Οι ηλεκτρομηχανικές συσκευές αποθήκευσης δεδομένων πολύ μικρής κλίμακας που βασίζονται στη χρήση ακίδων (probes) αποτελούν ανερχόμενες εναλλακτικές επιλογές για τη βελτίωση της πυκνότητας αποθήκευσης, του χρόνου πρόσβασης των δεδομένων και της απαιτούμενης ισχύος σε σχέση με τις συμβατικές συσκευές αποθήκευσης. Μία υλοποίηση μιας τέτοιας συσκευής χρησιμοποιεί θερμομηχανικές μεθόδους για την αποθήκευση πληροφορίας σε λεπτές μεμβράνες πολυμερών υλικών. Στην περίπτωση αυτή, η ψηφιακή πληροφορία αποθηκεύεται με τη μορφή κοιλωμάτων πάνω στο πολυμερές υλικό, τα οποία δημιουργούνται από τις ακίδες, διαμέτρου μερικών nm. Με στόχο την αύξηση του ρυθμού εγγραφής και ανάγνωσης χρησιμοποιούνται δισδιάστατες διατάξεις από ακίδες που λειτουργούν παράλληλα, με κάθε ακίδα να εκτελεί λειτουργίες εγγραφής /ανάγνωσης /διαγραφής σε ξεχωριστό αποθηκευτικό πεδίο. Η μετατόπιση του αποθηκευτικού μέσου σε σχέση με τη διάταξη των ακίδων επιτυγχάνεται με τη χρησιμοποίηση ηλεκτρομηχανικού συστήματος μικρής κλίμακας (MEMS). Η διάταξη MEMS αποτελείται από ένα μικρής κλίμακας σύστημα σάρωσης (microscanner) και από το τσιπ της δισδιάστατης διάταξης των ακίδων. Το σύστημα σάρωσης έχει δυνατότητα κίνησης σε δύο διευθύνσεις (x/y). Αντικείμενο της διπλωματικής εργασίας είναι η μοντελοποίηση του συστήματος σάρωσης μικρής κλίμακας. Η μοντελοποίηση του συστήματος έγινε με βάση το σύστημα του απλού αρμονικού ταλαντωτή με απόσβεση. Στα πλαίσια της εργασίας μελετάται η απόκριση του συστήματος σε διάφορους τύπους διεγέρσεων, ενώ για την προσομοίωση της συμπεριφοράς του microscanner αναπτύχθηκε εφαρμογή στην γλώσσα προγραμματισμού Visual Basic. Η εφαρμογή περιλαμβάνει γραφικό περιβάλλον με δυνατότητα ρύθμισης των παραμέτρων εξομοίωσης. / Micro-electro-mechanical-system (MEMS)-based scanning-probe storage devices are emerging as potential ultra-high-density, low-access-time, and low-power alternatives to conventional data storage. One implementation of probe-based storage uses thermomechanical means to store and retrieve information in thin polymer films. Digital information is stored by making indentations on the thin polymer film with the tips of atomic force microscope (AFM) cantilevers, which are a few nanometers in diameter. To increase the data rate, an array of probes is used, in which each probe performs read/ write/ erase operations over an individual storage field. Displacement of the storage medium relative to the array of cantilevers is achieved by using micro-electro-mechanical-system (MEMS). The MEMS assembly consists of the microscanner and the cantilever array chip. The microscanner with x and y motion range carries the storage medium. This diploma dissertation presents the modeling of the microscanner. The system models as a damped harmonic oscillator. The model response on different driven forces has been studied, whereas an application in Visual Basic has been generated to simulate the system motion. The application comprises graphic interface with simulation parameters modulation.

