Film Bulk Acoustic Resonator Ta Nb Dopant Cost
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Solution Overview
Problem
The high cost of rare earth metals used as dopants in film bulk acoustic resonators and the resulting increased manufacturing costs, along with issues of crystal abnormal growth and insertion loss characteristics due to the use of these metals, necessitate the development of alternative dopants that can provide comparable piezoelectric characteristics at a lower cost.
Innovation Solution
Incorporating Ta or Nb as dopants in the piezoelectric body, specifically within the range of 0.1 to 24 at% for Ta and 0.1 to 23 at% for Nb, to form AlTaN or AlNbN, which improves piezoelectric characteristics without introducing TaN or NbN, and using these dopants in the first and second electrodes to enhance material consistency and crystal alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rare earth metals are used as dopants in the piezoelectric body, then piezoelectric characteristics are improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive rare earth metal dopants with cheaper alternative dopants (such as lithium, sodium, potassium, or their compounds) in the piezoelectric body. This substitution maintains the necessary piezoelectric characteristics while significantly reducing manufacturing costs, directly addressing the technical contradiction between performance and cost.
Solution Approach 2:
The patent modifies the chemical composition parameters of the piezoelectric body by introducing specific dopants with controlled concentrations. By changing the dopant type and concentration parameters, the patent achieves optimal piezoelectric characteristics without relying on expensive rare earth metals, thus resolving the cost-performance contradiction.
2Reliability
If rare earth metals are used as dopants in the piezoelectric body, then piezoelectric characteristics are improved, but abnormal crystal growth occurs
Solution Approach 1:
The patent substitutes rare earth metal dopants with alternative dopants that do not induce abnormal crystal growth. The alternative dopants (lithium, sodium, potassium, or their compounds) maintain piezoelectric characteristics while ensuring stable crystal structure, thereby resolving the contradiction between performance improvement and structural stability.
Solution Approach 2:
The patent changes the dopant composition parameters to avoid the harmful effects of rare earth metals. By selecting dopants with appropriate ionic radii and chemical properties, the patent maintains the necessary piezoelectric effect while preventing crystal structure distortion and abnormal growth.
3Reliability
If rare earth metals are used as dopants in the piezoelectric body, then piezoelectric characteristics are improved, but insertion loss increases
Solution Approach 1:
The patent replaces rare earth metal dopants with alternative dopants that reduce energy loss. The alternative dopants maintain the piezoelectric coupling coefficient while minimizing insertion loss, thereby resolving the contradiction between achieving good piezoelectric characteristics and reducing energy loss.
Solution Approach 2:
The patent optimizes the dopant concentration and type parameters to achieve the desired balance between piezoelectric characteristics and energy loss. By carefully controlling the dopant composition, the patent improves the electromechanical coupling coefficient while keeping insertion loss within acceptable limits.
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 reduces manufacturing costs by using more affordable dopants while improving piezoelectric characteristics, preventing abnormal crystal growth, and enhancing insertion loss and attenuation characteristics of the film bulk acoustic resonator.
Implementation Method 1
when electric energy is applied to the first and second electrodes to induce an electric field in a piezoelectric layer, the electric field generates a piezoelectric phenomenon in the piezoelectric layer to allow the resonant part to vibrate in a predetermined direction
Implementation Method 2
forming a piezoelectric body on the first electrode by sputtering, under a nitrogen atmosphere, a single target including either one of AlTa including 0.1 to 24 at % of Ta and AlNb including 0.1 to 23 at % of Nb
Data Source
AI summary
A film bulk acoustic resonator includes: a first electrode disposed on a substrate; a piezoelectric body disposed on the first electrode and including AlN to which a dopant is added; and a second electrode disposed on the piezoelectric body and facing the first electrode such that the piezoelectric body is interposed between the second electrode and the first electrode, wherein the dopant includes either one of 0.1 to 24 at % of Ta and 0.1 to 23 at % of Nb.