Encapsulating Material for DRIE Fluid Ejection Heads
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Solution Overview
Problem
The existing fluid jet ejection head designs rely on a silicon shelf to protect metal layers from corrosion, which is time-consuming and costly to maintain, limiting the design of wider fluid supply slots and reducing the yield of usable ejection head chips due to alignment and etching issues.
Innovation Solution
The design incorporates an encapsulating material to isolate the metal layer from the fluid supply via, reducing the reliance on a silicon shelf and allowing for wider fluid supply vias without increasing the chip size, using a combination of silicon nitride, diamond-like-carbon, and silicon oxide layers to protect the metal layer during the DRIE process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silicon shelf is used to protect metal layers from corrosion, then the metal layer is protected from fluid exposure, but the manufacturing process becomes time-consuming and costly due to precise alignment and etching requirements
Solution Approach 1:
The patent removes the silicon shelf structure entirely and replaces it with an encapsulating material deposited directly on the metal layer. This extraction of the problematic silicon shelf eliminates the need for precise alignment and etching while maintaining corrosion protection through the encapsulating material that forms a continuous protective barrier.
Solution Approach 2:
The patent changes the protective mechanism from a geometric silicon shelf structure to a material-based encapsulating layer. By depositing encapsulating material (such as silicon oxide, silicon nitride, or diamond-like carbon) directly on the metal layer, the protection method transitions from structural to material-based, eliminating alignment constraints and improving manufacturing efficiency.
2Reliability
If a silicon shelf is used to protect metal layers, then corrosion protection is achieved, but the design of wider fluid supply slots is limited and chip yield is reduced due to alignment and etching issues
Solution Approach 1:
By removing the silicon shelf and its associated alignment and etching requirements, the patent enables greater design flexibility for fluid supply slot widths and improves manufacturing yield. The encapsulating material approach eliminates the critical dimensional constraints that previously limited design options.
Solution Approach 2:
The patent segments the protection function from the structural support function. The encapsulating material provides corrosion protection independently of any shelf structure, allowing the fluid supply slots to be designed optimally without being constrained by shelf width requirements.
3Productivity
If the fluid supply via is etched wider to increase fluid flow, then fluid refill rate increases, but the metal layer becomes exposed to corrosion without sufficient silicon shelf width
Solution Approach 1:
The patent applies the encapsulating material to the metal layer before etching the fluid supply via. This preliminary protective action ensures that the metal layer is already protected when the via is etched to any width, allowing maximum fluid flow without risk of corrosion exposure.
Solution Approach 2:
The encapsulating material serves as a pre-applied protective barrier that cushions the metal layer against potential corrosion from fluid exposure. This beforehand protection allows the fluid supply via to be etched as wide as needed for optimal refill rate without compromising metal layer integrity.
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 simplifies wafer inspection, reduces edge roughness, and increases fluid refill rates by eliminating the need for a silicon shelf, thereby enhancing production efficiency and reducing production costs while maintaining chip strength.
Implementation Method 1
The design incorporates an encapsulating material to isolate the metal layer from the fluid supply via, reducing the reliance on a silicon shelf and allowing for wider fluid supply vias without increasing the chip size, using a combination of silicon nitride, diamond-like-carbon, and silicon oxide layers to protect the metal layer during the DRIE process
Implementation Method 2
using a deep reactive ion etch (DRIE) process
Data Source
AI summary
An ejection head chip and method for a fluid ejection device and a method for reducing a silicon shelf width between a fluid supply via and a fluid ejector stack. The ejection head chip includes a silicon substrate and a fluid ejector stack deposited on the silicon substrate, wherein at least one metal layer of the fluid ejector stack is isolated from a fluid supply via etched in the ejection head chip by an encapsulating material.