Printhead Die Termination Rings for Kerf Chip Control
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Solution Overview
Problem
Kerf chipping during the sawing process can lead to defective inkjet printhead dies due to chipping and cracking, which are exacerbated by the corrosive ink environment, resulting in reduced fabrication yields and electrical failures.
Innovation Solution
The implementation of multiple concentric termination rings made of silicon dioxide (SiO2) grown into the silicon substrate, with a berm of TEOS and BPSG separating these rings, acts as kerf chip barriers to dissipate energy and prevent propagation into the functional area of the printhead die.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a saw blade is used to cut the wafer along the spacing between dies, then the printhead dies can be separated from the wafer, but kerf chipping occurs along the cut which leads to defective dies and reduced yield
Solution Approach 1:
The patent applies preliminary action by pre-forming a termination ring structure at the periphery of the printhead die before the sawing process. This termination ring acts as a pre-established barrier that prevents kerf chips from propagating into the functional area during the subsequent saw cut, thereby protecting die integrity while maintaining efficient separation.
Solution Approach 2:
The termination ring serves as an intermediary protective structure between the saw blade and the functional die area. It intercepts and contains kerf chips within the termination ring itself, preventing them from reaching and damaging the underlying functional components, thus mediating the harmful effect of the saw cut.
2Ease of manufacture
If the termination ring is made of deposited dielectric material, then it can be formed using standard fabrication processes, but the deposited material does not provide sufficient mechanical strength to prevent kerf chip propagation
Solution Approach 1:
The patent employs composite materials by combining a deposited dielectric material layer with a grown silicon dioxide layer to form the termination ring. The deposited dielectric layer provides ease of manufacture through standard fabrication processes, while the grown silicon dioxide layer provides the necessary mechanical strength and chemical stability to effectively prevent kerf chip propagation.
Solution Approach 2:
The patent applies parameter changes by transitioning from using only deposited dielectric material to using a combination of deposited and grown materials. This changes the material formation parameters to include thermal oxidation/growth processes, thereby enhancing the mechanical strength and chemical resistance of the termination ring while maintaining fabrication compatibility.
3Device complexity
If a single termination ring is used, then the structure is simple and easy to fabricate, but it provides insufficient protection against kerf chip propagation into the functional area
Solution Approach 1:
The patent applies segmentation by dividing the termination ring into multiple concentric rings instead of using a single continuous ring. These multiple termination rings are spaced apart, creating segmented protective zones that collectively provide enhanced protection against kerf chip propagation while maintaining a relatively simple fabrication process.
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 solution effectively reduces the occurrence of kerf chip-induced failures by providing multiple break points, enhancing the robustness of printhead dies against saw kerf chipping and cracking, thereby improving fabrication yields and preventing electrical failures in the corrosive ink environment.
Implementation Method 1
A termination ring is formed in a frame area of the printhead die. The termination ring includes a silicon dioxide (SiO2) layer grown into a surface of the silicon substrate.
Data Source
AI summary
A printhead die includes a SiO2 layer grown into a surface of a silicon substrate, and a dielectric layer deposited onto an interior surface area of a substrate. Multiple termination rings are formed around the interior surface area. Each ring is defined by an absence of the dielectric layer. A berm is located in between each termination ring. Each berm is defined by the presence of the dielectric layer.