Cancer is a world menace. After years of endeavor seeking the end of it, people started to realize that no matter how powerful the therapy could be, detection at early stage is always a cheaper, easier and more successful solution compared with curative methods for cancer developed onto its advanced stage. However, relatively few early-detection approaches have proven sufficiently effective and practical for mass use as a point-of-care tool. An early-cancer screening tool integrating the desired features of sensitive, informative, portable, and cost-effective is in need for the doctors. The progress in optical imaging and Micro-electro-mechanical system (MEMS) technology offers a promise for an innovative cancer screening alternative that is non-invasive, radiation-free, portable and potentially cost-effective. This dissertation investigates handheld instrumentation as multi-modalities of miniature imaging probes with various designs of MEMS devices, to obtain real-time images of epithelial tissue optical and physiological properties, combining the quantitative advantages of spectral analysis with the qualitative benefits of imaging to distinguish early cancer. This dissertation in sequence presents the handheld instruments in the fashions of Laser-scanning confocal microscopy (LSCM), optical diffuse reflectance imaging, nonlinear optical imaging modalities with their subsequent image-guided managements in oral cancer, skin cancer detection, circulating tumor cell (CTC) imaging, and imaging guided surgeries. One of the main challenges facing miniaturization lies in the mechanism of beam deflection across the sample. This dissertation introduces two generations of MEMS devices desgined, fabricated and incorporated in the imaging probes. A two-axis vertical comb driven silicon micromirror was used in the development of a handheld LSCM for oral cancer detection. Though obtaining numerous advantages, this first generation silicon MEMS micromirror suffers from small aperture size and high voltage requirement for actuation, which result in low collection efficiency in fluorescence imaging and medial safety concerns, respectively. Therefore a stainless steel scanner compatible with electrical discharge machining (EDM) process was fabricated with simplified process, low-voltage magnetic actuation and large fluorescence collection efficiency, with its capability demonstrated in the incorporation and embodiment of a handheld hyperspectral nonlinear imaging probe. Besides, software and controlling innovations for handheld imaging modalities are presented. A feedback controlling system for MEMS scanning status monitoring was developed for stabilized imaging rendering. For the sake of further improved imaging stability in handheld imaging and to enable on-site mosaic for large field viewing, a handheld mosaic system was developed and presented. / text

For elderly Canadians, the prevalence of vision impairment caused by degenerative retinal pathologies, such as age-related macular degeneration and retinitis pigmentosa, is at an occurrence rate of 14 percent, and on the rise. It has been shown that visual function can be restored by electrically stimulating intact retinal tissue with an array of micro-electrodes with suitable signals. Commercial retinal implants carrying such a micro-electrode array achieve this, but to date must receive power and data over copper wire cable passing through a permanent surgical incision in the eye wall (sclera). This project is defined by a collaboration with iBIONICS, who are developing retinal implants for treatment of such conditions. iBIONICS has developed the Diamond Eye retinal implant, along with several technology sub-systems to form a comprehensive and viable medical solution. Notably, the Diamond Eye system can be powered wirelessly, with no need for a permanent surgical incision. The thesis work is focused on the formulation, simulation and hardware demonstration of a powering system, mounted on glasses frame, for a retinal implant. The system includes a Micro-Electro-Mechanical System (MEMS) mirror that directs a laser beam to the implant through the pupil opening. The work presented here is built on two main components: an iterative predictor-corrector algorithm (Kalman filter) that estimates pupil coordinates from measurements provided by an image-based eye tracking algorithm; and an misalignment compensation algorithm that maps eye pupil coordinates into mirror coordinates, and compensates for misalignment caused by rigid body motions of the glasses lens mirror and the MEMS mirror with respect to the eye. Pupil tracker and misalignment compensation control performance are illustrated through simulated scenarios. The project also involves the development of a hardware prototype that is used to test algorithms and related software.

