SAW Device SiO2 Insulation for Wiring Isolation
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Solution Overview
Problem
The manufacturing process of surface acoustic wave devices is complicated and costly due to the need for insulating layers made of photosensitive resin to prevent short circuits between wiring patterns, which also leads to substrate deterioration and corrosion of IDT electrodes, especially when using corrodable metals.
Innovation Solution
A method involving the formation of a SiO2 film to improve frequency temperature characteristics, where the SiO2 film covers IDT electrodes and wiring patterns, and a photosensitive resin layer is applied and patterned to create insulating layers between crossing wiring patterns, preventing short circuits and corrosion by isolating the electrodes from the developer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulating layers made of photosensitive resin are formed to prevent short circuits between wiring patterns, then electrical isolation between wiring patterns is improved, but the manufacturing process becomes complicated and costly
Solution Approach 1:
The patent combines the insulating layer function with the SiO2 film that is already present for frequency temperature characteristic improvement. The SiO2 film serves dual purposes: as the base insulating layer and as the frequency temperature compensation layer, eliminating the need for separate photosensitive resin insulating layers and simplifying the manufacturing process.
Solution Approach 2:
The SiO2 film is given multiple functions: it acts as both the insulating layer for electrical isolation and as the frequency temperature characteristic improvement layer. This multi-functionality reduces the number of separate layers and manufacturing steps required.
2Reliability
If insulating layers made of photosensitive resin are formed to prevent short circuits, then electrical isolation is improved, but substrate deterioration occurs due to heat treatment
Solution Approach 1:
The patent removes the photosensitive resin layer from the structure, extracting the harmful element that causes substrate deterioration during heat treatment. The SiO2 film alone serves as the insulating layer, eliminating the source of heat-related substrate damage.
Solution Approach 2:
The patent eliminates the photosensitive resin layer which is a temporary, consumable material used only during manufacturing and then removed or covered. By replacing it with a permanent SiO2 film structure, the harmful heat treatment effects are avoided.
3Reliability
If insulating layers made of photosensitive resin are formed to prevent short circuits, then electrical isolation is improved, but IDT electrodes suffer corrosion from developer exposure
Solution Approach 1:
The patent removes the photosensitive resin layer that requires developer exposure during patterning. By eliminating this layer, the harmful developer exposure that causes IDT electrode corrosion is also eliminated, while electrical isolation is maintained through the SiO2 film structure.
Solution Approach 2:
The patent eliminates the photosensitive resin layer which is a temporary manufacturing aid that introduces harmful chemicals. The permanent SiO2 film structure replaces it, avoiding all developer-related corrosion issues.
4Adaptability or versatility
If wiring patterns are arranged to provide connections, then circuit functionality is improved, but short circuits occur between crossing wiring patterns
Solution Approach 1:
The patent uses three-dimensional wiring arrangements where wiring patterns cross each other in different layers or at angles, utilizing spatial dimensions to avoid short circuits while maintaining circuit connectivity. The SiO2 film provides continuous insulation in this three-dimensional configuration.
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 the manufacturing process, prevents substrate deterioration, and reduces corrosion of IDT electrodes, while ensuring high-density wiring and a compact device structure by securely isolating wiring patterns and improving frequency temperature characteristics.
Implementation Method 1
a film for improving frequency temperature characteristics made of SiO2 is formed on a piezoelectric substrate
Implementation Method 2
a photosensitive resin layer is applied and patterned to create insulating layers between crossing wiring patterns
Data Source
AI summary
A method for manufacturing a surface acoustic wave device includes the steps of forming an IDT electrode, a first wiring pattern, and a third wiring pattern on a piezoelectric substrate, forming an insulating film covering the IDT electrode and the wiring patterns, forming a photosensitive resin film, obtaining the photosensitive resin film, and forming a second wiring pattern on an insulating layer composed of the insulating film and the photosensitive resin film laminated on the insulating film so that the second wiring pattern three-dimensionally crosses the first wiring pattern.