Micro-electro-mechanical systems (MEMS) have revolutionized the field of sensing applications by enabling the miniaturization and integration of mechanical and electronic components in compact, cost-effective devices. MEMS gyroscopes, in particular, have introduced angular rate sensors to various fields, including consumer electronics, automotive, and the aerospace industry. The rising demand for advanced MEMS devices and their increasing complexity, however, introduce several challenges in their design process. This thesis explores different layout optimization techniques, namely parametric and level-set-based optimization, to aid designers in developing innovative MEMS layouts. The parametric optimization refines existing layouts starting from an initial guess, while the level-set algorithm presented is able to generate complete layouts from scratch. Two parametrically optimized layouts were designed to improve the mechanical compensation of the Zero-Rate Offset (ZRO) or quadrature error. These layouts were then manufactured, and tested in collaboration with STMicroelectronics. Concurrently, a level-set-based topology optimization approach was developed and applied to generate novel single-axis MEMS gyroscope architectures. This method enables the discovery of innovative MEMS layouts while optimizing their performance based on a given cost function and constraints. The results indicate that level-set topology optimization is a promising technique for the optimization of MEMS devices, especially if towards higher frequencies (such as modern MEMS resonators and time-keeping devices). Lastly, over 55,000 test structures were manufactured in collaboration with STMicroelectronics for the statistical validation of local wall-angle variations and to better understand the effect of dummy geometries placed in proximity of a MEMS spring. This thesis details the automation of the wafer-level testing program using LabVIEW and presents the preliminary results obtained, laying the foundation for further investigation.
I sistemi microelettromeccanici (MEMS) hanno rivoluzionato il campo sensoristico, consentendo la miniaturizzazione e l'integrazione di componenti meccanici ed elettronici in dispositivi compatti ed economici. I giroscopi MEMS, in particolare, hanno introdotto i sensori di velocità angolare in vari settori, tra cui l'elettronica di consumo, l'industria automobilistica e quella aerospaziale. La crescente domanda di dispositivi MEMS avanzati e la loro crescente complessità, tuttavia, introducono diverse sfide nel processo di progettazione. Questa tesi esplora diverse tecniche di ottimizzazione del layout, in particolare l'ottimizzazione parametrica e quella basata su tecniche level-set, utili al progettista per lo sviluppo di architetture MEMS innovative. L'ottimizzazione parametrica perfeziona i layout esistenti a partire da un'ipotesi di layout iniziale, mentre l'algoritmo level-set presentato è in grado di generare layout completi date le condizioni al contorno. Sono stati progettati due layout ottimizzati parametricamente per migliorare la compensazione meccanica dello Zero-Rate Offset (ZRO) o errore di quadratura. Questi layout sono stati poi prodotti e testati in collaborazione con STMicroelectronics. Contemporaneamente, è stato sviluppato e applicato un approccio di ottimizzazione topologica basato su level-set per generare nuove architetture di giroscopi MEMS a singolo asse. Questo metodo consente di investigare layout MEMS innovativi e di ottimizzarne le prestazioni in base a una determinata funzione di costo e opportuni vincoli. I risultati indicano che l'ottimizzazione topologica di tipo level-set è una tecnica promettente per l'ottimizzazione dei dispositivi MEMS, soprattutto se utilizzata per frequenze più elevate (quali ad esempio i moderni risonatori MEMS o dispositivi di time-keeping). Infine, in collaborazione con STMicroelectronics, sono state prodotte oltre 55.000 strutture test per la validazione statistica delle variazioni locali del wall angle e per comprendere meglio l'effetto di geometrie fittizie poste in prossimità di una molla MEMS. Questa tesi illustra l'automazione del programma di test a livello wafer implementato in LabVIEW e presenta i risultati preliminari ottenuti, fornendo le basi per ulteriori indagini.
Optimized inertial MEMS gyroscopes : design and testing of innovative layouts
Bonaccorsi, Giacomo
2022/2023
Abstract
Micro-electro-mechanical systems (MEMS) have revolutionized the field of sensing applications by enabling the miniaturization and integration of mechanical and electronic components in compact, cost-effective devices. MEMS gyroscopes, in particular, have introduced angular rate sensors to various fields, including consumer electronics, automotive, and the aerospace industry. The rising demand for advanced MEMS devices and their increasing complexity, however, introduce several challenges in their design process. This thesis explores different layout optimization techniques, namely parametric and level-set-based optimization, to aid designers in developing innovative MEMS layouts. The parametric optimization refines existing layouts starting from an initial guess, while the level-set algorithm presented is able to generate complete layouts from scratch. Two parametrically optimized layouts were designed to improve the mechanical compensation of the Zero-Rate Offset (ZRO) or quadrature error. These layouts were then manufactured, and tested in collaboration with STMicroelectronics. Concurrently, a level-set-based topology optimization approach was developed and applied to generate novel single-axis MEMS gyroscope architectures. This method enables the discovery of innovative MEMS layouts while optimizing their performance based on a given cost function and constraints. The results indicate that level-set topology optimization is a promising technique for the optimization of MEMS devices, especially if towards higher frequencies (such as modern MEMS resonators and time-keeping devices). Lastly, over 55,000 test structures were manufactured in collaboration with STMicroelectronics for the statistical validation of local wall-angle variations and to better understand the effect of dummy geometries placed in proximity of a MEMS spring. This thesis details the automation of the wafer-level testing program using LabVIEW and presents the preliminary results obtained, laying the foundation for further investigation.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/207417