Sensor Element Protective Film Contact Without Oxide Etching
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Solution Overview
Problem
When the film thickness of a protective film covering a functional film is very small, it is difficult to etch the native oxide film without damaging the protective film, leading to increased resistance values between the lead layer and the protective film.
Innovation Solution
A sensor element with a conductive protective film where the connected area has a sufficient thickness to ensure reliable electrical connection between the lead layer and the protective film, while the non-connected area is covered with an insulating film to prevent oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the protective film thickness is reduced to minimize damage to the functional film, then the protective film becomes thinner and more vulnerable to etching, but this makes it difficult to etch the native oxide film without completely removing the protective film
Solution Approach 1:
The protective film is designed with different thicknesses in different regions: a first thickness in the first region (where electrical connection is needed) and a second thickness in the second region (where protection is prioritized). This local variation allows the oxide removal process to access the protective film surface in the first region while maintaining sufficient thickness in the second region to prevent damage to the functional film.
Solution Approach 2:
The protective film is segmented into multiple regions with different thickness characteristics. The first region has a greater thickness to allow oxide removal and electrical connection, while the second region maintains a smaller thickness for optimal protection. This segmentation resolves the contradiction by dividing the protective film into functional zones.
2Reliability
If the native oxide film is etched to reduce resistance between lead layer and protective film, then electrical connection improves, but excessive etching completely removes the protective film and subjects the functional film to etching
Solution Approach 1:
By creating a local quality difference in protective film thickness between the first and second regions, the invention enables selective oxide removal. The lead layer contacts the protective film at the thicker first region where oxide can be removed, while the thinner second region remains protected during the etching process.
Solution Approach 2:
The protective film thickness is preliminarily varied before the oxide removal process. This preliminary action of creating thickness variation allows the subsequent oxide etching to proceed safely without damaging the functional film, as the thickness distribution is already optimized to protect vulnerable areas.
3Reliability
If the protective film thickness is increased to ensure reliable electrical connection, then connection reliability improves, but the protective film becomes thicker and may damage the functional film during processing
Solution Approach 1:
The protective film is designed with local quality variation where thickness differs between regions. The first region has greater thickness for reliable electrical connection, while the second region has smaller thickness to protect the functional film during processing, resolving the contradiction between connection reliability and film protection.
Solution Approach 2:
The thickness parameter of the protective film is changed spatially across different regions. By varying this parameter from a first thickness in the connection region to a second thickness in the protection region, the invention simultaneously achieves reliable electrical connection and functional film protection.
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 configuration allows for reliable electrical connection between the lead layer and the protective film even when the protective film thickness is very small, reducing resistance values and preventing damage to the functional film.
Implementation Method 1
The surface of the non-connected area of the protective film is covered with an insulating film
Implementation Method 2
a lead layer applying a voltage to the functional film through the protective film
Data Source
AI summary
To reliably electrically connect the lead layer and protective film that covers a functional film even when the film thickness of the protective film is very small. After formation of a conductive protective film on the surface of a functional film, reverse sputtering is performed with a part of the surface of the protective film covered with a mask to physically reduce a native oxide film formed on a part of the surface of the protective film that is not covered with the mask. Thereafter, a lead layer is formed on a part of the surface of the protective film that is not covered with the mask. This can remove the native oxide film formed on the protective film without requiring etching. Thus, even when the film thickness of the protective film is very thin, it is possible to electrically connect the lead layer and protective film without damaging the functional film.