Single Crystal Silicon Substrate With Vertical Side Walls
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional silicon substrates used in liquid discharge heads, such as ink-jet heads, face challenges in achieving a compact design with high resolution due to the formation of inclined through-holes, which increase the size of the device and reduce nozzle pitch, leading to lower resolution.
Innovation Solution
A single crystal silicon substrate is developed with a combination of crystal anisotropic etching for inclined through-holes and metal-assisted chemical etching for vertical through-holes, allowing for a more compact and high-resolution liquid discharge head design by forming a substrate with inclined and vertical side walls, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If through-holes are formed by crystal anisotropic etching to create inclined side walls, then the substrate can be etched with simple equipment, but the device size increases and resolution decreases
Solution Approach 1:
The patent segments the through-hole formation process into two distinct parts: the upper portion is formed by crystal anisotropic etching to create the inclined side wall, while the lower portion is formed by metal-assisted chemical etching to create the vertical side wall. This segmentation allows each etching method to perform its optimal function, resolving the contradiction between manufacturing simplicity and precision.
Solution Approach 2:
The patent applies different etching methods to different regions of the through-hole formation. The upper region uses crystal anisotropic etching for ease of manufacture, while the lower region uses metal-assisted chemical etching for precision. This local differentiation of etching quality allows the device to achieve both manufacturing simplicity and high resolution.
2Ease of manufacture
If through-holes are formed by crystal anisotropic etching, then the process is simple, but the device becomes large and productivity decreases
Solution Approach 1:
The through-hole formation is segmented into upper and lower portions with different etching characteristics. The lower portion uses metal-assisted chemical etching which creates vertical walls, allowing for compact device design and improved productivity, while the upper portion maintains the simplicity of crystal anisotropic etching.
Solution Approach 2:
The patent changes the etching parameters by introducing a metal catalyst layer that enables metal-assisted chemical etching. This parameter change transforms the etching process from one that creates inclined walls to one that creates vertical walls, reducing device size and improving productivity while maintaining process simplicity.
3Ease of manufacture
If all through-holes use inclined side walls, then etching is straightforward, but the substrate surface must be widely configured increasing device size
Solution Approach 1:
The patent applies local quality by making the side wall inclination angle position-dependent. The upper portion has an inclined side wall for easy etching, while the lower portion has a vertical side wall that minimizes the required substrate surface area, thereby reducing the overall device size.
Solution Approach 2:
The patent introduces a vertical dimension to the side wall configuration by creating a two-stage structure. The transition from inclined to vertical side walls in the lower portion allows the flow path to be more compact in the planar direction, reducing the substrate surface area required.
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 manufacture of a small, high-resolution liquid discharge head with improved productivity and reduced greenhouse gas usage, as the vertical side walls formed by metal-assisted chemical etching enhance the substrate's structure and reduce the device's size without the need for dry etching.
Implementation Method 1
the first through-hole is formed by crystal anisotropic etching
Implementation Method 2
the second through-hole is formed by metal-assisted chemical etching
Data Source
AI summary
A single crystal silicon substrate at least a part of which constitutes a flow path for liquid includes a first through-hole including an inclined side wall inclined with respect to a substrate surface of the single crystal silicon substrate, and a second through-hole constituting the flow path and including a side wall constituted by a vertical side wall more nearly vertical to the substrate surface than the inclined side wall is. The first through-hole is formed by crystal anisotropic etching. The second through-hole is formed by metal-assisted chemical etching.