinder high-resolution and fast inspection of large-area samples like semiconductor wafers.
Innovation Solution
A multi-electron beam inspection system with a movable stage and multiple static inspection columns generating parallel electron beams, focusing them on a two-dimensional array, and scanning the sample with a stationary pattern to enhance throughput and resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a scanning electron microscope with scan deflectors is used to inspect samples with high resolution, then measurement precision is improved, but device complexity increases and productivity decreases
Solution Approach 1:
The inspection system is divided into multiple independent inspection columns (e.g., 6 columns), each capable of generating and focusing its own electron beam. This segmentation allows parallel inspection of different areas of the sample simultaneously, increasing productivity while maintaining high resolution in each column without requiring complex scan deflectors across the entire system.
Solution Approach 2:
The system transitions from a single-beam sequential inspection approach to a multi-beam parallel inspection approach by adding the dimension of multiple inspection columns. Each column operates independently with its own beam path, enabling simultaneous inspection of multiple sample regions and effectively adding parallelism to the inspection process.
2Productivity
If multiple electron beams are used to inspect a sample in parallel to increase throughput, then productivity is improved, but measurement precision deteriorates
Solution Approach 1:
Each inspection column is designed as an independent unit with its own electron beam generation and focusing system. This ensures that each beam maintains high resolution capabilities independently, and the parallel operation of multiple columns does not compromise the precision of individual measurements while collectively increasing throughput.
Solution Approach 2:
Each inspection column provides localized high-resolution inspection of its specific sample region. The system ensures that each beam maintains optimal focus and resolution for its designated area, allowing parallel inspection without sacrificing local measurement precision.
3Area of stationary object
If scan deflectors are used to scan electron beams over the sample surface, then inspection coverage is improved, but device complexity and cost increase
Solution Approach 1:
The sample coverage is achieved through segmentation into multiple independent inspection columns, each covering a specific region. This eliminates the need for complex scan deflectors by distributing the coverage function across multiple simpler, parallel beam paths.
Solution Approach 2:
Multiple inspection columns are merged into a single integrated system that covers the entire sample area simultaneously. The combined output of all columns provides comprehensive coverage without requiring complex scanning mechanisms, as each column statically inspects its assigned 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 system achieves high-resolution inspection of large-area samples with increased speed by using many small, inexpensive inspection columns, allowing for rapid inspection of entire wafer surfaces with resolutions down to 10 nm or less.
Implementation Method 1
focusing the plurality of electron beams on the sample at a plurality of probe positions arranged in a two-dimensional array
Implementation Method 2
scanning the sample by moving the movable stage in a predetermined scanning pattern while maintaining the plurality of electron beams stationary
Implementation Method 3
detecting signal electrons emitted from the sample during the scanning for inspecting the sample
Data Source
AI summary
A method for inspecting a sample with a multi-electron beam inspection system (100) is described. The method includes: placing the sample on a movable stage (110) extending in an X-Y-plane; generating a plurality of electron beams (105) propagating toward the sample; focusing the plurality of electron beams on the sample at a plurality of probe positions (106) in a two-dimensional array; scanning the sample surface by moving the movable stage in a predetermined scanning pattern while maintaining the plurality of electron beams stationary; and detecting signal electrons emitted from the sample during the movement of the movable stage for inspecting the sample. Further, a multi-electron beam inspection system (100) for inspecting a sample according to the above method is described.