Acoustic Wave Device Dummy Electrode Short Circuit Prevention
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Solution Overview
Problem
Conventional acoustic wave devices experience short circuits between interdigital transducer (IDT) and reflector electrodes, leading to reduced yield due to incomplete dry etching and electrode film residues at gaps between these components.
Innovation Solution
Incorporating dummy electrodes positioned at specific distances relative to the IDT and reflector electrodes, which reduce the opening ratio of the resist film and facilitate stable dry etching by ensuring sufficient etching gas supply, thereby preventing short circuits and increasing yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bevel portions are formed at gaps between IDT electrode and reflector electrodes to prevent short circuit, then short circuit prevention is improved, but manufacturing precision deteriorates due to incomplete dry etching and electrode film residues
Solution Approach 1:
A dummy electrode is introduced as an intermediary element positioned between the IDT electrode and the reflector electrode. This dummy electrode serves as a mediator that modifies the etching process dynamics, ensuring complete removal of electrode films at the gaps while maintaining proper spacing to prevent short circuits. The dummy electrode acts as a temporary structure that facilitates the etching process without being part of the final functional device.
Solution Approach 2:
The dummy electrode is formed in advance before the final electrode structures are completed. By establishing this intermediary structure preliminarily, the etching process can proceed more effectively to remove all electrode film residues at the gaps. The dummy electrode prepares the structure for complete etching before being removed or integrated into the final design.
2Area of stationary object
If gap size between IDT electrode and reflector electrode is reduced to improve device compactness, then device area is reduced, but short circuit risk increases due to insufficient spacing
Solution Approach 1:
The dummy electrode serves as a spacing mediator that allows the use of smaller physical gaps between the IDT electrode and reflector electrode while maintaining adequate electrical isolation. By introducing this intermediary element, the device can achieve compact dimensions without compromising the reliability of the gap spacing for preventing short circuits.
3Manufacturing precision
If dummy electrode is added to stabilize dry etching process, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The dummy electrode is treated as a temporary, disposable structure used only during the manufacturing process. It is formed, used to stabilize the etching process, and then removed or integrated without serving a functional role in the final device. This approach allows the use of a complex-looking structure during manufacturing while keeping the final device relatively simple.
Solution Approach 2:
The dummy electrode is a simplified copy or replica of the actual electrode structures, lacking the full functionality but sufficient to perform the etching stabilization function. By using this simplified copy during manufacturing, the complex requirements of the final electrode structures are avoided during the critical etching 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
The use of dummy electrodes stabilizes the dry etching process, eliminating electrode film residues and preventing short circuits, thus enhancing the yield of acoustic wave devices by ensuring proper etching and maintaining the integrity of the device components.
Implementation Method 1
piezoelectric substrate, an interdigital transducer (IDT) electrode
Data Source
AI summary
An acoustic wave device includes a piezoelectric substrate, an interdigital transducer (IDT) electrode, a reflector electrode, and a dummy electrode. The IDT electrode includes electrode fingers extending in a predetermined direction. The reflector electrode faces the IDT electrode across a gap. The dummy electrode is situated on a straight line extending in the predetermined direction through the gap. At least one of the distance between the dummy electrode and the IDT electrode and the distance between the dummy electrode and the reflector electrode is larger than the distance between the IDT electrode and the reflector electrode. This acoustic wave device prevents a short circuit between the IDT electrode and the reflector electrode, thereby avoiding a decrease in its yield.