Charged Particle Beam Imaging Chamber Deformation Correction
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Solution Overview
Problem
The precision of charged particle beam image acquisition apparatuses is compromised due to chamber deformation caused by differential pressure between the internal vacuum and atmospheric pressure, leading to errors in the positional relationship between the target object and the electron beam optics, which affects the accuracy of pattern inspection in semiconductor wafer manufacturing.
Innovation Solution
The apparatus features a primary electron optical column positioned on the upper surface of a rectangular parallelepiped chamber with its intersection at the center, and a secondary electron optical column connected to the lower portion, supported by a stay to minimize deviations in the x and y directions, allowing for correction of height-direction errors through the movement of the stage and deflection of secondary electron beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the chamber is maintained in a vacuum state for electron beam irradiation and detection, then the electron beam can be properly irradiated and detected, but the differential pressure causes chamber deformation which results in errors in the relative positional relationship between the target object and the optics
Solution Approach 1:
The patent places the primary electron optical column on the upper surface of the chamber and the secondary electron optical column on the lower portion, utilizing the vertical dimension to separate the two optical systems. This spatial arrangement in different dimensions allows both columns to be positioned at locations experiencing minimal deformation, thereby maintaining positional accuracy despite chamber deformation caused by differential pressure.
Solution Approach 2:
The patent identifies and utilizes specific locations on the chamber where deformation is minimal - the center of the upper surface for the primary electron optical column and the lower portion for the secondary electron optical column. By placing the optics at these specific local positions with favorable deformation characteristics, the system maintains high positional accuracy while operating under vacuum conditions.
2Manufacturing precision
If the chamber deformation is minimized by supporting optics at specific locations, then positional accuracy is maintained, but the chamber still experiences deformation that affects the height direction
Solution Approach 1:
The patent incorporates a stage that can move in the height direction and deflectors that can adjust the trajectory of secondary electron beams. These dynamic components allow the system to compensate for height-direction deformation by actively adjusting the positional relationship between the target object and the optical columns, thereby maintaining imaging precision despite chamber shape changes.
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 precise image acquisition by correcting positional errors and maintaining high-precision imaging despite chamber deformation, ensuring accurate detection of pattern defects on semiconductor wafers.
Implementation Method 1
a primary charged particle beam optics irradiating the target object with a primary charged particle beam
Implementation Method 2
a secondary charged particle beam emitted as a result of an irradiation of the target object with the primary charged particle beam passing through the secondary charged particle beam optics
Data Source
AI summary
According to one aspect of the present invention, a charged particle beam image acquisition apparatus includes a rectangular parallelepiped chamber where a target object is disposed; a primary electron optical column placed on an upper surface of the chamber so that a point of intersection between two diagonal lines on the upper surface of the chamber is located at a center of a horizontal section of the primary electron optical column, a primary charged particle beam optics irradiating the target object with a primary charged particle beam being disposed in the primary electron optical column; and a secondary electron optical column connected to a lower portion of the primary electron optical column, a secondary charged particle beam optics being disposed in the secondary electron optical column and a secondary charged particle beam passing through the secondary charged particle beam optics.