Vacuum Wafer Stage Alignment Using Outer Edge Detection
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Solution Overview
Problem
Existing vacuum processing apparatuses face challenges in maintaining conveyance accuracy due to sliding, thermal deformation, and changes in relative positions between chambers, leading to reduced throughput and measurement accuracy, particularly in charged particle beam inspection apparatuses.
Innovation Solution
The apparatus measures the outer edge position of a sample wafer using detectors and adjusts the sample stage to match center coordinates, minimizing conveyance errors and ensuring accurate placement on the sample placement surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conveyance robot operates in a vacuum environment, then the sample can be conveyed without contamination, but sliding occurs at the contact portion between the sample and the hand due to lack of friction control
Solution Approach 1:
The patent replaces mechanical friction-based holding with magnetic field-based holding. The hand includes a magnet that magnetically attracts the ferromagnetic sample, providing reliable holding without sliding in the vacuum environment where conventional friction control is difficult.
Solution Approach 2:
The patent changes the physical property of the sample by making it ferromagnetic (or adding ferromagnetic elements), which enables magnetic interaction with the hand's magnet. This parameter change allows for effective holding and conveyance in vacuum without sliding.
2Productivity
If the robot operates repeatedly in a vacuum environment, then productivity increases, but thermal deformation of robot components occurs due to heat accumulation
Solution Approach 1:
The patent introduces a magnetic field as an intermediary between the hand and the sample. This magnetic field-based interaction is less sensitive to thermal deformation of mechanical components, allowing the system to maintain conveyance accuracy even when robot components undergo thermal expansion from repeated operations.
3Stability of the object's composition
If the preliminary exhaust chamber and vacuum sample chamber are firmly connected, then structural stability is improved, but impact during valve operations causes vibration that reduces measurement accuracy
Solution Approach 1:
The patent employs vibration isolation measures as beforehand cushioning against the impact from valve operations. By pre-positioning vibration damping elements or isolation mechanisms, the system protects the sample and measurement apparatus from harmful vibrations when the gate valve operates, maintaining measurement accuracy.
4Productivity
If the gate valve is operated during measurement, then throughput is improved, but vibration transmitted to the vacuum sample chamber reduces measurement accuracy
Solution Approach 1:
The patent uses vibration isolation and damping mechanisms as beforehand cushioning to protect ongoing measurements from valve operation vibrations. This allows the gate valve to be operated without significantly impacting measurement accuracy, enabling higher throughput.
5Manufacturing precision
If alignment marks are used on samples, then conveyance accuracy is improved, but samples without alignment marks cannot be accurately positioned
Solution Approach 1:
The patent replaces mechanical alignment mark-based positioning with magnetic field-based positioning. The hand's magnet and the sample's ferromagnetic properties create a consistent magnetic interaction that enables accurate conveyance and positioning without requiring alignment marks, thus improving versatility.
Solution Approach 2:
The patent enables samples to self-align through magnetic attraction between the hand's magnet and the sample's ferromagnetic elements. This self-aligning mechanism works regardless of whether alignment marks are present on the sample, improving compatibility with various sample types.
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 enhances conveyance accuracy, reduces edge exclusion, and improves yield and throughput by maintaining equal surface voltages across the sample, allowing for precise measurement and handling of various samples without alignment marks.
Implementation Method 1
a magnet is disposed in the hand, and a ferromagnetic substance is disposed in the sample
Data Source
AI summary
There is provided a vacuum processing apparatus capable of accurately matching reference coordinates of a sample placement surface of a stage and center coordinates of a sample when a conveyance robot conveys the sample to a sample stage. The vacuum processing apparatus according to the present disclosure measures a position of an outer edge of the sample conveyed into a vacuum sample chamber, and moves a sample stage below the sample conveyed into the vacuum sample chamber based on the measured position of the outer edge.