High Aspect Ratio Structure Manufacturing via Wet Etching
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Solution Overview
Problem
The existing methods for manufacturing high aspect ratio structures, such as X-ray metal grids, using dry etching are costly, and wet etching methods struggle to form concave portions with side surfaces perpendicular to the substrate due to isotropic etching, leading to increased manufacturing costs and inefficiencies.
Innovation Solution
A method involving a hole forming step, resist forming step, and concave portion forming step using wet etching, where holes are formed perpendicular to the substrate surface, allowing the etching solution to permeate and remove partition walls, resulting in concave portions with side surfaces perpendicular to the substrate, and an X-ray absorbing material is buried into these concave portions to create high aspect ratio structures like X-ray metal grids and ultrasonic probe manufacturing molds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dry etching is used to form concave portions, then manufacturing precision of high aspect ratio structures is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive dry etching equipment with a simple wet etching process using basic laboratory equipment (beaker, stirrer, temperature controller). The etching solution is consumed but can be refreshed, making the process economically viable for large substrates while achieving the required manufacturing precision through controlled isotropic etching.
Solution Approach 2:
The patent changes the etching parameters by controlling temperature (maintaining etching solution at 20-30°C), stirring speed (100-500 rpm), and etching time to achieve perpendicular side surfaces in concave portions. By optimizing these parameters, the wet etching process achieves precision comparable to dry etching without the high equipment cost.
2Ease of manufacture
If wet etching is used to form concave portions, then manufacturing cost decreases, but undercutting occurs due to isotropic etching
Solution Approach 1:
The patent applies a resist pattern on the substrate surface before etching, with the resist extending beyond the desired concave portion boundaries. This preliminary action compensates for the isotropic nature of wet etching by providing extra material that will be removed during etching, ensuring the final concave portion has perpendicular sides without undercutting.
Solution Approach 2:
The patent transitions from attempting to control etching in the horizontal dimension (trying to prevent lateral etching) to controlling the process in the vertical dimension (controlling etching depth and rate). By stirring the etching solution and controlling temperature, the patent achieves uniform vertical etching that produces perpendicular side surfaces despite the isotropic nature of the chemical reaction.
3Manufacturing precision
If large substrates (8 inch or more) are subjected to dry etching, then high aspect ratio structures are formed, but manufacturing cost further increases
Solution Approach 1:
The patent replaces expensive dry etching equipment with simple wet etching equipment that can handle large substrates. The etching solution is consumed during the process but can be refreshed, making the process economically viable for large substrates while achieving the required high aspect ratio structure formation through controlled isotropic etching with proper resist patterning.
Solution Approach 2:
The patent uses hydraulic principles by stirring the etching solution to ensure uniform distribution and removal of etching products. The stirring action (100-500 rpm) creates fluid flow that maintains consistent etching conditions across large substrates, enabling uniform high aspect ratio structure formation without the need for expensive dry etching equipment.
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 the cost-effective manufacturing of high aspect ratio structures with side surfaces perpendicular to the substrate, facilitating the production of X-ray diffraction grids and ultrasonic probe molds with improved X-ray permeability and absorption capabilities.
Implementation Method 1
a concave portion forming step of immersing the substrate into an etching solution to form a concave portion in the substrate corresponding to the second area
Implementation Method 2
a resist forming step of forming a first area with a resist layer and a second area without the resist layer on the principal surface provided with the plurality of holes
Data Source
AI summary
A method of manufacturing a high aspect ratio structure includes: a hole forming step of forming a plurality of holes in at least one principal surface of a substrate; a resist forming step of forming a first area with a resist layer and a second area without the resist layer on the principal surface provided with the plurality of holes after the hole forming step ends; and a concave portion forming step of immersing the substrate into an etching solution to form a concave portion in the substrate corresponding to the second area.