The broad theme of the present research investigation is Ion Assisted Deposition of thin films and its effect on the properties of thin films. Though this activity has been of interest to researchers for more than a decade, the development of different types of ion sources with control over the ion flux and energy, makes it a current topic of interest. Ion assisted deposition was successful in depositing thin films of many material with desired qualities, however, there are certain class of materials whose deposition has been rather difficult. This has mainly been attributed to higher energies and low ion flux of conventional ion sources. The advent of ECR ion sources for thin film deposition has given impetus to the deposition of such materials. This is due to the low energy high-density plasma generated in this type of sources. Hitherto, these sources were widely used in PECVD techniques and only recently the importance of ECR sources in PVD techniques has been realized. This thesis is on the development of ECR plasma source for ion assisted deposition of thin films using PVD techniques. This thesis is organized into six chapters. The first chapter gives an introduction on the ion assisted growth of thin films and the importance of ECR plasma. A detailed discussion on various aspects of ECR sources has been included. The design details on the development of ECR source have been discussed in the second chapter. The performance of ECR source as analyzed by the Langmuir probe are also discussed. Variation of plasma parameters like ion density, electron temperature, plasma potential and floating potential as a function of pressure and microwave power have been studied using Langmuir probe analysis. An ion density of the order of 1011/cm3 was measured at a distance of 8 cm from the plasma source with a microwave power of 400 watts. This was comparable to the ion density reported in downstream plasma of ECR sources. The behavior of plasma parameters with variation in microwave power and pressure was explained on the basis of microwave transmission above critical ion density and the microwave power absorption. The uniformity of the plasma parameters at the substrate position (29 cm from the ECR source) was found to be ± 2% over a diameter of 12 cm, which makes the ion source suitable for ion assisted deposition. The third chapter deals with the simulation and experimental study of the ECR sputtering process. ECR sputter type sources are equipped with cylindrical targets. The sputtered flux distribution on the substrate depends on target geometry, sputtering pressure and target-substrate distance. The effect of cylindrical geometry on the distribution of sputtered flux has been simulated by Monte Carlo methods. It is found that the sputtered flux distribution at different pressures and target-substrate distances in ECR sputter type source differs from the conventional glow discharge sputtering system equipped with planar targets. The simulated results are compared with the experimental results. The simulated data agree very well with the experimental data. The deposition and characterization of the TiN thin films for diffusion barrier applications in copper metallization have been discussed in the fourth chapter. Titanium nitride films are prepared by ECR sputtering. The effect of high density ion bombardment on the morphology, orientation and resistivity of the films was studied. It was observed that films with atomic smoothness could be prepared by ECR sputtering. Also the high density ion bombardment has been found to be effective for the film growth in (100) orientation. The behavior of TiN films deposited by this method as a diffusion barrier in copper metallization has been investigated. The resistivity measurements and RBS depth profile studies showed that up to 700°C there is no diffusion of copper into silicon. This shows that ECR sputtered TiN can be used as an effective diffusion barrier in copper metallization. The fifth chapter contains investigations on the ECR assisted growth of silicon nitride films. The films are characterized for composition, morphology and chemical bonding using AES, RBS, AFM, XPS and FTIR. AFM studies revealed that ion bombardment results in the reduction of surface roughness, which indicates dense film growth. The effect of ion assistance on the optical and electrical properties is studied in detail. Films prepared with microwave power ranging from 100 to 200 watts are having bandgap and refractive index of 4.9 eV and 1.92 respectively. Interface state density of silicon nitride films prepared in the above mentioned range was found to be 5x10 10 eVcm2. These films exhibited a resistivity of 10 13 Ω, cm and critical field of 4 MV/cm. The electrical conductivity in these films has been explained on the basis of Poole and Frenkel conduction. The low value of interface state density, higher resistivity, and critical field show that good quality SiN4 films can be deposited with low energy high density ECR plasma. A detailed summary of this research investigation has been discussed in the last chapter. The thesis is concluded with a discussion on the need of focused ECR source to establish ECR assisted deposition as a versatile technique for the growth of thin films.

