Masked Dry Etching of Microstructured Substrates Around Recesses
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Solution Overview
Problem
Existing methods fail to manufacture a fine recessed and projected structure on a substrate surface around recessed portions without forming it on the recessed portions themselves, and existing methods result in the structure being formed on the bottom surfaces of recessed portions when they have a bottom.
Innovation Solution
A manufacturing method involving a mask formation step, dry etching, and mask removal step to create a fine recessed and projected structure with an average period of 1 μm or less on the substrate surface around recessed portions, using etching gases like fluorine-based or chlorine-based gases, and alternating etching and protective gases to form streaky grooves and through-holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing methods (JP5797133B, JP2019-40039A, JP2019-153704A) are used to form fine recessed and projected structures, then fine structures smaller than micrometer size can be formed on the substrate surface, but the structures are formed on the recessed portions themselves rather than only on the surrounding surface
Solution Approach 1:
The patent applies preliminary action by forming a protective film on the recessed portions before the etching process. This protective film is applied in advance to prevent the fine recessed and projected structure from forming on the recessed portions during subsequent etching, while allowing it to form on the surrounding surface areas.
Solution Approach 2:
The patent applies local quality by creating different surface conditions in different areas: the recessed portions are covered with a protective film that prevents structure formation, while the surrounding surfaces remain exposed to allow fine recessed and projected structure formation. This creates spatially differentiated properties on the substrate surface.
2Manufacturing precision
If existing methods are used to form fine recessed and projected structures, then the structures can be formed with small periods, but they are also formed on the bottom surfaces of recessed portions when the recessed portions have a bottom
Solution Approach 1:
The protective film is applied preliminarily to the recessed portions before the etching process that forms the fine recessed and projected structure. This preliminary protection ensures that the bottom surfaces of recessed portions remain free of the fine structure while the surrounding areas develop the desired structure.
Solution Approach 2:
The protective film acts as an intermediary layer between the etching process and the recessed portion surfaces. It mediates the interaction by selectively blocking the formation of fine recessed and projected structure on recessed portions while allowing it on surrounding areas, thus controlling the spatial distribution of the structure.
3Manufacturing precision
If a mask is formed on the fine recessed and projected structure and dry etching is performed to form recessed portions with depth equal to or greater than double the difference in height, then the fine structure can be prevented from forming on recessed portion bottoms, but the process complexity increases
Solution Approach 1:
The mask is formed preliminarily on the fine recessed and projected structure before the dry etching process. This preliminary masking allows the etching to proceed with controlled depth, ensuring that the fine structure does not form on recessed portion bottoms while maintaining precision in the surrounding areas.
Solution Approach 2:
The process employs periodic action through alternating etching and protective gas supply during dry etching. This periodic cycle allows controlled etching depth and prevents excessive etching that would expose recessed portion bottoms, thereby controlling where the fine structure forms.
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
The method enables the formation of a fine recessed and projected structure only on the surface around recessed portions, providing enhanced control over the structure's placement and preventing its formation on the recessed portion bottoms, with applications in microwell plates and mold manufacturing.
Implementation Method 1
a dry etching step of etching the surface of the substrate from a side of the mask to form a recessed portion... in the dry etching step, streaky grooves along a depth direction of the recessed portions may be formed... An etching gas used in the dry etching step may include a fluorine-based gas or a chlorine-based gas
Data Source
AI summary
A structure is manufactured by forming a mask that has an opening pattern on a fine recessed and projected structure of a substrate having the fine recessed and projected structure with an average period of 1 μm or less on a surface thereof, etching the surface of the substrate from a side of the mask to form a recessed portion which has an opening greater than the average period of the fine recessed and projected structure according to the opening pattern of the mask, the recessed portion having a depth equal to or greater than double a difference in height between recesses and projections of the fine recessed and projected structure, and then removing the mask.