Doped Temperature Sensitive Layer for BAWR Sensitivity
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Solution Overview
Problem
Current bulk acoustic wave resonators (BAWRs) have limited temperature detection sensitivity due to negative temperature coefficients of frequency (TCF), which restricts accurate detection of resonant frequency changes with temperature variations.
Innovation Solution
A temperature sensing apparatus is developed with a temperature sensitive layer doped with impurities like boron, phosphorus, arsenic, germanium, antimony, silicon, and aluminum in silicon dioxide or silicon nitride, integrated with a piezoelectric layer and a passivation layer, enhancing the temperature coefficient of frequency (TCF) for improved sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If materials with negative TCF are used in BAWR layers, then the device structure is simple and manufacturing is easier, but temperature detection sensitivity is limited
Solution Approach 1:
The patent applies composite materials by combining a piezoelectric layer with a temperature-sensitive layer that has positive TCF characteristics. This composite structure integrates two functional materials: the piezoelectric material for acoustic wave generation and the temperature-sensitive material (doped SiO2 or SiN) for enhanced temperature detection, thereby achieving high temperature sensitivity while maintaining device functionality
Solution Approach 2:
The patent implements local quality by creating a specific temperature-sensitive layer with doped impurities (B, P, As, Ge, Sb, Si, Al) in SiO2 or SiN that is positioned adjacent to the piezoelectric layer. This localized region has distinct positive TCF properties that differ from the bulk materials, enabling enhanced temperature detection sensitivity at the critical interface region without altering the entire device structure
2Measurement precision
If a temperature sensitive layer doped with impurities is formed in SiO2 or SiN, then temperature detection sensitivity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by systematically varying the doping concentration and composition of impurities (B, P, As, Ge, Sb, Si, Al) in the SiO2 or SiN temperature-sensitive layer. By adjusting these material parameters, the patent optimizes the positive TCF characteristics to achieve high temperature sensitivity while maintaining compatibility with standard semiconductor manufacturing processes, thus balancing performance improvement with manufacturing feasibility
3Manufacturing precision
If the temperature sensitive layer is formed by doping impurities using in-situ process or implantation process, then doping precision is improved, but process complexity increases
Solution Approach 1:
The patent applies preliminary action by performing in-situ doping during the deposition process of the SiO2 or SiN temperature-sensitive layer. The impurities are incorporated into the layer structure during its formation, before subsequent processing steps. This preliminary incorporation ensures uniform doping distribution and precise control of TCF properties, while avoiding the need for separate, complex implantation steps that would increase process complexity
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 apparatus significantly increases temperature detection sensitivity, allowing for accurate detection of resonant frequency changes and enabling high-temperature sensing in hazardous environments, even in inaccessible spaces.
Implementation Method 1
a piezoelectric layer configured to convert an electrical signal into an acoustic wave
Implementation Method 2
The TCF refers to a coefficient indicating a rate at which a resonant frequency changes due to a change in temperature
Data Source
AI summary
A temperature sensing apparatus and method are described to detect a change in a frequency due to a change in a temperature. An infrared light sensing apparatus and method are also provided. The temperature sensing apparatus may include an electrode to generate an electrical signal, a piezoelectric layer to convert the electrical signal into an acoustic wave, and a temperature sensitive layer formed by doping impurities in one or more structures formed on a substrate. Additionally, the infrared light sensing apparatus may convert into heat infrared light incident to an infrared light absorption layer, using an infrared light reflection layer and the infrared light absorption layer. A temperature sensitive layer may detect a change in a resonant frequency based on a change in a temperature of the heat, and may detect a change in infrared light based on the change in the resonant frequency.