Two technologies, namely Laser Technology and Surface Modification Technology, have made rapid strides in the last few decades. The lasers have evolved from a simple laboratory curiosity to a matured industrial tool and its applications are limited only by imagination. Intense, coherent and monochromatic laser sources with power outputs ranging over several orders of magnitude have found innumerable applications in the realm of materials engineering. Reactive Pulsed Laser Deposition (PLD) is a powerful technique that utilises the power of a nanosecond pulsed laser for materials synthesis. Unlike conventional PLD, which require high density targets that are difficult to synthesize at a reasonable cost, the RPLD circumvents the need for one such ceramic target. This thesis presents a detailed and judicious use of this technique for synthesis of hard ceramic multilayer coatings using elemental metal targets. Transition metal nitrides having rock salt structure are known to exhibit superior properties such as hardness and wear resistance and hence formed the basis for the development of first generation coatings. Further improvements through alloying of these binary compounds with metal or metalloid components lead to the development of second generation coatings. As the demand for functional materials increased, surface modification technology alias surface engineering, grew in leaps and bounds. As the large number of coating requirements for optimal performance could not be fulfilled by a single homogeneous material, third generation coatings, comprising multilayer coatings, were developed. It is this aspect of combining the advantages of RPLD process to synthesize ceramic multilayer coatings, provides the main motivation for the present research work. In this thesis, a systematic study presented for synthesis of nanocrystalline and stoichiometric TiN and NbN thin films using RPLD through ablation of high purity titanium and niobium targets, in the presence of low pressure nitrogen gas. A novel Secondary Ion Mass Spectrometry (SIMS) based analysis was developed to effectively deduce the important process parameters in minimum trials to arrive at desired composition. The validity of this SIMS based method, for optimization of process parameters to get stoichiometric nitride films, was proved beyond any speculation by corroborative Proton Elastic Backscattering Spectrometric (PEBS) analysis. SIMS was also used to characterize the [NbN/TiN] multilayers. The feasibility of growing nanocrystalline multilayers with varying thicknesses has been demonstrated. Nanomechanical properties including hardness and adhesion strength of monolithic TiN and NbN films and multilayers were evaluated. The thesis is organised into six chapters. The first chapter gives a brief account on the history and development of ‘surface engineering’. The second chapter provides a comprehensive description of the experimental facility developed in-house to pursue research on PLD grown ceramic thin films and multilayers. Thin film synthesis procedure for ex-situ SIMS and TEM analyses is described. Brief introduction is also presented on the characterization techniques used in this study to investigate the surface, interface and microstructural aspects of PLD grown films with underlying basic principles. The third and fourth chapter describes the synthesis and characterization of titanium nitride and niobium nitride thin films using RPLD technique, respectively. SIMS was used in depth profiling mode, for optimization of three important process parameters, viz., nitrogen gas pressure, substrate temperature and laser pulse energy, to get stoichiometric nitride films. Further, films were characterized using GIXRD, TEM, XPS and PEBS for their structure and composition. AFM measurements were made to elucidate the surface morphological features. PEBS was effectively used to estimate the nitrogen concentration in a quantitative manner and the results corroborate well with the SIMS measurements. Having succeeded in synthesizing stoichiometric TiN and NbN films, further studies on the nanomechanical properties of monolithic TiN and NbN films and their multilayers were carried out and these results form the contents of the fifth chapter. The findings of the work reported in this thesis are concluded in Chapter 6 and few possible suggestions were presented as future directions. Both the monolithic TiN and NbN coatings showed a deposition pressure dependent hardness variation. The hardness of these monolithic films was found to be around 30 GPa, higher than the hardness values obtained by other conventional techniques. Keeping total thickness of the multilayers constant at 1 μm, [NbN/TiN] multilayers having bilayer periods ranging from 50 nm to 1000 nm, were synthesized. A systematic enhancement in hardness upto ~ 40 GPa was observed for [NbN/TiN]10 with the modulus of the multilayer remaining almost constant. The pileup observed around the indentation edge is indicative of toughening in multilayers. The tribological properties of multilayer films showed a better performance in terms of low coefficient of friction and regeneration of coating surfaces as revealed from the nanotribological studies. Overall, the multilayer coatings exhibited better performance in terms of hardness, toughness and adhesion with the substrate material.