Growth and Characterization of Ti-Si-N Thin Films

Ti-Si-N and Ti-Al-Si-N thin solid films have been studied by analytical electron microscopy, X-ray diffraction, scanning tunneling microscopy, X-ray photoelectron spectroscopy, elastic recoil detection analysis, nanoindentation, and ab initio calculations. I find that arc evaporated (Ti1-xSix)Ny films can be grown as cubic solid solutions up to x = 0.09 with a dense columnar microstructure. Films with higher Si content up to x = 0.20 assumes an extremely defect-rich, feather-like structure consisting of cubic TiN:Si nanocrystallite bundles with low-angle grain boundaries caused by thermodynamically driven Si segregation. Correspondingly, the N content in the films increases close to linear with the Si content from y = 1.00 (x = 0) to y = 1.13 (x = 0.20). Annealing of the films at 1000 °C yields a metastable crystalline SiNz (1.0 ≤ z ≤ 1.33) tissue phase in 0.04 ≤ x ≤ 0.20 films which is (semi)-coherent to TiN. These films are compositionally stable and exhibit retained hardness between 31-42 GPa up to 1000 °C. At 1100-1200 °C, the tissue phase amorphizes and all SiNz diffuse out of the films, followed by recrystallization of the cubic phase. Hard turning testing was performed on (Ti0.83Si0.17)N1.09. Analysis of the tool-chip interface prepared by focused ion beam revealed shear deformation in the film and an adhering layer consisting of the work-piece material and Si and N from the film. For (Ti0.33Al0.67)1-xSix)N (0 ≤ x ≤ 0.29) films the NaCl structure cubic (Ti,Al)N solid solution phase is predominant at low Si contents, which gradually changes to a dominating hexagonal wurtzite (Al,Ti,Si)N solid solution for 0.04 ≤ x ≤ 0.17. Additional Si results in amorphization. Annealing experiments at 600-1000 °C yields spinodal decomposition of c-(Al,Ti)N into c-AlN and c-TiN, with corresponding age hardening. The h-(Al,Ti,Si)N films exhibit precipitation of c- TiN with smaller volume than the host lattice, which results in tensile cracks formations and age hardening. Films with c-(Ti,Al)N perform best in turning applications, while films with h- (Al,Ti,Si)N form cracks and fail. Finally, I have characterized the nature of metastable crystalline SiNz phases and the interface between TiN(001) and SiNz. Magnetron sputtering was used to deposit TiN/SiNz(001) nanolaminate films with varying SiNz and TiN layer thicknesses. Maximum hardness is obtained when SiNz forms coherent interfaces with TiN…


1 Introduction
1.1 Research Goals
2 Thin Film Processing
2.1 Plasma Basics
2.2 DC Magnetron Sputtering
2.3 Arc Evaporation
2.4 Thin Film Growth
2.4.1 Epitaxial Films
2.4.2 Polycrystalline Films
2.5 Metastable Phases
2.5.1 Low-Temperature Synthesis
2.5.2 Ion-Bombardment Induced Effects
2.6 Residual Stress
3 Thin Film Characterization
3.1 X-ray Diffraction
3.1.1 Sin2-method
3.2 Electron Microscopy
3.2.1 Scanning Electron Microscopy
3.2.2 Transmission Electron Microscopy
3.2.3 Scanning Transmission Electron Microscopy
3.2.4 Sample Preparation
3.3 Scanning Tunneling Microscopy
3.4 Chemical Analysis
3.4.1 Energy Dispersive X-ray Spectroscopy
3.4.2 Electron Energy-Loss Spectroscopy
3.4.3 Elastic Recoil Detection Analysis
3.4.4 X-ray Photoelectron Spectroscopy
3.5 Nanoindentation
4 Theoretical Modeling
4.1 Background
4.2 Density Functional Theory
4.2.1 Approximations for Many-Body Interactions
4.2.2 Plane Waves and Pseudopotentials
4.3 Surface Calculations and Ionic Relaxation
5 The Ti-Si-N System
5.1 Titanium Nitride
5.2 Silicon Nitride
5.3 Ti-Si-N Thin Films
5.3.1 TiN-SiNx Nanocomposites
5.3.2 TiN/SiNx Multilayers and Superlattices
5.3.3 Hardening in nanocrystalline materials
5.3.4 Metastable Ti-Si-N and Ti-Al-N
5.3.5 Age Hardening
5.4 Phase Identification for Ti-Si-N Thin Films
6 Summary of the Papers and Contribution to the Field
6.1 Nature of (Ti1-xSix)Ny Alloy Films
6.1.1 (Ti0.33Al0.67)1-xSixN Alloy Films
6.2 TiN/SiNx Nanolaminate Films
6.3 SiNx/TiN Surface Reconstructions
7 Future Outlook

Author: Flink, Axel

Source: Linkoping University

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