Low – κ dielectric materials play a very important role in the fabrication of integrated circuits (IC). Materials with a very low dielectric constant are necessary for use as inter layer dielectrics (ILDs), because they increase the efficiency of the ICs by reducing the resistance capacitance delays and power consumption of the circuits. This thesis presents the deposition and characterisation of Silsesquioxane (SSQ) materials, particularly Methyl Silsesquioxane (MSQ) and Poly Phenyl Methyl Silsesquioxane (PMSQ) thin films by spin coating and subsequent annealing. The changes to the film post plasma exposure were studied using a wide range of characterisation techniques such as spectroscopic ellipsometry, stylus profilometry, FTIR, TGA, water contact angle measurement, XPS, AFM, SEM, EDX, AFM, dielectric constant measurement of the thin films, etc. The study on MSQ films were carried out to have a better understanding of film deposition, processing, and characterisation techniques as these studies are widely reported in literature because of its use as an ILD material. The deposited MSQ thin films had a κ - value of ~ 2.6 ± 0.1. Significant increase in the κ - value was observed upon exposure of these films to SF6 and O2 plasmas due to the deteriorating effect of the plasma on the films. Deposited PMSQ thin films had a κ - value of ~ 2.7 ± 0.1 and they did not show any considerable variation in their κ - value upon exposure to SF6 and O2 plasmas, even though significant erosion of the PMSQ film was observed during the exposure of the film to SF6 plasma. Modern day electronics require materials with very low dielectric constants for optimal performance. Several approaches are used commercially to further reduce the κ – value of dielectric materials used for ILD applications. Porosity was introduced into the vi PMSQ thin films by sacrificial porogen technique to further reduce the dielectric constant of the thin films using Heptakis (2,3,6-tri-O-methyl)-β-cyclodextrin (tCD) as the porogen material. Changes in the PMSQ films due to the introduction of porosity were studied which showed a reduction in the density and the κ – value of the film. A reduction of ~ 25% in density was observed in the XRR measurements of the porous films and the κ – value of the films were reduced by ~ 20% from κ = 2.7 ±0.1 to κ = 2.2 ±0.1 by the introduction of porosity. The effect of plasma exposure on the porous PMSQ films resulted in an increase in the dielectric constant of the porous material. The thesis also analyses the expected variations in the film density and κ-value and compares it with the observed density and κ-value. It also calculates a rough estimate of the change in the surface area of the film as a result of porosity integration. Experimental demonstrations of a novel method to pattern the dielectric film surface namely Nano sphere Lithography is presented in the final section of this thesis.