Multi-Beam Electron Inspection Stage Segmentation
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Solution Overview
Problem
Existing pattern inspection apparatuses face challenges in reducing the time required for the 'step and repeat' operation, leading to inefficiencies due to the need for large attenuation mechanisms in limited spaces, which increases settling time and reduces actual inspection time.
Innovation Solution
A pattern inspection apparatus is designed with a multi-beam electron beam system, featuring a primary stage that moves over the entire inspection region and a secondary micromotion stage that moves within a shorter stroke, allowing for simultaneous scanning and reducing the need for extensive attenuation mechanisms, thereby minimizing settling time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a heavy stage is used to move the substrate through a long stroke for complete surface inspection, then the entire substrate can be inspected, but the settling time increases and inspection efficiency decreases
Solution Approach 1:
The stage system is divided into two independent stages: a first stage for long-stroke movement to cover the entire substrate surface, and a second (micromotion) stage for short-stroke high-precision positioning. This segmentation allows each stage to be optimized for its specific function, with the lighter second stage requiring less settling time.
Solution Approach 2:
The second stage (micromotion stage) is placed on top of the first stage, creating a nested configuration. The first stage handles coarse positioning over the long stroke, while the second stage performs fine positioning over a shorter stroke, combining the advantages of both long travel and fast settling.
2Loss of time
If a large attenuation mechanism is installed to attenuate the heavy stage, then the stage can be stopped quickly, but the mechanism occupies excessive space in the limited apparatus
Solution Approach 1:
The attenuation mechanism is applied only to the second (micromotion) stage, not the entire heavy first stage. This segmented approach allows for a compact attenuation mechanism that fits within the limited space while still providing sufficient settling speed for the critical micromotion stage.
Solution Approach 2:
Instead of uniformly attenuating the entire heavy stage system, the attenuation mechanism is locally applied to the lighter second stage where it is most effective and space-efficient. This localized approach optimizes the balance between settling time and space consumption.
3Measurement precision
If the stage moves through a long stroke to inspect the entire substrate surface, then complete coverage is achieved, but the attenuation mechanism becomes excessively large
Solution Approach 1:
The movement function is segmented between two stages: the first stage provides the long stroke for complete substrate coverage, while the second stage provides the shorter stroke for high-precision positioning. This segmentation allows the attenuation mechanism to be sized appropriately for the second stage only, reducing overall complexity.
Solution Approach 2:
The system transitions from a single-stage one-dimensional long-stroke movement to a two-stage system combining long-stroke coarse movement with short-stroke fine movement. This dimensional change in the control architecture allows for more efficient attenuation mechanism design.
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 configuration enables faster scanning and reduces the time spent on settling, enhancing the efficiency of the inspection process by allowing continuous movement of the primary stage while the secondary stage performs precise positioning, thus shortening overall inspection time.
Implementation Method 1
a detector configured to detect secondary electrons emitted from the substrate because the substrate is irradiated with the multi-beams
Data Source
AI summary
A pattern inspection apparatus includes a column to scan a substrate on which a pattern is formed, using multi-beams composed of a plurality of electron beams, a first stage to be able to move up to a first stroke by which an entire surface of an inspection region of the substrate can be irradiated with the multi-beams, a second stage, arranged on the first stage, to be able to move up to a second stroke sufficiently shorter than the first stroke and to place the substrate thereon, and a detector to detect secondary electrons emitted from the substrate because the substrate is irradiated with the multi-beams.