For mobile electronics such as Smartphones, Smartcards or wearable devices there is a trend towards an increasing functionality as well as miniaturisation. In this development Micro Electro- Mechanical Systems (MEMS) are an important key element for the realisation of functions such as motion detection. The specifications given by such devices together with the limited available space demand advanced packaging technologies. The 3D-Wafer Level Packaging (3D-WLP) enables one solution for a miniaturised MEMS package by using techniques such as Wafer Level Bonding (WLB) and Through Silicon Vias (TSV). This technology increases the effective area of the MEMS device by elimination dead space, which is typically required for other approaches based on wire bond assembly. Within this thesis, different TSV technology concepts with respect to a 3D-WLP for MEMS have been developed. Thereby, the focus was on a copper based technology as well as on two major TSV implementation methods. This comprises a Via Middle approach based on the separated TSV fabrication in the cap wafer as well as a Via Last approach with a TSV implementation in either the MEMS or cap wafer, respectively. For each option with its particular challenges, corresponding process modules have been developed. In the Via Middle approach, the wafer-related etch rate homogeneity determines the TSV reveal from the wafer backside Here, a reduction of the TSV depth down to 80 μm is favourable as long as the desired Cu-thermo-compression bonding (Cu-TCB) is performed before the thinning. For the TSV metallisation, a Cu electrochemical deposition method was developed, which allows the deposition of one redistribution layer as well as the bonding patterns for Cu-TCB at the same time. In the Via Last approach, the TSV isolation represents one challenge. Chemical Vapour Deposition processes have been investigated, for which a combination of PE-TEOS and SA-TEOS as well as a Parylene deposition yield the most promising results. Moreover, a method for the realisation of a suitable bonding surface for the Silicon Direct Bonding method has been developed, which does not require any wet pre treatment of the fabricated MEMS patterns. A functional MEMS acceleration sensor as well as Dummy devices serve as demonstrators for the overall integration technology as well as for the characterisation of electrical parameters. / Im Bereich mobiler Elektronik, wie z.B. bei Smartphones, Smartcards oder in Kleidung integrierten Geräten ist ein Trend zu erkennen hinsichtlich steigender Funktionalität und Miniaturisierung. Bei dieser Entwicklung spielen Mikroelektromechanische Systeme (MEMS) eine entscheidende Rolle zur Realisierung neuer Funktionen, wie z.B. der Bewegungsdetektion. Die Anforderungen derartiger Bauteile zusammen mit dem begrenzten zur Verfügung stehenden Platz erfordern neuartige Technologien für die Aufbau- und Verbindungstechnick (engl. Packaging) der Bauteile. Das 3D-Wafer Level Packaging (3D-WLP) ermöglicht eine Lösung für eine miniaturisierte MEMS-Bauform unter Nutzung von Techniken wie dem Waferlevelbonden (WLB) und den Siliziumdurchkontaktierungen (TSV von engl. Through Silicon Via). Diese Technologie erhöht die effektive aktive Fläche des MEMS Bauteils durch die Reduzierung von Toträumen, welche für andere Ansätze wie der Drahtbond-Montage üblich sind. In der vorliegenden Arbeit wurden verschiedene Technologiekonzepte für den Aufbau von 3D-WLP für MEMS erarbeitet. Dabei lag der Fokus auf einer Kupfer-basierten Technologie sowie auf zwei prinzipiellen Varianten für die TSV-Implementierung. Dies umfasst den Via Middle Ansatz, welcher auf der TSV Herstellung auf einem separaten Kappenwafer beruht, sowie den Via Last Ansatz mit einer TSV Herstellung entweder im MEMS-Wafer oder im Kappenwafer. Für beide Varianten mit individuellen Herausforderungen wurden entsprechende Prozessmodule entwickelt. Beim Via Middle Ansatz ist die Wafer-bezogene Ätzratenhomogenität des Siliziumtiefenätzen entscheidend für das spätere Freilegen der TSVs von der Rückseite. Hier hat sich eine Reduzierung der TSV-Tiefe auf bis zu 80 μm vorteilhaft erwiesen insofern, das Kupfer-Thermokompressionsbonden (Cu-TKB) vor dem Abdünnen erfolgt. Zur Metallisierung der TSVs wurde ein Cu Galvanikprozess erarbeitet, welcher es ermöglicht gleichzeitig eine Umverdrahtungsebene sowie die Bondstrukturen für das Cu-TKB zu erzeugen. Beim Via Last Ansatz ist die TSV Isolation eine Herausforderung. Es wurden CVD (Chemische Dampfphasenabscheidung) Prozesse untersucht, wobei eine Kombination aus PE-TEOS und SA-TEOS sowie eine Parylene Beschichtung erfolgversprechende Ergebnisse liefern. Des Weiteren wurde eine Methode zur Erzeugung bondfähiger Oberflächen für das Siliziumdirektbonden erarbeitet, welche eine Nass-Vorbehandlung des MEMS umgeht. Ein realer MEMS-Beschleunigungssensor sowie Testaufbauten dienen zur Demonstration der Gesamtintegrationstechnologie sowie zur Charakterisierung elektrischer Parameter.

