Development of PZT-based MEMS FabryPerot Interferometer with eutectic bonding and its interface electronics
Eutectic 본딩을 이용한 PZT 기반 MEMS Fabry-Perot 간섭계 및 인터페이스 회로 개 발
초록/요약
In this study, we present the development and optimization of a PZT-based MEMS Fabry-Perot Interferometer (FPI) with various configurations to enhance its performance characteristics. The initial design involved a single-pole PZT configuration, which demonstrated promising results with a transmission rate exceeding 50% at a wavelength of 850 nm. However, the bonding process using Au-TiO2 presented challenges, resulting in weak bonding and the appearance of multiple peaks. Furthermore, the peak shifting capability of the PZT material was limited, and the full width at half maximum (FWHM) was relatively narrow at 20 nm. To overcome these limitations, we investigated a modified FPI design utilizing four bulky PZT poles. This configuration showed improved FWHM of 11 nm and easy fabrication process due to the absence of bonding requirements. However, the maximum transmission rate at 850 nm was reduced to 15%, resulting in high transmission loss, which posed a significant drawback. To address the transmission loss issue, we proposed a novel FPI design with double PZT poles. This configuration demonstrated a transmission rate of 20% at 850 nm, offering a moderate improvement over the previous design. While the FWHM increased to 30 nm, the innovative use of double PZT poles allowed for effective modulation of the center peak wavelength from 855 nm to 845 nm, providing fine-tuning capabilities at low voltages. The bonding process was improved using Au-Au bonding, which enhanced the overall device reliability. However, the maximum transmission rate at 850 nm remained relatively low, highlighting an area for further improvement. These findings showcase the successful development and optimization of PZT-based MEMS Fabry-Perot Interferometers with varying configurations. The results obtained from simulation and experimental analyses demonstrate good agreement and highlight the potential for future advancements in this field. Despite the remaining challenges, such as the need for improved transmission rates at the desired wavelength and reduced FWHM, the presented designs provide valuable insights for further research and development in the field of advanced MEMS-based optical devices.
more목차
Chapter 1 Introduction 1
Chapter 2 Optimal design consideration 9
2. 1 Operating mechanism 9
2. 2 Structural Parameters 15
2. 2. 1 Mirror 15
2. 2. 2 Cavity 17
2. 2. 3 PZT actuator (m=2, 3, 4, 5…) 17
2. 3 Annealing while preventing interdiffusion 17
2. 4 Polarization 19
2. 5 Bonding 21
2. 6 Interdiffusion 22
Chapter 3 Analytical modeling and COMSOL simulation 23
3. 1. Analytical modeling in MATLAB 23
3. 2. COMSOL simulations 24
3. 2. 1. PZT parameters 24
3. 2. 2. Calculation of PZT elongations 25
Chapter 4 Three different types of FPI 27
4. 1 FPI with a single PZT pole 27
4. 1. 1. Overall view of FPI 27
4. 1. 2. Virtual lab simulations to predict performances 28
4. 1. 3. Fabrications by MEMS process including 30
4. 1. 3. 1. PZT deposition process 32
4. 1. 3. 2. Annealing in RTA 33
4. 1. 3. 3. Polarization 35
4. 1. 3. 4. Bonding 35
4. 1. 3. 5. Fabricated devices 36
4. 2 FPI with 4 bulky PZT 37
4. 2. 1. Overall view of FPI 37
4. 2. 2. Fabrication 37
4. 2. 3. Fabricated devices 38
4. 3 FPI with double PZT poles 39
4. 3. 1. Overall view of FPI 39
4. 3. 2. Virtual lab simulations 39
4. 3. 3. Fabrication 40
4. 3. 4. Fabricated devices 40
Chapter 5 Interface Electronics (IE) 41
5. 1. Purpose of IE 41
5. 2. Requirements of IE 41
5. 3. Constituting components and units 41
5. 4. Operating mechanism 42
5. 5. Performances of IE 42
5. 6. Long term stability of peak in DC voltage (duty cycle) 43
5. 7. Temperature variation effects in FPI properties when shining the light 45
5. 8. Testing setup 46
Chapter 6 Results 47
6. 1. FPI with a single PZT pole 47
6. 1. 1 SEM and cross-sectional view 47
6. 1. 2. AFM & EDS of mirror 48
6. 1. 3. C-V for elongation checks of PZT depending on bias and polarity 49
6. 1. 4. Transmission test without bias 50
6. 1. 5 Transmission test with Bias via interface electronics 52
6. 2. FPI with 4 bulky PZT poles 54
6. 2. 1. C-V for elongation checks of PZT depending on bias and polarity 54
6. 2. 2. Transmission test without bias 54
6. 2. 3. Transmission test with Bias via interface electronics 55
6. 2. 4. Transmission analysis 56
6. 3. FPI with a double PZT poles 57
6. 3. 1. COMSOL simulations 57
6. 3. 2. PZT elongation 58
6. 3. 3. Transmission test without bias 59
6. 3. 4. Transmission test with Bias via interface electronics 59
6. 4. Comparisons of all three FPIs 61
6. 5. Summary of New findings and contributions to this technology 61
Chapter 7 Conclusion and future work 62
References 64
Research achievements 67
