Title Page
Contents
ABSTRACT 11
Chapter 1. Introduction 12
1.1. Atomic Layer Deposition (ALD) 12
1.1.1. Molecular layer deposition (MLD) 14
1.2. Titanicone growth using Ethylene glycol 15
1.2.1. Known mechanism 15
1.2.2. The parts that are not explained in the mechanism 18
1.3. Stability of Titanicone 22
1.3.1. Motivation 22
Chapter 2. Experimental section 24
2.1. MLD Reactors 24
2.1.1. The MLD reactor for in-situ analysis 24
2.1.2. MLD process on a Si-wafer deposition for post- treatment 25
2.2. In-situ tools 26
2.2.1. Fourier transform Infrared Spectroscopy (FTIR) 26
2.2.2. Quartz Crystal Microbalance (QCM) 28
2.2.3. Quadrupole Mass Spectrometer (QMS) 30
2.3. Ex-situ tools 30
2.3.1. X-Ray Photoelectron Spectroscopy (XPS) 30
2.3.2. Atomic Force Microscopy (AFM) 31
Chapter 3. Results and Discussion 32
3.1. Titanicone growth mechanism 32
3.1.1. FTIR results 32
3.1.2. QCM results 42
3.1.3. QMS results 44
3.2. Stability of titanicone films 49
3.2.1. Thickness reduction 49
Chapter 4. Conclusion 59
References 60
Abstract (in Korean) 65
Table 1. Titanicone MLD reference with various organic precursors. 16
Table 2. The ratio of Cl/Ti of titanicone films from various reference. 21
Table 3. Experimental conditions for FTIR measurements when each precursor was injected. 27
Table 4. Summarized band assignments of the vibrational frequencies (cm⁻¹) for the ethylene moieties formed during ethylene glycol exposure. 34
Table 5. Summarized values of mass gain obtained by a cycle of sequential MLD 43
Table 6. The summarized atomic ratio of titanicone films of the non-etched samples (0 s) from Figure 16. 52
Table 7. RMS Roughness values of the aged titanicone samples obtained at different resolutions depending on each deposition temperature. 55
Figure 1. Schematic figure of an ALD cycle from Ref.[9] 13
Figure 2. Proposed mechanism by Abdulagatov et al. in Ref.[29] 17
Figure 3. Schematic diagram of which all ethylene glycol suffers double reaction on the TiClx surfaces in case of (a) all TiCl₄ species absorb in monodentate form... 20
Figure 4. A schematic diagram for the ALD system with FTIR, QCM, and QMS. 24
Figure 5. FTIR spectrum of a bare silica sample in this work. 28
Figure 6. Saturation curve obtained as increasing exposure time of ethylene glycol. The MLD process consists of TiCl₄ (2 s)-Purge (60 s)-EG (X s)-Purge (60 s). 29
Figure 7. Difference FTIR spectra during the sequential exposures of TiO₂ ALD (01 - 04) and titanicone MLD (06 - 10) using TiCl₄ and either water or EG,... 33
Figure 8. Difference FTIR spectra during the sequential exposures of titanicone MLD (11 - 12) using TiCl₄ and EG, deposited at : (a) 80 ℃; (b) 150 ℃,... 39
Figure 9. Enlarged spectra from Fig. 7 for magnifying the spectra from 01-TiCl₄ to 05-TiCl4 deposited at (a) 80 ℃ and (b) 150 ℃, respectively. 41
Figure 10. In-situ QCM data represented as mass gain per cycle in 5 titanicone MLD using TiCl₄ and EG deposited at: (a) : 80 ℃; (b) 150 ℃, respectively. 42
Figure 11. Survey spectra of QMS obtained during the sequential exposure of each precursor: TiCl₄ (a); and ethylene glycol (b). Process temperature was 80... 45
Figure 12. The mass signal of m/z=28 was tracked during titanicone MLD cycles deposited by either two exposure techniques: single long exposure: (a) at 80 ℃... 46
Figure 13. The mass signal of m/z=36 was tracked during titanicone MLD cycles deposited by either two exposure techniques: single long exposure: (a)... 48
Figure 14. In-situ QCM data of mass gain during the MLD cycle and subsequent water etching step. 49
Figure 15. (a) : Thickness decline of the titanicon films as water etching time increases at each deposition temperatures and (b) : thickness comparison after... 50
Figure 16. XPS depth profiling data of as-deposited samples deposited at 80 ℃ (a) and 110 ℃ (b); water treated samples deposited at 80 ℃ (c) and 110 ℃ (d); respectively. 51
Figure 17. AFM data of titanicone samples aged in the air for 2 weeks depends on different deposition temperatures (a) at 80 ℃ and (b) at 110 ℃; respectively. 54
Figure 18. In-situ QMS signal tracing the fragments of m/z=18, 36, and 44. 56
Figure 19. Difference FTIR spectra during the MLD cycle followed by subsequent water exposure steps (a), and Al₂O₃-coated silica reacts with ethylene oxide... 57
Scheme 1. A plausible example of intramolecular hydrogen bonding of TiCH2CH2OH surface species. 34
Scheme 2. Suggested reaction pathways after ethylene glycol exposure on the TIClx species.[이미지참조] 35
Scheme 3. A plausible mechanism for acid-catalyzed intramolecular cyclization. 36
Scheme 4. A plausible mechanism for the reaction of Equilibrium reaction between surface species formed by the double- and single-reactions. 36
Scheme 5. Suggested reaction pathways after TiCl₄ exposure on the surface III. 38
Scheme 6. A possible acid-catalyzed ethylene glycol production mechanism held on titanicone films during TiO₂ ALD procedures. 41
Scheme 7. Proposed reaction pathway of titanicone films under a water exposure. 53
Scheme 8. Reaction pathway between the Al-OH and ethylene oxide 57