For mobile electronics such as Smartphones, Smartcards or wearable devices there is a trend towards an increasing functionality as well as miniaturisation. In this development Micro Electro- Mechanical Systems (MEMS) are an important key element for the realisation of functions such as motion detection. The specifications given by such devices together with the limited available space demand advanced packaging technologies. The 3D-Wafer Level Packaging (3D-WLP) enables one solution for a miniaturised MEMS package by using techniques such as Wafer Level Bonding (WLB) and Through Silicon Vias (TSV). This technology increases the effective area of the MEMS device by elimination dead space, which is typically required for other approaches based on wire bond assembly. Within this thesis, different TSV technology concepts with respect to a 3D-WLP for MEMS have been developed. Thereby, the focus was on a copper based technology as well as on two major TSV implementation methods. This comprises a Via Middle approach based on the separated TSV fabrication in the cap wafer as well as a Via Last approach with a TSV implementation in either the MEMS or cap wafer, respectively. For each option with its particular challenges, corresponding process modules have been developed. In the Via Middle approach, the wafer-related etch rate homogeneity determines the TSV reveal from the wafer backside Here, a reduction of the TSV depth down to 80 μm is favourable as long as the desired Cu-thermo-compression bonding (Cu-TCB) is performed before the thinning. For the TSV metallisation, a Cu electrochemical deposition method was developed, which allows the deposition of one redistribution layer as well as the bonding patterns for Cu-TCB at the same time. In the Via Last approach, the TSV isolation represents one challenge. Chemical Vapour Deposition processes have been investigated, for which a combination of PE-TEOS and SA-TEOS as well as a Parylene deposition yield the most promising results. Moreover, a method for the realisation of a suitable bonding surface for the Silicon Direct Bonding method has been developed, which does not require any wet pre treatment of the fabricated MEMS patterns. A functional MEMS acceleration sensor as well as Dummy devices serve as demonstrators for the overall integration technology as well as for the characterisation of electrical parameters.:Bibliographische Beschreibung 3 Vorwort 13 List of symbols and abbreviations 15 1 Introduction 23 2 Fundamentals on MEMS and TSV based 3D integration 25 2.1 Micro Electro-Mechanical systems 25 2.1.1 Basic Definition 25 2.1.2 Silicon technologies for MEMS 26 2.1.3 MEMS packaging 29 2.2 3D integration based on TSVs 33 2.2.1 Overview 33 2.2.2 Basic processes for TSVs 34 2.2.3 Stacking and Bonding 47 2.2.4 Wafer thinning 48 2.3 TSV based MEMS packaging 50 2.3.1 MEMS-TSVs 50 2.3.2 3D-WLP for MEMS 52 3 Technology development for a 3D-WLP based MEMS 57 3.1 Target integration approach for 3D-WLP based MEMS 57 3.1.1 MEMS modules using 3D-WLP based MEMS 57 3.1.2 Integration concepts 58 3.2 Objective and requirements for the proposed 3D-WLP of MEMS 60 3.2.1 Boundary conditions 60 3.2.2 Technology concepts 63 3.3 Selected approaches for TSV implementation in MEMS 64 3.3.1 Via Last Technology 64 3.3.2 Via Middle technology 69 4 Development of process modules 75 4.1 Characterisation 75 4.2 TSV related etch processes 77 4.2.1 Equipment 77 4.2.2 Deep silicon etching 78 4.2.3 Etching of the buried dielectric layer 84 4.2.4 Patterning of TSV isolation liner – spacer etching 90 4.2.5 Summary 92 4.3 TSV isolation 93 4.3.1 Principle considerations 93 4.3.2 Experiment 95 