Metal Grating Structure Manufacturing via Thermal Oxidation and Electroforming
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Solution Overview
Problem
Existing methods for manufacturing X-ray diffraction gratings with high aspect ratios are cumbersome and prone to voids due to insufficient insulating films, which hinder the precise filling of metal parts in the grating structure.
Innovation Solution
A method involving thermal oxidation to form a silicon oxide insulating layer on the inner surface of a silicon substrate's concave portions, followed by electroforming to fill the metal parts, ensuring electrical insulation and preventing metal growth on the sidewalls, thus achieving a high aspect ratio and reducing void formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electroforming is used to fill metal parts in high aspect ratio structures, then metal filling is attempted, but voids form and metal growth occurs on sidewalls due to insufficient insulating films
Solution Approach 1:
The patent applies preliminary action by forming the insulating film on the sidewalls of the concave portion before the electroforming process. This pre-formed insulating layer prevents metal from growing on the sidewalls during electroforming, and the subsequent selective removal of the insulating film from the bottom surface enables precise metal filling only where needed, eliminating void formation.
2Manufacturing precision
If high aspect ratio structures are manufactured, then diffraction grating performance is improved, but manufacturing complexity increases due to cumbersome processes
Solution Approach 1:
The patent segments the insulating film into two functional parts: a sidewall insulating film that remains to prevent metal growth, and a bottom insulating film that is removed to enable metal filling. This segmentation allows the electroforming process to be simplified while achieving high aspect ratio structures, as the segmented approach eliminates the need for complex repeated patterning and plating steps.
3Ease of manufacture
If insulating films are made thinner to reduce process steps, then manufacturing is simplified, but metal growth occurs on sidewalls during electroforming
Solution Approach 1:
The patent applies local quality by creating different insulating film configurations in different locations: a thicker insulating film is formed on the sidewalls to prevent metal growth, while the insulating film on the bottom surface is selectively removed. This local differentiation ensures that metal growth is prevented only where needed (on sidewalls) while allowing precise metal filling at the bottom, achieving both ease of manufacture and manufacturing precision.
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 allows for the precise formation of metal parts with high aspect ratios, effectively suppressing voids and enabling the manufacture of diffraction gratings suitable for X-ray Talbot interferometers and Talbot-Lau interferometers with improved precision and efficiency.
Implementation Method 1
an insulating layer forming step of forming an insulating layer on an inner surface of the concave portion by a thermal oxidation method
Implementation Method 2
an electroforming step of applying voltage to the silicon substrate to fill the concave portion with metal by an electroforming method
Data Source
Figure 1
Figure 2A~2C
Figure 3A~3C
AI summary
According to a method for manufacturing a metal grating structure of the present invention, in filling a concave portion formed in a silicon substrate (30), for instance, a slit groove (SD) with metal by an electroforming method, an insulating layer (34) is formed in advance on an inner surface of the slit groove (SD) as an example of the concave portion by a thermal oxidation method. Accordingly, the metal grating structure manufacturing method is advantageous in finely forming metal parts of the grating structure. A metal grating structure of the present invention is manufactured by the above manufacturing method, and an X-ray imaging device of the present invention is incorporated with the metal grating structure.