EUV Camera Positioning for Mask Inspection Beam Path Alignment
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Solution Overview
Problem
Adjusting the imaging beam path between a photomask and an EUV camera in a mask inspection device is challenging due to limited space in the vacuum housing, necessitating large adjustments that are often not feasible.
Innovation Solution
The EUV camera is mounted on the vacuum housing and its position is adjustable between discrete or continuous positions using an adjusting mechanism, allowing displacements and tilts to align the beam path accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the EUV camera is mounted on the vacuum housing, then the imaging beam path can be defined, but the adjusting travel required for optical alignment is too large to be feasible within the vacuum housing
Solution Approach 1:
Instead of moving optical elements within the vacuum housing to adjust the beam path, the invention inverts the approach by moving the EUV camera itself relative to the vacuum housing. This allows the camera to be positioned at different locations along the optical axis, achieving the required alignment adjustment without needing large adjusting travels for optical components within the limited vacuum housing space.
Solution Approach 2:
The invention introduces an additional degree of freedom by allowing the EUV camera to be positioned at multiple locations along the optical axis (Z-direction), rather than only adjusting optical elements within a fixed plane. This dimensional change enables the camera to be moved along the beam path to achieve proper focus and alignment, effectively solving the space limitation problem.
2Measurement precision
If optical elements are adjusted within the vacuum housing to align the beam path, then imaging quality can be improved, but the limited space in the vacuum housing prevents sufficient adjusting travel
Solution Approach 1:
Rather than adjusting optical elements within the constrained vacuum housing, the invention inverts the problem by making the EUV camera movable relative to the housing. This allows the camera to be repositioned along the optical axis to achieve proper imaging alignment, eliminating the need for large adjusting travels of optical components within the limited housing space.
Solution Approach 2:
The invention introduces dynamic adjustability by enabling the EUV camera to be moved between different positions relative to the vacuum housing. This dynamic positioning capability allows the system to adapt to different alignment requirements without being constrained by the fixed, limited space within the vacuum housing, thereby improving imaging quality while respecting the space constraint.
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 enables precise alignment of the EUV camera relative to the vacuum housing, compensating for offsets and aberrations, thereby improving imaging quality and reducing mechanical stress on the device.
Implementation Method 1
a projection lens for imaging a portion of an EUV photomask onto an image sensor of the EUV camera
Data Source
AI summary
A mask inspection device, comprising a vacuum housing, an EUV camera and, arranged in the interior of the vacuum housing, a projection lens for imaging at least one portion of an EUV photomask onto an image sensor of the EUV camera. The EUV camera is mounted on the vacuum housing. The position of the EUV camera is adjustable between a first position and a second position relative to the vacuum housing by use of an adjusting mechanism. The invention also relates to a method for adjusting a mask inspection device.