4.3.3 Results 97 4.3.4 Summary 102 4.4 Metallisation of TSV and RDL 103 4.4.1 Plating base and experimental setup 103 4.4.2 Investigations related to the ECD process 106 4.4.3 Pattern plating 117 4.4.4 Summary 123 4.5 Wafer Level Bonding 124 4.5.1 Silicon direct bonding 124 4.5.2 Thermo-compression bonding by using ECD copper 128 4.5.3 Summary 134 4.6 Wafer thinning and TSV back side reveal 134 4.6.1 Thinning processes 134 4.6.2 TSV reveal processes 136 4.6.3 Summary 145 4.7 Under bump metallisation and solder bumps 146 5 Demonstrator design, fabrication and characterisation 149 5.1 Single wafer demonstrator for electrical test 149 5.1.1 Demonstrator design and test structure layout 149 5.1.2 Demonstrator fabrication 150 5.1.3 Electrical measurement 151 5.1.4 Summary 153 5.2 Via Last based TSV fabrication in the MEMS device wafer 153 5.2.1 Layout of the MEMS device with TSVs 153 5.2.2 Fabrication of TSVs and wafer thinning 154 5.2.3 Characterisation of the fabricated device 155 5.2.4 Summary 156 5.3 Via Last based cap-TSV for very thin MEMS devices 157 5.3.1 Design 157 5.3.2 Fabrication 158 5.3.3 Characterisation 161 5.3.4 Summary 162 5.4 Via Middle approach based on thinning after bonding 163 5.4.1 Design 163 5.4.2 Results and characterisation 164 5.4.3 Summary 166 6 Conclusion and outlook 167 Appendix A: Typical requirements on a MEMS package and its functions 171 Appendix B: Classification of packaging and system integration techniques 173 B.1 Packaging of electronic devices in general 173 B.2 Single Chip Packages 174 B.3 System integration 175 B.4 3D integration based on TSVs 180 Bibliography 183 List of figures 193 List of tables 199 Versicherung 201 Theses 203 Curriculum vitae 205 Own publications 207 / Im Bereich mobiler Elektronik, wie z.B. bei Smartphones, Smartcards oder in Kleidung integrierten Geräten ist ein Trend zu erkennen hinsichtlich steigender Funktionalität und Miniaturisierung. Bei dieser Entwicklung spielen Mikroelektromechanische Systeme (MEMS) eine entscheidende Rolle zur Realisierung neuer Funktionen, wie z.B. der Bewegungsdetektion. Die Anforderungen derartiger Bauteile zusammen mit dem begrenzten zur Verfügung stehenden Platz erfordern neuartige Technologien für die Aufbau- und Verbindungstechnick (engl. Packaging) der Bauteile. Das 3D-Wafer Level Packaging (3D-WLP) ermöglicht eine Lösung für eine miniaturisierte MEMS-Bauform unter Nutzung von Techniken wie dem Waferlevelbonden (WLB) und den Siliziumdurchkontaktierungen (TSV von engl. Through Silicon Via). Diese Technologie erhöht die effektive aktive Fläche des MEMS Bauteils durch die Reduzierung von Toträumen, welche für andere Ansätze wie der Drahtbond-Montage üblich sind. In der vorliegenden Arbeit wurden verschiedene Technologiekonzepte für den Aufbau von 3D-WLP für MEMS erarbeitet. Dabei lag der Fokus auf einer Kupfer-basierten Technologie sowie auf zwei prinzipiellen Varianten für die TSV-Implementierung. Dies umfasst den Via Middle Ansatz, welcher auf der TSV Herstellung auf einem separaten Kappenwafer beruht, sowie den Via Last Ansatz mit einer TSV Herstellung entweder im MEMS-Wafer oder im Kappenwafer. Für beide Varianten mit individuellen Herausforderungen wurden entsprechende Prozessmodule entwickelt. Beim Via Middle Ansatz ist die Wafer-bezogene Ätzratenhomogenität des Siliziumtiefenätzen entscheidend für das spätere Freilegen der TSVs von der Rückseite. Hier hat sich eine Reduzierung der TSV-Tiefe auf bis zu 80 μm vorteilhaft erwiesen insofern, das Kupfer-Thermokompressionsbonden (Cu-TKB) vor dem Abdünnen erfolgt. Zur Metallisierung der TSVs wurde ein Cu Galvanikprozess erarbeitet, welcher es ermöglicht gleichzeitig