Electronic properties of interfaces produced by silicon wafer hydrophilic bonding [Elektronische Ressource] / Maxim Trushin. Betreuer: Jürgen Reif

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• Publié par: brandenburgische_technische_universitat_cottbus
• Publié le: 01 janvier 2011
• Nombre de lectures: 54
• Langue: English
• Poids de l'ouvrage: 17 Mo

Extrait

Electronic properties of interfaces produced by
silicon wafer hydrophilic bonding



Von der Fakultät für Mathematik, Naturwissenschaften und Informatik
der Brandenburgischen Technischen Universität Cottbus



zur Erlangung des akademischen Grades

Doktor der Naturwissenschaften
(Dr. rer. nat.)


genehmigte Dissertation




vorgelegt von


Magister in Physik
Maxim Trushin
geboren am 18. März 1981 in Samarkand, Uzbekistan




Gutachter: Prof. Dr. rer. nat. habil. Jürgen Reif
Gutachter: Prof. Dr. sc. nat. Martin Kittler
Gutachter: Prof. Dr. Oleg Vyvenko


Tag der mündlichen Prüfung: 15 Juli 2011



2
Contents

Introduction ____________________________________________________________6
Aim of the work_________________________________________________7
Outline of the thesis______________________________________________8
Chapter 1. Fundamentals of the experimental methods used ____________________9
1.1 Metal-semiconductor contact and Schottky diode ______________________10
1.2 Details and principles of DLTS method ______________________________13
1.3 Isothermal spectroscopy (ITS) method ______________________________18
1.4 Summary for Chapter 1 __________________________________________19
Chapter 2. Electronic properties of dislocations in silicon ______________________21
2.1 Structure of Dislocations in Si _____________________________________22
2.2 Dislocation-related shallow 1D-bands _______________________________24
2.3 Electrical charge associated with dislocations _________________________26
2.4 Experimental observation of dislocation-related localized states___________28
2.5 Experimental observations of the shallow 1D bands ____________________35
2.6 Optical properties of dislocations in Si_______________________________37
2.7 Summary for Chapter 2___________________________________________41
Chapter 3. Dislocation networks produced by silicon wafer direct bonding _______42
3.1 Details of semiconductor wafer direct bonding technique ________________43
3.2 Hydrophobic wafer bonding _______________________________________44
3.3 Hydrophilic wafer bonding________________________________________48
3.4 Difference between large-angle (LA) and small-angle (SA) grain
boundaries ____________________________________________________50
3.5 Interactions of dislocations composing the DN ________________________52
3.6 Summary for Chapter 3___________________53
Chapter 4. Samples description and experimental details ______________________54
4.1 Investigated samples_____________________________________________55
4.2 Contacts preparation_____________________________________________56
4.3 DLTS spectrometer used in the present work________57
4.4 Summary for Chapter 4___________________________________________58
Chapter 5. Local electronic states of interfaces between hydrophilically bonded
wafers with different misorientation angles __________________________________59
5.1 Calculations of the interface trap density from DLTS peaks amplitude in the
case of narrow 2D trap distribution _________________________________60
5.2 DLTS spectra of four bonded samples_______________________________62
5.3 Traps profiling _________________________________________________64
3
5.4 Energetic levels and capture cross sections of DN-related hole
traps_________________________________________________________68
5.5 DLTS peak shape analysis _______________________________________74
5.6 PL spectra of investigated samples _________76
5.7 Results of TEM investigations_____________________________________78
5.8 DLTS – PL correlation. Levels participating in D1 transition_____________82
5.9 Possible origins of deep traps in SA-samples__________________________85
5.10 Correlations of the shallow ST1/ST3 and SD traps concentrations with the
total length of 60° dislocations D and triple knots density N __________87 60 3x
5.11 Traps origin in LA-samples ______________________________________89
5.12 Summary for Chapter 5 _________________________________________92
Chapter 6. Capacitance-voltage and current-voltage characteristics
of Gr-1 and Gr-3 samples ______________________________________________94
6.1 Interface charge definition from CV measurements____________________95
6.2 Peculiarities of Gr-1 & Gr-3 sample IV characteristics and their
correlations with the CV curves___________________________________102
6.3 Energy-band diagram for Gr-1 and Gr-3 samples_____________________105
6.4 Calculations of the electric current ________________________________107
6.5 Estimations of the trap concentrations from the IV characteristics________109
6.6 Acceptor profiles in the near surface region _________________________113
6.7 Built-in voltages and DN charges in Gr-1 and Gr-3 samples
at T =300K_________________________17 MEAS
6.8 Discussion on the charge state of the detected traps ___________________119
6.9 Summary for Chapter 6 __________________21
Chapter 7. Field-enhanced emission from the shallow dislocation-related states __123
7.1 DLTS spectra measured with different reverse biases __________________124
7.2 Voltage dependence of the activation enthalpies of ST1/ST3 traps.
Simulation of ST1 and ST3 peaks shape_____________________________127
7.3 Possible mechanisms for the field enhanced emission 30
7.4 Calculation of the electric field at the position of DN __________________134
7.5 Electric field dependence of E energies derived from DLTS ____________136 a
7.6 Poole-Frenkel coefficient as obtained from the ITS measurements________139
7.7 Comparison of Poole-Frenkel coefficients derived from ITS and DLTS
measurements _________________________________________________144
7.8 Previously observed events of field-enhanced emission_________________147
7.9 Possible reasons for ST1/ST3 DLTS and ITS peaks broadening __________147
7.10 Electric field influence on the emission from the shallowest
SN1/SN3 traps ________________________149
4
7.11 Summary of the Chapter 7_______________________________________150
Chapter 8. Theory of Poole-Frenkel effect due to elastic strain field of dislocation _151
8.1. Theory of Poole-Frenkel effect due to elastic strain fields of isolated
screw and 60° dislocations_______________________________________152
8.2. Stress fields close to the dislocation network_________________________159
8.3. Comparisons with the experimental results __________________________163
8.4. Possible origins of t h e shallow traps_______________________________165
8.5. Comparison with other estimations of dislocation-related 1D bands
energy position ________________________67
8.6. Summary for the Chapter 8 ______________________________________169
Chapter 9. Summary____________________________________________________171
References ____________________________________________________________173
Acknowledgments ______________________________________________________180


