Etch-Stop Layer Groove Prevents Notching in Liquid Ejection Head Substrates
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Solution Overview
Problem
Existing methods for forming liquid supply ports in liquid ejection heads, such as dry etching, suffer from notching issues that can spread and affect the reliability and size of the chip, particularly due to variations in etching time and substrate thickness, leading to potential printing performance issues.
Innovation Solution
A process involving the formation of a groove around the piercing aperture region on the substrate's surface, with an etch-stop layer embedded within the groove, prevents notching spread by stopping etching at the etch-stop layer, maintaining the shape and reliability of the liquid supply port.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dry etching is performed from the back surface to the front surface to form a piercing aperture, then the liquid supply port can be formed with an almost perpendicular form and smaller chip size, but notching occurs when the etched surface reaches the etch-stop layer, causing the opening portion to spread and potentially reach heat-generating elements or wiring, thereby lowering reliability
Solution Approach 1:
A groove is formed around the piercing aperture region before the dry etching process. This preliminary groove structure serves as a physical barrier that prevents notching from spreading laterally when the etched surface reaches the etch-stop layer, thus maintaining the perpendicular form of the piercing aperture while preventing the opening portion from spreading to heat-generating elements or wiring.
Solution Approach 2:
The etch-stop layer is segmented by forming a groove around the piercing aperture region. This segmentation creates an isolated etch-stop layer structure that prevents lateral propagation of notching while still allowing the dry etching to form the piercing aperture with the required perpendicularity.
2Area of stationary object
If the opening portion of the liquid supply port is spread by notching, then the chip size can be reduced, but the reliability is lowered due to potential contact with heat-generating elements or wiring
Solution Approach 1:
The groove is formed in advance around the piercing aperture region to establish a protective barrier before etching. This preliminary structure allows the opening portion to be minimized for small chip size while the groove prevents any lateral spread from reaching heat-generating elements or wiring, thus maintaining reliability.
3Ease of manufacture
If etching is performed without a groove structure, then the process is simpler, but notching spread occurs due to variations in etching time and substrate thickness, affecting printing performance
Solution Approach 1:
The groove structure is formed as a preliminary step before dry etching. While this adds one process step, it provides a robust physical barrier that compensates for variations in etching time and substrate thickness, ensuring consistent liquid supply port shape and preventing notching spread, thus improving manufacturing precision.
Solution Approach 2:
The groove acts as a cushioning barrier that absorbs and contains the notching effect before it can spread laterally. This beforehand cushioning structure protects against the harmful effects of etching variations, maintaining liquid supply port shape consistency despite variations in etching time and substrate thickness.
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 inhibits the spread of notching, maintaining the shape and reliability of the liquid supply port, reducing chip size variations and improving productivity by preventing excessive etching, thus enhancing the overall performance of liquid ejection heads.
Implementation Method 1
Dry etching is then performed from a back surface of the element substrate to the etch-stop layer to form a piercing aperture
Implementation Method 2
when an etched surface reaches the etch-stop layer, a phenomenon called notching in which the etching proceeds to a direction perpendicularly to a supply port forming direction (hereinafter also referred to as a lateral direction or plane direction) by influence of charging occurs
Data Source
AI summary
The invention provides a process for producing a substrate with a piercing aperture, the piercing aperture being formed by conducting dry etching from the side of a second surface opposite to a first surface of a substrate to the first surface, the process comprising, in the following order, the steps of (a) forming a groove around a region where the piercing aperture is formed in the first surface of the substrate, (b) forming an etch-stop layer in the region where the piercing aperture is formed in the first surface of the substrate and in the interior of the groove, and (c) forming the piercing aperture by conducting the dry etching from the side of the second surface.