eine Umverdrahtungsebene sowie die Bondstrukturen für das Cu-TKB zu erzeugen. Beim Via Last Ansatz ist die TSV Isolation eine Herausforderung. Es wurden CVD (Chemische Dampfphasenabscheidung) Prozesse untersucht, wobei eine Kombination aus PE-TEOS und SA-TEOS sowie eine Parylene Beschichtung erfolgversprechende Ergebnisse liefern. Des Weiteren wurde eine Methode zur Erzeugung bondfähiger Oberflächen für das Siliziumdirektbonden erarbeitet, welche eine Nass-Vorbehandlung des MEMS umgeht. Ein realer MEMS-Beschleunigungssensor sowie Testaufbauten dienen zur Demonstration der Gesamtintegrationstechnologie sowie zur Charakterisierung elektrischer Parameter.:Bibliographische Beschreibung 3 Vorwort 13 List of symbols and abbreviations 15 1 Introduction 23 2 Fundamentals on MEMS and TSV based 3D integration 25 2.1 Micro Electro-Mechanical systems 25 2.1.1 Basic Definition 25 2.1.2 Silicon technologies for MEMS 26 2.1.3 MEMS packaging 29 2.2 3D integration based on TSVs 33 2.2.1 Overview 33 2.2.2 Basic processes for TSVs 34 2.2.3 Stacking and Bonding 47 2.2.4 Wafer thinning 48 2.3 TSV based MEMS packaging 50 2.3.1 MEMS-TSVs 50 2.3.2 3D-WLP for MEMS 52 3 Technology development for a 3D-WLP based MEMS 57 3.1 Target integration approach for 3D-WLP based MEMS 57 3.1.1 MEMS modules using 3D-WLP based MEMS 57 3.1.2 Integration concepts 58 3.2 Objective and requirements for the proposed 3D-WLP of MEMS 60 3.2.1 Boundary conditions 60 3.2.2 Technology concepts 63 3.3 Selected approaches for TSV implementation in MEMS 64 3.3.1 Via Last Technology 64 3.3.2 Via Middle technology 69 4 Development of process modules 75 4.1 Characterisation 75 4.2 TSV related etch processes 77 4.2.1 Equipment 77 4.2.2 Deep silicon etching 78 4.2.3 Etching of the buried dielectric layer 84 4.2.4 Patterning of TSV isolation liner – spacer etching 90 4.2.5 Summary 92 4.3 TSV isolation 93 4.3.1 Principle considerations 93 4.3.2 Experiment 95 4.3.3 Results 97 4.3.4 Summary 102 4.4 Metallisation of TSV and RDL 103 4.4.1 Plating base and experimental setup 103 4.4.2 Investigations related to the ECD process 106 4.4.3 Pattern plating 117 4.4.4 Summary 123 4.5 Wafer Level Bonding 124 4.5.1 Silicon direct bonding 124 4.5.2 Thermo-compression bonding by using ECD copper 128 4.5.3 Summary 134 4.6 Wafer thinning and TSV back side reveal 134 4.6.1 Thinning processes 134 4.6.2 TSV reveal processes 136 4.6.3 Summary 145 4.7 Under bump metallisation and solder bumps 146 5 Demonstrator design, fabrication and characterisation 149 5.1 Single wafer demonstrator for electrical test 149 5.1.1 Demonstrator design and test structure layout 149 5.1.2 Demonstrator fabrication 150 5.1.3 Electrical measurement 151 5.1.4 Summary 153 5.2 Via Last based TSV fabrication in the MEMS device wafer 153 5.2.1 Layout of the MEMS device with TSVs 153 5.2.2 Fabrication of TSVs and wafer thinning 154 5.2.3 Characterisation of the fabricated device 155 5.2.4 Summary 156 5.3 Via Last based cap-TSV for very thin MEMS devices 157 5.3.1 Design 157 5.3.2 Fabrication 158 5.3.3 Characterisation 161 5.3.4 Summary 162 5.4 Via Middle approach based on thinning after bonding 163 5.4.1 Design 163 5.4.2 Results and characterisation 164 5.4.3 Summary 166 6 Conclusion and outlook 167 Appendix A: Typical requirements on a MEMS package and its functions 171 Appendix B: Classification of packaging and system integration techniques 173 B.1 Packaging of electronic devices in general 173 B.2 Single Chip Packages 174 B.3 System integration 175 B.4 3D integration based on TSVs 180 Bibliography 183 List of figures 193 List of tables 199 Versicherung 201 Theses 203 Curriculum vitae 205 Own publications 207