5
Introduction.
Like human defects, those of crystals come in
a seemingly endless variety, many dreary and
depressing, and a few fascinating.
N. Ashcroft & N. Mermin.

Silicon now is the leading material in the areas of microelectronic and photovoltaic
applications. The electronic chip industry of the present days produces complex circuitry,
boasting over one billion components in a single processor with the size of an individual
transistor (gate length) going down to 20 nm [Intel roadmap 2009]. However, in recent
years some concerns about the evolution of this industry have been raised which are related
with the fundamental materials and processing aspects [Pavesi 2003]. Currently used
interconnects based on Cu wiring will cause serious problems in future such as complexity
of their architecture (more than 10 layers of metal levels), non-acceptable delay in signal
propagation, heat penalty, signal latency and crosstalk etc., in case of further reduction in
dimensions and increasing in the density of metal lines.
A possible solution to these problems is looked for in optics: on-chip optical
interconnects are able to overcome these problems and will be essential for future
integrated circuits [Pavesi 2003] [Jalali 2008]. Many key photonic components compatible
with CMOS-technology have been already demonstrated, as for example optical
waveguides [Pavesi 2003], electro-optical modulator [Oehme 2006], fast and sensitive Ge
detector [Liu 2004]. However, an appropriate light emitter, also compatible with CMOS-
technology, is still lacking. Different approaches for such light emitters have been
suggested, among them intra-atomic optical transitions in Er atoms in Er-doped Si [Zheng
1994], luminescence of -FeSi2 precipitates in Si [Lourenco 2003] and optical transitions
in SiGe quantum cascade structures [Zakharov 2003].
Another promising conception of silicon-based light emitting diode (LED) was
proposed exploiting the dislocation-related luminescence